BGP Flapping

Unanswered Question
Jun 24th, 2010

We have two systems running BGP fine with other neighbors but they are flapping between each other.  Connectivity between the two loopbacks is fine.

Here is the log, have you seen this before?  Configs are listed below.

Jun 24 16:01:32.276 EDT: BGP: 96.34.212.10 active went from Idle to Active
Jun 24 16:01:32.276 EDT: BGP: 96.34.212.10 open active, local address 96.34.212.93
Jun 24 16:01:32.276 EDT: BGP: ses global 96.34.212.10 (0) act read request no-op
Jun 24 16:01:32.276 EDT: BGP: ses global 96.34.212.10 (0) act Adding topology IPv4 Unicast:base
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active went from Active to OpenSent
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active sending OPEN, version 4, my as: 20115, holdtime 20 seconds, ID 6022D45
D
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active send message type 1, length (incl. header) 50
Jun 24 16:01:32.280 EDT: BGP: ses global 96.34.212.10 (0) act IPv4 Unicast:base write request no-op
Jun 24 16:01:32.280 EDT: BGP: ses global 96.34.212.10 (0) act IPv4 Unicast:base read request no-op
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcv message type 1, length (excl. header) 26
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcv OPEN, version 4, holdtime 180 seconds
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcv OPEN w/ OPTION parameter len: 16
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcvd OPEN w/ optional parameter type 2 (Capability) len 6
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active OPEN has CAPABILITY code: 1, length 4
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active OPEN has MP_EXT CAP for afi/safi: 1/1
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcvd OPEN w/ optional parameter type 2 (Capability) len 2
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active OPEN has CAPABILITY code: 128, length 0
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active OPEN has ROUTE-REFRESH capability(old) for all address-families
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcvd OPEN w/ optional parameter type 2 (Capability) len 2
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active OPEN has CAPABILITY code: 2, length 0
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active OPEN has ROUTE-REFRESH capability(new) for all address-families
Jun 24 16:01:32.280 EDT: BGP: nbr global 96.34.212.10 neighbor does not have IPv4 MDT topology activated
Jun 24 16:01:32.280 EDT: BGP: ses global 96.34.212.10 (0) act IPv4 Unicast:base mdt prepare old peer: BGP_MDT_STYLE_NONE
or Internal Problem
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active rcvd OPEN w/ remote AS 20115
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active went from OpenSent to OpenConfirm
Jun 24 16:01:32.280 EDT: BGP: 96.34.212.10 active went from OpenConfirm to Established
Jun 24 16:01:32.280 EDT: BGP: ses global 96.34.212.10 (1) act IPv4 Unicast:base Assigned ID
Jun 24 16:01:32.280 EDT: %BGP-5-ADJCHANGE: neighbor 96.34.212.10 Up
Jun 24 16:01:32.484 EDT: BGP: ses global 96.34.212.10 (1) IPv4 Unicast:base write request no-op


Jun 24 16:01:52.730 EDT: BGP: 96.34.212.10 rcv message type 3, length (excl. header) 2
Jun 24 16:01:52.730 EDT: %BGP-3-NOTIFICATION: received from neighbor 96.34.212.10 4/0 (hold time expired) 0 bytes
Jun 24 16:01:52.730 EDT: BGP: 96.34.212.10 went from Established to Closing
Jun 24 16:01:52.730 EDT: %BGP-5-ADJCHANGE: neighbor 96.34.212.10 Down BGP protocol initialization
Jun 24 16:01:52.730 EDT: BGP: nbr_topo global 96.34.212.10 IPv4 Unicast:base (1) NSF no stale paths state is NSF not active
Jun 24 16:01:52.730 EDT: BGP: nbr_topo global 96.34.212.10 IPv4 Unicast:base (1) Resetting ALL counters.
Jun 24 16:01:52.730 EDT: BGP: 96.34.212.10 closing
Jun 24 16:01:52.730 EDT: BGP: nbr_topo global 96.34.212.10 IPv4 Unicast:base (1) Resetting ALL counters.
Jun 24 16:01:52.730 EDT: BGP: 96.34.212.10 went from Closing to Idle
Jun 24 16:01:52.730 EDT: BGP: nbr global 96.34.212.10 Open active delayed 12288ms (35000ms max, 60% jitter)

Jun 24 16:02:04.027 EDT: BGP: 96.34.212.10 active went from Idle to Active
Jun 24 16:02:04.027 EDT: BGP: 96.34.212.10 open active, local address 96.34.212.93
Jun 24 16:02:04.031 EDT: BGP: ses global 96.34.212.10 (0) act read request no-op
Jun 24 16:02:04.031 EDT: BGP: ses global 96.34.212.10 (0) act Adding topology IPv4 Unicast:base
Jun 24 16:02:04.031 EDT: BGP: 96.34.212.10 active went from Active to OpenSent
Jun 24 16:02:04.031 EDT: BGP: 96.34.212.10 active sending OPEN, version 4, my as: 20115, holdtime 20 seconds, ID 6022D45

I have this problem too.
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Giuseppe Larosa Fri, 06/25/2010 - 09:34

Hello David,

I would focus on the following debug lines:

Jun 24 16:01:32.280 EDT: BGP: nbr global 96.34.212.10 neighbor does not have IPv4 MDT topology activated
Jun 24 16:01:32.280 EDT: BGP: ses global 96.34.212.10 (0) act IPv4 Unicast:base mdt prepare old peer: BGP_MDT_STYLE_NONE
or Internal Problem

it looks like router1 detects that the other peer cannot talk on address-family MDT and prepares itself to do something for backward compatibility and fails in this attempt

later we see that remote peer has sent a notification message closing the session

Jun 24 16:01:52.730 EDT: BGP: 96.34.212.10 rcv message type 3, length (excl. header) 2
Jun 24 16:01:52.730 EDT: %BGP-3-NOTIFICATION: received from neighbor 96.34.212.10 4/0 (hold time expired) 0 bytes
Jun 24 16:01:52.730 EDT: BGP: 96.34.212.10 went from Established to Closing

this may mean the session was stucked and no BGP hello has been received

I would check this aspect of MDT address family on neighbor if you have access to it or I would contact the router's adminstrator

Hope to help

Giuseppe

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