Dual, Triple (and probably quad) WAN with multiple active WAN links and source routing

From DD-WRT Wiki

Jump to: navigation, search

Contents

[edit] Dual, Triple (and probably quad) WAN with multiple active WAN links and source routing

This tutorial shows how to implement multiple active WAN links, source routing, and fail-over with DD-WRT. This has been tested in dual and triple WAN configurations. Scripts are list-based, so they should support a quad WAN configuration.

[edit] Multi-WAN Goals and Requirements:

Modular design for scalability and testing;

  • All WAN interfaces usable concurrently for traffic inbound from the Internet.
  • Fault detection parameters configurable for each WAN interface;
  • Detect failure of local loop/first hop, ISP routing, and excessive packet loss;
  • Software fault detection and correction;
  • Configuration through a single file;
  • Easily reconfigurable routing;
  • Dynamic DNS support for DHCP WAN addresses; and
  • Seamless response to WAN IP address changes by DHCP.

[edit] Theory of Operation

Two scripts form the core of Multi-WAN: linkd and changewan. Each WAN interface is monitored by an instance of linkd. Each instance is independently configurable. A status file for each interface is maintained by linkd in /tmp/wan/status.*. When linkd detects a change of WAN status, changewan is called to evaluate the change. A status word, composed of two bits per interface, is assembled by changewan. This value is processed through a case statement to chose the appropriate routing configuration.

Remaining package files are described below.

[edit] My Configuration

My current configuration is a Netgear R7000 with two high speed connections (200/20 and 20/1.5 Mbps), plus a 2 Mbps backup. In normal (default) mode, the 200 Mbps connection handles entertainment streaming and most devices. The 20 Mbps connection is used for VoIP and trading – the top 64 IP addresses in the LAN subnet. Should either high speed connection fail, all traffic is routed to the surviving high speed connection. The 2 Mbps connection is a final backup, used if both high speed connections are unavailable.

My prior configuration was a Linksys e3000 with two high speed connections (50/5 and 20/1.5 Mbps), plus a 2 Mbps backup. The e3000 could only sustain 80 to 90 Mbps, leading to the R7000 upgrade.

[edit] Installing and Configuring the Multi-WAN Package

First, complete single WAN configuration of your router. Configuration steps are well documented elsewhere, so details are not included here.

Single WAN configuration checklist:

  • Install an appropriate DD-WRT version, this configuration has been tested on r14929, r15962 and 24345M;
  • Internet interface on WAN port;
  • Time server;
  • DHCP server;
  • Configure static DNS servers – DNS servers must be accessible through all WAN interfaces.;
  • DDNS if applicable;
  • Wireless configuration;
  • syslog;
  • ssh management;
  • Firewall and configure port mapping;
  • Web access;
  • Remote access;
  • Enable cron;
  • JFFS; and
  • SNMP.

Set the following NVRAM configuration variables through the nvram set and commit interface:

  • ddns?_hostname: Dynamic DNS service hostname for each WAN interface, e.g., ddns2, ddns3;
  • ddns?_username: Dynamic DNS service user name;
  • ddns?_passwd: Dynamic DNS service password;
  • email_admin: E-mail address(es) for administrative messages, e.g., logwatch;
  • email_dest: E-mail address(es) for event notifications;
  • email_passwd: E-mail server password;
  • email_server: E-mail server hostname;
  • email_user: E-mail server user name;
  • route_ips: List of IP addresses for Internet routing tests by linkd, addresses should be on separate networks and outside of your ISPs, a null list will inhibit routing tests;
  • wan?_ipaddr: WAN IP address – static addresses are set by user, dynamic addresses are set by udhcpc, e.g., wan2, wan3;
  • wan?_netmask: WAN interface netmask; and
  • wan?_ifname: WAN interface name, e.g., vlan2, vlan3.

Set the following /jffs/scripts/wan/global environment variables with a text editor:

  • WANLIST: List of monitored WAN interfaces, e.g., wan, wan2, wan3;
  • STATICWANLIST: List of WAN interfaces with static IP addresses – exclude wan;
  • DHCPLIST: List of WAN interfaces configured by DHCP; and
  • BASEDHCP: Name of the VLAN configured by the DD-WRT base configuration, usually vlan2.

