routes with cost

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May 11th, 2007
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Hi all, when adding 2 routes to a destination but using different next hops, you use a cost for failover right, how does the router know that the other end device is down ? or will this only work when pointing through 2 different local interfaces on the router ?

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royalblues Fri, 05/11/2007 - 00:34
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The router tracks the status of the interface which is connecting to the next hop.

When the protocol goes down, the router flushes that route from the table and uses the other one.

The next hop ip must be reachable from the interface conencting to the local router.

HTH, rate if it does


mohammedmahmoud Fri, 05/11/2007 - 00:56
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Hi Carl,

First of all when using different routes with failover we use AD (Administrative Distance) not cost, and the route with higher AD (the backup) is called a floating static route.

In old IOS to have this working you must have set the route to the outgoing interface rather than the next-hop, but in recent IOSs, pointing the route to the next-hop the router does its recursive tests and make sure that the interface going to the next-hop must be up/up for the route to be in the routing table.

HTH, please do rate all helpful replies,

Mohammed Mahmoud.


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