Redundant T1's for failover between two 2600 routers

[matt95gsr]

I've got two offices with 2600 routers and a T1 between them. Currently the remote office uses the T1 to send all traffic over to the main office, including using the main office's internet access. This works well enough, except when the T1 goes down, which is more often than we would like. So, there has been another (frac)T1 ordered from another carrier. The desire is to have the new T1 take over if the first fails. My question is: what's the best way?

should I simply go with static routes with different metrics, or is there a better way? For instance, is this sufficient and will it work the way that is desired?

ip route 192.168.1.0 255.255.255.0 serial0/0 10 {primary T1}
ip route 192.168.1.0 255.255.255.0 serial0/1 20 {second. T1}


Any thoughts? Thanks very much!

 

[lui3]

both would work. however the configuration that you are proposing here will also load balance packets across the links depending on the speed associated with each interface. do you want to provide load balancing when both are up and failover when one goes down or do you want to have the second t1 for failover only.

in that case you should be able to use the backup interface command to accomplish this as well

interface serial 0
backup interface serial 1

there is also another option depending on the IOS that you are using. in 12.3 you can use rtr probe packets to monitor the state of link and failover to a redundant link in case of wan failure. check out page 9 of the second quarter of 2004 Packet Magazine. There is a great write up on it. you should be able to find that issue on ciscos website as well.

the rtr probe packets essentially ping the main interface and when the packets stop returning after a configured time interval the second link is brought up and used.

have fun.