Multi-home with same provider, BGP convergence issues

Raymond Macharia rmacharia at gmail.com
Fri Mar 13 13:02:21 CDT 2009


Hi Nicholas,a simple schematic would help together with configs of how you
are announcing your IP blocks. But with what you have indicated, you may
need to manipulate your announcements (for example using prepend)  and make
sure that you don't have the same IP blocks  being advertised from the two
links at the same time.
Again with more info I may provide you with a more accurate response

Regards

Raymond Macharia

On Fri, Mar 13, 2009 at 3:19 PM, Nicholas R. Cappelletti <
nick at switchtower.org> wrote:

> 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.
>
> ---
>
> Nick Cappelletti
> nick at switchtower.org
>
>


-- 
Raymond Macharia



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