Whats wrong with this BGP? Low Tblver, high and stable outq, delay in establishing bgp

[Ugur Ersoy]

Hi guys,

Seems like there is something wrong with our BGP peering, it has lower tblver compared to other peerings established on router, and 1001 value in OutQ. There is one other BGP applied on same pyhsical interface, same MTU, same configuration. It works well, any ideas?

First one is fine, second is quite problamaticm, it flaps as well. It takes almost 2.5min to step out of openconfirm state.

Here it is:  

Neighbor        V           AS             MsgRcvd     MsgSent         TblVer    InQ OutQ            Up/Down    State/PfxRcd

172.16.152.81 4        xxxxx         11734            46752            374396  0       0                     1w1d         4
172.16.154.81 4        xxxxx            6                   57                    1        0     1001                 00:01:39   4

[Amit Goyal]

Hi Ugur,

It still looks to be an MTU issue. May be from configuration prospective you have kept MTU same for both BGP peering but there could be bottle necking for neighbor 172.16.154.81.

Are you able to ping this neighbor with a packet size equal to MTU and df-bit set?

Please rate if it helps.

HTH

-Amit

[Ugur Ersoy]

Hi Amit, thanks for your answer. We found out the reason, problem is more likely because of slot/card problem on  cisco xr (neighbor). waiting for rma.

by the way, ping with df-bit and 1700b size is fine.

[Amit Goyal]

Thanks Ugur,

I still feel that BGP packets were not able to reach remote device from your device and they were stuck in Out queue. It happens normally in case of MTU issue only. But may be in your case remote device is not able to process BGP packets and due to lack of ACK, your cisco device kept them in out queue.

HTH

-Amit