[185611] in North American Network Operators' Group
Re: IGP choice
daemon@ATHENA.MIT.EDU (Matthew Petach)
Fri Oct 30 09:35:04 2015
X-Original-To: nanog@nanog.org
In-Reply-To: <CACXVQYCTk4oHVuXMQtYGEF1o0DxdftAaZy6MYQmNTFZk8tGY9g@mail.gmail.com>
Date: Fri, 30 Oct 2015 06:34:58 -0700
From: Matthew Petach <mpetach@netflight.com>
Cc: "nanog@nanog.org" <nanog@nanog.org>
Errors-To: nanog-bounces@nanog.org
On Thu, Oct 22, 2015 at 12:35 PM, Dave Bell <me@geordish.org> wrote:
> On 22 October 2015 at 19:41, Mark Tinka <mark.tinka@seacom.mu> wrote:
>> The "everything must connect to Area 0" requirement of OSPF was limiting
>> for me back in 2008.
>
> I'm unsure if this is a serious argument, but its such a poor point
> today. Everything has to be connected to a level 2 in IS-IS. If you
> want a flat area 0 network in OSPF, go nuts. As long as you are
> sensible about what you put in your IGP, both IS-IS and OSPF scale
> very well.
It is rather nice that IS-IS does not require level-2 to be
contiguous, unlike area 0 in OSPF. It is a valid topology
in IS-IS to have different level-2 areas connected by
level-1 areas, though you do have to be somewhat
careful about what routes you propagate into-and-back-out-of
the intervening level-1 area.
But other than that, yeah, the two protocols are
pretty much homologous.
Matt
