Advanced wireless settings

From DD-WRT Wiki

(Difference between revisions)
Jump to: navigation, search
Revision as of 21:16, 19 June 2010 (edit)
Phuzi0n (Talk | contribs)
(Import http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51039)
← Previous diff		 Current revision (02:52, 25 November 2020) (edit) (undo)
Qayshp (Talk | contribs)
m (→Authentication Type - formatting: missing line break)
 
(30 intermediate revisions not shown.)
Line 1: Line 1:
 +{{languages|Advanced_wireless_settings}}
==Introduction== ==Introduction==
-This page contains more robust explanations of Advanced Wireless Settings than the built in help provides.+Before reading this page please be familiar with [[Basic_Wireless_Settings|Basic Wireless Settings]].
-==Advanced Wireless Settings==+This page contains more robust explanations of Advanced Wireless Settings than the built in help provides. It was originally authored by Stephen Suley in [http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51039 this thread]. Note, this is mainly for '''Broadcom''' Routers.
-Authentication Type+
-The default is set to Auto.+
-Currently using "Shared key" seems to cause problems. This should be left to auto with current builds.+
 +See [[Atheros/ath_wireless_settings|QCA wireless settings]] page for specific info for '''Qualcomm Atheros''' advanced settings.
-The help file says...+== Advanced Wireless Settings ==
-Allows either Open System or Shared Key authentication to be used. For Open System authentication, the sender and the recipient do NOT use a WEP key for authentication. For Shared Key authentication, the sender and recipient use a WEP key for authentication. If you want to use only Shared Key authentication, then select Shared Key.+
 +=== Authentication Type ===
-How it works:+'''Available Settings:''' Auto, Shared Key
-The following steps occur when two devices use Shared Key Authentication:+
-1. The client adapter sends an authentication request to the access point.+'''Default Setting:''' Auto
-2. The access point sends back a challenge text to the client adapter.+
-3. The client uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and it sends the encrypted text to the access point.+
-4. The access point decrypts the encrypted text using its configured WEP key that corresponds to the client's default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the client share the same WEP key, and the access point authenticates the client.+
-5. The client will now connect to the network.+
-If the decrypted text does not match the original challenge text (that is, the access point and station do not share the same WEP key), then the access point will refuse to authenticate the station, and the station will be unable to communicate with either the 802.11 network or Ethernet network.+'''Recommended Setting:''' Auto
--------------------------------------------------------+'''The help file says...''' * Allows either Open System or Shared Key authentication to be used. For Open System authentication, the sender and the recipient do NOT use a WEP key for authentication. For Shared Key authentication, the sender and recipient use a WEP key for authentication. If you want to use only Shared Key authentication, then select Shared Key.
--This would add an additional layer of connection authentication for wireless clients. Using this feature means you must modify the wifi adapter settings on a client before it can connect to this device. 
 +'''How it works:'''
--Client wifi adapters must support "Shared Key" authentication to use this setting.+The following steps occur when two devices use Shared Key Authentication:
 +# The client adapter sends an authentication request to the access point.
 +# The access point sends back a challenge text to the client adapter.
 +# The client uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and it sends the encrypted text to the access point.
 +# The access point decrypts the encrypted text using its configured WEP key that corresponds to the client's default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the client share the same WEP key, and the access point authenticates the client.
 +# The client will now connect to the network.
--If using a client connected to the router over wireless and you set authentication key to shared, from auto, and your computer doesn't support shared, you will lose all Internet access and access to the webgui and you will have to connect with a wire to the router to change the setting back to auto. You can also do a hard reset to get it back to defaults to fix this. 
--I equate using "Shared key" to adding authentication security to the "Phase 1" of the wifi connection process 
 +If the decrypted text does not match the original challenge text (that is, the access point and station do not share the same WEP key), then the access point will refuse to authenticate the station, and the station will be unable to communicate with either the 802.11 network or Ethernet network.
--Changing this from the default value would be for security reasons.+-This would add an additional layer of connection authentication for wireless clients. Using this feature means you must modify the wifi adapter settings on a client before it can connect to this device.
 +-Client wifi adapters must support "Shared Key" authentication to use this setting.
-Basic Rate+-If using a client connected to the router over wireless and you set authentication key to shared, from auto, and your computer doesn't support shared, you will lose all Internet access and access to the webgui and you will have to connect with a wire to the router to change the setting back to auto. You can also do a hard reset to get it back to defaults to fix this.
-The default value is set to Default.+
 +-I equate using "Shared key" to adding authentication security to the "Phase 1" of the wifi connection process
-Help file says...+-Changing this from the default value would be for security reasons.
-Depending on the wireless mode you have selected, a default set of supported data rates will be selected. The default setting will ensure maximum compatibility with all devices. You may also choose to enable all data rates by selecting ALL. For compatibility with older Wireless-B devices, select 1-2Mbps.+
 +=== Basic Rate ===
-MIMO - Transmission Fixed Rate+'''Available Settings:''' Default, 1-2Mbps, all
-The default setting is Auto. The range is from 6.5 to 130Mbps.+
 +'''Default Setting:''' Default
 +'''Recommended Setting:''' Default
-Help file says...+'''The help file says...''' * Depending on the wireless mode you have selected, a default set of supported data rates will be selected. The default setting will ensure maximum compatibility with all devices. You may also choose to enable all data rates by selecting ALL. For compatibility with older Wireless-B devices, select 1-2Mbps.
-The idea is the same as "Transmission Fixed Rate" You can select from a range of MIMO transmission speeds, or keep the default setting, Auto, to have the router automatically use the fastest possible data rate and enable the Auto-Fallback feature. Auto-Fallback will negotiate the best possible connection speed between the router and a wireless client.+
-How it works: 
-This parameter is uesd for 802.11n transmissions only. 802.11g ,b and a tramissions from the router use the "Transmission Fixed Rate" parameter. 
-IEEE 802.11n builds on previous 802.11 standards by adding multiple-input multiple-output (MIMO).MIMO uses multiple transmitter and receiver antennas to improve the system performance. MIMO is a technology which uses multiple antennas to coherently resolve more information than possible using a single antenna. Two important benefits it provides to 802.11n are antenna diversity and spatial multiplexing.MIMO technology relies on multipath signals. Multipath signals are the reflected signals arriving at the receiver some time after the line of sight (LOS) signal transmission has been received.MIMO uses the multipath signal's diversity to increase a receiver's ability to recover the message information from the signal.+'''How it works:'''
-Another ability MIMO technology provides is Spatial Division Multiplexing (SDM). SDM spatially multiplexes multiple independent data streams, transferred simultaneously within one spectral channel of bandwidth. MIMO SDM can significantly increase data throughput as the number of resolved spatial data streams is increased. Each spatial stream requires a discrete antenna at both the transmitter and the receiver. In addition, MIMO technology requires a separate radio frequency chain and analog-to-digital converter for each MIMO antenna which translates to higher implementation costs compared to non-MIMO systems.+?
 +=== MIMO - Transmission Fixed Rate ===
-Transmission Fixed Rate+'''Available Settings:''' Auto, a range of values from 6.5Mbps upwards
-The default setting is Auto. The range is from 1 to 54Mbps.+
 +'''Default Setting:''' Auto
-Help file says...+'''Recommended Setting:''' Auto
-The rate of data transmission should be set depending on the speed of your wireless network. You can select from a range of transmission speeds, or keep the default setting, Auto, to have the router automatically use the fastest possible data rate and enable the Auto-Fallback feature. Auto-Fallback will negotiate the best possible connection speed between the router and a wireless client.+
 +'''The help file says...'''
 +* The idea is the same as "Transmission Fixed Rate" You can select from a range of MIMO transmission speeds, or keep the default setting, Auto, to have the router automatically use the fastest possible data rate and enable the Auto-Fallback feature. Auto-Fallback will negotiate the best possible connection speed between the router and a wireless client.
-How it works: 
-CTS Protection mode+'''How it works:'''
-The default mode value is set to Auto.+
 +This parameter is used for 802.11n transmissions only. 802.11a/b/g transmissions from the router use the "Transmission Fixed Rate" parameter.
-The help file says...+IEEE 802.11n builds on previous 802.11 standards by adding multiple-input multiple-output (MIMO). MIMO uses multiple transmitter and receiver antennas to improve the system performance. MIMO is a technology which uses multiple antennas to coherently resolve more information than possible using a single antenna. Two important benefits it provides to 802.11n are antenna diversity and spatial multiplexing. MIMO technology relies on multipath signals. Multipath signals are the reflected signals arriving at the receiver some time after the line of sight (LOS) signal transmission has been received. MIMO uses the multipath signal's diversity to increase a receiver's ability to recover the message information from the signal.
-When set to Auto, a protection mechanism will ensure that your Wireless-B devices will connect to the Wireless-G router when many Wireless-G devices are present. However, performance of your Wireless-G devices may be decreased.+
 +Another ability MIMO technology provides is Spatial Division Multiplexing (SDM). SDM spatially multiplexes multiple independent data streams, transferred simultaneously within one spectral channel of bandwidth. MIMO SDM can significantly increase data throughput as the number of resolved spatial data streams is increased. Each spatial stream requires a discrete antenna at both the transmitter and the receiver. In addition, MIMO technology requires a separate radio frequency chain and analog-to-digital converter for each MIMO antenna which translates to higher implementation costs compared to non-MIMO systems.
-How it works: 
-CTS Protection mode is a is a protection mechanism that operates on the physical (PHY) level frame. At a very high level summary of the process when multiple devices are connected to an access point, they can occasionally be transmitting data to the access point at the same time because neither one can see the other client well enough to determine if it is transmitting on the channel or not. When this happens, the AP will discard both pieces of colliding data, thus contributing to error rates. CTS (clear to send) protection skirts this issue by delegating which device gets to transmit at a given time. 
 +=== Transmission Fixed Rate ===
-CTS Protection mode and DD-wrt:+'''Available Settings:''' Auto, range from 1 to 54 Mbps
-In its default configuration dd-wrt uses it as a to provide a way of ensuring coexistence between the legacy and the new wifi devices. Adding to that by using CTS protection mode and modifying RTS threshold value you can tweak the operation of the CTS protection mechanism this can then be combined with the Fragmentation Threshold tweak to help troubleshoot\fix connectivity and\or performance issues etc. Remember tweaking the CTS protection process by manipulating the RTS and the Fragmentation Threshold value often comes at a price usually by decreasing the overall throughput to the WLAN.+
 +'''Default Setting:''' Auto
 +'''Recommended Setting:''' Auto
-Once CTS Protection mode is configured correctly within your WLAN environment there are specific scenarios that occur and the software will activate the CTS protection mechanisms;+'''The help file says...''' * The rate of data transmission should be set depending on the speed of your wireless network. You can select from a range of transmission speeds, or keep the default setting, Auto, to have the router automatically use the fastest possible data rate and enable the Auto-Fallback feature. Auto-Fallback will negotiate the best possible connection speed between the router and a wireless client.
-Here are a few examples of what triggers CTS to be employed by the dd-wrt router software. 
-CTS Protection trigger 1; - NON-default dd-wrt behavior+'''How it works:'''
-A client that wants to use the radio channel to send data packet(s) of a size that is equal or above the defined RTS threshold value.+
-CTS Protection trigger 2; -default dd-wrt behavior+?
-A 802.11g client attempts to connect to a SSID that is using channel bonding. Transmissions using a 40 MHz channel in the presence of 802.11a or 802.11g clients require using CTS protection mode. This will apply the CTS protection mechanism on both 20 MHz halves of the 40 MHz channel, to prevent interference with legacy devices and allow proper operation of the 802.11a and 802.11g clients.+
-CTS Protection trigger 3; -default dd-wrt behavior 
-If you are running in mixed wireless mode on a 802.11n router and you have 802.11b clients in your environment. CTS Protection is used to allow the 802.11b client to operate correctly and also not to interfere with the operation of the 802.11a,g, and N client transmissions. 
-Also;+=== CTS Protection mode ===
-- An 11b device associates to the AP. - same as trigger 3+
-- An 11b AP on the same channel can be heard by the AP - variant on trigger 3+
-- The AP hears an 11g AP that is in protection because of an 11b device associated. -another variation of the trigger 3 event.+
 +'''Available Settings:''' Auto, Disabled
 +'''Default Setting:''' Auto
 +'''Recommended Setting:''' Auto
-**NOTE: Trigger 1 will never happen on the dd-wrt default configuration due to the the default values of the RTS Threshold being 2347 and the the Fragmentation Threshold value being 2346. Based on the data packet fragmentation threshold default value at 2346 in size dd-wrt will apply fragmentation to all packets meeting this criteria. Because of this fragmentation process the 2347 packet size needed to trigger the RTS threshold is never reached.+'''The help file says...''' * When set to Auto, a protection mechanism will ensure that your Wireless-B devices will connect to the Wireless-G router when many Wireless-G devices are present. However, performance of your Wireless-G devices may be decreased.
-For a closer look at what happens in one of these cases lets look at a case like trigger number 1 list above and the steps in the CTS protection process. 
 +'''How it works:'''
-Example. A client that wants to use the radio channel to send data packet(s) of a size that is equal or above the defined RTS threshold value.+CTS Protection mode is a protection mechanism that operates on the physical (PHY) level frame. At a very high level summary of the process when multiple devices are connected to an access point, they can occasionally be transmitting data to the access point at the same time because neither one can see the other client well enough to determine if it is transmitting on the channel or not. When this happens, the AP will discard both pieces of colliding data, thus contributing to error rates. CTS (clear to send) protection skirts this issue by delegating which device gets to transmit at a given time.
 +CTS Protection mode and DD-wrt:
-Steps in the CTS Protection mode process for the above example.+In its default configuration dd-wrt uses it as a to provide a way of ensuring coexistence between the legacy and the new wifi devices. Adding to that by using CTS protection mode and modifying RTS threshold value you can tweak the operation of the CTS protection mechanism this can then be combined with the Fragmentation Threshold tweak to help troubleshoot\fix connectivity and\or performance issues etc. Remember tweaking the CTS protection process by manipulating the RTS and the Fragmentation Threshold value often comes at a price usually by decreasing the overall throughput to the WLAN.
-1.) The client wishing to send date over the channel first sends an RTS (request to send) packet to the AP.+Once CTS Protection mode is configured correctly within your WLAN environment there are specific scenarios that occur and the software will activate the CTS protection mechanisms;
-2.) As the AP broadcast it beacons packet over the WLAN as part of its normal operation, The beacon packet has information within it that declares to all the clients on the entire WLAN not to try and send any information for a specified period of time. The AP then sends a CTS packet to the client that requested the CTS in the first place. The AP has made a single client the "owner" of the wifi channel and then the AP listens only to that client until it is done transmitting; its in protection mode.+Here are a few examples of what triggers CTS to be employed by the dd-wrt router software.
-3.)The process is repeated for all request to transfer data,which for whatever reason triggers the CTS protection mechanisms, on a first come first serve basis.+CTS Protection trigger 1; - NON-default dd-wrt behavior A client that wants to use the radio channel to send data packet(s) of a size that is equal or above the defined RTS threshold value.
 +CTS Protection trigger 2; -default dd-wrt behavior A 802.11g client attempts to connect to a SSID that is using channel bonding. Transmissions using a 40 MHz channel in the presence of 802.11a or 802.11g clients require using CTS protection mode. This will apply the CTS protection mechanism on both 20 MHz halves of the 40 MHz channel, to prevent interference with legacy devices and allow proper operation of the 802.11a and 802.11g clients.
 +CTS Protection trigger 3; -default dd-wrt behavior If you are running in mixed wireless mode on a 802.11n router and you have 802.11b clients in your environment. CTS Protection is used to allow the 802.11b client to operate correctly and also not to interfere with the operation of the 802.11a,g, and N client transmissions.
-TWEAK:+Also; - An 11b device associates to the AP. - same as trigger 3 - An 11b AP on the same channel can be heard by the AP - variant on trigger 3 - The AP hears an 11g AP that is in protection because of an 11b device associated. -another variation of the trigger 3 event.
-Implementing additional CTS Protection mode triggers and there frequency of operation on top of the default dd-wrt CTS protection mode configuration;+
-1.) The AP running dd-wrt has the CTS Protection mode is set to Auto by default and then you could adjust the RTS threshold value to something lower then 2346 (Which is the default fragmentation threshold value on dd-wrt) on the AP.+NOTE: Trigger 1 will never happen on the dd-wrt default configuration due to the default values of the RTS Threshold being 2347 and the Fragmentation Threshold value being 2346. Based on the data packet fragmentation threshold default value at 2346 in size dd-wrt will apply fragmentation to all packets meeting this criteria. Because of this fragmentation process the 2347 packet size needed to trigger the RTS threshold is never reached.
-2.) All clients connected to the dd-wrt AP are configured for CTS\RTS mode as apposed to setting of "disabled" or "CTS-Self" mode.+For a closer look at what happens in one of these cases lets look at a case like trigger number 1 list above and the steps in the CTS protection process.
