Re: comments on draft-kohno-ipv6-prefixlen-p2p-00.txt

A note you may find interesting in this context is:

http://www.ietf.org/rfc/rfc5375.txt
5375 IPv6 Unicast Address Assignment Considerations. G. Van de Velde,
      C. Popoviciu, T. Chown, O. Bonness, C. Hahn. December 2008.  
(Format:
      TXT=83809 bytes) (Status: INFORMATIONAL)

You already reviewed RFC 3627, which is good.

On Nov 9, 2009, at 3:44 PM, Miya Kohno wrote:

> Thank you, Tatsuya, for your thorough review.
>
> I think both of your points are apposite. We'll reflect them into  
> the -01 version.
>
> Thanks again,
> Miya
>> -----Original Message-----
>> From: JINMEI Tatuya / 神明達哉 [mailto:jinmei@isc.org]
>> Sent: Monday, November 09, 2009 2:37 PM
>> To: Miya Kohno; Becca Nitzan; randy@psg.com; maz@iij.ad.jp
>> Cc: ipv6@ietf.org
>> Subject: comments on draft-kohno-ipv6-prefixlen-p2p-00.txt
>>
>> (resending as I seem to have submitted the original one from the  
>> wrong
>> address)
>>
>> I've read this draft.  I don't have a strong opinion on the
>> proposal per se, but have a couple of minor comments:
>>
>> 1. In Section 4, the draft says:
>>
>>   However, Subnet-router
>>   anycast address has not been implemented and in practice, this has
>>   not been a problem.
>>
>> I'm afraid "has not been implemented" is too strong.  In
>> fact, we have "implemented" it in the KAME/BSD IPv6 stack in
>> that we implemented special restrictions (at that time) on
>> anycast addresses and had experimentally assigned
>> subnet-router anycast addresses on PC-based
>> IPv6 routers.  In general, it's difficult to declare
>> something hasn't been implemented because it eliminates any
>> minor implementation activity, which is almost impossible to prove.
>>
>> I have no objection to the conclusion itself (i.e. not a problem in
>> practice) and would rephrase it to something like this:
>>
>>   However, Subnet-router anycast addresses have not been (widely)
>>   deployed, and this has not been a problem in practice.
>>
>> 2. In section 5, it states:
>>
>>         1) A rule described in ICMPv6 [RFC4443] indicates that a
>>         Destination Unreachable (Code 3) message should be sent by a
>>         router rather than forwarding packets back onto
>> point-to-point
>>         links from which they were received if their destination
>>         address belongs to the link itself.
>>
>> This sentence is clear, but IMO is not perfectly accurate
>> because an address doesn't belong t(or isn't assigned to) a
>> *link*; it's assigned to an interface.  The corresponding
>> text of RFC4443 reads:
>>
>>   One specific case in which a Destination Unreachable
>> message is sent
>>   with a code 3 is in response to a packet received by a
>> router from a
>>   point-to-point link, destined to an address within a
>> subnet assigned
>>   to that same link (other than one of the receiving router's own
>>   addresses).
>>
>> where it's a *subnet* that is assigned to the link.  So, to
>> be very accurate, I'd propose to revise the text (e.g.) as follows:
>>
>>         1) A rule described in ICMPv6 [RFC4443] indicates [...]
>>         if their destination address matches a subnet that belongs to
>>         the link itself.
>>
>> ---
>> JINMEI, Tatuya
>> Internet Systems Consortium, Inc.
>>
> --------------------------------------------------------------------
> IETF IPv6 working group mailing list
> ipv6@ietf.org
> Administrative Requests: https://www.ietf.org/mailman/listinfo/ipv6
> --------------------------------------------------------------------