BGP multihome failover - route manipulation

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Jul 30th, 2012
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I'm looking for a way to manipulate the default gateway based on source.  I have 2 public IP ranges and I'd like range 1.1.1.0 to route through rt1 and range 2.2.2.0 to route through rt2.  A default route 0.0.0.0 from rt1/isp1 is advertised to rt2 for failover in the event of a rt1/isp1 failure.  This provides failover of the 1.1.1.0 network to route through isp2.


When traffic from 2.2.2.0 hits rt2 I'd like it to be routed out isp2 as long as that path is available.  When the path is not available it should route to rt1.


HSRP for 1.1.1.0 points to rt1 primarily and hsrp for 2.2.2.0 pointing to rt2 primarily.  iBGP and EIGRP are running between the routers. 


What is the best way to send the 2.2.2.0 traffic out via isp2?  (Currenly there's a default route from rt1 sending it to isp1)  I'm sure I can use an ACL matching 2.2.2.0, route-map and set-next-hop but I'm not sure how to account for an isp2 failover?  Track something on the isp2 side?


Any ideas?



/DK

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dking88 Mon, 08/06/2012 - 11:56
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Thanks Edison.


I ended up configuring a route-map for the 2.2.2.2 network and applying the set-next-hop based on a tracked IP on the ISP2 side.  It looks like it should work but I'm having an issue when testing.  One of the peers to ISP2 (there are 2 for some reason) terminates once I shut down the ISP2 link.  The route-map on RT1 is as follows.


access-list 1 permit 1.1.1.0 0.0.0.255

access-list 2 permit 2.2.2.0 0.0.0.255

route-map Outgoing-routes permit 10

  match ip address 1

route-map Outgoing-routes permit 10

  match ip address 2

  set as-path prepend 65005 65005 65005

dking88 Wed, 08/08/2012 - 13:08
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Update:  The above configuration worked.  The peer terminated because the router wasn't advertising the 2nd peer network.


Everything is working now.  Thanks.

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