WAN router with isdn router

[alvin75]

Hi,

We have a lease line (WAN router) that connect to the internet. is it possible to have an isdn router to backup the primary link in case the WAN router fails?

If that is possible, any examples or configuration notes on how to configure the isdn router and the WAN router?

many thanks.

alvin

[adammurphy]

yes this is possible. The simplest way i can think of is to run HSRP between the 2 routers ethernet (LAN) interfaces. Set the primary router to have the higest priority (say 200) and the ISDN router to have the lowest priority (say 100). As for the ISDN Router Config you'll have to figure out how you want it to work. always up or dial on demand type of thing.

Also for that matter you can run Gateway load balance protocol between the 2 routers which is like HSRP found here (http://www.cisco.com/en/US/products/sw/iosswrel/ps1839/products_feature_guide09186a00801541c8.html)

[adammurphy]

Sample HSRP Conifg

!WAN router Config

interface fa 1/0

standby track Serial1/0

standby 10 ip 123.123.123.123

standby 10 ip 124.124.124.124 secondary

standby 10 priority 200

standby 10 preempt

!ISDN router

interface fa 1/0

standby 10 ip 123.123.123.123

standby 10 ip 124.124.124.124 secondary

standby 10 priority 100

standby 10 preempt

Here's a HSRP doc. This might help. http://www.cisco.com/univercd/cc/td/doc/cisintwk/ics/cs009.htm

[n3tn0tw0rk]

I changed CCO ID's

But i found you a doc that i think is on the right path for your ISDN config.

http://www.cisco.com/en/US/tech/tk801/tk133/technologies_configuration_example09186a008009455e.shtml