Subject: Re: draft-ipngwg-default-addr-select-00.txt

From: [email-masked]
Date: Fri, 29 Oct 1999 16:49:22 -0400

Wait, wait, wait....

Why would one put link local addresses in a router extension header?

I checked with RF C2460, and there is no documentation of a restriction
related to such an address.
I think that it is A BUG  rather than A FEATURE.

The more I think about this, the more I think that the *universal
restriction* should be that a node MUST NEVER FORWARD packets based on a
DESTINATION ADDRESS WITH NO TOPOLOGICAL INFORMATION  (for lack of a better
term).  If we make one exception we open a Pandora box.

 A link-local address has no topological information, albeit a site-local
address has: the subnet number, or ID, which makes a crucial difference:
site local packets can be forwarded within the site.

Alex

Steve Deering <[email-masked]> on 10/29/99 02:10:17 PM

Sent by:  Steve Deering <[email-masked]>

To:   [email-masked]
cc:   [email-masked] (Alex Conta/US/3Com)
Subject:  Re: draft-ipngwg-default-addr-select-00.txt

At 10:44 AM -0700 10/29/99, Sam Manthorpe wrote:
> > >...link-local destinations can't be forwarded between interfaces,...
> >
> > Link-locals *can* be forwarded between interfaces connected to the same
link.
>
>I'm probably missing something silly here, but isn't that a bad
>thing to do?  Doesn't it lead to duplication of packets on the wire?
Yes, it is not a desirable steady state to be in.  (That's why I
mentioned in my previous message that a router finding itself doing
that ought to issue a Redirect to try to make it stop.)
>Or are you talking about source routing (in which case there may be
>some reason to do that if the packet contains some interesting
>hop-by-hop option)?
No, I wasn't thinking of source routing, but that is another (better)
example of how the situation might arise.
Steve
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From: "Matt Crawford" <[email-masked]>
Date: Fri, 29 Oct 1999 16:18:18 -0500

Alex, you SEEM to be saying that if I'm talking to a node on my link,
with link-local addresses, and it goes mobile, the router (its home
agent) is not allowed to do anything to keep our communication going.
(Once again, I may know a bit too little about mobileipv6.)  If that
IS what you're saying, I disagree with it.

				Matt

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From: Francis Dupont <[email-masked]>
Date: Fri, 29 Oct 1999 23:20:50 +0200

In your previous mail you wrote:

   
   
=> in fact this is not the case here because the topological information
exists: the link-local address is in the incoming link (or if you prefer
incoming and outgoing links must be the same).
 But I agree to use link-local addresses in a router extension header
is rather silly. I believe the whole multiple interfaces for a link
is far simpler to understand (and to implement) if the link is associated
to a super/virtual interface. The only remaining issue in this case is
the number of needed link-local addresses...

Regards

[email-masked]

---

From: Francis Dupont <[email-masked]>
Date: Sat, 30 Oct 1999 00:47:45 +0200

Alex, you SEEM to be saying that if I'm talking to a node on my link,
   with link-local addresses, and it goes mobile, the router (its home
   agent) is not allowed to do anything to keep our communication going.
   (Once again, I may know a bit too little about mobileipv6.)

=> routing headers used by mobile IPv6 are in a different case because
addresses are for the same node (ie. packets don't go on a wire).

Regards

[email-masked]

PS: I don't know if mobility is usable with link-local addresses
because the return of a mobile at home will be a cause of conflicts
(between the mobile and its home agent for the shared link-local address)
but this is another topic for another mailing list...
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