[radvd-devel-l] Fwd: Re: RADVD PATCH: send zero router lifetime when exiting

Thorsten Kuefer (JOIN) thorsten.kuefer at uni-muenster.de
Fri Apr 8 04:39:20 EDT 2005

Subject: Re: RADVD PATCH: send zero router lifetime when exiting
Date: Donnerstag 07 April 2005 14:54
From: Pekka Savola <pekkas at netcore.fi>
To: "Thorsten Kuefer (JOIN)" <thorsten.kuefer at uni-muenster.de>

On Thu, 7 Apr 2005, Thorsten Kuefer (JOIN) wrote:
> I am doing some renumbering tests with IPv6 using radvd. Thereby I noticed
> the feature that the default route is removed when exiting radvd. I think
> for a hardware router RFC2461bis section 6.2.5 sound reasonable but a
> software like radvd should at least give a configuration option for this to
> the user. In my scenario I would like to keep the advertised default route
> until it expires.

I can see this may cause issues in some case, but there are problems
as well.  For example, with multiple routers on the link, all
advertising as a default router, removing the route by a failing
router seems to make sense.

Maybe there could be a config option not to remove the default route,
but I'm a bit uncomfortable doing this because it's in the spec, and
implemented by others this way as well (at least in KAME).

Maybe this should be brought up in the ipv6 at ietf.org list?  At least,
it might make sense for you to send this on radvd-devel-l list if some
folks have opinions about this either way.

> There are also some other cases e.g. when radvd is accidentally killed or
> dies unexpectedly where all clients would loose IPv6 connectivity even if
> routing could continue without problems.

Note that this doesn't happen if radvd would dump core or killed with
KILL signal, because the code to remove the default route would not
get executed.

Pekka Savola                 "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

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