 +Example. A client that wants to use the radio channel to send data packet(s) of a size that is equal or above the defined RTS threshold value.
-***NOTE Typically the The RTS Threshold value on dd-wrt is only lowered when needed to address or troubleshoot some sort of connectivity or performance issue with a client or all clients on a WLAN. Adjusting the value is a balancing act between getting your problem fixed and losing overall WLAN speed. The more times CTS protection mode is triggered in a period of time "its frequency" the more impact it will have; good or bad. So start with 2340, then 2320, 2300 etc...+Steps in the CTS Protection mode process for the above example.
 +1.) The client wishing to send date over the channel first sends an RTS (request to send) packet to the AP.
-Guide when to use and why.+2.) As the AP broadcast it beacons packet over the WLAN as part of its normal operation, The beacon packet has information within it that declares to all the clients on the entire WLAN not to try and send any information for a specified period of time. The AP then sends a CTS packet to the client that requested the CTS in the first place. The AP has made a single client the "owner" of the wifi channel and then the AP listens only to that client until it is done transmitting; its in protection mode.
--If your trying to tweak out every drop of performance in an ideal setup then you can disable this on the AP and clients. Test again to see if it helps for better results, it should.+3.)The process is repeated for all request to transfer data,which for whatever reason triggers the CTS protection mechanisms, on a first come first serve basis.
--If you want to try 40MHz with your 802.11n clients you might want to start with CTS Protection set to Auto. You do this in case you have 802.11a or g or even some N clients that do not support 40GHz transmissions or "channel bonding" as it is sometimes called.+TWEAK: Implementing additional CTS Protection mode triggers and there frequency of operation on top of the default dd-wrt CTS protection mode configuration;
--If you have a 802.11n based router running in mixed wireless mode that you want to connect 802.11b clients you need to have CTS protection mode set to Auto meaning enabled.+1.) The AP running dd-wrt has the CTS Protection mode is set to Auto by default and then you could adjust the RTS threshold value to something lower then 2346 (Which is the default fragmentation threshold value on dd-wrt) on the AP.
--If CTS Protection makes things faster a network redesign might be needed.+2.) All clients connected to the dd-wrt AP are configured for CTS\RTS mode as apposed to setting of "disabled" or "CTS-Self" mode.
--"CTS to self" based protection - an alternate implementation method of CTS; where by the device willing to send frames over the WLAN first sends a CTS frame to itself. "CTS to self" based protection has less overhead, but it must be taken into account that this only protects against devices receiving CTS frame (e.g. if there are 2 "hidden" stations, there is no use for them to use "CTS to self" protection, because they will not be able to receive CTS sent by other station - in this case stations must use RTS/CTS so that other station knows not to transmit by seeing CTS transmitted by AP).If you have set the CTS protection mode to disabled on the dd-wrt AP, then this is a good choice for the client configuration.+NOTE Typically the The RTS Threshold value on dd-wrt is only lowered when needed to address or troubleshoot some sort of connectivity or performance issue with a client or all clients on a WLAN. Adjusting the value is a balancing act between getting your problem fixed and losing overall WLAN speed. The more times CTS protection mode is triggered in a period of time "its frequency" the more impact it will have; good or bad. So start with 2340, then 2320, 2300 etc...
 +Guide when to use and why.
 +-If your trying to tweak out every drop of performance in an ideal setup then you can disable this on the AP and clients. Test again to see if it helps for better results, it should.
-Frame Burst+-If you want to try 40MHz with your 802.11n clients you might want to start with CTS Protection set to Auto. You do this in case you have 802.11a or g or even some N clients that do not support 40GHz transmissions or "channel bonding" as it is sometimes called.
-The default is set to Disabled.+
 +-If you have a 802.11n based router running in mixed wireless mode that you want to connect 802.11b clients you need to have CTS protection mode set to Auto meaning enabled.
-Help file say...+-If CTS Protection makes things faster a network redesign might be needed.
-Frame burst allows packet bursting which will increase overall network speed though this is only recommended for approx 1-3 wireless clients, Anymore clients and there can be a negative result and throughput will be affected.+
 +-"CTS to self" based protection - an alternate implementation method of CTS; where by the device willing to send frames over the WLAN first sends a CTS frame to itself. "CTS to self" based protection has less overhead, but it must be taken into account that this only protects against devices receiving CTS frame (e.g. if there are 2 "hidden" stations, there is no use for them to use "CTS to self" protection, because they will not be able to receive CTS sent by other station - in this case stations must use RTS/CTS so that other station knows not to transmit by seeing CTS transmitted by AP).If you have set the CTS protection mode to disabled on the dd-wrt AP, then this is a good choice for the client configuration.
-How it works?+=== Frame Burst ===
-Frame-bursting is a technique in wireless technology supported by the draft 802.11e Quality of Service specification. Frame Bursting may increase the throughput of any (point-to-point) 802.11A, B, G or N link connection in certain conditions. This is done by reducing the overhead associated with the wireless session from either:+
-* Access Point to Client and vice versa+'''Available Settings:''' Enable, Disable
-* Client to Client in ad-hoc mode.+
-This can result in the ability to support higher data throughput in mixed and uniform networks.+'''Default Setting:''' Disable
-It enhances the ability of a wireless client to upload data at faster speeds by using the inter-frame wait intervals to "burst" a sequence of up to three packets before waiting the required period. This allows more data to be sent and less waiting to occur, however, can result in unfair allocation of airtime where there are a mix of clients of which only some support Frame-Bursting as the inter-frame wait periods are contention periods where other stations with data to send can seize the air and send their data.+'''Recommended Setting:''' Disable
 +'''The help file says...'''
 +* Frame burst allows packet bursting which will increase overall network speed though this is only recommended for approx 1-3 wireless clients, Anymore clients and there can be a negative result and throughput will be affected.
-------------------------------------------------------- 
--Frame Burst is useful when transferring large data, but the benefits are not as big as most people hope for. 
--It allows, as name says, a client to burst many frames in a short amount of time.+'''How it works:'''
 +Frame-bursting is a technique in wireless technology supported by the draft 802.11e Quality of Service specification. Frame Bursting may increase the throughput of any (point-to-point) 802.11A, B, G or N link connection in certain conditions. This is done by reducing the overhead associated with the wireless session from either: * Access Point to Client and vice versa
 +* Client to Client in ad-hoc mode.
-Beacon Interval 
-Range 1 and 65,535 milliseconds. The default value is 100. 
-The help file says...+This can result in the ability to support higher data throughput in mixed and uniform networks.
-The Beacon Interval value indicates the frequency interval of the beacon. A beacon is a packet broadcast by the router to synchronize the wireless network. 50 is recommended in poor reception.+
-How it Works:+It enhances the ability of a wireless client to upload data at faster speeds by using the inter-frame wait intervals to "burst" a sequence of up to three packets before waiting the required period. This allows more data to be sent and less waiting to occur, however, can result in unfair allocation of airtime where there are a mix of clients of which only some support Frame-Bursting as the inter-frame wait periods are contention periods where other stations with data to send can seize the air and send their data.
 +-Frame Burst is useful when transferring large data, but the benefits are not as big as most people hope for.
-The term beacon signifies a specific data transmission from the wireless access point (AP), which carries the SSID, the channel number and security protocols such as WEP (Wired Equivalent Protection) or WPA (Wi-Fi Protected Access). This transmission does not contain the link layer address of another Wi-Fi device, therefore it can be received by any LAN client.The beacon frame, which is a type of management frame, can be likened with the "heartbeat" of a wireless LAN, enabling stations to establish and maintain communications in an orderly fashion.+-It allows, as name says, a client to burst many frames in a short amount of time.
-What is a Beacon Interval 
-As mentioned above, the beacon interval is a fixed, configurable parameter. Typically, the beacon interval setting is not touched at all in the WLAN network installation phase, but the default value selected by the equipment supplier is used. If the beacon interval is long, maximum capacity in the Access Point is achieved. However, it will the take a long time for WLAN terminals to scan for Access Points in the area and to update RSSI and load information for already found Access Points. This obviously reduces terminal throughput and wastes battery. On the other hand, if the beacon interval in short, passive scanning performed by the WLAN terminals will be faster, but the overall capacity of the Access Point will be reduced. 
 +=== Beacon Interval ===
 +'''Available Settings:''' range from 10 to 65535 ms
-**NOTE There are no special rules for sending beacons, and they must be sent using the mandatory 802.11 carrier sense multiple access / collision avoidance (CSMA/CA) algorithm. If another station is sending a frame when the beacon is to be sent, then the access point (or NIC in an ad hoc network) must wait. As a result, the actual time between beacons may be longer than the beacon interval. Clients, however, compensate for this inaccuracy by utilizing the timestamp found within the beacon packet information.+'''Default Setting:''' 100 ms
 +'''Recommended Setting:''' 50 ~ 300 for 2.4 GHz & 75 ~ 250 for 5 GHz
-What is a Beacon?+'''The help file says...''' * The Beacon Interval value indicates the frequency interval of the beacon. A beacon is a packet broadcast by the router to synchronize the wireless network. 50 is recommended in poor reception.
-A typical beacon frame is approximately fifty bytes long, with about half of that being a common frame header and cyclic redundancy checking (CRC) field. As with other frames, the header includes source and destination MAC addresses as well as other information regarding the communications process. The destination address is always set to all ones, which is the broadcast Medium Access Control (MAC) address. This forces all other stations on the applicable channel to receive and process each beacon frame. The CRC field provides error detection capability.+
-The beacon's frame body resides between the header and the CRC field and constitutes the other half of the beacon frame. Each beacon frame carries the following information in the frame body: 
-Beacon interval. This represents the amount of time between beacon transmissions. Before a station enters power save mode, the station needs the beacon interval to know when to wake up to receive the beacon (and learn whether there are buffered frames at the access point).+'''How it works:'''
 +The term beacon signifies a specific data transmission from the wireless access point (AP), which carries the SSID, the channel number and security protocols such as WEP (Wired Equivalent Protection) or WPA (Wi-Fi Protected Access). This transmission does not contain the link layer address of another Wi-Fi device, therefore it can be received by any LAN client.The beacon frame, which is a type of management frame, can be likened with the "heartbeat" of a wireless LAN, enabling stations to establish and maintain communications in an orderly fashion.
-Timestamp. After receiving a beacon frame, a station uses the timestamp value to update its local clock. This process enables synchronization among all stations that are associated with the same access point.+What is a Beacon Interval As mentioned above, the beacon interval is a fixed, configurable parameter. Typically, the beacon interval setting is not touched at all in the WLAN network installation phase, but the default value selected by the equipment supplier is used. If the beacon interval is long, maximum capacity in the Access Point is achieved. However, it will the take a long time for WLAN terminals to scan for Access Points in the area and to update RSSI and load information for already found Access Points. This obviously reduces terminal throughput and wastes battery. On the other hand, if the beacon interval in short, passive scanning performed by the WLAN terminals will be faster, but the overall capacity of the Access Point will be reduced.
 +NOTE There are no special rules for sending beacons, and they must be sent using the mandatory 802.11 carrier sense multiple access / collision avoidance (CSMA/CA) algorithm. If another station is sending a frame when the beacon is to be sent, then the access point (or NIC in an ad hoc network) must wait. As a result, the actual time between beacons may be longer than the beacon interval. Clients, however, compensate for this inaccuracy by utilizing the timestamp found within the beacon packet information.
-Service Set Identifier (SSID). The SSID identifies a specific wireless LAN. Before associating with a particular wireless LAN, a client must have the same SSID configured as the access point. By default, access points include the SSID in the beacon frame to enable sniffing functions (such as that provided by Windows XP) to identify the SSID and automatically configure the wireless network interface card (NIC) with the proper SSID. DD-Wrt also has an option to disable the SSID from being broadcast in beacon frames to reduce security issues.+What is a Beacon?
 +A typical beacon frame is approximately fifty bytes long, with about half of that being a common frame header and cyclic redundancy checking (CRC) field. As with other frames, the header includes source and destination MAC addresses as well as other information regarding the communications process. The destination address is always set to all ones, which is the broadcast Medium Access Control (MAC) address. This forces all other stations on the applicable channel to receive and process each beacon frame. The CRC field provides error detection capability.
-Supported rates. Each beacon carries information that describes the rates that the particular wireless LAN supports. For example, a beacon may indicate that only 1, 2, and 5.5Mbps data rates are available. As a result, an 802.11b station would stay within limits and not use 11 Mbps. With this information, stations can use performance metrics to decide which access point to associate with.+The beacon's frame body resides between the header and the CRC field and constitutes the other half of the beacon frame. Each beacon frame carries the following information in the frame body:
 +Beacon interval. This represents the amount of time between beacon transmissions. Before a station enters power save mode, the station needs the beacon interval to know when to wake up to receive the beacon (and learn whether there are buffered frames at the access point).
-Parameter Sets. The beacon includes information about the specific signaling methods (such as frequency hopping spread spectrum, CTS Protection mode and RTS Threshold,direct sequence spread spectrum, etc.). For example, a beacon would include in the appropriate parameter set the channel number that an 802.11b access point is using. Likewise, a beacon belonging to frequency hopping network would indicate hopping pattern and dwell time.+Timestamp. After receiving a beacon frame, a station uses the timestamp value to update its local clock. This process enables synchronization among all stations that are associated with the same access point.
 +Service Set Identifier (SSID). The SSID identifies a specific wireless LAN. Before associating with a particular wireless LAN, a client must have the same SSID configured as the access point. By default, access points include the SSID in the beacon frame to enable sniffing functions (such as that provided by Windows XP) to identify the SSID and automatically configure the wireless network interface card (NIC) with the proper SSID. DD-Wrt also has an option to disable the SSID from being broadcast in beacon frames to reduce security issues.
-Capability Information. This signifies requirements of stations that wish to belong to the wireless LAN that the beacon represents. For example, this information may indicate that all clients must use wired equivalent privacy (WEP) in order to participate on the network.+Supported rates. Each beacon carries information that describes the rates that the particular wireless LAN supports. For example, a beacon may indicate that only 1, 2, and 5.5Mbps data rates are available. As a result, an 802.11b station would stay within limits and not use 11 Mbps. With this information, stations can use performance metrics to decide which access point to associate with.
 +Parameter Sets. The beacon includes information about the specific signaling methods (such as frequency hopping spread spectrum, CTS Protection mode and RTS Threshold,direct sequence spread spectrum, etc.). For example, a beacon would include in the appropriate parameter set the channel number that an 802.11b access point is using. Likewise, a beacon belonging to frequency hopping network would indicate hopping pattern and dwell time.
-Traffic Indication Map (TIM). An access point periodically sends the TIM within a beacon to identify which stations using power saving mode have data frames waiting for them in the access point's buffer. The TIM identifies a station by the association ID that the access point assigned during the association process.+Capability Information. This signifies requirements of stations that wish to belong to the wireless LAN that the beacon represents. For example, this information may indicate that all clients must use wired equivalent privacy (WEP) in order to participate on the network.
 +Traffic Indication Map (TIM). An access point periodically sends the TIM within a beacon to identify which stations using power saving mode have data frames waiting for them in the access point's buffer. The TIM identifies a station by the association ID that the access point assigned during the association process.
-**NOTE Today beacon frames also contain a load information that informs WLAN terminals currently connected to a specific Access Point or considering making a handover to that Access Point about the load situation. This information helps the WLANterminals in making correct handover decision, in addition to the information from the comparisons of RSSI readings obtained by scanning, and thus ensures that WLAN traffic is divided more evenly between all Access Points in the area.+NOTE Today beacon frames also contain a load information that informs WLAN terminals currently connected to a specific Access Point or considering making a handover to that Access Point about the load situation. This information helps the WLANterminals in making correct handover decision, in addition to the information from the comparisons of RSSI readings obtained by scanning, and thus ensures that WLAN traffic is divided more evenly between all Access Points in the area.
 +TWEAK:
 +By increasing the beacon interval, you can reduce the number of beacons and associated overhead, but that will likely delay the association and roaming process because stations scanning for available access points may miss the beacons.
-TWEAK:+You can decrease the beacon interval, which increases the rate of beacons. This will make the association and roaming process very responsive; however, the network will incur additional overhead and throughput will go down.
 +In addition, stations using power save mode will need to consume more power because they'll need to awaken more often, which reduces power saving mode benefits. In an idle network, beacons dominate all other traffic.
