Subject: Tunneling of packets destined for link local address

From: Ichiro Okajima <[email-masked]>
Date: Tue, 15 Oct 2002 20:42:06 +0900

Hello,

I would like to know how an IPv6 router processes a tunneling packet
in which the destination address of outer packet is a global address
of one of interfaces and the destination address of inner packet
is link local address such as solicited node multicast address.

Is tunneling of packets destined for link local address just prohibited?

If it were allowed, does a router decapsulate the inner packet and send
it to the interface which the destination address of the outer packet
indicates?

How about in the case that the destination address of the outer packet
is subnet router anycast address?

Regards,

Ichiro Okajima
NTT DoCoMo 

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From: Robert Elz <[email-masked]>
Date: Tue, 15 Oct 2002 19:01:48 +0700

Date:        Tue, 15 Oct 2002 20:42:06 +0900
    From:        Ichiro Okajima <[email-masked]>
    Message-ID:  <[email-masked]>

  | Is tunneling of packets destined for link local address just prohibited?

Yes, of course, but ...

  | If it were allowed, does a router decapsulate the inner packet and send
  | it to the interface which the destination address of the outer packet
  | indicates?

No, the tunnel provides its own virtual interface.   The link local
address needs to be the one assigned to that virtual interface, or
the packet will be discarded.   It can't cross over to any other
interface (real or otherwise).

  | How about in the case that the destination address of the outer packet
  | is subnet router anycast address?

That's fine, if the box is a router, configured to answer that address
on that interface, then it will reply.

kre

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From: Pekka Savola <[email-masked]>
Date: Tue, 15 Oct 2002 15:08:55 +0300 (EEST)

> Is tunneling of packets destined for link local address just prohibited?

No, it's allowed.
 
> it to the interface which the destination address of the outer packet

I believe the answer is "the tunnel pseudo-interface performing 
decapsulation".  Whether that's useful is another story..
 
> is subnet router anycast address?

The same.

-- 
Pekka Savola                 "Tell me of difficulties surmounted,
Netcore Oy                   not those you stumble over and fall"
Systems. Networks. Security.  -- Robert Jordan: A Crown of Swords