[51634] in North American Network Operators' Group
Re: AT&T NYC
daemon@ATHENA.MIT.EDU (alex@yuriev.com)
Tue Sep 3 08:33:36 2002
Date: Tue, 3 Sep 2002 08:33:17 -0400 (EDT)
From: alex@yuriev.com
To: "Stephen J. Wilcox" <steve@opaltelecom.co.uk>
Cc: bdragon@gweep.net, nanog@merit.edu
In-Reply-To: <Pine.LNX.4.21.0209031020430.11781-100000@staff.opaltelecom.net>
Errors-To: owner-nanog-outgoing@merit.edu
> > > >
> > > > > > Has anybody mentioned the benefits of ISIS as an IGP to them.
> > > > >
> > > > > Link-state protocols are evil, and when they break, they *really* break.
> > > > > I still do not see a compeling argument for not using BGP as your IGP.
> > >
> > > Convergence time?
> >
> > What is better - relatively long convergence time on affected routes or a
> > problem on unaffected route?
> >
> > Ask your customers. They do not care if someone else is having a problem.
> > They care that they dont.
>
> Do you run a decent sized network?
No, I have never touched a router in my life.
> Convergence time in the order of that taken by BGP is not acceptable,
> things go crazy when traffic pours in and theres no routes to carry it.
This is a great blanked statement. What is convergence time?
> Other example, what about static dialup users, they dial up and wait a few
> minutes whilst their route is installed throughout BGP??
That is why their route is *nailed* via BGP to the router that *always*
provide connectivity to them. If they have to move, BGP injectors are your
friends. Takes seconds.
> > > > With link-state, one interface flap can mean doing SPF on every route.
> > > > If "every route" is only a couple hundred, rather than 100K, you fare
> > >
> > > As you say disable synchronization and try and control the physical reach of
> > > your igp by some mechanism.. areas, summaries, ASes etc
> >
> > Which is exactly what you are doing when you inject nailed routes into bgp.
>
> No its not? I'm suggesting some level of order can help control the number of
> routers required to reconverge a network, I dont see the comparison with
> inserting routes in BGP which is how the routes get in not how they converge.
If you dont have a network wide meltdown due to IGP failure you wont need to
wait for entire network to come up. It is timing of discrete events. Isn't
math grand.
Alex