-By increasing the beacon interval, you can reduce the number of beacons and associated overhead, but that will likely delay the association and roaming process because stations scanning for available access points may miss the beacons.+Guide to tweaking: The amount of overhead that the transmissions of beacon frames generate is substantial; however, the beacon serves a variety of functions. For example, each beacon transmission identifies the presence of an access point.
-You can decrease the beacon interval, which increases the rate of beacons. This will make the association and roaming process very responsive; however, the network will incur additional overhead and throughput will go down.+How a beacon interval impacts the client By default, radio NICs passively scan all RF channels and listen for beacons coming from access points in order to find a suitable access point. When a beacon is found, the radio NIC learns a great deal about that particular network. This enables a ranking of access points based on the received signal strength of the beacon, along with capability information regarding the network. The radio NIC can then associate with the most preferable access point. After association, the station continues to scan for other beacons in case the signal from the currently-associated access point become too weak to maintain communications. As the radio NIC receives beacons from the associated access point, the radio NIC updates its local clock to maintain timing synchronization with the access point and other stations. In addition, the radio NIC will abide by any other changes, such as data rate, that the frame body of the beacon indicates. The beacons also support stations implementing power saving mode. With infrastructure networks, the access point will buffer frames destined for sleeping stations and announce which radio NICs have frames waiting through the TIM (DTIMS) that's part of the beacon
-In addition, stations using power save mode will need to consume more power because they'll need to awaken more often, which reduces power saving mode benefits.+Do clients send beacon frames too??... As apposed to beacons sent out by AP's, Clients send out "probe request" frames; It's like an opposite to a beacon, clients use a probe request packets to play there role in the 802.11 WLAN. An 802.11 probe response frame is very similar to a beacon frame, except that probe responses don't carry the TIM info and are only sent in response to a probe request. A client may send a probe request frame to trigger a probe response when the client needs to obtain information from another client on the same WLAN. A client, for instance, will broadcast a probe request when using active scanning to determine which access points are within range for possible association. Some sniffing software (e.g., NetStumbler) tools send probe requests so that access points will respond with desired info.
-In an idle network, beacons dominate all other traffic.+
 +-Beacons are packets sent by an access point to synchronize a wireless network.
-Guide to tweaking:+-Normal Traffic Indication Message(TIM)s that are present in every beacon are for signaling the presence of unbuffered unicast data.
-The amount of overhead that the transmissions of beacon frames generate is substantial; however, the beacon serves a variety of functions. For example, each beacon transmission identifies the presence of an access point.+
-How a beacon interval impacts the client 
-By default, radio NICs passively scan all RF channels and listen for beacons coming from access points in order to find a suitable access point. 
-When a beacon is found, the radio NIC learns a great deal about that particular network. This enables a ranking of access points based on the received signal strength of the beacon, along with capability information regarding the network. The radio NIC can then associate with the most preferable access point. After association, the station continues to scan for other beacons in case the signal from the currently-associated access point become too weak to maintain communications. As the radio NIC receives beacons from the associated access point, the radio NIC updates its local clock to maintain timing synchronization with the access point and other stations. In addition, the radio NIC will abide by any other changes, such as data rate, that the frame body of the beacon indicates. The beacons also support stations implementing power saving mode. With infrastructure networks, the access point will buffer frames destined for sleeping stations and announce which radio NICs have frames waiting through the TIM (DTIMS) that's part of the beacon 
 +=== DTIM Interval ===
-Do clients send beacon frames too??...+'''Available Settings:''' range from 1 to 255
-As apposed to beacons sent out by AP's, Clients send out "probe request" frames; It's like an opposite to a beacon, clients use a probe request packets to play there role in the 802.11 WLAN. An 802.11 probe response frame is very similar to a beacon frame, except that probe responses don't carry the TIM info and are only sent in response to a probe request. A client may send a probe request frame to trigger a probe response when the client needs to obtain information from another client on the same WLAN. A client, for instance, will broadcast a probe request when using active scanning to determine which access points are within range for possible association. Some sniffing software (e.g., NetStumbler) tools send probe requests so that access points will respond with desired info.+
--Beacons are packets sent by an access point to synchronize a wireless network.+'''Default Setting:''' 1
--Normal Traffic Indication Message(TIM)s that are present in every beacon are for signaling the presence of unbuffered unicast data.+'''Recommended Setting:''' 1 (assuming default beacon interval of 100 is used)
 +'''The help file says...''' * Indicates the interval of the Delivery Traffic Indication Message (DTIM). A DTIM field is a countdown field informing clients of the next window for listening to broadcast and multicast messages. When the router has buffered broadcast or multicast messages for associated clients, it sends the next DTIM with a DTIM Interval value. Its clients hear the beacons and awaken to receive the broadcast and multicast messages.
-DTIM Interval 
-The default value is 1. 
 +'''How it works:'''
-Help file says..+A Delivery Traffic Indication Message is a kind of Traffic Indication Message(TIM) which informs the clients about the presence of buffered and/or multicast/broadcast data on the access point. It is generated within the periodic beacon at a frequency specified by the DTIM Interval. After a DTIM, the access point will send the multicasted/broadcasted data on the channel following the normal channel access rules (CSMA/CA).
-Indicates the interval of the Delivery Traffic Indication Message (DTIM). A DTIM field is a countdown field informing clients of the next window for listening to broadcast and multicast messages. When the router has buffered broadcast or multicast messages for associated clients, it sends the next DTIM with a DTIM Interval value. Its clients hear the beacons and awaken to receive the broadcast and multicast messages.+
 +According to the 802.11 standards, a Delivery Traffic Indication Message (DTIM) period value is a number that determines how often a beacon frame includes a Delivery Traffic Indication Message, and this number is included in each beacon frame. A DTIM is included in beacon frames, according to the DTIM period, to indicate to the client devices whether the access point has buffered broadcast and/or multicast data waiting for them. Following a beacon frame that includes a DTIM, the access point will release the buffered broadcast and/or multicast data, if any exists.
 +Since beacon frames are sent using the mandatory 802.11 carrier sense multiple access/collision detection (CSMA/CD) algorithm, the access point must wait if a client device is sending a frame when the beacon is to be sent. As a result, the actual time between beacons may be longer than the beacon interval. Client devices that awaken from power-save mode may find that they have to wait longer than expected to receive the next beacon frame. Client devices, however, compensate for this inaccuracy by utilizing the time-stamp found within the beacon frame.
-How it works:+The 802.11 standards define a power-save mode for client devices. In power-save mode, a client device may choose to sleep for one or more beacon intervals waking for beacon frames that include DTIMs. When the DTIM period is 2, a client device in power-save mode will awaken to receive every other beacon frame. Upon entering power-save mode, a client device will transmit a notification to the access point, so that the access point will know how to handle unicast traffic destined for the client device. The client device will begin to sleep according to the DTIM period.
-A Delivery Traffic Indication Message is a kind of Traffic Indication Message(TIM) which informs the clients about the presence of buffered and/or multicast/broadcast data on the access point. It is generated within the periodic beacon at a frequency specified by the DTIM Interval. After a DTIM, the access point will send the multicasted/broadcasted data on the channel following the normal channel access rules (CSMA/CA).+
-Acording to the 802.11 standards, a Delivery Traffic Indication Message (DTIM) period value is a number that determines how often a beacon frame includes a Delivery Traffic Indication Message, and this number is included in each beacon frame. A DTIM is included in beacon frames, according to the DTIM period, to indicate to the client devices whether the access point has buffered broadcast and/or multicast data waiting for them. Following a beacon frame that includes a DTIM, the access point will release the buffered broadcast and/or multicast data, if any exists.+-The higher the DTIM period, the longer a client device may sleep and therefore the more power that particular client device may potentially save.
-Since beacon frames are sent using the mandatory 802.11 carrier sense multiple access/collision detection (CSMA/CD) algorithm, the access point must wait if a client device is sending a frame when the beacon is to be sent. As a result, the actual time between beacons may be longer than the beacon interval. Client devices that awaken from power-save mode may find that they have to wait longer than expected to receive the next beacon frame. Client devices, however, compensate for this inaccuracy by utilizing the time-stamp found within the beacon frame.+-Client devices in wireless networks may have conflicting requirements for power consumption and communication throughput when in power-save mode. For example, laptops may require relatively high communication throughput and may have low sensitivity to power consumption. Therefore, a relatively low DTIM period, for example 1, may be suitable for laptops . However, cellphones may require relatively low communication throughput and may be operated by batteries of relatively low capacity. Therefore, a relatively high DTIM period, for example 8, may be suitable for cellphones. Further, PDA\Smart phones may require a medium to high communication throughput and may be operated by batteries of relatively low capacity. Therefore, a medium DTIM period, for example a value of 4, may be suitable for these devices.
-The 802.11 standards define a power-save mode for client devices. In power-save mode, a client device may choose to sleep for one or more beacon intervals waking for beacon frames that include DTIMs. When the DTIM period is 2, a client device in power-save mode will awaken to receive every other beacon frame. Upon entering power-save mode, a client device will transmit a notification to the access point, so that the access point will know how to handle unicast traffic destined for the client device. The client device will begin to sleep according to the DTIM period.+-Currently, an access point is able to store only a single DTIM period. Consequently, different client devices in power-save mode will all wake up for the same beacon frames according to the DTIM period. Currently, a network manager may need to balance the conflicting requirements for power consumption and communication throughput when in power-save mode of client devices in different wireless networks when configuring the DTIM period of an access point. In the future an access point with support for two or more SSIDs may have SSID-dependent DTIM periods rather than a single DTIM period for all SSIDs. In other words, the network manager may configure the access point with DTIM periods on a per SSID basis. A network manager may consider the requirements of power consumption and communication throughput of client devices in a particular wireless networks when determining which DTIM period to configure for which SSID. A higher DTIM period may increase the potential savings in power consumption but may reduce the communication throughput, and vice versa
 +=== Fragmentation Threshold ===
 +'''Available Settings:''' range from 256 to 2346
--------------------------------------------------------------------------------------+'''Default Setting:''' 2346
 +'''Recommended Setting:''' 2346
 +'''The help file says...''' * It specifies the maximum size for a packet before data is fragmented into multiple packets. If you experience a high packet error rate, you may slightly increase the Fragmentation Threshold. Setting the Fragmentation Threshold too low may result in poor network performance. Only minor modifications of this value are recommended.
--The higher the DTIM period, the longer a client device may sleep and therefore the more power that particular client device may potentially save. 
--Client devices in wireless networks may have conflicting requirements for power consumption and communication throughput when in power-save mode. For example, laptops may require relatively high communication throughput and may have low sensitivity to power consumption. Therefore, a relatively low DTIM period, for example 1, may be suitable for laptops . However, cellphones may require relatively low communication throughput and may be operated by batteries of relatively low capacity. Therefore, a relatively high DTIM period, for example 8, may be suitable for cellphones. Further, PDA\Smart phones may require a medium to high communication throughput and may be operated by batteries of relatively low capacity. Therefore, a medium DTIM period, for example a value of 4, may be suitable for these devices. 
 +'''How it works:'''
--Currently, an access point is able to store only a single DTIM period. Consequently, different client devices in power-save mode will all wake up for the same beacon frames according to the DTIM period. Currently, a network manager may need to balance the conflicting requirements for power consumption and communication throughput when in power-save mode of client devices in different wireless networks when configuring the DTIM period of an access point. In the future an access point with support for two or more SSIDs may have SSID-dependent DTIM periods rather than a single DTIM period for all SSIDs. In other words, the network manager may configure the access point with DTIM periods on a per SSID basis. A network manager may consider the requirements of power consumption and communication throughput of client devices in a particular wireless networks when determining which DTIM period to configure for which SSID. A higher DTIM period may increase the potential savings in power consumption but may reduce the communication throughput, and vice versa+The Threshold for fragmentation to occur is a 802.11 configuration parameter. This is an optional feature, the 802.11 standard and dd-wrt includes the ability for access points to fragment packets for improving performance in the presence of RF interference and marginal coverage areas
 +To use fragmentation means to divide 802.11 frames into smaller pieces (fragments) that are sent separately to the destination. Each fragment consists of a MAC Layer header, frame check sequence (FCS), and a fragment number indicating its ordered position within the frame. Because the source transmits each fragment independently, the receiving destination replies with a separate acknowledgement for each fragmen
 +-Fragmentation only applies to frames having a unicast (address assigned to a single host on your network) receiver address.
-Fragmentation Threshold+-The use of fragmentation can increase the reliability of frame transmissions. Because of sending smaller frames, collisions are much less likely to occur.
-Range: 256 - 2346. This value should remain at its default setting of 2346.+
 +-Similar to RTS, a good method to find out if you should activate fragmentation is to monitor the wireless LAN for collisions. If you find a relatively large number of collisions, then try using fragmentation. This can improve throughput if the fragmentation threshold is set just right.
-The Help file says..+-try setting the fragmentation threshold to around 800 bytes first, then tweak it until you find the best results.
-It specifies the maximum size for a packet before data is fragmented into multiple packets. If you experience a high packet error rate, you may slightly increase the Fragmentation Threshold. Setting the Fragmentation Threshold too low may result in poor network performance. Only minor modifications of this value are recommended.+
 +-As with any 802.11 tuning mechanisms, the goal is to improve performance.
 +-If what you do improves throughput, then you're doing the right thing.
 +-If hidden nodes are present the use of RTS and\or CTS could be a better way to reduce collisions.
-How it Works: 
-The Threshold for fragmentation to occur is a 802.11 configuration parameter.This is an optional feature, the 802.11 standard and dd-wrt includes the ability for access points to fragment packets for improving performance in the presence of RF interference and marginal coverage areas 
-To use fragmentation means to divide 802.11 frames into smaller pieces (fragments) that are sent separately to the destination. Each fragment consists of a MAC Layer header, frame check sequence (FCS), and a fragment number indicating its ordered position within the frame. Because the source transmits each fragment independently, the receiving destination replies with a separate acknowledgement for each fragmen+=== RTS Threshold ===
 +'''Available Settings:''' range from 0 to 2347
 +'''Default Setting:''' 2347
 +'''Recommended Setting:''' 2347
-------------------------------------------------------------------------------------------+'''The help file says...''' * The router sends Request to Send (RTS) frames to a particular receiving station and negotiates the sending of a data frame. After receiving an RTS, the wireless station responds with a Clear to Send (CTS) frame to acknowledge the right to begin transmission.
--Fragmentation only applies to frames having a unicast (address assigned to a single host on your network) receiver address. 
--The use of fragmentation can increase the reliability of frame transmissions. Because of sending smaller frames, collisions are much less likely to occur.+'''How it works:'''
--Similar to RTS, a good method to find out if you should activate fragmentation is to monitor the wireless LAN for collisions. If you find a relatively large number of collisions, then try using fragmentation. This can improve throughput if the fragmentation threshold is set just right.+The RTS Threshold value is a configurable parameter within the CTS Protection mechanism. The RTS threshold is used as a trigger to engage the back and forth of RTS and CTS messages between AP and client. The triggers purpose is a type of ''handshaking'' approach that provides and additional layer of control over the use of the shared medium, or in the case of DD-WRT the ''Radio Channel'' or WLAN. If enabled, A node (client) wishing to send data initiates the process by sending a Request to Send frame (RTS).
--try setting the fragmentation threshold to around 800 bytes first, then tweak it until you find the best results.+How the RTS Threshold value works in DD-WRT. As discussed in the CTS Protection mode section of this document, when a packet that a DD-WRT access point is transmitting is larger than the RTS threshold set in the configuration, DD-WRT will initiate the CTS Protection mode ''handshaking'' function. If the network packet being sent is smaller or fragmented to a size lower than the preset RTS threshold size, the CTS Protection mode mechanism will still not be enabled for that packet. Note if the packet size happens to be equal to the threshold, DD-WRT will not use CTS.
