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

Masataka Ohta mohta at necom830.hpcl.titech.ac.jp
Wed Dec 28 20:51:00 CST 2011


Valdis.Kletnieks at vt.edu wrote:

>> 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,

Note that the end to end argument has the following
statement I omitted to quote:

	(Sometimes an incomplete version of the function provided
	by the communication system may be useful as a performance
	enhancement.)

That is, there are incomplete solutions by intermediate systems
which sometimes work.

> 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"(*).

With manual configuration, you can do anything. But, aren't we
talking about autoconfiguration?

> 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.

Usually? Can you see the word "complete" in the end to end argument?

> Quick sanity check on the hypothesis: Does Windows ship with an IGP enabled by
> default?

Sanity check with Windows? Are you sure?

> If not, why does the net continue to function just fine without it?

It is often incomplete and incorrect unnecessarily requiring
manual reconfigurations.

> (*) 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.

If you are saying SLAAC is not enough in your case with
complicated manual management, I don't think I have to
argue against you on how to simplify it.

						Masataka Ohta



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