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Webcast-Catalyst9k
New Member

Policy routing backup scenario

Hi

I have the following scenario :

Router A is connected through a Frame Relay PVC to a private IP backbone running BGP.

Router B is also connected to this private IP backbone. Router A can see router C user LAN through EBGP and vice-versa.

Router A is connected to the Internet through a Fast Ethernet. An IPSEC box on that Fast Ethernet is configured to encrypt data over the Internet towards the Router B, also connected to the Internet the same way as router A.

RIP is run over this tunnel to advertise user LAN subnets from A to B and vice-versa.

The idea is to route high priority traffic between router A LAN and Router C through the IP backbone (very reliable) whereas the Internet route is used for Lotus Notes traffic.

High priority traffic path : A -- private IP backbone -- router C

Lotus Notes path : A--Fast Eth--B--IPSEC over Internet--FastEth--C

POLICY ROUTING :

Match condition : Lotus Notes port

Set : fast Ethernet interface as next hop

My question is what happens on router A if the Internet route is down ? I want Lotus Notes traffic to be able to be re-routed through the private Ip backbone path.

Does that automatically happens when :

- The Fast Ethernet goes down ?

- Fast Ethernet is up but RIP does not advertise router B to router A anymore due to an IPSEC or Internet problem ?

Thanks

2 REPLIES
New Member

Re: Policy routing backup scenario

First make sure you have a route to both legs. Then utilize multiple “set interface” commands within the route map, and use “set default interface” to ensure the path you wish traffic to take under optimal conditions is employed.

New Member

Re: Policy routing backup scenario

If the FastEthernet interface is down and you have an alternate interface/next hop specified in your "set" statement all traffic will take the alternate path. If the FastEthernet interface/next hop is up your route-map will send all traffic to that interface regardless of the state of the links on the other router (Router B). The way I get around this problem is to have a route on Router B that points back across the same link to Router A in the event WAN links on Router B are down. Probably not the most elegant solution but it works.

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