--As with any 802.11 tuning mechanisms, the goal is to improve performance.+Tweak: In DD-WRT, the default configuration after a flash sets the CTS Protection mode not to get triggered to protect transmissions by RTS. This is due to the fact that Sending RTS frames is turned off by default (threshold >=2347bytes). If the packet size the node wants to transmit is larger than the threshold, the RTS/CTS handshake gets triggered. If the packet size is equal to or less than threshold the data frame gets sent immediately.
--If what you do improves throughput, then you're doing the right thing.+The method for enabling RTS-CTS triggers on DD-WRT is different than with client NICs. For DD-WRT, you enable RTS-CTS handshaking triggers within WebGUI by setting a specific packet size threshold (0 - 2347 bytes) in the user configuration interface; only minor modifications are recommended.
--If hidden nodes are present the use of RTS and\or CTS could be a better way to reduce collisions.+Set this value to a 2340 bytes as a start, test, then if needed try a lower value, etc.
 +Save. Apply. Reboot.
 +Rollback Set the value back to its default value of 2347 bytes and disable RTS threshold triggers in the CTS Protection mode operation on the router.
-RTS Threshold+=== Max Associated Clients ===
-Range: 0 - 2347. Default value of 2347 (bytes).+
 +'''Available Settings:''' range from 1 to 256
-The Help file says..+'''Default Setting:''' depends on the router, usually 128
-The router sends Request to Send (RTS) frames to a particular receiving station and negotiates the sending of a data frame. After receiving an RTS, the wireless station responds with a Clear to Send (CTS) frame to acknowledge the right to begin transmission.+
 +'''Recommended Setting:''' What ever you want
-How it Works:+'''The help file says...''' *
-The RTS Threshold value is a configurable parameter within the CTS Protection mechanism. The RTS threshold is used as a trigger to engage the back and forth of RTS and CTS messages between AP and client. The triggers purpose is a type of “handshaking” approach that provides and additional layer of control over the use of the shared medium, or in the case of DD-WRT the “Radio Channel” or WLAN. If enabled, A node (client) wishing to send data initiates the process by sending a Request to Send frame (RTS).+
-How the RTS Threshold value works in DD-WRT. 
-As discussed in the CTS Protection mode section of this document, when a packet that a DD-WRT access point is transmitting is larger than the RTS threshold set in the configuration, DD-WRT will initiate the CTS Protection mode “handshaking” function. If the network packet being sent is smaller or fragmented to a size lower than the preset RTS threshold size, the CTS Protection mode mechanism will still not be enabled for that packet. Note if the packet size happens to be equal to the threshold, DD-WRT will not use CTS. 
 +'''How it works:'''
-Tweak:+This number will determine how many clients can be connected to the routers wireless LAN (WLAN)
-In DD-WRT, the default configuration after a flash sets the CTS Protection mode not to get triggered to protect transmissions by RTS. This is due to the fact that Sending RTS frames is turned off by default (threshold >=2347bytes). If the packet size the node wants to transmit is larger than the threshold, the RTS/CTS handshake gets triggered. If the packet size is equal to or less than threshold the data frame gets sent immediately.+
-The method for enabling RTS-CTS triggers on DD-WRT is different than with client NICs. For DD-WRT, you enable RTS-CTS handshaking triggers within WebGUI by setting a specific packet size threshold (0 - 2347 bytes) in the user configuration interface; only minor modifications are recommended. 
-Set this value to a 2340bytes as a start, test, then if needed try a lower value….etc…+=== AP Isolation ===
-Save. Apply. Reboot.+'''Available Settings:''' Enable, Disable
-Rollback+'''Default Setting:''' Disable
-Set the value back to its default value of 2347bytes and disable RTS threshold triggers in the CTS Protection mode operation on the router.+
-**A 30/30/30/ hard reset will also set this parameter back to the default value.+'''Recommended Setting:''' Disable for private home Wi-Fi with trusted users, enable for public/guest Wi-Fi hotspot
 +'''The help file says...''' * This setting isolates wireless clients so access to and from other wireless clients are stopped.
-Max Associated Clients+'''How it works:'''
-Range: 1 - 256. Default is 128.+
 +Wireless access points work by bridging the wireless port to the wired switch ports and router port. Everything happens at the MAC address level and does not involve IP addresses,NETBIOS over TCP/IP (also known as MS Networking). Just MAC addresses.
-The Help file says..+The wireless bridge builds a bridging table consisting of a table of "heard" (or sniffed) MAC addresses that appear on various ports. Think of the router having just 3 available ports; Wireless, Ethernet switch, and router port. If the destination MAC address of a port is shows up in the MAC address table as sitting on a specific port, only that port gets the traffic. Broadcasts, which have no destination MAC address are sent to all ports.
 +When this feature is enabled the software builds a logical rule (or filter) for these MAC addresses and ports that says:
-How it Works:+"If the packet originates on the wireless port, it can only send and receive packets that are destined or originate from the router port or ethernet switch port."
-This number will determine how many clients can be connected to the routers wireless LAN (WLAN)+
 +Not a very complex rule, but one which totally prevents wireless client to client traffic. Not even broadcasts will go from wireless client to client.
-------------------------------------------------------------------------------------------+-prevents one wireless client communicating with another wireless client.
--+-This breaks the connection between WLAN and WLAN
 +-No improvement in performance, performance is exactly the same. The difference is in "reliability" or ability to survive in a multi-path environment.
 +-You enable this if you are running a hotspot. Click Network Neighborhood in a motel sometime, see if the motel needs to set AP isolation.
-AP Isolation+-Changing this from the default value would be for security reasons.
-The default value is Disabled.+
-The Help file says..+=== TX Antenna / RX Antenna ===
-This setting isolates wireless clients so access to and from other wireless clients are stopped.+
 +'''Available Settings:''' 1, 1+2, 1+3, 1+2+3, 1+2+3+4 (varies by router)
-How it Works:+'''Default Setting:''' Varies by router
-Wireless access points work by bridging the wireless port to the wired switch ports and router port. Everything happens at the MAC address level and does not involve IP addresses,NETBIOS over TCP/IP (also known as MS Networking). Just MAC addresses.+
-The wireless bridge builds a bridging table consisting of a table of "heard" (or sniffed) MAC addresses that appear on various ports. Think of the router having just 3 available ports; Wireless, Ethernet switch, and router port. If the destination MAC address of a port is shows up in the MAC address table as sitting on a specific port, only that port gets the traffic. Broadcasts, which have no destination MAC address are sent to all ports.+'''Recommended Setting:''' Varies by router
-When this feature is enabled the software builds a logical rule (or filter) for these MAC addresses and ports that says:+This setting is critical for proper, smooth, fast Wi-Fi performance. 2x2:2 routers will either have TX/RX chains at 1+2/1+2, 1+3/1+3, 1+2/1+3, or 1+3/1+2. This can take some time to find the proper setting but its worth it, you can more easily find the correct setting by using a 802.11n client thats capable of 300 Mbps link. Note the TX/RX link rates on the wireless status page, when set incorrectly one or both of the rates will drop to a much lower speed such as 200, 170, 81 etc. This is best done with the client less than 10 feet from the AP with clear line of sight. Some routers with chains set incorrectly such as D-Link DIR-615 C1, will deny connections to clients, heavily reduce throughput, and other errors. Searching the FCC ID of your router will aid in setting the correct chain settings. Some popular routers such as the Netgear WNDR3700 v1/2/4 and D-Link DIR-825 B1/B2 require both chains set at 1+2 for proper Wi-Fi performance. '''Default is not always right!*'''
-"If the packet originates on the wireless port, it can only send and receive packets that are destined or originate from the router port or ethernet switch port."+''<nowiki>* With builds around r21061 or later, most units have the proper defaults preset & invalid options removed, such as 1+2+3 for TX/RX on WNDR3700 v1, v2, & v4 as the router only has 2 chains each therefor only has 1 & 1+2 available to be selected. While a </nowiki>Asus N66U have 1+2+3 as they are 3x3:3 units. An example 4x4:4 unit is the R7800.''
 +''<nowiki>* </nowiki>''The option may have disappeared in recent builds (>336XX).
-Not a very complex rule, but one which totally prevents wireless client to client traffic. Not even broadcasts will go from wireless client to client.+'''The help file says...''' * This is used in conjunction with external antennas to give them optimum performance. On some router models left and right antennas may be reversed depending on you point of view.
-------------------------------------------------------------------------------------------+'''How it works:'''
 +This value determines which Antenna connection is used for the purposes of Rx and Tx functions.
--prevents one wireless client communicating with another wireless client. 
--This breaks the connection between WLAN and WLAN+=== Preamble ===
--No improvement in performance, performance is exactly the same. The difference is in "reliability" or ability to survive in a multi-path environment.+'''Available Settings:''' Short, Long, Auto
--You enable this if you are running a hotspot. Click Network Neighborhood in a motel sometime, see if the motel needs to set AP isolation.+'''Default Setting:''' Long
--Changing this from the default value would be for security reasons.+'''Recommended Setting:''' Short
 +'''The help file says...''' * If your wireless device supports the short preamble and you are having trouble getting it to communicate with other 802.11b devices, make sure that it is set to use the long preamble.
-TX Antenna / RX Antenna 
-Values are Auto, Left, Right, default value is Auto. 
 +'''How it works:'''
-The Help file says..+The preamble is used to communicate to the receiver that data is on its way. Technically speaking, it is the first portion of the Physical Layer Convergence Protocol/Procedure (PLCP) Protocol Data Unit (PDU). The preamble allows the receiver to acquire the wireless signal and synchronize itself with the transmitter. A header is the remaining portion and contains additional information identifying the modulation scheme, transmission rate and length of time to transmit an entire data frame.
-This is used in conjunction with external antennas to give them optimum performance. On some router models left and right antennas may be reversed depending on you point of view.+
 +Long Preamble: * Compatible with legacy IEEE* 802.11 systems operating at 1 and 2 Mbps (Megabits per second)
 +* PLCP with long preamble is transmitted at 1 Mbps regardless of transmit rate of data frames
 +* Total -Long Preamble transfer time is a constant at 192 usec (microseconds)
-How it Works: 
-This value determines which Antenna connection is used for the purposes of Rx and Tx functions. 
 +Short Preamble: * Not compatible with legacy IEEE 802.11 systems operating at 1 and 2 Mbps -PLCP with short preamble: Preamble is transmitted at 1 Mbps and header at 2 Mbps - -Total Long Preamble transfer time is a constant at 96 usec (microseconds)
 +* Unless you have 802.11b (1 or 2Mbits/sec) client radios in your system, there's no need for a long preamble. The default for most access points is "automatic". It only enables long preambles when associated with a 1 or 2Mbit/sec client radio.
 +* Most access points (AP) and broadband WiFi routers are configured for a Long Preamble or have a setting that automatically detects the preamble and adjusts accordingly. A majority of client WiFi adapters should also be pre-configured in the same manner. This is done as a precautionary measure for networks that may still employ legacy devices.
------------------------------------------------------------------------------------------- 
-- 
-Preamble 
-Values are Long and Short and Auto, default value is Long 
 +=== Shortslot Override ===
-The Help file says..+'''Available Settings:''' Short, Long, Auto
-If your wireless device supports the short preamble and you are having trouble getting it to communicate with other 802.11b devices, make sure that it is set to use the long preamble.+
 +'''Default Setting:''' Auto
-How it Works:+'''Recommended Setting:''' Short
-The preamble is used to communicate to the receiver that data is on its way. Technically speaking, it is the first portion of the Physical Layer Convergence Protocol/Procedure (PLCP) Protocol Data Unit (PDU). The preamble allows the receiver to acquire the wireless signal and synchronize itself with the transmitter. A header is the remaining portion and contains additional information identifying the modulation scheme, transmission rate and length of time to transmit an entire data frame.+
 +'''The help file says...''' *
-Long Preamble: 
--Compatible with legacy IEEE* 802.11 systems operating at 1 and 2 Mbps (Megabits per second)+'''How it works:'''
--PLCP with long preamble is transmitted at 1 Mbps regardless of transmit rate of data frames -Total+
--Long Preamble transfer time is a constant at 192 usec (microseconds)+
-Short Preamble:+Short Slot Times - The amount of time a device waits after a collision before retransmitting a packet. You can increase throughput on 802.11g, 2.4-GHz radios by enabling Shortslot override (most .11g radios enable this by default). Reducing the slot time from the standard 20 microseconds to the 9-microsecond short slot time decreases the overall backoff, which increases throughput. Backoff, which is a multiple of the slot time, is the random length of time a station waits before sending a packet on the LAN.
--Not compatible with legacy IEEE 802.11 systems operating at 1 and 2 Mbps+Many 802.11g radios support Shortslot override, but some do not. When Shortslot override is enabled, the wireless device uses the short slot time only when all clients associated to the 802.11g, 2.4-GHz radio support Shortslot override. Shortslot override is an 802.11g-only feature and does not apply to 802.11a radios.
--PLCP with short preamble: Preamble is transmitted at 1 Mbps and header at 2 Mbps -+
--Total Long Preamble transfer time is a constant at 96 usec (microseconds)+
 +SUMMARY: Slot times should transition from 20us to 9us when a "pure" .11g environment exists for that AP. Also applies to NG networks.
------------------------------------------------------------------------------------------- 
 +=== TX Power ===
--Unless you have 802.11b (1 or 2Mbits/sec) client radios in your system, there's no need for a+'''Broadcom:'''
-long preamble. The default for most access points is "automatic". It only enables long preambles when associated with a 1 or 2Mbit/sec client radio.+
--Most access points (AP) and broadband WiFi routers are configured for a Long Preamble or have a setting that automatically detects the preamble and adjusts accordingly. A majority of client WiFi adapters should also be pre-configured in the same manner. This is done as a precautionary measure for networks that may still employ legacy devices.+'''Available Settings:''' Auto or Manual
 +'''Default Setting:''' Auto
 +'''Recommended Setting:''' Auto, unless you know what you are doing.
-Shortslot Override 
-Values are Long and Short and Auto, default value is Auto 
-The Help file says..v+'''Atheros and others:'''
-nothing.+
 +'''Available Settings:''' 0 ~ 999
-How it Works:+'''Default Setting:''' 16 ~ 30 dBm (varies by router)
-Short Slot Times - The amount of time a device waits after a collision before retransmitting a packet. You can increase throughput on 802.11g, 2.4-GHz radios by enabling Shortslot override (most .11g radios enable this by default). Reducing the slot time from the standard 20 microseconds to the 9-microsecond short slot time decreases the overall backoff, which increases throughput. Backoff, which is a multiple of the slot time, is the random length of time a station waits before sending a packet on the LAN.+
-Many 802.11g radios support Shortslot override, but some do not. When Shortslot override is enabled, the wireless device uses the short slot time only when all clients associated to the 802.11g, 2.4-GHz radio support Shortslot override. Shortslot override is an 802.11g-only feature and does not apply to 802.11a radios.+'''Recommended Setting:''' Highest dBm your radios & local laws legally allow**
-SUMMARY: Slot times should transition from 20us to 9us when a "pure" .11g environment exists for that AP.+**Recommended Setting
 +Some people believe that "high" TX power (i.e., greater than 25 dBm), may be of concern to one's health. That is not the case but each to their own. So if that's you then 22 - 25 dBm should be sufficient; any lower & range starts to significantly drop (unless you want to of course & if you have an older router than only does something like 18 dBm, no need). In case you are wondering, every 3 dBm is doubled the power, so 13 dBm is twice as much as 10 dBm, & so on; but don't worry, 30 dBm is only 1 watt.
-------------------------------------------------------------------------------------------+'''The help file says...''' * A safe increase of up to 70 would be suitable for most users. Higher power settings are not recommended for users due to excess heat generated by the radio chipset, which can affect the life of the router.
-- 
-TX Power+'''How it works:'''
-The default value is 70 (mW) MilliWatts+
 +The milliwatt (symbol:mW) is equal to one thousandth (10-3) of a watt. A typical laser pointer might output 5 milliwatts.
-The Help file says..+This setting will determine the number of milliwatts used to power the radio signal output from the router.
-A safe increase of up to 70 would be suitable for most users. Higher power settings are not recommended for users due to excess heat generated by the radio chipset, which can affect the life of the router.+
 +'''TWEAK'''
 +<pre>wl -i eth1 txpwr 70 #will set your adapter to 70 mW for the 5GHz </pre>
 +<pre>wl -i eth0 txpwr 70 #will set your adapter to 70 mW for the 2.4GHz</pre>
 +<pre>wl -i eth1 txpwr1 #check transmitt power for 5 GHz</pre>
 +<pre>wl -i eth0 txpwr1 #check transmitt power for 2.4 GHz* Buffalo HP units should not exceed about 30 due to their built in amp. </pre>
 +* Linksys ships out their units with the TX power set to 28 mW by default.
-How it Works:+* mW \ Dbm Power Conversion Table
-The milliwatt (symbol:mW) is equal to one thousandth (10-3) of a watt. A typical laser pointer might output 5 milliwatts.+
-This setting will determine the number of milliwatts used to power the radio signal output from the router.+* mW -- 1 2 3 4 5 6 8 10 12 15 20 25 30 40 50 60 80 100
 +* DBm -1 2 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
-TWEAK 
-wl -i eth1 txpwr 70 //will sett you adapter to 70 mW for the 5GHz+'''How to convert dBm to mW'''
-wl -i eth0 txpwr 70 //will sett you adapter to 70 mW for the 2.4GHz+
-wl -i eth1 txpwr1 //check transmitt power for 5 GHz+
-wl -i eth0 txpwr1 //check transmitt power for 2.4 GHz+
-------------------------------------------------------------------------------------------+The power conversion of dBm to mW is given by the formula:
 +P(mW) = 10 ^ (P(dBm) / 10)
--Buffalo HP units should not exceed about 30 due to their built in amp.+So .. '''1dBm = 1.258925mW'''
--Linksys ships out there units with the TX power set to 28 mW by default. 
--mW \ Dbm Power Conversion Table+'''How to convert mW to dBm'''
-mW -- 1 2 3 4 5 6 8 10 12 15 20 25 30 40 50 60 80 100+
-DBm -1 2 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20+
 +The power conversion of mW to dBm is given by the formula:
 +P(dBm) = 10 * log10(P(mW) / 1)
-Afterburner+''On most calculators, log10 would be labeled as LOG.''
-The default value is Disabled.+
-The Help file says..+[https://www.rapidtables.com/electric/dBm.html#dBm_to_Calculator Conversion Calculator | dBm <--> mW]
-This should only be used with WRT54GS Models and only in conjunction with other Linksys "GS" wireless clients that also support Linksys "Speedbooster" technology.+
-How it Works:+=== Afterburner ===
