IGPs in use

Mon Oct 12 21:56:48 UTC 1998

On Mon, Oct 12, 1998 at 10:42:00PM +0100, Chrisy Luke wrote:
> On Mon, 12 Oct 1998, Ben Black wrote:
> 
> > I would say BGP is an exterior gateway protocol and using iBGP as an IGP is
> > unwise.  Much like posting to nanog when you have no clue.
> 
> Hm. How do your multiple border routers pass routes between themselves,
> then? Is that not, by definition, an IGP? Simply because it doesn't have to
> worry about which "random sized network that might or might not move" goes
> where doesn't exclude the validity of it's IGP status. I don't know of any
> other protocol that carries BGP data as an IGP (AS Path, MED's etc) in a
> way suitable for re-export.
> 

perhaps i should have said "using iBGP as the only IGP" to avoid a flood
of pedantic replies.  iBGP is, after all, by definition, not an external
protocol.  it is also, like so many knobs to twist in engineering, not
for use in every situation.  however, i don't really see that using iBGP
as your predominant IGP in a network of several hundred routers can
eliminate network or administrative complexity (as claiming a "lack" of
such things implies).  and if your network is smaller than that, why not
just use a routing protocol designed for the task?

just because BGP is your hammer doesn't mean every problem is a nail.

ben

> Moreover, many people do use it as their sole or predominant IGP, 
> particularly where convergance time because of failure isn't an issue and
> adjacancies don't need to be built using an LSA model (ie, lack of
> network or administrative complexity).
> 
> Chris.
> -- 
> == chris at easynet.net, chrisy at flix.net, chrisy at flirble.org
> == Systems Manager for Easynet, part of Easynet Group PLC.