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

[BALLA Attila]

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