[c-nsp] BGP Best Practice

[Dmitry Kiselev]

On Wed, Jun 07, 2006 at 02:09:27PM +0200, Kristian Larsson wrote:

> > Hello all,
> > 
> > Does anyone know of a good document that sets out BGP best practice for
> > Internet useage?
> > 
> > I'm specifically looking for something that states policy regarding intra-AS
> > routing i.e. that all eBGP speakers must be connected together via iBGP or
> > at worst some kind of redistribution into and out of an IGP.
> You will probably be best off using fully meshed
> iBGP. If you redistribute to OSPF and then back
> you will loose all community attributes, lpref and
> so on. Also, if you have some switches not capable
> of a 180k table in OSPF you will not be able to
> use those.



When redistributed into OSPF each prefix will traverse
across network as separate Type 5 LSA. It is VERY BAD idea
to stress internal routers with 180k OSPF updates.
IS-IS, AFAIR, has about 30k routes limitation due LSP
fragmentation logic.


> I've actually never heard of anyone redisting an
> entire BGP table into IGP..
> 
> If you have a lot of routers, a route reflector
> might be worth considering.
> 
> > I've had a brief scan of RFC1771 and 1772 and can't find anything that
> > states this clearly (although it is hinted at in more than one area)
> > 
> > ("*The use of the term Autonomous System here stresses the fact that ? the
> > administration of an AS appears to other ASs to have a single coherent
> > interior routing plan and presents a consistent picture of what destinations
> > are reachable through it"*  from 1771 is the best I could find)

-- 
Dmitry Kiselev