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Beginner

Help with BGP convergance.....

We have a WAN on MPLS that is using

BGP. We are getting 25 to 35 second convergance but we need to do better. I have the router config's and a drawing of the

network if someone thinks they could help us improve this. Thanks in advance.......

18 REPLIES 18
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Should I expect to see a difference it reconvergance time between the two?

James Brockman

Network Engineer

Ahold Account

HP Enterprise Services

Telephone +1 717.240.5568

Email James.Brockman@hp.com

1149 Harrisburg Pike, Carlisle, PA 17013

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More than likely not since bgp timers are controlling convergence. I usually test mine by shutting the interface.

HTH, John *** Please rate all useful posts ***
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AS 6Xnnn

Private

Giant C Store

On the right in the light blue....

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James,

BGP keepalives are important to validate BGP sessions health and to avoid routing blackholes.

if you are setting your keepalive interval & holddown timers in production you need to be very careful. Setting the timers  too small results in fast  peering deactivateion detection and lead to false positives and disruption of BGP session  and exessibe route flapping,

For fast-external-failover, this feature is enable by default for eBGP sessions using the BGP process command bgp fast-external-failover and used for point-point links on a none-shared link when the peers are directly connected. Using it on NBMA and ethernet interfaces might be inefficient.

A more advance version is called fast peering session deactivation which can be setup using the neighbor command "neighbor 1.1.1.1 fall-over. This feature applies to both iBGP & eBGP and does not rely on interface state instead uses IGP. Once the IGP route disappear, the BGP session gets immediately torn down and used for none-direct conencted peers.

Francisco