[Ballot comment]
I'd prefer if the IANA considerations section was kept after the
document was published.  The fact two codepoints were registered
and a new registry was created is interesting and relevant.

[Ballot comment]
I'd prefer if the IANA considerations section was kept after the
document was published.  The fact two codepoints were registered
and a new registry was created is interesting and relevant.

This needs a few updates to handle the DISCUSSes.  My understanding was that there was an agreement on a few citations to add to handle the concern of it being under-specified; the other DISCUSSes seem reasonably straightforward.

[Ballot comment]
I don't think this document has enough information in order to create
an interoperable implementation of the spec.  I'm concerned that there
may be unwritten knowledge necessary to make this work.
Alternatively, it may all become clear if you have a better
understanding of the normative references than I do. 
However I definitely do not have enough confidence in this document to support publication.

[Ballot discuss]
>  0                  1                  2                  3
>  0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
>  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>  |  Type = 236  |    Length    |          Metric ..            |
>  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>  |          .. Metric            |U|X|S| Reserve |  Prefix Len  |
>  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>  |  Prefix ...
>  +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
>  |Sub-TLV Len(*) | Sub-TLVs(*) ...
>  * - if present
>
>  U - up/down bit
>  X - external original bit
>  S - subtlv present bit
>
>  This structure MAY appear any number of times (including none) within
>  the TLV.

What does "this structure" refer to? The entire thing? Can the protocol where these TLVs are carried deal with zero-length TLVs? This seems strange. Perhaps you meant the part after the Length field? But this should then be explicitly specified. Or the subtlv part? That too should then be specified.

Please clarify.

[Ballot comment]
This is in fact the fourth or fifth protocol that is supported using IS-IS (the first two were DECnet Phase 4 and CLNP which were pretty much supported simultaneously, then came IPv4, then came NLSP for routing IPX, which is so similar to IS-IS that some implementations use a single implementation to support both NLSP and IS-IS). Thus many of the questions that implementors might otherwise have, have already been answered in previous work.

I think that it would make sense for the security considerations section to include informational references to RFC3567 and to draft-ietf-opsec-current-practices-02.txt. Possible replacement text for section 8 would be:

  8  Security Considerations

  This document raises no new security considerations. Authentication of
  IS-IS packets may optionally be provided using the extension specified
  in [RFC3567]. A threat model as well as operational security features
  which are commonly deployed in networks is provided in [OPSECPRACTICES].

then add to references:

  [RFC3567]  "Intermediate System to Intermediate System (IS-IS)
  Cryptographic Authentication", T.Li and R.Atkinson, July 2003.

  [OPSECPRACTICES]  "Operational Security Current Practices",
  draft-ietf-opsec-current-practices-02.txt, work in progress,
  July 2005.

(note that this last one has timed out but will be updated very soon
as -03).

Reference 2 is clearly obsolete, and needs to be replaced by something.
I am pretty sure that this would be:

  [RFC3784]  "Intermediate System to Intermediate System (IS-IS)
  Extensions for Traffic Engineering (TE)", H. Smit and T.Li, June 2004.

Most likely we should also add a reference to:

  [RFC2966]  "Domain-wide Prefix Distribution with Two-Level IS-IS",
  T. Li, T. Przygienda, H. Smit, October 2000.

I am told that all deployments (except pure CLNS deployments) use
wide-metrics-only. Thus the use of wide metrics seems fine. It might
be worthwhile to write a different very short RFC deprecating the use
of narrow (ie original) metrics.

[Ballot comment]
Might be a good idea to reference RFC2460 at the start of the document.

Need a 2119 ref at the end of the doc.

Last Call Comment from Pekka Savloa:

From: Pekka Savola <pekkas@netcore.fi>
Subject: Re: Last Call: 'Routing IPv6 with IS-IS' to Proposed Standard
Date: Wed, Feb 8 10:51:24
To: iesg@ietf.org
Cc: isis-wg@ietf.org

There is a procedural problem here: a normative reference to
[[RFC3784]] (references list not updated), which is informational,
while this spec is going for Standards Track.  This is a down-ref
issue.

On our network, we also observed a Cisco bug where the router
redistributed FE80::/10 an FF00::/8 into IS-IS, which caused a bit of
mess.  Maybe the document should say something about this.

--
Pekka Savola                "You each name yourselves king, yet the
Netcore Oy                    kingdom bleeds."
Systems. Networks. Security. -- George R.R. Martin: A Clash of Kings

[Ballot comment]
Extra comments from Gemn-ART review by Elwyn Davies:

s2/s5: The IPv6 protocol identifier is not new with this specification.  If I understand correctly it is defined in ISO/IEC TR 9577 (in the 1999 update at least).  There should be a reference to this document.

s2: I think it would be appropriate to discuss whether the updates of ref [2] (now RFC3784) for IPv4 are a prerequisite for implementing the changes in this document. At first I didn't *think* they were but the statement that the IPv6 stuff 'uses' the semantics etc of [2]  doesn't make this totally clear, and omitting RFC3784 support would result (but I may be confused) in a combination of  'narrow' (6 bit)  link metrics and 'wide' (24-32 bit) path metrics for IPv6. Is this reasonable?

