Subject: (ngtrans) RE: link-local addresses in transition-mechanisms

From: Richard Draves <[email-masked]>
Date: Mon, 26 Jun 2000 13:45:36 -0700

> To briefly summarize some off-list discussion: the MLD spec 
> says that MLD messages use a link-local source address. The 
> multicast-over-6to4 draft uses a degenerate form of MLD over 
> 6to4, so the messages should use a link-local source address 
> taken from the 6to4 interface. The  6to4 draft says the 6to4 
> interface forms a link-local address following the rules 
> specified in the transition-mechanisms draft for configured 
> tunnels.

itojun & Francis both disagreed with changing the wording in the
transition-mechanisms draft. This leaves two main possibilities - changing
the 6to4 draft (putting in explicit MUST wording about how the link-local
address is formed) or changing the multicast-over-6to4 draft (saying that
MLD over 6to4 does not use the link-local address).

I don't like having special restrictions on the 6to4 interface's link-local
address. Partly I'm concerned it would reduce code-sharing opportunities in
implementations, since 6to4 interfaces share tons of code with configured &
automatic tunnel interfaces. Partly I'm concerned that itojun & Francis's
objections could apply to 6to4 interfaces as well.

I think at this point I favor changing the multicast-over-6to4 draft, so the
MLD messages sent from 6to4 gateway to 6to4 relay do not use the 6to4
link-local address. Instead the v6 source address could be a) a global 6to4
address or b) a v4-compatible address. Either way, the receiving 6to4 relay
could reliably extract a v4 address from the v6 source address.

Rich

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From: Alain Durand <[email-masked]>
Date: Mon, 26 Jun 2000 17:10:51 -0700

Richard Draves wrote:

> This leaves two main possibilities - changing

The 6to4 draft has been discussed long enough, is ready to go and has value
in itself, even without the multicast part.
The multicast-over-6to4 draft is new work in progress.
So if one has to change, and there is no strong technical case to
get the 6to4 to change, then I would suggest to change the
multicast-over-6to4 draft.

    - Alain.

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From: Jim Bound <[email-masked]>
Date: Mon, 26 Jun 2000 21:32:39 -0400

I agree with you alain........
/jim