On Fri, Oct 17, 2008 at 05:31:54PM -0700, JINMEI Tatuya / 神明達哉 wrote:
> In this case, the DHCPv6 server (or a relay, which would also rely on
> a router and wouldn't work in this situation anyway) can send out an
> RA with the router lifetime being 0 and with a prefix information
> option.  The server could actually keep sending such minimum RA,
> whether or not other routers are active.

As my own peculiar brand of server implementer, this means a few
things that I would wind up doing (can't speak for other
implementors);

I would have to implement at least the RA message, and probably also
reception of RS messages, within my DHCPv6 server software (so as to
ease and correct administrator configuration).

I would, in order to ensure the offered configuration was usable at
the moment it was delivered, and unable to sense the presence or
absence of prefix configuration within the client, have to follow
every DHCPv6 Reply with an RA (with maybe some optimization later).

When I look at it that way, again as my own personal breed of DHCPv6
server implementor, it is far easier for me to adopt a new
configuration option now (at a time when DHCPv6 deployment is still
beginning and malleable), than it is to implement a great deal more
software.

It's the difference between one line in a table of option formats
in our software, and whole sections of new code, more sockets to
open, maintain, etc.


As my own peculiar brand of client implementer, this also means at
least one thing that I would wind up doing.  In this case, we cannot
predict that other server implementors will offer RA (it certainly is
not stated in RFC 3315).  So I would still default to /64 sized subnet
masks.  I have not made up my mind on whether I would have to
implement router solicitation in the client, or what I would have the
client do when it reached a bound sate without prefix configuration.


It is my opinion that when you take the long view in maintenance of
these protocols and networks, the only easy way out is to provide a
single configuration protocol.  It is a vast DHCPv6 client
simplification to obsolete RA, and run the client upon interface
initialization.  Much more of a gain than the extra implementation
in new options (which are just a few entries in a table and some
shell scripting).

-- 
Ash bugud-gul durbatuluk agh burzum-ishi krimpatul.
Why settle for the lesser evil?  https://secure.isc.org/store/t-shirt/
-- 
David W. Hankins        "If you don't do it right the first time,
Software Engineer                    you'll just have to do it again."
Internet Systems Consortium, Inc.               -- Jack T. Hankins

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