Floating Static Routes

[yuchenglai]

Hi all,

I have a question about floating static routes. On a broadcast media, if I have two floating static route, each with a different AD and each specifying a different next-hop ip address, recursing out to the same ethernet interface, how would the router know when not to insert the particular static route into the RIB when the remote next-hop ip address falls off of the network?  This is assuming that the outgoing ethernet interface is in the up/up status when this event happens.

David

[Giuseppe Larosa · Accepted solution]

Hello David,

the use of static routes over shared media has been historically a problem in the past.

without a way to check the IP next-hop it would be used until the ARP entry expires in the ARP cache that is up to 4 hours with default timers!!!

Nowdays you can make use of IP SLA to verify that the IP next hop is really alive quickly

see the link below

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

depending on the IOS version of your device IP SLA or rtr responder can be configured

Hope to help

Giuseppe

[yuchenglai]

Thanks Giuseppe!