Multi-WAN package configuration:

  • Copy Multi-WAN package tarball to /jffs/scripts/wan and extract contents, located here: https://www.dropbox.com/sh/ji5fgci1z0i4gq4/AACRGIfFJzw7mw7zouHEv8dta?dl=0
  • Remove port(s) from vlan1 for new WAN link(s)
    • Dual: nvram set vlan1ports="2 3 4 8*"
    • Triple: nvram set vlan1ports="3 4 8*"
  • Create VLANs for new WAN connection:
    • Dual: nvram set vlan3ports="1 8" && nvram set vlan3hwname=et0
    • Triple: nvram set vlan4ports="2 8" && nvram set vlan4hwname=et0
    • nvram commit

For a DHCP-only configuration, add to Startup in Control Panel at Administration->Commands->Startup:

sleep 5
udhcpc -i vlan3 -p /var/run/udhcpc-vlan3.pid -s /jffs/scripts/wan/udhcpc-vlan3
#Note: The next two lines are only for a triple wan configuration
sleep 5
udhcpc -i vlan4 -p /var/run/udhcpc-vlan4.pid -s /jffs/scripts/wan/udhcpc-vlan4
sleep 20
/jffs/scripts/wan/clockupdate
/jffs/scripts/dnsupdate
/jffs/scripts/wan/monitord &

For a static IP-only configuration, verify wan?_ipaddr, wan?_netmask, and wan?_ifname in nvram for each interface, then add to Startup in Control Panel at Administration->Commands->Startup:

sleep 5
/jffs/scripts/wan/configstatic
sleep 20
/jffs/scripts/wan/clockupdate
/jffs/scripts/dnsupdate
/jffs/scripts/wan/monitord &

Add to Firewall in Control Panel at Administration->Commands->Firewall:

/jffs/scripts/wan/firewall
/jffs/scripts/wan/route

Add the following cron jobs in Control Panel at Administration->Management->Additional cron jobs:

* * * * * root /jffs/scripts/wan/procmon
5 0,6,12,18 * * * root /jffs/scripts/wan/ddnsupdateall # delete if not using dynamic DNS
0 10 * * * root /jffs/scripts/wan/clockupdate
0 11 * * * root /jffs/scripts/wan/logwatch
0 0,3,6,9,12,15,18,21 * * * root /jffs/scripts/wan/apprestart

Link linkdupdate to /jffs/etc/config/linkdupdate.ipup to trigger update when the vlan2 DHCP address changes, command:

ln /jffs/scripts/wan/linkdupate /jffs/etc/config/linkdupdate.ipup

Reboot router.

Time to test the configuration:

  • Verify that all WAN interfaces are up and have public IP addresses. This may require reconfiguration of your ISP's equipment to provide your dd-wrt router a public IP address;
  • Test that configroute properly routes for each state: default, wan, wan2, and wan3;
  • Check local dns configuration: `cat /etc/resolv.conf` should reflect proper domain and servers;
  • TTest sendstatus.new and sendstatus.old: `./sendstatus test test` – configured e-mail address should receive messages, copy the appropriate version to sendstatus;
  • Verify the following processes are running:
    • monitord;
    • linkd: one for each WAN interface; and
    • udhcpc: one for each DHCP-configured WAN interface;
  • Check status files: cat /tmp/wan/status* -- route should be default, wan interfaces up;
  • In a separate window, watch the wanlogger output: `tail -f /tmp/wan/wan.log` and execute the following commands:
    • ifconfig vlan2 down: wan goes to down state; all traffic flows to wan2; test that traffic flows as anticipated;
    • ifconfig vlan2 up: wan goes to link status;
    • ./configroutes wan2: adds route test routing entries for wan; wan will go into recovering state; wan will remain in recovering state through the configured restore delay period, or you can force the link up immediately by executing ./linkup wan; routing restored to default; test that traffic flows as anticipated;
    • ifconfig vlan3 down: wan2 goes to down state and all traffic is routed to wan; test that traffic flows as anticipated;
    • ifconfig vlan3 up: wan2 goes to link status;
    • ./configroutes wan: adds route test routing entries for wan2; wan2 will go into recovering state; wan2 will remain in recovering state through the configured restore delay period, or you can force the link up early by executing **./linkup wan2; routing restored to default; test that traffic flows as anticipated;
  • For a triple WAN configuration:
    • ifconfig vlan2 down && ifconfig vlan3 down: wan and wan2 go to down state and all traffic is routed to wan3; test that traffic flows as anticipated;
    • ifconfig vlan2 up && ifconfig vlan3 up: wan and wan2 go to link status;
    • ./configroutes wan3: adds route test entries for wan and wan2; wan and wan2 will go into recovering state; wan and wan2 will remain in recovering state through the configured restore delay period, or you can force links up early by executing ./linkup wan2 && ./linkup wan2; routing restored to default; test that traffic flows as anticipated.