-Just how do the Super G and Afterburner modes work?+'''Available Settings:''' Enabled or Disabled
-The 125-Mbit/s Afterburner technology uses just one channel. Instead of bonding two channels of data together, it squeezes more data through a single channel by reducing overhead and aggregrating smaller packets of data into larger ones.+'''Default Setting:''' Disabled
-In particular, Super G has been criticised in the past for using so much of the Wi-Fi band that other networks in the vicinity, which normally would automatically seek out and use non-overlapping channels to avoid interference problems, could be severely impacted.+'''Recommended Setting: '''Enabled if you need the feature, best to get a better router.
-By contrast, Super G gets part of its speed increase from "bonding" data from two non-overlapping wireless channels together (normal Wi-Fi uses only 1 out of the 11 channels in the 2.4-GHz range). This channel bonding, though, increases the potential for troublesome interference with microwave ovens, with cell phones and with other Wi-Fi networks (see our feature comparing the different speed boost technologies).+'''The help file says...''' * This should only be used with WRT54GS Models and only in conjunction with other Linksys "GS" wireless clients that also support Linksys "Speedbooster" technology.
-Check if Your Router Supports Afterburner 
-1.Connect to your router using telnet or ssh. Telnet/SSH and the Command Line 
-2.Type wl cap and press enter. It will return a list of capabilities. 
-3.If afterburner is listed you may enable Afterburner on the Advanced Settings tab under Wireless in DD-WRT. 
-TWEAK+'''How it works:'''
-You would enable this feature when you are tring to get all the proformance out of your 2.4GHz network running 802.11g mode or better only and you would only enable Afterburner when your hardware supports afterburner and your enviroment meets the requirements as well.+Just how do the Super G and Afterburner modes work?
-To set afterburner from the CMD enter the follwoing commands;+The 125-Mbit/s Afterburner technology uses just one channel. Instead of bonding two channels of data together, it squeezes more data through a single channel by reducing overhead and aggregrating smaller packets of data into larger ones.
-wl set wl0_afterburner=on+In particular, Super G has been criticised in the past for using so much of the Wi-Fi band that other networks in the vicinity, which normally would automatically seek out and use non-overlapping channels to avoid interference problems, could be severely impacted.
-wl set wl_afterburner=on+By contrast, Super G gets part of its speed increase from "bonding" data from two non-overlapping wireless channels together (normal Wi-Fi uses only 1 out of the 11 channels in the 2.4-GHz range). This channel bonding, though, increases the potential for troublesome interference with microwave ovens, with cell phones and with other Wi-Fi networks (see our feature comparing the different speed boost technologies).
 +Check if Your Router Supports Afterburner 1.Connect to your router using telnet or ssh. Telnet/SSH and the Command Line 2.Type wl cap and press enter. It will return a list of capabilities. 3.If afterburner is listed you may enable Afterburner on the Advanced Settings tab under Wireless in DD-WRT.
 +TWEAK
-------------------------------------------------------------------------------------------+You would enable this feature when you are tring to get all the proformance out of your 2.4GHz network running 802.11g mode or better only and you would only enable Afterburner when your hardware supports afterburner and your enviroment meets the requirements as well.
--This speed-enhancing feature is available on all DD-WRT enabled G routers. It is hardware independent. Afterburner will only improve speeds when used with clients that also have the Speedbooster/Afterburner feature; use with "normal" 802.11g clients will actually lower performance.+To set afterburner from the CMD enter the follwoing commands;
--Afterburner can be used in networks that also have 802.11b devices, and will not disable the use of them.+wl set wl0_afterburner=on
--Afterburner can help in environments dense with wireless signals.+wl set wl_afterburner=on
--Many MiniPCI cards built into notebooks and many PC Cards are based on Broadcom chips whose configurations support Afterburner+-This speed-enhancing feature is available on all DD-WRT enabled G routers. It is hardware independent. Afterburner will only improve speeds when used with clients that also have the Speedbooster/Afterburner feature; use with "normal" 802.11g clients will actually lower performance.
--In order to enjoy the benefits of Afterburner a.k.a. SpeedBooster, all clients and the AP must support afterburner.+-Afterburner can be used in networks that also have 802.11b devices, and will not disable the use of them.
--About 33 percent faster in real world file transfer test than basic 802.11g mode equipment+-Afterburner can help in environments dense with wireless signals.
--Afterburner is also known as:+-Many MiniPCI cards built into notebooks and many PC Cards are based on Broadcom chips whose configurations support Afterburner
-SpeedBooster+-In order to enjoy the benefits of Afterburner a.k.a. SpeedBooster, all clients and the AP must support afterburner.
-SuperSpeed+
-Turbo G 125mbps+
-125HSM+
-125* High Speed+
-G Plus+
 +-About 33 percent faster in real world file transfer test than basic 802.11g mode equipment
-Afterburner is not:+-Afterburner is also known as:
-Super-G / 108 mbps (Super-G is an Atheros technology)+
-XPress Technology is Dell's version of Frame Bursting, not Afterburner.+
 +SpeedBooster SuperSpeed Turbo G 125mbps 125HSM 125* High Speed G Plus
 +Afterburner is not: Super-G / 108 mbps (Super-G is an Atheros technology) XPress Technology is Dell's version of Frame Bursting, not Afterburner.
-Bluetooth Coexistence Mode 
-Values are Enable and Disable and Preemption,The default value is Disabled. 
-The Help file says..+=== Bluetooth Coexistence Mode ===
 +'''Available Settings:''' Enable, Disable, and Preemption
-How it Works:+'''Default Setting:''' Disable
 +'''Recommended Setting:''' Preemption
-------------------------------------------------------------------------------------------+'''The help file says...''' *
--I have had problems with bluetooth transfers (big big transfers), with this enabled, the problem has been solved. 
 +'''How it works:'''
-Wireless GUI Access+An 802.11 device and Bluetooth can interfere with each other when the 802.11 device operates on the 2.4 GHz band. All Bluetooth devices operate at the 2.4 GHz band. If you experience wireless disconnects, decreased range or speed, and other connectivity issues when you turn on some of your Bluetooth devices, try to change this option to "Enable" (this will make the router and Bluetooth device to take turns in using the spectrum for communication) or "Preemption" (the router will inform the Bluetooth device about the channel it is operating on, and the Bluetooth device can preemptively disable communication on the respective Bluetooth channels). Please note that this option requires your Bluetooth device to "cooperate". If the Bluetooth device doesn't implement the coexistence techniques, using this option will have no effect.
-The default value is Enabled.+
-Help file says..+-I have had problems with bluetooth transfers (big big transfers), with this enabled, the problem has been solved.
-The setting allows access to the routers setup (GUI) from wireless clients. Disable this if you wish to block all wireless clients from accessing the setup pages.+
-How it works: 
 +=== Wireless GUI Access ===
--------------------------------------------------------------------------------------------------------+'''Available Settings:''' Enable or Disable
 +'''Default Setting:''' Enable
--Once you have your dd-wrt configured you can enable this setting and no wireless clients will be able to access the routers dd-wrt GUI.+'''Recommended Setting:''' Enable, but largely up to the admin
--Wireless clients can still access the router over telnet and ssh when this setting is disabled.+'''The help file says...''' * The setting allows access to the routers setup (GUI) from wireless clients. Disable this if you wish to block all wireless clients from accessing the setup pages.
--Changing this from the default value would be for security reasons. 
-Wireless Network Mode+'''How it works:'''
-Default Value: Mixed+
 +-Once you have your dd-wrt configured you can enable this setting and no wireless clients will be able to access the routers dd-wrt GUI.
-Help file says..+-Wireless clients can still access the router over telnet and ssh when this setting is disabled.
-How it works:+-Changing this from the default value would be for security reasons.
-In Mixed mode, DD-wrt routers are able to offer various wifi network types (B, G and N) at the same time from a single 2.4GHz radio. 802.11n transmission is always embedded in an 802.11a, for 5GHz radios, or 802.11g for 2.4GHz radio transmissions. This is called Mixed Mode Format protection (also known as L-SIG TXOP Protection).+
 +=== Radio Time Restrictions ===
-Wireless Channel+'''Available Settings:''' Enable, Disable
-Default values are Channel Selection is 6, and channel width is 20MHz.+
 +'''Default Setting:''' Disable
-Help File says....+'''Recommended Setting:''' Disable, if you need it Enable it.
-Select the appropriate channel from the list provided to correspond with your network settings (in North America between channel 1 and 11, in Europe 1 and 13, in Japan all 14 channels). All devices in your wireless network must use the same channel in order to function correctly. Try to avoid conflicts with other wireless networks by choosing a channel where the upper and lower three channels are not in use.+
 +Click the green boxes to disable the wireless router for a given hour, or click the always on or always off buttons. Then click apply. You need to have an ntp server set and the correct timezone on the Setup – Basic Setup page in order for this to work correctly.
-How it works... 
-IEEE 802.11 is a set of standards that are published for the purposes of carrying out wireless local area network (WLAN) computer communication in the 2.4, 3.6 and 5 GHz frequency bands. They are implemented by the IEEE LAN/MAN Standards Committee ( aka "IEEE 802"). 
 +=== Wireless Multimedia Support Settings ===
-2.4GHz Channels+'''Available Settings:'''
-2.4GHz band in the 802.11 standard uses radio frequencies in the range of 2.412-2.484 GHz. 802.11 splits up the frequencies within the band into 14 radio channels, numbered 1-14. These are the 14 channels designated in the 2.4 GHz range spaced 5 MHz apart (with the exception of a 12 MHz spacing before Channel 14). The frequency range of a channel partially overlaps with the next one, so not all the channels are therefore independent. By default on a 2.4GHz band radio DD-WRT routers, channels 1, 6 and 11 have no overlap with each other; those three channels are known in the wireless community as the "standard" for wireless channel independence within the 2.4GHz band.+
-In North America this 2.4GHz "band" is implemented by dividing the 2.4GHz band into 13 channels each with a width of 22 MHz but also spaced only 5 MHz apart, with channel 1 centred on 2412 MHz and 13 on 2472, to which Japan adds a 14th channel 12 MHz above channel 13.+WMM Support: Enable or Disable
-5GHz Channels+No-Acknowledgement: Enable or Disable
-5GHz band in the 802.11 standard uses radio frequencies in the range of 4.980 GHz to 5.825 GHz. 802.11 splits up the frequencies within the band into 42 wireless radio channels, numbered 7 to 196. These are the 42 channels designated in the 5 GHz range and they are spaced 5 MHz apart. The frequency range of a channel partially overlaps with the next one, so not all the channels are therefore independent but unlike the 2.4GHz band the 5GHz band offers many more non overlapping channels.+'''Default Setting:'''
-In North America this 5GHz "band" is implemented by dividing the 5GHz band into 24 channels (36 to 165) each with a width of 22 MHz but also spaced only 5 MHz apart, with channel 36 centred on 5.180 GHz and 165 on 5.825 GHz.+WMM Support: Enable
 +No-Acknowledgement: Disable
 +'''Recommended Setting: '''
-**NOTE - The specifics of the frequency range and how channels are allocated is regulated by each country. Usually constrained in part by how each country allocates radio spectrum to various services. For example, in the 2.4Ghz band Japan has implemented 1 to 14 wireless channels, Europe #1-#13 and the FCC in the US decided with 1 to 11 wireless channels all within the same band. DD-WRT allows the use of all channels; this doesn't mean your client wireless adapter can support channels outside of its licensed region.+WMM Support: Enable
 +No-Acknowledgement: Disable
-How it works in DD-WRT:+Short for Wi-Fi Multimedia, is a Wi-Fi Alliance interoperability certification that provides a basic QoS "best effort" like function to Wi-Fi as well as other functions such as power saving, its a requirement & part of the 802.11n (& newer) specification. Disabling WMM will result in clients (ones that strictly obey specifications which is 90% of them) falling back to 802.11a/g rates (54M), the same way as using TKIP with WPA2 does.
-To configure your radio channels in the WebGUI you browse to the "Basic Settings" under the "Wireless" page on your DD-WRT router.+
-If you have dual band router (ie. Two Radios inside the router) you will see two sections for configurations listed in this page with the headings as "wl0" for the 2.4GHz radio and "wl1" for the 5GHz radio.+As for the various boxes below that, it would be better to use [https://www.dd-wrt.com/wiki/index.php/Quality_of_Service Quality of Service (QoS)] than to start changes those boxes.
- +
-DD-WRT has channel configuration settings that must be configured;+
- +
-Wireless mode, this determines if the router will be used as an Access Point, Repeater, Client or in an Ad-hoc configuration mode. Channel options are only avalaible to a router running in AP or Ad-Hoc wireless mode.+
- +
-Wireless Network mode, this setting determines what wireless protocols will be offered to the wireless clients that try to connect to the router. Depending on the wireless network mode your radio is configured for DD-WRT will have additional channel options for you to configure if you choose.+
- +
-Channel Width+
-A feature of DD-WRT is the Channel Width value(10Mhz, 20MHz or 40MHz). It allows a user to decide if DD-WRT will force the use of narrow, standard or wide channel use of the 2.4GHz band.+
- +
-10Mhz - Narrow channel - (more non overlapping channels but less bandwidth)+
- +
-20Mhz - Default DD-WRT configuration for the 2.4GHz band.+
- +
-40Mhz - Wide channel - (less non overlapping channels but more bandwidth)+
--If 40MHz is selected as the channel width the wireless channel will be bonded with another ajacent channel to provide more preformance. The channel the router uses to bond to the orgional wireless channel selection is known as the "wide channel". The orgional wireless channel selection bonds with either a channel above or below itself. DD-WRT uses the "Wide Channel" value to give the admin the option to select the upper or lower channel in refence to the main channel selection.+
- +
- +
- +
- +
-For an example of the channel options lets exmine DD-WRT running on "Linksys WRT610n" hardware which happens to be a 802.11n Dual-Band Router.+
- +
- +
-wl0 radio ( 2.4GHz band )+
- +
- +
-802.11b/g and n and mixed modes of all three are offered by DD-WRT running on top of 802.11n hardware , no matter which mode is selected the 2.4GHz band radio can only use radio frequencies in the range of 2412-2484 MHz (channels 1 to 14);+
- +
-Wireless Mode: AP+
-Wireless Network Mode: B-Only, G-Only and BG-Mixed+
- +
- +
-DD-WRT channel options when configured in the wireless modes above:+
- +
-1) - Channel Selection+
-Channel selections offered by DD-WRT are 1 to 14 or the DD-WRT "Auto" channel selection feature.+
- +
-Wireless Mode: AP+
-Wireless Network Mode: N-Only and Mixed+
- +
-DD-WRT channel options when configured in the wireless modes above:+
- +
-1) - Wireless Channel Selection+
-Channel selections offered by DD-WRT are 1 to 14 or the DD-WRT "Auto" channel selection feature.+
- +
-2) - Wireless Channel Width+
-"Auto" can be selected as well to use the DD-WRT of automatic selection of wireless channel width. As a note if "Auto" is selected for the wireless channel width the wireless channel selection will be reset to use the "Auto" feature when you click save.+
- +
-3) - Wide Channel selection.+
-DD-WRT uses the "Wide Channel" value to give the admin the option to select the upper or lower channel in refence to the main wireless channel selection.+
- +
- +
-***NOTE - If 40MHz is selected as the channel width value in mixed mode wireless network configuration the use of CTS protection mode must enabled. This feature provides a mechonism for 802.11g clients to be able to connect and operate correctly on the same 2.4GHz radio.+
- +
- +
- +
-wl1 radio ( 5GHz band )+
- +
- +
-802.11a, n and mixed modes of both are offered by DD-WRT running on top of 802.11n hardware , no matter which mode is selected the 5GHz band radio can only use radio frequencies in the range of 5.170GHz to 6.080GHz (channels 34 - 216).+
- +
-Wireless Mode: AP+
-Wireless Network Mode: A-Only+
- +
-DD-WRT channel options when configured in the wireless modes above:+
- +
-1) - Channel Selection+
-Channel selections offered by DD-WRT are 34 to 216 or the DD-WRT "Auto" wireless channel selection feature.+
- +
- +
- +
-Wireless Mode: AP+
-Wireless Network Mode: N-Only and NA-Only+
- +
-DD-WRT channel options when configured in the wireless modes above:+
- +
-1) - Wireless Channel Selection+
-Channel selections offered by DD-WRT are 34 to 216 or the DD-WRT "Auto" wireless channel selection feature.+
- +
-2) - Wireless Channel Width+
-"Auto" can be selected as well to use the DD-WRT of automatic selection of wireless channel width. As a note if "Auto" is selected for the wireless channel width the wireless channel selection will be reset to use the "Auto" feature when you click save.+
- +
-3) - Wide Channel selection.+
-DD-WRT uses the "Wide Channel" value to give the admin the option to select the upper or lower channel in refence to the main wireless channel selection.+
- +
-***NOTE - If 40MHz is selected as the channel width value in mixed mode wireless network configuration the use of CTS protection mode must enabled. This feature provides a mechonism for 802.11a clients to be able to connect and operate correctly on the same 5GHz radio.+
- +
- +
- +
--------------------------------------------------------------------------------------------------------+
- +
--If you want to introduce channel bonding in your wireless enviroment you should also start with "CTS Protection" set to Auto as well.+
- +
- +
- +
-Sensitivity Range (ACK Timing)+
-Default Value: 2000 meters+
- +
- +
-Help file says..+
-Adjusts the ack timing in Atheros typical way based on the maximum distance in meters .A value of 0 disables ack timing completely for broadcom firmwares. On Atheros based firmwares a value of 0 will turn into auto ack timing mode+
- +
- +
- +
-How it works:+
-1.) AP sends a message: Everybody wait X time for a response+
-2.) Client receives+
-3.) Client sends a response to the AP called and ACK - Acknowledges the command waiting for X time.+
-4.) AP sees the ACK+
-5.) Other Clients and AP are free to send+
- +
- +
--------------------------------------------------------------------------------------------------------+
- +
- +
--Ack timing adjustment is used for distance links when the time needed to tramit is greater then than the amount of time the sender waits before retrying to transmit the same packet again.+
- +
- +
--You want to set the ack timing to 2x the distance between bridged routers measured in meters.+
- +
- +
--If the ACK timing is too high it will not affect the throughput that much. If the ACK time is too low it can drop your throughput to the point of being unusable and can even make the system not connect.+
- +
- +
--Recommended setting is to 0 for a household network. Which for linksys users means dd-wrt doesn't use ACK timing at all.+
- +
--Maximum theororetical ACK timeouts (not sure on thouroughness) 802.11a : 409us ~ 61km 802.11b : 744us ~ 111km 802.11g : 372us ~ 55km+
==References== ==References==
Advanced Wireless Settings Reference Guide - http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51039 Advanced Wireless Settings Reference Guide - http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51039
 +
 +[[Category:Wlan]]
 +[[Category:Advanced tutorials]]
 +[[Category:Settings]]
 +[[Category:Documentation]]

