[c-nsp] Can not establish MP-BGP sessions

[Alex]

Hi Andy,
Couple of questions:
1/ Can you ping between PE1 and PE2 _loopbacks_ across the circuit when 
"mpls ip" is ON on both Gi4/0/1 and Gi0/2?
2/ Can you establish BGP session between _interface_ addresses when "mpls 
ip" is ON on both Gi4/0/1 and Gi0/2?
Rgds
Alex

--------------------------------------------------
From: "Andy Saykao" <andy.saykao at staff.netspace.net.au>
Date: 16 November 2009 04:31
To: <cisco-nsp at puck.nether.net>
Subject: [c-nsp] Can not establish MP-BGP sessions

> Hi All,
>
> We migrated a link between two pops onto a Switched Ethernet circuit and
> since then we can't pass MPLS VPN traffic between those two pops from
> PE1 to PE2 because PE1 and PE2 can not establish a MP-BGP session.
>
> ------------------------- 
> BGP log on PE1:
> -------------------------
> Nov 16 14:26:48.693 AEDT: %BGP-5-ADJCHANGE: neighbor 172.16.99.4 Down
> BGP Notification sent
> Nov 16 14:26:48.693 AEDT: %BGP-3-NOTIFICATION: sent to neighbor
> 172.16.99.4 4/0 (hold time expired) 0 bytes
>
> -------------------------
> Topology:
> -------------------------
> POP1 [PE1 (lo99:172.16.99.13) --- Switched Ethernet --> P1 ] -->  POP2
> [P2 --> PE2 (lo99:172.16.99.4)]
>
> -------------------------
> P1:
> -------------------------
> interface GigabitEthernet4/0/1
> description Connection to P2
> bandwidth 150000
> ip address 203.17.96.x 255.255.255.252
> load-interval 30
> negotiation auto
> mpls ip
>
> -------------------------
> P2:
> -------------------------
> interface GigabitEthernet0/2
> description Connection to P1
> bandwidth 150000
> ip address 203.17.96.x 255.255.255.252
> load-interval 30
> media-type gbic
> speed auto
> duplex auto
> negotiation auto
> mpls ip
>
> Interesting thing to note is that if I remove "mpls ip" from P1's
> interface, the MP-BGP sessions are formed between PE1 and PE2 and stay
> up. When I put "mpls ip" back on the interface, the MP-BGP session times
> out with the error messgage in the BGP log above.
>
> The only thing that has changed is the introduction of the new Switched
> Ethernet circuit. I was thinking that it might have something to do with
> jumbo frames but our UpStream Providers tells me that they have
> configured jumbo frames on either end of the link plus I can ping end
> from P1 to P2 with  byte sizes larger than 8000 bytes.
>
> Has anyone got any ideas as to why the MP-BGP sessions all of a sudden
> can no longer stay up and what further debug/troubleshooting i can do?
>
> Thanks.
>
> Andy
>
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