[c-nsp] BGP Hold Time Expired, but why?

Christian Koch christian at broknrobot.com
Sat Jul 19 02:38:07 EDT 2008


sorry forgot to specify

the bgp session from aR1 to bR2 is the session in question

ck

On Sat, Jul 19, 2008 at 2:21 AM, Christian Koch <christian at broknrobot.com>
wrote:

> Hello -
>
> I have the following topology in lab, testing different failure scenarios.
> When i disconnect the link between aR1 and bR1, what would appear to be
> normal happens - ospf and ldp neighbor go down.
>
> When i re-connect the link between aR1 and bR1, the interface comes back
> up,
> osfp/ldp neighbor is re-established.
>
> 3minutes later, bgp holdtime expires , and all links are up..
>
> aR1-----------------bR1
> |                         |
> |                         |
> |                         |
> |                         |
> aR2-----------------bR2
>
>
> Some Notes
> - All Links 10GE
> - Full ibgp mesh
> - Peering is to loopbacks
> - OSPF as IGP
> - Loopbacks in OSPF
> - MPLS Enabled on Interfaces
>
>
> OSPF cost between aR1 and aR2 is 1
> OSPF cost between bR1 and bR2 is 1
> OSPF cost between aR1 and bR1 is 250
> OSPF cost betwen aR2 and bR2 is 500
>
> MTU 9216 between aR1 and aR2, aR1 and bR1, aR2 AND BR2
> MTU 9182 between bR1 and bR2
>
>
> IOS on aR1 and aR2 is 12.2.33.SRB2 -  SUP720
> IOS on bR1 and bR2 is 12.33.SRC - RSP720
>
>
> i am stumped, any ideas would be helpful in trying to understand why the
> bgp session is going down
> due to expired hold time, when all links are up..
>
> thanks!
>
> ck
>
>
>
>
>
>


-- 
^christian$


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