Multi-home with same provider, BGP convergence issues

Fri Mar 13 12:19:32 UTC 2009

Hello,

I have sort of an interesting problem, that probably has an easy fix.  I've ran into a continuous BGP convergence problem on the cores of the network I administer every time I bring up both of our Savvis connections (we have a single OC-12 and 2 1GigE connections in a multi-hop configuration).

The connections are on separate border devices separated again by a set of cores routers.  There is a set of core routers per building and each building has its own Savvis connection along with other connections from other providers.  All the equipment is Cisco gear.  We've been running with multiple connections from Savvis for some time, but recently reconfigured the GigE lines to multi-hop to help with balancing, only then, did we experience this BGP convergence issue.

>From what my colleagues and I have read so far is that turning on "bgp deterministic-med" on all the BGP speaking devices should help in this situation, but I don't see how using MEDS is going to help us.

I can provide a .png of our current setup for reference or any further information needed.  Any help anyone can provide will be greatly appreciated.

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Nick Cappelletti
nick at switchtower.org