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

[Miya Kohno <[e-mail]>]

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:[e-mail]] 
> Sent: Monday, November 09, 2009 2:37 PM
> To: Miya Kohno; Becca Nitzan; [e-mail]; [e-mail]
> Cc: [e-mail]
> 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.
>