[f-nsp] BGP best path on a XMR

Mike Leber mleber at he.net
Mon Jul 23 15:21:21 EDT 2007


Typical reason for the below would be the next hop isn't in the routing
table of that router.

Do the two routers share their connected and static routes via an IGP,
such as OSPF?

If not, setting that up would fix it.

On Mon, 23 Jul 2007, Morten Isaksen wrote:

> Hi!
> 
> I have two XMR's that that each has a BGP connection to an upstream
> provider and i IBGP link between them. I am trying to force traffic to
> some prefixes via one of the upstreams and have made a route map that
> set the local pref i bit higher for these prefixes, but the XMR seems
> to ignore this. Or maybe I have misunderstood the best path algorithm.
> 
> SSH at BGP-2>sh ip bgp route detail 194.255.106.0
> Number of BGP Routes matching display condition : 2
> Status A:AGGREGATE B:BEST b:NOT-INSTALLED-BEST C:CONFED_EBGP D:DAMPED
>        E:EBGP H:HISTORY I:IBGP L:LOCAL M:MULTIPATH m:NOT-INSTALLED-MULTIPATH
>        S:SUPPRESSED F:FILTERED s:STALE
> 1       Prefix: 194.255.0.0/16,  Status: BE,  Age: 2d22h10m20s
>          NEXT_HOP: 217.74.212.65,  Learned from Peer: 217.74.212.65 (29542)
>           LOCAL_PREF: 100,  MED: none,  ORIGIN: igp,  Weight: 0
>            AS_PATH: 29542 9167 3308
>             COMMUNITIES: 9167:50203 29542:301 29542:321 43027:310
>             Adj_RIB_out count: 1,  Admin distance 20
> 2       Prefix: 194.255.0.0/16,  Status: I,  Age: 0h15m39s
>          NEXT_HOP: 194.19.218.157,  Learned from Peer: 77.75.166.253 (43027)
>           LOCAL_PREF: 110,  MED: none,  ORIGIN: igp,  Weight: 0
>            AS_PATH: 3308
>             COMMUNITIES: 43027:300
>        Last update to IP routing table: 2d22h10m20s, 1 path(s) installed:
>        Route is advertised to 1 peers:
>         77.75.166.253(43027)
> 
> 
> In my world route 2 should be preferred since it has the highest local
> pref, but the XMR prefers route 1.
> 
> Can somebody explain why? And how do I make it choose route 2 as the best path?
> 
> -- 
> Morten Isaksen
> http://www.misak.dk/blog/
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> foundry-nsp at puck.nether.net
> http://puck.nether.net/mailman/listinfo/foundry-nsp
> 

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