[c-nsp] eigrp on pe-ce with backdoor link

[Brian Turnbow]

There were some bugs related to eigrp and MPLS VPN awhile back that were pretty nasty, however I don't remember the ids or versions .
If you use OSPF , what happens ?



-----Original Message-----
From: cisco-nsp-bounces at puck.nether.net [mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of BALLA Attila
Sent: mercoledì 2 febbraio 2005 11.12
To: cisco-nsp at puck.nether.net
Subject: [c-nsp] eigrp on pe-ce with backdoor link

Hi,

   I have a test network with three 7200 routers (PE1, PE2 and PE3), they are connected to each other via FastEthernet. PExs form an MPLS core, and
PE2 is a route-reflector.
   CE1 and CE2 is connected to PE1 via serial link.
   CE3 is connected to PE2 via serial link.
   There is a backdoor Ethernet segment between the CExs, with high delay and low bandwidth parameters, so the Serial link would be the preffered uplink.
   There is a connected LAN segment and a Loopback at PE3.
   These are in the same VRF, and we use EIGRP on PE-CE.


   If I use 12.0(27)S4 on the PEx routers, then everything is working properly. Only the convergence is slow (about 3 minutes)
   But we would like to use npe-g1 also, and 12.0S doesn't support it...

   And if we use 12.2(25)S2 for example on PE3, then we get a great routing loop. PE2 sees the PE3's Loopback toward CE3 router, and CE3 sees it toward CE2 and so on...

   I think the problem is around the bgp best-path selection, and cost community.
   I read the config guide on cco about 12.0(27)S and it sais there are no configuration required... (which is true with this release but 12.2(25)S)
   I don't use any special thing: I don't use SOO, because I don't want to upgrade to CExs, and I do only redistribute eigrp routes into bgp (with redistribute eigrp 1) and redistribute bgp routes into eigrp address-family (with redistrubite bgp <as> 100000 100 255 1 1500)

   Does anybody have a similar scenario? How do you configure properly this bgp cost community?

Best Regards:
   Attila

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