Failover on Cisco Router 1800 having DSL & Leased Line

[Mohammed Yaseen Ansari]

Hi there!

Below is my description:

• Leased line is between dammam      to dubai and the dammam office is getting internet from dubai.
• The ip address of Dammam      office is class A (Public IP) x.x.x.x and for dubai it is y.y.y.y which we are      using as proxy for accessing internet.
• I purchase the local DSL      direct line connection through cable from Local Provider and this ip address range is      192.168.1.0 - 192.168.1.254.
• Is it possible to use the DSL      line as failover, so if one line goes down the user should remove proxy      and can use local internet.
• The router which is using is      cisco 1800.

I believe that failover is possible, 100%, but would like to know how I can do it and requesting for sharing more inputs about failover in this case.

Documents will be much appreciated...

Thanks & Regards,

Yaseen

[chad patterson · Accepted solution]

This is possible and relatively simple to acheive: depending on whether you are NATing or not. Either way it can be acheived with IP SLA and Tracking.

• If no NAT then refer here: http://esalonia.net/2010/08/10/dual-wan-link-failover-with-ip-slas/
• If NAT then refer here:  http://www.cisco.com/en/US/products/sw/secursw/ps1018/products_configuration_example09186a00809454c7.shtml

You might look at this discussion.

If were you I might just use both as the primary, and load share between the two using PfR/OER. I have done that and it works well. Refer to the second document that.

[chad patterson]

By the way, I highly recommend including this line in your config:

ip nat translation tcp-timeout 3600

as it will prevent some of the memory fragmentation issues that may arise due to the NATing.