Subject: Re: Peculiar ICMP6 redirect rejection
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Robert Elz <kre@munnari.OZ.AU>
List: tech-net
Date: 08/19/2002 17:45:46
    Date:        Sat, 17 Aug 2002 17:48:48 +0200 (CEST)
    From:        der Mouse <mouse@Rodents.Montreal.QC.CA>
    Message-ID:  <200208171623.MAA29406@Sparkle.Rodents.Montreal.QC.CA>

I suspect this topic has just about exhausted itself...

  | The initial message was not "why aren't redirects working".  They were
  | working, sort of.

Yes, I know that.   It was just ...

  | itojun> I bet you're using global addresses ...

was the most likely explanation (first glance) for the particular
message you reported.

  | me> You'd lose that bet.
  | me> [mini-rant which started this thread off]


  | That may be the theory, but it is not the practice, and until we get
  | something better than AAAA records,

I have no idea what the DNS has to do with this in particular.

  | (Given
  | what you say about dynamic renumbering, I can't understand why people
  | backed off from A6 records;

Nor can I, but this isn't the place for that debate.

I will just point out that some others don't believe that renumbering
can ever work, and others believe (I think) that it is important,
and has to work, but won't ever happen often, or quickly, enough to
bother spending time or energy on optimising it.

  | I don't see any way to get rid of the EUI64-based LL address in the
  | network startup scripts without hardwiring knowledge of the EUI64
  | chosen by the kernel into those scripts.  Do you really think it's sane
  | to have startup scripts that look like

If you actually have some reason to do that, then I don't see why not.

It is also possible, though I haven't actually tried it, that if the
very first IPv6 thing that you do to an interface is to manually assign it
a LL address, then the automatically generated one won't exist.   That
would make some sense, but I don't know if the implementation does that.

I'm also not sure what the ipv6 mode (in NetBSD/KAME) "host" means, as
distinct from "autohost" in this context, as I only ever use the latter.

  | I find this particularly peculiar since the ifconfig manpage says
  | "delete does not work for IPv6 addresses.  Use -alias with explicit
  | IPv6 address instead.", which runs counter both to what you recommend
  | and to my (and apparently your) experience.

Yes, I have seen that too.  And yes, "delete" seems to work for me, "-alias"
just seems like a v4 mechanism.

  | Oh, stop trying to confuse the issue.  In computer contexts, "illegal"
  | means "forbidden by the specificaion",

I was just not sure when you explicitly quoted "illegal".

  | Perhaps I am using the wrong term, then.  Static routing, as I use the
  | term, *by definition* means you don't want to pay attention to
  | redirects, because static routing means routing that does not change
  | expect by explicit administrator action.  And an
  | automatically-generated redirect does not qualify.

That's more locked down routing, though I'm not sure it has a well
used term, as it isn't very common.

static routing generally just means not using dynamic routing, which
generally means "I configure a route to use" (as in the use of /etc/mygate
in IPv4).

After that, whatever the routers/redirects manage to do to get the
packets to the right place is fine - I'm still using static routing.

In any case, the conclusions from all of this are that IPv6 really does
expect that routes will use LL addresses.   Implementations may allow you
to get away without doing that, but don't rely upon it, or expect much
support.   And if you don't like the way NetBSD handles LL addresses, suggest

Last, it doesn't seem as if there's been any response to the substance of
the message you originally posted (why the redirect seemed to be handled