s3: This section lacks precise definitions of several of the fields:  In particular the length field is unspecified.  By analogy with s5.3 of RFC1195 one could ASSUME that it is the total length of the value part of the TLV excluding the first two octets but that assumes that everything said for IP(v4) applies for IPv6 - which is not made explicit.  To avoid uncertainty it would be worth being explicit.  Similarly the encoding of the metric (presumably unsigned 32 bit integer), the possible values of prefix length  and the number of octets of prefix are not made explicit.

s3:  s/external original/external origin/

s3: '...the octet following the prefix will contain the length of the sub-TLV portion of the structure': Aside from the redundancy of this octet (the sub-TLV length can (probably) be derived from the overall length and the prefix length fields unless the TLV length does not cover the sub-TLVs as well), it needs to be made clear if this length includes or excludes the length octet itself.  I would suggest repeating section 4.2 of RFC3784 which would also make it clear that the draft doesn't define any sub-TLVs and notes the limitations of the size of sub-TLVs that are possible (slightly different in this case).

s4: Again the length is not precisely defined.

s6: I don't think it is very clear how the various preference rules in RFC1195, RFC2966 and this document are supposed to be integrated.

s6: Copying over some of the reasoning for the choice of the maximum metric from RFC3784 would not go amiss.

s9: Ref [2] is RFC2784.  Need a reference to ISO/IEC TR 9577:1999.

[Ballot discuss]
It doesn't seem that this spec contains sufficient information (or normative references) for an independent implementor. The fact that established ISIS
implementors have added IPv6 doesn't mean the independent implementors could
do so based on this spec. This was pointed out during IETF Last Call but
the gaps have not been filled, and I haven't seen any feedback to indicate
that the WG discussed this point.

Specifically, quoting the Gen-ART review by Elwyn Davies:

This new draft adds a third address family but does not discuss the interaction of IPv6 with IPv4 (or OSI).  This wouldn't matter if the multi-topology extensions (draft-ietf-isis-wg-multi-topology-11.txt) were being used but for the basic protocol I think something needs to be said about some new classes of routers (in principle there are now six possibilities { {OSI}, {IPv4}, {IPv6}, {OSI, IPv4}, {OSI, IPv6}, {IPv4, IPv6}, (OSI, IPv4, IPv6}}).  RFC1195 indicates that routers need to be configured with their domain type (essentially the common set of address families supported by all nodes in the domain) which would need to be extended to cover the extra family. (This issue is mentioned in many presentations on the use of a single instance of IS-IS for routeing IPv4 and IPv6).

Aside from this fairly fundamental issue, it was not clear to me where the additional preference rules specified in s6 had to be integrated into the fairly complex preference rules already specified in s3.10 of RFC1195 or what their relationship was to the preference rules given in s3.2 of RFC2966 (the semantics of the up/down bit used in the IPv6 Reachability TLVs appear to be derived through ref [2] which is now RFC3784 which in turn defers to RFC2966).

Talking of RFC3784, there is no clear statement as to whether implementation of the RFC3784 extensions is a necessary prerequisite for these extensions: if I understand correctly, NOT implementing RFC3784 means that only 'narrow' metrics would be available for IS link specifications but the IPv6 extensions only provide for 'wide' path metrics, whereas RFC1195+RFC3784 gives a choice of wide and narrow for both IS links and IPv4 paths.  I am not clear if the situation would be reasonable without RFC3784 support.

Another related area which is really rather buried in these specifications is the issue of separate metrics for the various address families.  This may be obvious to afficionados of IS-IS but the fact that the SPF is run separately for each metric gets rather lost.  Referring back to the original specification it is possible that the SPF is run multiple times for the same address family if multiple metrics are defined - originally to handle multiple TOS metrics.  A reminder of this would not go amiss.  Presumably we have to wait for TE extensions to get multiple metrics for IPv6.

Overall I felt that the draft lacked attention to detail and there were areas (especially s6) which amounted to 'hand-waving' rather than rigorous specification.  This seems slightly surprising as there are (I believe) several implementations already in service.

[Ballot comment]
Section 4 says:
  >
  > This TLV maps directly to [1]'s "IP Interface Address" TLV.
  >
  Suggested rewording:
  >
  > This TLV maps directly to the "IP Interface Address" TLV defined
  > in [1].

[Ballot discuss]
The following issue was raised by Pekka Savola on the OPS Directorate list.

I sent an IETF Last Call on 8 Feb:
http://www1.ietf.org/mail-archive/web/isis-wg/current/msg01549.html

There was no response.

First off, there is procedural down-ref problem, but that's not my main concern.  My main concern is that the doc doesn't say anything about special prefixes which should not be routed using IS-IS.

The document should say either:

  1) that sender implementations should consider what prefixes or interface addresses to advertise, and receivers likewise for receiving (without specifying or giving examples what these might be), or

  2) above, and mention those prefixes, either as examples or as normative.  This affects at least multicast, link-local, loopback, etc. prefixes for both v4 and v6.

We noticed this problem with two major vendors about a year ago (one leaked link-local stuff, the other accepted it), and it caused some mess.  1) seems suboptimal from interop perspective.

Hence, I think the document must say something on this.

IANA Comments:
Upon approval of this document the IANA will update the IS-IS codepoint registry
(http://www.iana.org/assignments/isis-tlv-codepoints) so that TLV codes 232 and 236 refer to this document's RFC number.  We understand these to be the only IANA Actions.

State Changes to New Version Needed (WG/Author)                    from Token@wg or Author                                by IESG Member

State Changes to Token@wg or Author                                from Reading List                                      by IESG Member