[edit] Troubleshooting

Two troubleshooting mechanisms are included. Wanlogger levels can be set to $LOG_DEBUG to be more verbose. These levels can be set globally in the global configuration file or locally overridden in each script. Additionally, setting a DEBUG environment variable prior to script execution will configure 'set -x' in scripts executed from the command line.

[edit] Customizing Your Configuration

My configuration is probably only a starting point. Configuration changes are made in these files:

  • global: tuning parameters, file locations, and log levels;
  • changewan: mapping wan states to wan routing configurations;
  • configroutes: multi-wan routing configuration, and;
  • route: source route subnet definitions.

[edit] Multi-WAN Files

apprestart: Restarts httpd to stop its 100 percent CPU utilization

changewan: Changes routes based on current WAN interface status. The Multi-WAN States spreadsheet is provided to help route planning.

clockupdate: Updates the router system clock from ntp_server.

configroutes: Configures routes as selected by changewan.

ddnsupdate: Updates DynDNS for a specific DHCP WAN interface.

ddnsupdateall: Updates DynDNS for all DHCP WAN interfaces.

dnsupdate: Updates resolv.conf with wan_domain and wan_dns.

firewall: Configures the router firewall.

global: Global configuration file.

linkd: Monitors a WAN link to detect faults and track status – one linkd for each WAN interface.

linkdupdate: Triggers re-read of linkd global configuration and network parameters for running linkd instances. Link to /jffs/etc/config/linkdupdate.ipup to trigger update when the vlan2 DHCP address changes.

linkup: Forces a WAN link in Recovering state to Up status.

monitord: Monitors the status of vital processes (linkd, udhcpc, and cron) and relaunches processes when necessary.

monitordupdate: Triggers re-read of monitord configuration from global.

procmon: Launched by cron to check that monitord is running and to relaunch monitord when necessary.

route: Configures base IP routes.

sendstatus.old, sendstatus.new: Sends status messages, old and new versions are included to support multiple DD-WRT versions.

/tmp/wan/logwatch.*: logwatch output files

/tmp/wan/status*: Current route selection and WAN interface status. WAN interface status values maintained by linkd:

  • up: Interface is successfully passing traffic to the Internet.
  • recovering: Interface can successfully pass traffic to the Internet, but has experienced a failure within the configured restore delay.
  • link: Interface is passing traffic to its first-hop gateway, but not to the Internet.
  • down: Interface is not passing traffic to its gateway.

Route interface status values – user configurable in changewan and configroute:

  • default: Traffic from the /26 LAN subnet is routed to wan2. Other traffic routed to wan.
  • wan: All traffic is routed to wan.
  • wan2: All traffic is routed to wan2.
  • wan3: All traffic is routed to wan3.

/tmp/wan/wan.log: active wanlogger output file.

/tmp/wan/wan.log.*: archived wanlogger output files.

udhcpc-vlan3: udhcpc configuration file for wan2/vlan3. The target WAN interface is configured within this file.

udhcpc-vlan4: udhcpc configuration file for wan3/vlan4. The target WAN interface is configured within this file.

/tmp/wan/wan.log: Output of wanlogger, use 'tail -f' to monitor continuously.

[edit] Multi-WAN files located here

https://www.dropbox.com/sh/ji5fgci1z0i4gq4/AACRGIfFJzw7mw7zouHEv8dta?dl=0