Change route if next hop is not available

Unanswered Question
Oct 24th, 2008

Here is the scenario:

Cisco Router is behind a Cable modem. This same cisco router has another ethernet connection to another Cisco router. I want the default route to go out the cable modem. But in the event the connection on the far side of the cable is down I want the default route to over to the other cisco router.

I know that a floating static will not work because the interface between the Cisco router and the cable modem hasn't gone down. I know that policy routing to verify the next hop will not work because it isn't another Cisco device on the other of the cable modem.

Is there a way I can constantly ping another device on the back side of the cable modem to verify that it is available, if it isn't to some how change the default route in the routing table. (i.e. TCL scripting of other method). I really appreciate everyone's help.

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Jon Marshall Fri, 10/24/2008 - 14:21

You could consider using reliable static routing with object tracking which tracks the reachability of an IP address and if it becomes unreachable can remove a route and use a different one. See this link for more details -


http://www.cisco.com/en/US/docs/ios/12_3/12_3x/12_3xe/feature/guide/dbackupx.html#wp1072790


You could also consider looking into EEM which involves TCL scripting. If you want to pursue this i suggest you post this question into Network Infrastructure -> Network Management where there is a Cisco expert with a lot of EEM knowledge.


Jon

Joseph W. Doherty Fri, 10/24/2008 - 14:47

Newer IOSs support using SLAs as an enhanced tracking method.


[edit]

Sorry Jon, didn't see your post until after I posted mine. Good you posted reference to object tracking. BTW: there's another post asking similar question. If you see, would be good to also provide your reference again.


[edit2]

Jon, never mind hunting other posts, I just amended my posts pointing to your post here.

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