Current revision

English •  Deutsch •  Español •  Français •  Italiano •  日本語 •  Polski •  Português •  Русский •  Svenska •  ‪中文(中国大陆)‬ •  ‪中文(台灣)‬ • 

Contents

[edit] Introduction

Before reading this page please be familiar with Basic Wireless Settings.

This page contains more robust explanations of Advanced Wireless Settings than the built in help provides. It was originally authored by Stephen Suley in this thread. Note, this is mainly for Broadcom Routers.

See QCA wireless settings page for specific info for Qualcomm Atheros advanced settings.

[edit] Advanced Wireless Settings

[edit] Authentication Type

Available Settings: Auto, Shared Key

Default Setting: Auto

Recommended Setting: Auto


The help file says... * Allows either Open System or Shared Key authentication to be used. For Open System authentication, the sender and the recipient do NOT use a WEP key for authentication. For Shared Key authentication, the sender and recipient use a WEP key for authentication. If you want to use only Shared Key authentication, then select Shared Key.


How it works:

The following steps occur when two devices use Shared Key Authentication:

  1. The client adapter sends an authentication request to the access point.
  2. The access point sends back a challenge text to the client adapter.
  3. The client uses its configured 64-bit or 128-bit default key to encrypt the challenge text, and it sends the encrypted text to the access point.
  4. The access point decrypts the encrypted text using its configured WEP key that corresponds to the client's default key. The access point compares the decrypted text with the original challenge text. If the decrypted text matches the original challenge text, then the access point and the client share the same WEP key, and the access point authenticates the client.
  5. The client will now connect to the network.


If the decrypted text does not match the original challenge text (that is, the access point and station do not share the same WEP key), then the access point will refuse to authenticate the station, and the station will be unable to communicate with either the 802.11 network or Ethernet network.

-This would add an additional layer of connection authentication for wireless clients. Using this feature means you must modify the wifi adapter settings on a client before it can connect to this device.

-Client wifi adapters must support "Shared Key" authentication to use this setting.

-If using a client connected to the router over wireless and you set authentication key to shared, from auto, and your computer doesn't support shared, you will lose all Internet access and access to the webgui and you will have to connect with a wire to the router to change the setting back to auto. You can also do a hard reset to get it back to defaults to fix this.

-I equate using "Shared key" to adding authentication security to the "Phase 1" of the wifi connection process

-Changing this from the default value would be for security reasons.

[edit] Basic Rate

Available Settings: Default, 1-2Mbps, all

Default Setting: Default

Recommended Setting: Default

The help file says... * Depending on the wireless mode you have selected, a default set of supported data rates will be selected. The default setting will ensure maximum compatibility with all devices. You may also choose to enable all data rates by selecting ALL. For compatibility with older Wireless-B devices, select 1-2Mbps.


How it works:

?


[edit] MIMO - Transmission Fixed Rate

Available Settings: Auto, a range of values from 6.5Mbps upwards

Default Setting: Auto

Recommended Setting: Auto

The help file says...

  • The idea is the same as "Transmission Fixed Rate" You can select from a range of MIMO transmission speeds, or keep the default setting, Auto, to have the router automatically use the fastest possible data rate and enable the Auto-Fallback feature. Auto-Fallback will negotiate the best possible connection speed between the router and a wireless client.


How it works:

This parameter is used for 802.11n transmissions only. 802.11a/b/g transmissions from the router use the "Transmission Fixed Rate" parameter.

IEEE 802.11n builds on previous 802.11 standards by adding multiple-input multiple-output (MIMO). MIMO uses multiple transmitter and receiver antennas to improve the system performance. MIMO is a technology which uses multiple antennas to coherently resolve more information than possible using a single antenna. Two important benefits it provides to 802.11n are antenna diversity and spatial multiplexing. MIMO technology relies on multipath signals. Multipath signals are the reflected signals arriving at the receiver some time after the line of sight (LOS) signal transmission has been received. MIMO uses the multipath signal's diversity to increase a receiver's ability to recover the message information from the signal.

Another ability MIMO technology provides is Spatial Division Multiplexing (SDM). SDM spatially multiplexes multiple independent data streams, transferred simultaneously within one spectral channel of bandwidth. MIMO SDM can significantly increase data throughput as the number of resolved spatial data streams is increased. Each spatial stream requires a discrete antenna at both the transmitter and the receiver. In addition, MIMO technology requires a separate radio frequency chain and analog-to-digital converter for each MIMO antenna which translates to higher implementation costs compared to non-MIMO systems.


[edit] Transmission Fixed Rate

Available Settings: Auto, range from 1 to 54 Mbps

Default Setting: Auto

Recommended Setting: Auto

The help file says... * The rate of data transmission should be set depending on the speed of your wireless network. You can select from a range of transmission speeds, or keep the default setting, Auto, to have the router automatically use the fastest possible data rate and enable the Auto-Fallback feature. Auto-Fallback will negotiate the best possible connection speed between the router and a wireless client.


How it works:

?


[edit] CTS Protection mode

Available Settings: Auto, Disabled

Default Setting: Auto

Recommended Setting: Auto

The help file says... * When set to Auto, a protection mechanism will ensure that your Wireless-B devices will connect to the Wireless-G router when many Wireless-G devices are present. However, performance of your Wireless-G devices may be decreased.


How it works:

CTS Protection mode is a protection mechanism that operates on the physical (PHY) level frame. At a very high level summary of the process when multiple devices are connected to an access point, they can occasionally be transmitting data to the access point at the same time because neither one can see the other client well enough to determine if it is transmitting on the channel or not. When this happens, the AP will discard both pieces of colliding data, thus contributing to error rates. CTS (clear to send) protection skirts this issue by delegating which device gets to transmit at a given time.

CTS Protection mode and DD-wrt:

In its default configuration dd-wrt uses it as a to provide a way of ensuring coexistence between the legacy and the new wifi devices. Adding to that by using CTS protection mode and modifying RTS threshold value you can tweak the operation of the CTS protection mechanism this can then be combined with the Fragmentation Threshold tweak to help troubleshoot\fix connectivity and\or performance issues etc. Remember tweaking the CTS protection process by manipulating the RTS and the Fragmentation Threshold value often comes at a price usually by decreasing the overall throughput to the WLAN.

Once CTS Protection mode is configured correctly within your WLAN environment there are specific scenarios that occur and the software will activate the CTS protection mechanisms;

Here are a few examples of what triggers CTS to be employed by the dd-wrt router software.

CTS Protection trigger 1; - NON-default dd-wrt behavior A client that wants to use the radio channel to send data packet(s) of a size that is equal or above the defined RTS threshold value.

CTS Protection trigger 2; -default dd-wrt behavior A 802.11g client attempts to connect to a SSID that is using channel bonding. Transmissions using a 40 MHz channel in the presence of 802.11a or 802.11g clients require using CTS protection mode. This will apply the CTS protection mechanism on both 20 MHz halves of the 40 MHz channel, to prevent interference with legacy devices and allow proper operation of the 802.11a and 802.11g clients.

CTS Protection trigger 3; -default dd-wrt behavior If you are running in mixed wireless mode on a 802.11n router and you have 802.11b clients in your environment. CTS Protection is used to allow the 802.11b client to operate correctly and also not to interfere with the operation of the 802.11a,g, and N client transmissions.

Also; - An 11b device associates to the AP. - same as trigger 3 - An 11b AP on the same channel can be heard by the AP - variant on trigger 3 - The AP hears an 11g AP that is in protection because of an 11b device associated. -another variation of the trigger 3 event.

NOTE: Trigger 1 will never happen on the dd-wrt default configuration due to the default values of the RTS Threshold being 2347 and the Fragmentation Threshold value being 2346. Based on the data packet fragmentation threshold default value at 2346 in size dd-wrt will apply fragmentation to all packets meeting this criteria. Because of this fragmentation process the 2347 packet size needed to trigger the RTS threshold is never reached.

For a closer look at what happens in one of these cases lets look at a case like trigger number 1 list above and the steps in the CTS protection process.

Example. A client that wants to use the radio channel to send data packet(s) of a size that is equal or above the defined RTS threshold value.

Steps in the CTS Protection mode process for the above example.

