[nsp] ospf default routes and bgp injection

[Oliver Boehmer (oboehmer)]

Nick,

I think it really depends on what you want to achieve and wich IGP
you're using. As general arguments:

1) customer routes in IGP don't scale. While OSPF/ISIS on modern
platforms (RISC CPU's) works just fine with 5000+ routes in your IGP,
scaling to 10000 and above might be a challenge

2) The more routes you carry in your IGP, the longer PRC takes
installing the routes in your RIB. This will be in issue if you want to
tune your IGP for faster (i.e. sub-second) convergence

I think one can find addtl. arguments if your specific network and
routing topology is taken into account.

	oli

----Original Message----
From: cisco-nsp-bounces at puck.nether.net
[mailto:cisco-nsp-bounces at puck.nether.net] On Behalf Of Nick Kraal
Sent: Dienstag, 6. April 2004 14:45 To: cisco-nsp at puck.nether.net
Subject: Re: [nsp] ospf default routes and bgp injection

> Following up on this one. We all know that the IGP of choice used
> should carry only infrastructure networks and kept as small as
> possible. The rest should be announced via iBGP. Is there a document
> that explains this rationale clear --having some difficulty
> convincing some folks. 
> 
> Thanks in advance,
> 
> -nick/
> 
> ----- Original Message -----
> From: "Gert Doering" <gert at greenie.muc.de>
> To: "Christopher J. Wolff" <chris at bblabs.com>
> Cc: <cisco-nsp at puck.nether.net>
> Sent: Thursday, April 01, 2004 5:49 AM
> Subject: Re: [nsp] ospf default routes and bgp injection
> 
> 
> > Hi,
> > 
> > On Wed, Mar 31, 2004 at 09:58:12AM -0700, Christopher J. Wolff
> > wrote: 
> > > I've considered ibgp as an end-to-end solution however never went
> > > so far as to implement it.
> > 
> > Completely overkill in this network.  If there's no BGP speaker
> > "down the road", there is not much use in having all those routers
> > actually carry BGP information. 
> > 
> > > My concern is making sure that the entire routing table
> > > isn't propagated all the way to the edge device, which could be
> > > something minimal like a 2611XM.  Any thoughts?  Thank you for
> > > your advice. 
> > 
> > Have the BGP speakers distribute an OSPF (or EIGRP, or even RIP :) )
> > default route to the smaller boxes.
> > 
> > gert
> > --
> > USENET is *not* the non-clickable part of WWW!
> > 
> //www.muc.de/~gert/
> > Gert Doering - Munich, Germany gert at greenie.muc.de
> > fax: +49-89-35655025
> gert at net.informatik.tu-muenchen.de
> > _______________________________________________
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> > 
> 
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