Re: IPv6 migration steps for mid-scale isp

[Måns Nilsson <mansaxel () besserwisser org>]

Subject: Re: IPv6 migration steps for mid-scale isp Date: Wed, Sep 20, 2017 at 12:04:45PM -0300 Quoting Owen DeLong 
(owen () delong com):

> > iBGP is scalable, you can introduce router reflectors to avoid full mesh
> > peering between PE routers – and the sky if your limit!
>
> I think in general most serious networks consider this a question of OSPF
> vs. ISIS for IGP and BGP is the only choice for EGP.
>
> I find it interesting that you don’t even mention ISIS in your discussion.
>
> I don’t know of any substantial networks running EIGRP these days. I’m not
> saying they don’t exist, but they are certainly rare exceptions.

The fact that we'll be running dual-stack for perhaps another decade and
that there are no 36-hour days available makes the choice very simple;
IS-IS is my preferred choice. One routing instance less. 

But, I'd rather limit the IS-IS scope to "links and loopbacks" -- there
is no need to have link-state flooding for a customer network that will
always be originated from one specific access router. iBGP is much more
appropriate for that. As long as I'll have one working path up to that
router I can rely on BGP to tell me where the network is.

The key is the time domain. If the topology is likely to be changing
slowly (customer moves premises or commissions new connection), use
BGP to signal it. If the topology is potentially unstable, i.e. subject
to backhoes and similar, use IS-IS.

Oh, by the way; I concur with Owen: EIGRP is not done. I've stumbled
on it once the last decade, and it was a PABX network engineer who
insisted.
-- 
Måns Nilsson     primary/secondary/besserwisser/machina
MN-1334-RIPE           SA0XLR            +46 705 989668
Am I in GRADUATE SCHOOL yet?

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