Re: 6MAN WG Last Call:draft-ietf-6man-ipv6-subnet-model-00.txt

[JINMEI Tatuya / 神明達哉 <[e-mail]>]

At Tue, 27 Oct 2009 06:24:47 -0400,
Brian Haberman <[e-mail]> wrote:

>       Title     : IPv6 Subnet Model: the Relationship between
>                   Links and Subnet Prefixes
>       Author(s) : H. Singh, et al.
>       Filename  : draft-ietf-6man-ipv6-subnet-model-05.txt
>       Pages     : 11
>       Date      : 2009-05-15
> 
> as a Proposed Standard.  Substantive comments and statements of support
> for advancing this document should be directed to the mailing list.
> Editorial suggestions can be sent to the document editor.  This last
> call will end on October 14, 2009.

I've read the latest version of the draft and support for advancing
it.  I'm glad this document now focuses on its original issue (and
sorry for the process delay if it was due to my objection to previous
versions and my slow responses).

I have one minor technical comment.  In Introduction the draft states:

   In addition to the Prefix List, individual addresses are on-link if
   they are the target of a Redirect Message indicating on-link, or the
   source of a valid Neighbor Solicitation or Neighbor Advertisement
   message.  Note that Redirect Messages can also indicate an address is
   off-link.  Individual address entries can be expired by the Neighbor
   Unreachability Detection mechanism.

Technically, (in my understanding) Redirect Messages do not directly
indicate an address is off-link.  What they can indicate are:
1. an address is on-link
2. an address is reachable via a different router than the redirect
   sender

normally #2 means the address is off-link, but, again, technically, my
understanding is that it doesn't have to be so.

Frankly, I don't understand the rationale of this note in this context
in the first place (I don't see any problem even if we remove this
sentence), but if the intent is to just note the role of redirect is
not limited to show an address being on-link, I'd suggest rephrase the
"Note that..." sentence as follows:

   Note that Redirect Messages can also designate an alternate better
   router to reach an address, in which case the address is normally
   off-link.

---
JINMEI, Tatuya
Internet Systems Consortium, Inc.