Re: question about draft-ietf-ipv6-scoping-arch-02.txt

[JINMEI Tatuya / $B?@L@x#:H(B <jinmei@xxxxxxxxxxxxxxxxxxxxx>]

>>>>> On Mon, 30 Aug 2004 11:20:27 -0700, 
>>>>> "Ghanwani, Anoop" <anoop.ghanwani@hp.com> said:

>> One possible scenario I can think of is some special link where hosts
>> do not want to or cannot perform link-layer address resolution for
>> their neighbors and simply send all packets to the default router.
>> The router is supposed to know the link-layer address of the
>> destination (or know how to get the link-layer address), and forwards
>> the packet to the destination.  If the destination is a link-local
>> address, the packet is likely to be sent back to the incoming link.

> Is this behavior supported by the IPv6 spec?

I'm not really sure which part you are referring to by "this
behavior", but regarding the following part:

   hosts
   do not want to or cannot perform link-layer address resolution for
   their neighbors and simply send all packets to the default router.

I believe the following part of RFC2461 (in Section 3.2) implies the
scenario:

     non-broadcast multiple access (NBMA)
                    - Redirect, Neighbor Unreachability Detection and
                      next-hop determination should be implemented as
                      described in this document.  Address resolution,
                      and the mechanism for delivering Router
                      Solicitations and Advertisements on NBMA links is
                      not specified in this document.  Note that if
                      hosts support manual configuration of a list of
                      default routers, hosts can dynamically acquire the
                      link-layer addresses for their neighbors from
                      Redirect messages.

Regarding the behavior of the router that forwards packets to a
link-local destination back to the same link, I don't know of any
other documents that explicitly allows the behavior.  But this is
exactly the reason why we clarified that in
draft-ietf-ipv6-scoping-arch.  And I'm 100% sure that this behavior is
the intended one by (one of) the original designer(s) of IPv6, Steve
Deering.  (Perhaps you can google his words on this at the ML archive
or something)
 
> This behavior is in conflict with Section 2.5.8 of RFC 2373 which 
> states:  "Routers must not forward any packets with link-local 
> source or destination addresses to other links."

I see we've already understood this does not conflict in this thread
by other posts, so I won't make further comments on it.

					JINMEI, Tatuya
					Communication Platform Lab.
					Corporate R&D Center, Toshiba Corp.
					jinmei@isl.rdc.toshiba.co.jp

p.s. as you may have noticed, the IESG has just approved this draft as
a proposed standard.  I personally don't think the discussion in this
thread requires further changes on the draft before publication, and
so I'm going to work on final editorial stuff with the RFC editor.  If
I miss something critical, however, please let me know ASAP.

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