Policy routing failover question

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May 6th, 2002
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Hi

Suppose I apply policy routing to route FTP traffic to a next hop (next hop A) and other traffic (based on tcp/udp port #) out to another interface (next hop B)

If next hop A is down and disappar from the router routing table, I would like FTP to be routed over next hop B

After reading Cisco policy based documents I cannot find the answer to my question. I just want to make sure there is a backup route for FTP

Is it possible ?

Thanks

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mnordhoff Mon, 05/06/2002 - 10:41
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I have had a similar issue and have done the following...


Use multiple next-hop addresses in the "set" portion of your route-map. For example, say Router-A has a WAN connection to both Router-B and Router-C. The link between Router-A and Router-B is using IP subnet 192.168.0.0/30 where Router-A is 192.168.0.1 and Router-B is 192.168.0.2. The link between Router-A and Router-C is using IP subnet 192.168.0.4/30 where Router-A is 192.168.0.5 and Router-C is 192.168.0.6. You can configure the "set" portion of your route-map in Router-A to point to Router-B then Router-C using the statement 'set ip next-hop 192.168.0.2 192.168.0.6'. This way the desired traffic will traverse the link between Router-A and Router-B if that link is up or the link between Router-A and Router-C if the other link is down.


Hope this helps. If not let me know as there is another alternative if you need to re-route WAN traffic from Router-A based on the state of WAN links on Routers B and C.


- MN

atlov Mon, 05/06/2002 - 11:14
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Thanks very much for your help. I didn't know you could set 2 different next hops on the set commande. I will test this in the lab. I guess the other solution you are referring to is based on a GRE tunnel.

Thanks again

mnordhoff Mon, 05/06/2002 - 12:07
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You're welcome!


My other solution is not based on a GRE tunnel though Cisco recommended that as a possible solution. It is based on passing routing updates across a link that will bring the packet back to the originating router if the WAN links on the target router are down.


Do you have any configuration examples/information on the GRE tunnel alternative?

atlov Thu, 05/09/2002 - 05:57
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Hi

I actually don't have any information on the GRE tunnel alternative. All I saw was the reply made to your policy routing over Frame Relay message on April the 30th.

Thanks

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