BGP Session Flapping with dual AS

Hi Team,

Working on the lab for BGP Dual AS I am running into a problem where
the BGP session between the eBGP peers is constantly flapping and I
just can't understand where the problem could be. Following the
relevant configurations on both peers:

======Peer 155.1.45.4=======

router bgp 146
 no synchronization
 bgp log-neighbor-changes
 network 155.1.146.0 mask 255.255.255.0
 aggregate-address 155.1.0.0 255.255.0.0 summary-only
 neighbor 155.1.45.5 remote-as 200
 neighbor 155.1.45.5 local-as 100 no-prepend replace-as dual-as
 neighbor 155.1.45.5 remove-private-as
 neighbor 155.1.146.1 remote-as 146
 neighbor 204.12.1.254 remote-as 54
 neighbor 204.12.1.254 local-as 100 no-prepend replace-as
 neighbor 204.12.1.254 remove-private-as
 no auto-summary

======Peer 155.1.45.5=========

router bgp 200
 no synchronization
 bgp log-neighbor-changes
 bgp dampening 4
 neighbor 155.1.0.2 remote-as 200
 neighbor 155.1.0.2 route-reflector-client
 neighbor 155.1.23.3 remote-as 200
 neighbor 155.1.45.4 remote-as 146
 neighbor 155.1.45.4 remove-private-as
 neighbor 155.1.58.8 remote-as 200
 neighbor 155.1.58.8 route-reflector-client
 neighbor 155.1.108.10 remote-as 200
 neighbor 155.1.108.10 route-reflector-client
 no auto-summary

Here the log messages and the debug TCP on peer 45.5

Rack1R5#
*Dec 17 19:03:23.330: tcp0: O SYNRCVD 155.1.45.4:11528 155.1.45.5:179
seq 1925862638
        OPTS 4 ACK 2264873293 SYN WIN 16384
*Dec 17 19:03:23.358: tcp0: O ESTAB 155.1.45.4:11528 155.1.45.5:179
seq 1925862639
        DATA 64 ACK 2264873338 PSH WIN 16339
*Dec 17 19:03:23.386: %BGP-5-ADJCHANGE: neighbor 155.1.45.4 Up
*Dec 17 19:03:23.386: tcp0: O ESTAB 155.1.45.4:11528 155.1.45.5:179
seq 1925862703
        DATA 366 ACK 2264873357 PSH WIN 16320
*Dec 17 19:03:23.450: tcp0: O ESTAB 155.1.45.4:11528 155.1.45.5:179
seq 1925863069
        DATA 54 ACK 2264873771 PSH WIN 15906
*Dec 17 19:03:23.470: tcp0: O ESTAB 155.1.45.4:11528 155.1.45.5:179
seq 1925863123
        DATA 38 ACK 2264873877 PSH WIN 15800
*Dec 17 19:03:23.690: tcp0: O ESTAB 155.1.45.4:11528 155.1.45.5:179
seq 1925863161
        ACK 2264874151 WIN 15526
Rack1R5#
*Dec 17 19:03:54.082: %BGP-5-ADJCHANGE: neighbor 155.1.45.4 Down BGP
Notification sent
*Dec 17 19:03:54.082: %BGP-3-NOTIFICATION: sent to neighbor 155.1.45.4
3/11 (invalid or corrupt AS path) 13 bytes 40020A02 04006400 36003200
3C
Rack1R5#
*Dec 17 19:03:54.082: BGP: 155.1.45.4 Bad attributes FFFF FFFF FFFF
FFFF FFFF FFFF FFFF FFFF 0033 0200 0000 1840 0101 0040 020A 0204 0064
0036 0032 003C 4003 049B 012D 0408 7108 70
*Dec 17 19:03:54.082: tcp0: O ESTAB 155.1.45.4:11528 155.1.45.5:179
seq 1925863161
        DATA 34 ACK 2264874351 PSH WIN 15326
*Dec 17 19:03:54.102: tcp0: O CLOSEWAIT 155.1.45.4:11528
155.1.45.5:179 seq 1925863195
        ACK 2264874352 WIN 15326
*Dec 17 19:03:54.182: tcp0: O LASTACK 155.1.45.4:11528 155.1.45.5:179
seq 1925863195
        ACK 2264874352 FIN PSH WIN 15326

I would appreciate if someone could provide any pointers on what I
could be missing here.

Thanks and regards,

Jorge

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Received on Thu Dec 17 2009 - 12:39:47 ART