Misconceptions, was: IPv6 RA vs DHCPv6 - The chosen one?

Valdis.Kletnieks at vt.edu Valdis.Kletnieks at vt.edu
Wed Dec 28 19:04:45 UTC 2011

On Wed, 28 Dec 2011 21:56:19 +0900, Masataka Ohta said:

> According to the end to end argument, the only possible solution
> to the problem, with no complete or correct alternatives, is to
> let hosts directly participate in IGP activities.

That's only for hosts that are actively trying to communicate on more than one
interface at a time, and even then quite often the *actual* right answer isn't
"run an IGP", it's "insert static routes for the subnets you need to reach via
the other interface"(*).

Meanwhile, out in the real world, 98% of actual  hosts have a *really* easy
routing decision - they can make a choice of any of one routers to reach the
destination.  If it's a laptop that has both a wireless and a wired connection
active, usually a simple "prefer wired" or "prefer wireless" is sufficient.

Quick sanity check on the hypothesis: Does Windows ship with an IGP enabled by
default?  If not, why does the net continue to function just fine without it?

Hmm.. Thought so.  Maybe an IGP on end hosts isn't quite as needed on
production networks as an academic paper from years ago might suggest.

(*) If you think I'm going to run an IGP on some of my file servers when
"default route to the world out the public 1G interface, and 5 static routes
describing the private 10G network" is actually the *desired* semantic because
if anybody re-engineers the 10G net enough to make me change the routes, I have
*other* things to change as well, like iptables entries and /etc/exports and so
on.  I don't *want* an IGP changing that stuff around wiithout the liveware
taking a meeting to discuss deployment of the change.

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