1.) The client wishing to send date over the channel first sends an RTS (request to send) packet to the AP.

2.) As the AP broadcast it beacons packet over the WLAN as part of its normal operation, The beacon packet has information within it that declares to all the clients on the entire WLAN not to try and send any information for a specified period of time. The AP then sends a CTS packet to the client that requested the CTS in the first place. The AP has made a single client the "owner" of the wifi channel and then the AP listens only to that client until it is done transmitting; its in protection mode.

3.)The process is repeated for all request to transfer data,which for whatever reason triggers the CTS protection mechanisms, on a first come first serve basis.

TWEAK: Implementing additional CTS Protection mode triggers and there frequency of operation on top of the default dd-wrt CTS protection mode configuration;

1.) The AP running dd-wrt has the CTS Protection mode is set to Auto by default and then you could adjust the RTS threshold value to something lower then 2346 (Which is the default fragmentation threshold value on dd-wrt) on the AP.

2.) All clients connected to the dd-wrt AP are configured for CTS\RTS mode as apposed to setting of "disabled" or "CTS-Self" mode.

NOTE Typically the The RTS Threshold value on dd-wrt is only lowered when needed to address or troubleshoot some sort of connectivity or performance issue with a client or all clients on a WLAN. Adjusting the value is a balancing act between getting your problem fixed and losing overall WLAN speed. The more times CTS protection mode is triggered in a period of time "its frequency" the more impact it will have; good or bad. So start with 2340, then 2320, 2300 etc...

Guide when to use and why.

-If your trying to tweak out every drop of performance in an ideal setup then you can disable this on the AP and clients. Test again to see if it helps for better results, it should.

-If you want to try 40MHz with your 802.11n clients you might want to start with CTS Protection set to Auto. You do this in case you have 802.11a or g or even some N clients that do not support 40GHz transmissions or "channel bonding" as it is sometimes called.

-If you have a 802.11n based router running in mixed wireless mode that you want to connect 802.11b clients you need to have CTS protection mode set to Auto meaning enabled.

-If CTS Protection makes things faster a network redesign might be needed.

-"CTS to self" based protection - an alternate implementation method of CTS; where by the device willing to send frames over the WLAN first sends a CTS frame to itself. "CTS to self" based protection has less overhead, but it must be taken into account that this only protects against devices receiving CTS frame (e.g. if there are 2 "hidden" stations, there is no use for them to use "CTS to self" protection, because they will not be able to receive CTS sent by other station - in this case stations must use RTS/CTS so that other station knows not to transmit by seeing CTS transmitted by AP).If you have set the CTS protection mode to disabled on the dd-wrt AP, then this is a good choice for the client configuration.


[edit] Frame Burst

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disable

The help file says...

  • Frame burst allows packet bursting which will increase overall network speed though this is only recommended for approx 1-3 wireless clients, Anymore clients and there can be a negative result and throughput will be affected.


How it works:

Frame-bursting is a technique in wireless technology supported by the draft 802.11e Quality of Service specification. Frame Bursting may increase the throughput of any (point-to-point) 802.11A, B, G or N link connection in certain conditions. This is done by reducing the overhead associated with the wireless session from either: * Access Point to Client and vice versa

  • Client to Client in ad-hoc mode.


This can result in the ability to support higher data throughput in mixed and uniform networks.

It enhances the ability of a wireless client to upload data at faster speeds by using the inter-frame wait intervals to "burst" a sequence of up to three packets before waiting the required period. This allows more data to be sent and less waiting to occur, however, can result in unfair allocation of airtime where there are a mix of clients of which only some support Frame-Bursting as the inter-frame wait periods are contention periods where other stations with data to send can seize the air and send their data.

-Frame Burst is useful when transferring large data, but the benefits are not as big as most people hope for.

-It allows, as name says, a client to burst many frames in a short amount of time.


[edit] Beacon Interval

Available Settings: range from 10 to 65535 ms

Default Setting: 100 ms

Recommended Setting: 50 ~ 300 for 2.4 GHz & 75 ~ 250 for 5 GHz

The help file says... * The Beacon Interval value indicates the frequency interval of the beacon. A beacon is a packet broadcast by the router to synchronize the wireless network. 50 is recommended in poor reception.


How it works:

The term beacon signifies a specific data transmission from the wireless access point (AP), which carries the SSID, the channel number and security protocols such as WEP (Wired Equivalent Protection) or WPA (Wi-Fi Protected Access). This transmission does not contain the link layer address of another Wi-Fi device, therefore it can be received by any LAN client.The beacon frame, which is a type of management frame, can be likened with the "heartbeat" of a wireless LAN, enabling stations to establish and maintain communications in an orderly fashion.

What is a Beacon Interval As mentioned above, the beacon interval is a fixed, configurable parameter. Typically, the beacon interval setting is not touched at all in the WLAN network installation phase, but the default value selected by the equipment supplier is used. If the beacon interval is long, maximum capacity in the Access Point is achieved. However, it will the take a long time for WLAN terminals to scan for Access Points in the area and to update RSSI and load information for already found Access Points. This obviously reduces terminal throughput and wastes battery. On the other hand, if the beacon interval in short, passive scanning performed by the WLAN terminals will be faster, but the overall capacity of the Access Point will be reduced.

NOTE There are no special rules for sending beacons, and they must be sent using the mandatory 802.11 carrier sense multiple access / collision avoidance (CSMA/CA) algorithm. If another station is sending a frame when the beacon is to be sent, then the access point (or NIC in an ad hoc network) must wait. As a result, the actual time between beacons may be longer than the beacon interval. Clients, however, compensate for this inaccuracy by utilizing the timestamp found within the beacon packet information.

What is a Beacon?

A typical beacon frame is approximately fifty bytes long, with about half of that being a common frame header and cyclic redundancy checking (CRC) field. As with other frames, the header includes source and destination MAC addresses as well as other information regarding the communications process. The destination address is always set to all ones, which is the broadcast Medium Access Control (MAC) address. This forces all other stations on the applicable channel to receive and process each beacon frame. The CRC field provides error detection capability.

The beacon's frame body resides between the header and the CRC field and constitutes the other half of the beacon frame. Each beacon frame carries the following information in the frame body:

Beacon interval. This represents the amount of time between beacon transmissions. Before a station enters power save mode, the station needs the beacon interval to know when to wake up to receive the beacon (and learn whether there are buffered frames at the access point).

Timestamp. After receiving a beacon frame, a station uses the timestamp value to update its local clock. This process enables synchronization among all stations that are associated with the same access point.

Service Set Identifier (SSID). The SSID identifies a specific wireless LAN. Before associating with a particular wireless LAN, a client must have the same SSID configured as the access point. By default, access points include the SSID in the beacon frame to enable sniffing functions (such as that provided by Windows XP) to identify the SSID and automatically configure the wireless network interface card (NIC) with the proper SSID. DD-Wrt also has an option to disable the SSID from being broadcast in beacon frames to reduce security issues.

Supported rates. Each beacon carries information that describes the rates that the particular wireless LAN supports. For example, a beacon may indicate that only 1, 2, and 5.5Mbps data rates are available. As a result, an 802.11b station would stay within limits and not use 11 Mbps. With this information, stations can use performance metrics to decide which access point to associate with.

Parameter Sets. The beacon includes information about the specific signaling methods (such as frequency hopping spread spectrum, CTS Protection mode and RTS Threshold,direct sequence spread spectrum, etc.). For example, a beacon would include in the appropriate parameter set the channel number that an 802.11b access point is using. Likewise, a beacon belonging to frequency hopping network would indicate hopping pattern and dwell time.

Capability Information. This signifies requirements of stations that wish to belong to the wireless LAN that the beacon represents. For example, this information may indicate that all clients must use wired equivalent privacy (WEP) in order to participate on the network.

Traffic Indication Map (TIM). An access point periodically sends the TIM within a beacon to identify which stations using power saving mode have data frames waiting for them in the access point's buffer. The TIM identifies a station by the association ID that the access point assigned during the association process.

NOTE Today beacon frames also contain a load information that informs WLAN terminals currently connected to a specific Access Point or considering making a handover to that Access Point about the load situation. This information helps the WLANterminals in making correct handover decision, in addition to the information from the comparisons of RSSI readings obtained by scanning, and thus ensures that WLAN traffic is divided more evenly between all Access Points in the area.

TWEAK:

By increasing the beacon interval, you can reduce the number of beacons and associated overhead, but that will likely delay the association and roaming process because stations scanning for available access points may miss the beacons.

You can decrease the beacon interval, which increases the rate of beacons. This will make the association and roaming process very responsive; however, the network will incur additional overhead and throughput will go down.

In addition, stations using power save mode will need to consume more power because they'll need to awaken more often, which reduces power saving mode benefits. In an idle network, beacons dominate all other traffic.

Guide to tweaking: The amount of overhead that the transmissions of beacon frames generate is substantial; however, the beacon serves a variety of functions. For example, each beacon transmission identifies the presence of an access point.

How a beacon interval impacts the client By default, radio NICs passively scan all RF channels and listen for beacons coming from access points in order to find a suitable access point. When a beacon is found, the radio NIC learns a great deal about that particular network. This enables a ranking of access points based on the received signal strength of the beacon, along with capability information regarding the network. The radio NIC can then associate with the most preferable access point. After association, the station continues to scan for other beacons in case the signal from the currently-associated access point become too weak to maintain communications. As the radio NIC receives beacons from the associated access point, the radio NIC updates its local clock to maintain timing synchronization with the access point and other stations. In addition, the radio NIC will abide by any other changes, such as data rate, that the frame body of the beacon indicates. The beacons also support stations implementing power saving mode. With infrastructure networks, the access point will buffer frames destined for sleeping stations and announce which radio NICs have frames waiting through the TIM (DTIMS) that's part of the beacon

Do clients send beacon frames too??... As apposed to beacons sent out by AP's, Clients send out "probe request" frames; It's like an opposite to a beacon, clients use a probe request packets to play there role in the 802.11 WLAN. An 802.11 probe response frame is very similar to a beacon frame, except that probe responses don't carry the TIM info and are only sent in response to a probe request. A client may send a probe request frame to trigger a probe response when the client needs to obtain information from another client on the same WLAN. A client, for instance, will broadcast a probe request when using active scanning to determine which access points are within range for possible association. Some sniffing software (e.g., NetStumbler) tools send probe requests so that access points will respond with desired info.

-Beacons are packets sent by an access point to synchronize a wireless network.

-Normal Traffic Indication Message(TIM)s that are present in every beacon are for signaling the presence of unbuffered unicast data.


[edit] DTIM Interval

Available Settings: range from 1 to 255

Default Setting: 1

Recommended Setting: 1 (assuming default beacon interval of 100 is used)

The help file says... * Indicates the interval of the Delivery Traffic Indication Message (DTIM). A DTIM field is a countdown field informing clients of the next window for listening to broadcast and multicast messages. When the router has buffered broadcast or multicast messages for associated clients, it sends the next DTIM with a DTIM Interval value. Its clients hear the beacons and awaken to receive the broadcast and multicast messages.


How it works:

A Delivery Traffic Indication Message is a kind of Traffic Indication Message(TIM) which informs the clients about the presence of buffered and/or multicast/broadcast data on the access point. It is generated within the periodic beacon at a frequency specified by the DTIM Interval. After a DTIM, the access point will send the multicasted/broadcasted data on the channel following the normal channel access rules (CSMA/CA).

According to the 802.11 standards, a Delivery Traffic Indication Message (DTIM) period value is a number that determines how often a beacon frame includes a Delivery Traffic Indication Message, and this number is included in each beacon frame. A DTIM is included in beacon frames, according to the DTIM period, to indicate to the client devices whether the access point has buffered broadcast and/or multicast data waiting for them. Following a beacon frame that includes a DTIM, the access point will release the buffered broadcast and/or multicast data, if any exists.

Since beacon frames are sent using the mandatory 802.11 carrier sense multiple access/collision detection (CSMA/CD) algorithm, the access point must wait if a client device is sending a frame when the beacon is to be sent. As a result, the actual time between beacons may be longer than the beacon interval. Client devices that awaken from power-save mode may find that they have to wait longer than expected to receive the next beacon frame. Client devices, however, compensate for this inaccuracy by utilizing the time-stamp found within the beacon frame.

The 802.11 standards define a power-save mode for client devices. In power-save mode, a client device may choose to sleep for one or more beacon intervals waking for beacon frames that include DTIMs. When the DTIM period is 2, a client device in power-save mode will awaken to receive every other beacon frame. Upon entering power-save mode, a client device will transmit a notification to the access point, so that the access point will know how to handle unicast traffic destined for the client device. The client device will begin to sleep according to the DTIM period.

-The higher the DTIM period, the longer a client device may sleep and therefore the more power that particular client device may potentially save.

-Client devices in wireless networks may have conflicting requirements for power consumption and communication throughput when in power-save mode. For example, laptops may require relatively high communication throughput and may have low sensitivity to power consumption. Therefore, a relatively low DTIM period, for example 1, may be suitable for laptops . However, cellphones may require relatively low communication throughput and may be operated by batteries of relatively low capacity. Therefore, a relatively high DTIM period, for example 8, may be suitable for cellphones. Further, PDA\Smart phones may require a medium to high communication throughput and may be operated by batteries of relatively low capacity. Therefore, a medium DTIM period, for example a value of 4, may be suitable for these devices.

-Currently, an access point is able to store only a single DTIM period. Consequently, different client devices in power-save mode will all wake up for the same beacon frames according to the DTIM period. Currently, a network manager may need to balance the conflicting requirements for power consumption and communication throughput when in power-save mode of client devices in different wireless networks when configuring the DTIM period of an access point. In the future an access point with support for two or more SSIDs may have SSID-dependent DTIM periods rather than a single DTIM period for all SSIDs. In other words, the network manager may configure the access point with DTIM periods on a per SSID basis. A network manager may consider the requirements of power consumption and communication throughput of client devices in a particular wireless networks when determining which DTIM period to configure for which SSID. A higher DTIM period may increase the potential savings in power consumption but may reduce the communication throughput, and vice versa


[edit] Fragmentation Threshold

Available Settings: range from 256 to 2346

Default Setting: 2346

Recommended Setting: 2346

The help file says... * It specifies the maximum size for a packet before data is fragmented into multiple packets. If you experience a high packet error rate, you may slightly increase the Fragmentation Threshold. Setting the Fragmentation Threshold too low may result in poor network performance. Only minor modifications of this value are recommended.


How it works:

The Threshold for fragmentation to occur is a 802.11 configuration parameter. This is an optional feature, the 802.11 standard and dd-wrt includes the ability for access points to fragment packets for improving performance in the presence of RF interference and marginal coverage areas

To use fragmentation means to divide 802.11 frames into smaller pieces (fragments) that are sent separately to the destination. Each fragment consists of a MAC Layer header, frame check sequence (FCS), and a fragment number indicating its ordered position within the frame. Because the source transmits each fragment independently, the receiving destination replies with a separate acknowledgement for each fragmen

-Fragmentation only applies to frames having a unicast (address assigned to a single host on your network) receiver address.

-The use of fragmentation can increase the reliability of frame transmissions. Because of sending smaller frames, collisions are much less likely to occur.

-Similar to RTS, a good method to find out if you should activate fragmentation is to monitor the wireless LAN for collisions. If you find a relatively large number of collisions, then try using fragmentation. This can improve throughput if the fragmentation threshold is set just right.

-try setting the fragmentation threshold to around 800 bytes first, then tweak it until you find the best results.

-As with any 802.11 tuning mechanisms, the goal is to improve performance.

-If what you do improves throughput, then you're doing the right thing.

-If hidden nodes are present the use of RTS and\or CTS could be a better way to reduce collisions.


