[AusNOG] BGP Question

[Joshua D'Alton]

http://blog.ine.com/2010/11/22/understanding-bgp-convergence/

in other words, es they only send the updated prefixes (or should).


On Mon, Dec 23, 2013 at 10:20 AM, Alex Samad - Yieldbroker <
Alex.Samad at yieldbroker.com> wrote:

> Hi
>
> Currently I peer with 3 transits (2 with primary and backup links).   I
> use 2 cisco and 1 routeros routers in play.
>
> I have been relooking at our BGP setup.  Part of that process was to
> filter right down, having a google and a read I have come down to these
> rules
>
> On the in filter
> * block non routable, multicast and loopback
> * block 0/1-32 routes (only allow 0/0)
> * filter to allow only prefix's with 2 AS
> * allow specific prefix that have specific AS as the last hop (we have
> identified certain AS's that our clients are on that we would like to take
> more than 2 AS prefix's)
> * we add a local pref for all prefix's from 1 transit right now, but I am
> looking at changing that to just adding local pref for 0/0 instead
> * we drop all /24-32 prefix's
>
> On out bound filter
> * only publishing our /24
> * block everything else
>
>
> The main limiter is the cisco' the amount of memory, for routeros I can
> just reconfigure the VM...  the move from 3 as to 2 as the number of
> routers went from 400k (or maybe 100K) to 15k roughly ..
>
>
> I'm just about to talk to our transits to send us full BGP tables and a
> thought occurred to me, if I am filtering a majority of the prefix's, does
> the peers router keep trying to send me that info or does BGP work such
> that a full table is sent on initiation and then only updates afterwards ?
>
> Basically I don't want to have to received and drop all those prefix's
> each time the BGP peers update( or each bgp cycle)
>
> Any other comments welcome ?
>
>
> A
>
>
>
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