Re: I-D ACTION:draft-ietf-v6ops-addcon-00.txt

[Brian E Carpenter <brc@zurich.ibm.com>]

Just a few comments on this:

> 1.  Introduction
>
>    The Internet Protocol Version 6 (IPv6) Addressing Architecture [23]
>    defines three main types of addresses: unicast, anycast and
>    multicast.  This document focuses on unicast addresses, for which
>    there are currently three principal allocated types: Global Unique
>    Addresses [12] ('globals'), Unique Local IPv6 Addresses [22] (ULAs)
>    and 6bone address space [3].

It's a bit odd to include 6bone space as a "focus" item since all
you say is that it's history.

> 2.2.  Unique Local IPv6 Addresses
...
>    Because a ULA and a global site prefix are both /48 length, an
>    administrator can choose to use the same subnetting (and host
>    addressing) plan for both prefixes.

The RIRs are moving away from a rigid /48 policy. It would be safer
to start this sentence with "When" instead of "Because".
And on the same topic...

> 2.4.  Network Level Design Considerations

I suggest adding a bullet at the end of this section along these
lines:

o It is possible that as registry policies evolve, a small site
  may experience an increase in prefix length when renumbering,
  e.g. from /48 to /56. For this reason, the best practice is
  number subnets compactly rather than sparsely, and to
  use low-order bits as much as possible when numbering subnets.
  In other words, even if a /48 is allocated, act as though
  only a /56 is available. Clearly, this advice does not apply
  to large sites and enterprises that have an intrinsic need
  for a /48 prefix.

      Brian