[edit] RTS Threshold

Available Settings: range from 0 to 2347

Default Setting: 2347

Recommended Setting: 2347

The help file says... * The router sends Request to Send (RTS) frames to a particular receiving station and negotiates the sending of a data frame. After receiving an RTS, the wireless station responds with a Clear to Send (CTS) frame to acknowledge the right to begin transmission.


How it works:

The RTS Threshold value is a configurable parameter within the CTS Protection mechanism. The RTS threshold is used as a trigger to engage the back and forth of RTS and CTS messages between AP and client. The triggers purpose is a type of handshaking approach that provides and additional layer of control over the use of the shared medium, or in the case of DD-WRT the Radio Channel or WLAN. If enabled, A node (client) wishing to send data initiates the process by sending a Request to Send frame (RTS).

How the RTS Threshold value works in DD-WRT. As discussed in the CTS Protection mode section of this document, when a packet that a DD-WRT access point is transmitting is larger than the RTS threshold set in the configuration, DD-WRT will initiate the CTS Protection mode handshaking function. If the network packet being sent is smaller or fragmented to a size lower than the preset RTS threshold size, the CTS Protection mode mechanism will still not be enabled for that packet. Note if the packet size happens to be equal to the threshold, DD-WRT will not use CTS.

Tweak: In DD-WRT, the default configuration after a flash sets the CTS Protection mode not to get triggered to protect transmissions by RTS. This is due to the fact that Sending RTS frames is turned off by default (threshold >=2347bytes). If the packet size the node wants to transmit is larger than the threshold, the RTS/CTS handshake gets triggered. If the packet size is equal to or less than threshold the data frame gets sent immediately.

The method for enabling RTS-CTS triggers on DD-WRT is different than with client NICs. For DD-WRT, you enable RTS-CTS handshaking triggers within WebGUI by setting a specific packet size threshold (0 - 2347 bytes) in the user configuration interface; only minor modifications are recommended.

Set this value to a 2340 bytes as a start, test, then if needed try a lower value, etc.

Save. Apply. Reboot.

Rollback Set the value back to its default value of 2347 bytes and disable RTS threshold triggers in the CTS Protection mode operation on the router.


[edit] Max Associated Clients

Available Settings: range from 1 to 256

Default Setting: depends on the router, usually 128

Recommended Setting: What ever you want

The help file says... *


How it works:

This number will determine how many clients can be connected to the routers wireless LAN (WLAN)


[edit] AP Isolation

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disable for private home Wi-Fi with trusted users, enable for public/guest Wi-Fi hotspot

The help file says... * This setting isolates wireless clients so access to and from other wireless clients are stopped.


How it works:

Wireless access points work by bridging the wireless port to the wired switch ports and router port. Everything happens at the MAC address level and does not involve IP addresses,NETBIOS over TCP/IP (also known as MS Networking). Just MAC addresses.

The wireless bridge builds a bridging table consisting of a table of "heard" (or sniffed) MAC addresses that appear on various ports. Think of the router having just 3 available ports; Wireless, Ethernet switch, and router port. If the destination MAC address of a port is shows up in the MAC address table as sitting on a specific port, only that port gets the traffic. Broadcasts, which have no destination MAC address are sent to all ports.

When this feature is enabled the software builds a logical rule (or filter) for these MAC addresses and ports that says:

"If the packet originates on the wireless port, it can only send and receive packets that are destined or originate from the router port or ethernet switch port."

Not a very complex rule, but one which totally prevents wireless client to client traffic. Not even broadcasts will go from wireless client to client.

-prevents one wireless client communicating with another wireless client.

-This breaks the connection between WLAN and WLAN

-No improvement in performance, performance is exactly the same. The difference is in "reliability" or ability to survive in a multi-path environment.

-You enable this if you are running a hotspot. Click Network Neighborhood in a motel sometime, see if the motel needs to set AP isolation.

-Changing this from the default value would be for security reasons.


[edit] TX Antenna / RX Antenna

Available Settings: 1, 1+2, 1+3, 1+2+3, 1+2+3+4 (varies by router)

Default Setting: Varies by router

Recommended Setting: Varies by router

This setting is critical for proper, smooth, fast Wi-Fi performance. 2x2:2 routers will either have TX/RX chains at 1+2/1+2, 1+3/1+3, 1+2/1+3, or 1+3/1+2. This can take some time to find the proper setting but its worth it, you can more easily find the correct setting by using a 802.11n client thats capable of 300 Mbps link. Note the TX/RX link rates on the wireless status page, when set incorrectly one or both of the rates will drop to a much lower speed such as 200, 170, 81 etc. This is best done with the client less than 10 feet from the AP with clear line of sight. Some routers with chains set incorrectly such as D-Link DIR-615 C1, will deny connections to clients, heavily reduce throughput, and other errors. Searching the FCC ID of your router will aid in setting the correct chain settings. Some popular routers such as the Netgear WNDR3700 v1/2/4 and D-Link DIR-825 B1/B2 require both chains set at 1+2 for proper Wi-Fi performance. Default is not always right!*

* With builds around r21061 or later, most units have the proper defaults preset & invalid options removed, such as 1+2+3 for TX/RX on WNDR3700 v1, v2, & v4 as the router only has 2 chains each therefor only has 1 & 1+2 available to be selected. While a Asus N66U have 1+2+3 as they are 3x3:3 units. An example 4x4:4 unit is the R7800.

* The option may have disappeared in recent builds (>336XX).

The help file says... * This is used in conjunction with external antennas to give them optimum performance. On some router models left and right antennas may be reversed depending on you point of view.


How it works:

This value determines which Antenna connection is used for the purposes of Rx and Tx functions.


[edit] Preamble

Available Settings: Short, Long, Auto

Default Setting: Long

Recommended Setting: Short

The help file says... * If your wireless device supports the short preamble and you are having trouble getting it to communicate with other 802.11b devices, make sure that it is set to use the long preamble.


How it works:

The preamble is used to communicate to the receiver that data is on its way. Technically speaking, it is the first portion of the Physical Layer Convergence Protocol/Procedure (PLCP) Protocol Data Unit (PDU). The preamble allows the receiver to acquire the wireless signal and synchronize itself with the transmitter. A header is the remaining portion and contains additional information identifying the modulation scheme, transmission rate and length of time to transmit an entire data frame.

Long Preamble: * Compatible with legacy IEEE* 802.11 systems operating at 1 and 2 Mbps (Megabits per second)

  • PLCP with long preamble is transmitted at 1 Mbps regardless of transmit rate of data frames
  • Total -Long Preamble transfer time is a constant at 192 usec (microseconds)


Short Preamble: * Not compatible with legacy IEEE 802.11 systems operating at 1 and 2 Mbps -PLCP with short preamble: Preamble is transmitted at 1 Mbps and header at 2 Mbps - -Total Long Preamble transfer time is a constant at 96 usec (microseconds)

  • Unless you have 802.11b (1 or 2Mbits/sec) client radios in your system, there's no need for a long preamble. The default for most access points is "automatic". It only enables long preambles when associated with a 1 or 2Mbit/sec client radio.
  • Most access points (AP) and broadband WiFi routers are configured for a Long Preamble or have a setting that automatically detects the preamble and adjusts accordingly. A majority of client WiFi adapters should also be pre-configured in the same manner. This is done as a precautionary measure for networks that may still employ legacy devices.



[edit] Shortslot Override

Available Settings: Short, Long, Auto

Default Setting: Auto

Recommended Setting: Short

The help file says... *


How it works:

Short Slot Times - The amount of time a device waits after a collision before retransmitting a packet. You can increase throughput on 802.11g, 2.4-GHz radios by enabling Shortslot override (most .11g radios enable this by default). Reducing the slot time from the standard 20 microseconds to the 9-microsecond short slot time decreases the overall backoff, which increases throughput. Backoff, which is a multiple of the slot time, is the random length of time a station waits before sending a packet on the LAN.

Many 802.11g radios support Shortslot override, but some do not. When Shortslot override is enabled, the wireless device uses the short slot time only when all clients associated to the 802.11g, 2.4-GHz radio support Shortslot override. Shortslot override is an 802.11g-only feature and does not apply to 802.11a radios.

SUMMARY: Slot times should transition from 20us to 9us when a "pure" .11g environment exists for that AP. Also applies to NG networks.


[edit] TX Power

Broadcom:

Available Settings: Auto or Manual

Default Setting: Auto

Recommended Setting: Auto, unless you know what you are doing.


Atheros and others:

Available Settings: 0 ~ 999

Default Setting: 16 ~ 30 dBm (varies by router)

Recommended Setting: Highest dBm your radios & local laws legally allow**

    • Recommended Setting

Some people believe that "high" TX power (i.e., greater than 25 dBm), may be of concern to one's health. That is not the case but each to their own. So if that's you then 22 - 25 dBm should be sufficient; any lower & range starts to significantly drop (unless you want to of course & if you have an older router than only does something like 18 dBm, no need). In case you are wondering, every 3 dBm is doubled the power, so 13 dBm is twice as much as 10 dBm, & so on; but don't worry, 30 dBm is only 1 watt.

The help file says... * A safe increase of up to 70 would be suitable for most users. Higher power settings are not recommended for users due to excess heat generated by the radio chipset, which can affect the life of the router.


How it works:

The milliwatt (symbol:mW) is equal to one thousandth (10-3) of a watt. A typical laser pointer might output 5 milliwatts.

This setting will determine the number of milliwatts used to power the radio signal output from the router.

TWEAK 

wl -i eth1 txpwr 70 #will set your adapter to 70 mW for the 5GHz 
wl -i eth0 txpwr 70 #will set your adapter to 70 mW for the 2.4GHz
wl -i eth1 txpwr1 #check transmitt power for 5 GHz
wl -i eth0 txpwr1 #check transmitt power for 2.4 GHz* Buffalo HP units should not exceed about 30 due to their built in amp.
  • Linksys ships out their units with the TX power set to 28 mW by default.
  • mW \ Dbm Power Conversion Table
  • mW -- 1 2 3 4 5 6 8 10 12 15 20 25 30 40 50 60 80 100
  • DBm -1 2 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20


How to convert dBm to mW

The power conversion of dBm to mW is given by the formula:

P(mW) = 10 ^ (P(dBm) / 10)

So .. 1dBm = 1.258925mW


How to convert mW to dBm

The power conversion of mW to dBm is given by the formula:

P(dBm) = 10 * log10(P(mW) / 1)

On most calculators, log10 would be labeled as LOG.


Conversion Calculator | dBm <--> mW

[edit] Afterburner

Available Settings: Enabled or Disabled

Default Setting: Disabled

Recommended Setting: Enabled if you need the feature, best to get a better router.

The help file says... * This should only be used with WRT54GS Models and only in conjunction with other Linksys "GS" wireless clients that also support Linksys "Speedbooster" technology.


How it works:

Just how do the Super G and Afterburner modes work?

The 125-Mbit/s Afterburner technology uses just one channel. Instead of bonding two channels of data together, it squeezes more data through a single channel by reducing overhead and aggregrating smaller packets of data into larger ones.

In particular, Super G has been criticised in the past for using so much of the Wi-Fi band that other networks in the vicinity, which normally would automatically seek out and use non-overlapping channels to avoid interference problems, could be severely impacted.

By contrast, Super G gets part of its speed increase from "bonding" data from two non-overlapping wireless channels together (normal Wi-Fi uses only 1 out of the 11 channels in the 2.4-GHz range). This channel bonding, though, increases the potential for troublesome interference with microwave ovens, with cell phones and with other Wi-Fi networks (see our feature comparing the different speed boost technologies).

Check if Your Router Supports Afterburner 1.Connect to your router using telnet or ssh. Telnet/SSH and the Command Line 2.Type wl cap and press enter. It will return a list of capabilities. 3.If afterburner is listed you may enable Afterburner on the Advanced Settings tab under Wireless in DD-WRT.

TWEAK

You would enable this feature when you are tring to get all the proformance out of your 2.4GHz network running 802.11g mode or better only and you would only enable Afterburner when your hardware supports afterburner and your enviroment meets the requirements as well.

To set afterburner from the CMD enter the follwoing commands;

wl set wl0_afterburner=on

wl set wl_afterburner=on

-This speed-enhancing feature is available on all DD-WRT enabled G routers. It is hardware independent. Afterburner will only improve speeds when used with clients that also have the Speedbooster/Afterburner feature; use with "normal" 802.11g clients will actually lower performance.

-Afterburner can be used in networks that also have 802.11b devices, and will not disable the use of them.

-Afterburner can help in environments dense with wireless signals.

-Many MiniPCI cards built into notebooks and many PC Cards are based on Broadcom chips whose configurations support Afterburner

-In order to enjoy the benefits of Afterburner a.k.a. SpeedBooster, all clients and the AP must support afterburner.

-About 33 percent faster in real world file transfer test than basic 802.11g mode equipment

-Afterburner is also known as:

SpeedBooster SuperSpeed Turbo G 125mbps 125HSM 125* High Speed G Plus

Afterburner is not: Super-G / 108 mbps (Super-G is an Atheros technology) XPress Technology is Dell's version of Frame Bursting, not Afterburner.


[edit] Bluetooth Coexistence Mode

Available Settings: Enable, Disable, and Preemption

Default Setting: Disable

Recommended Setting: Preemption

The help file says... *


How it works:

An 802.11 device and Bluetooth can interfere with each other when the 802.11 device operates on the 2.4 GHz band. All Bluetooth devices operate at the 2.4 GHz band. If you experience wireless disconnects, decreased range or speed, and other connectivity issues when you turn on some of your Bluetooth devices, try to change this option to "Enable" (this will make the router and Bluetooth device to take turns in using the spectrum for communication) or "Preemption" (the router will inform the Bluetooth device about the channel it is operating on, and the Bluetooth device can preemptively disable communication on the respective Bluetooth channels). Please note that this option requires your Bluetooth device to "cooperate". If the Bluetooth device doesn't implement the coexistence techniques, using this option will have no effect.

-I have had problems with bluetooth transfers (big big transfers), with this enabled, the problem has been solved.


[edit] Wireless GUI Access

Available Settings: Enable or Disable

Default Setting: Enable

Recommended Setting: Enable, but largely up to the admin

The help file says... * The setting allows access to the routers setup (GUI) from wireless clients. Disable this if you wish to block all wireless clients from accessing the setup pages.


How it works:

-Once you have your dd-wrt configured you can enable this setting and no wireless clients will be able to access the routers dd-wrt GUI.

-Wireless clients can still access the router over telnet and ssh when this setting is disabled.

-Changing this from the default value would be for security reasons.


[edit] Radio Time Restrictions

Available Settings: Enable, Disable

Default Setting: Disable

Recommended Setting: Disable, if you need it Enable it.

Click the green boxes to disable the wireless router for a given hour, or click the always on or always off buttons. Then click apply. You need to have an ntp server set and the correct timezone on the Setup – Basic Setup page in order for this to work correctly.


[edit] Wireless Multimedia Support Settings

Available Settings:

WMM Support: Enable or Disable

No-Acknowledgement: Enable or Disable

Default Setting:

WMM Support: Enable

No-Acknowledgement: Disable

Recommended Setting:

WMM Support: Enable

No-Acknowledgement: Disable

Short for Wi-Fi Multimedia, is a Wi-Fi Alliance interoperability certification that provides a basic QoS "best effort" like function to Wi-Fi as well as other functions such as power saving, its a requirement & part of the 802.11n (& newer) specification. Disabling WMM will result in clients (ones that strictly obey specifications which is 90% of them) falling back to 802.11a/g rates (54M), the same way as using TKIP with WPA2 does.

As for the various boxes below that, it would be better to use Quality of Service (QoS) than to start changes those boxes.

[edit] References

Advanced Wireless Settings Reference Guide - http://www.dd-wrt.com/phpBB2/viewtopic.php?t=51039

Retrieved from "http://wiki.dd-wrt.com/wiki/index.php/Advanced_wireless_settings"