Subject: [RTG-DIR] RtgDir review: draft-ietf-mpls-ipv6-pw-lsp-ping-03.txt

From: "Bocci, Matthew (Matthew)" <[email-masked]>
Date: Wed, 21 Nov 2012 17:12:32 +0100

Hello,

I have been selected as the Routing Directorate reviewer for this draft.
The Routing Directorate seeks to review all routing or routing-related
drafts as they pass through IETF last call and IESG review, and sometimes
on special request. The purpose of the review is to provide assistance to
the Routing ADs. For more information about the Routing Directorate,
please see http://www.ietf.org/iesg/directorate/routing.html

Although these comments are primarily for the use of the Routing ADs, it
would be helpful if you could consider them along with any other IETF Last
Call comments that you receive, and strive to resolve them through
discussion or by updating the draft.

Document: draft-ietf-mpls-ipv6-pw-lsp-ping-03.txt
Reviewer: Matthew Bocci
Review Date: 21st November 2012
IETF LC End Date: 9th November 2012
Intended Status: Standards Track

Summary:

This document is basically ready for publication, but has a few minor
issues that should be considered prior to publication.

Comments:

Generally I found this to be a very well written and readable draft. There
are a few minor issues that I have listed below, mainly relating to the
use of terminology.

Major Issues:

No major issues found.

Minor Issues:

Title: The title of the draft is "Label Switched Path (LSP) Ping for IPv6
Pseudowire FECs". This might be confusing as it suggests that there are
special PW FECs for IPv6. In fact, PW FECs are agnostic to the underlying
IP version. Therefore, I suggest changing this to something like "Label
Switched Path (LSP) Ping for Pseudowire FECs Advertised over IPv6".

Abstract, 1st paragraph: The abstract (and only the abstract) refers to PW
LSPs, but this is not common terminology in existing RFCs. It is true that
each direction of an MPLS PW is comprised of a unidirectional LSP, but it
might be better to try to align more closely with common terminology and
call them the LSPs used for each direction of an MPLS PW.

Abstract, 2nd paragraph: The draft refers to an IPv6 PW. However, this
term could be confused with the colloquial term for an IP Layer 2
transport PW, which is a specific PW type that can carry IPv4 or IPv6. I
suggest replacing this term with 'a PW that is setup and maintained using
an IPv6 LDP session.' Likewise, the short version of the draft title in
the draft headers could be clarified to something like 'PW LSP Ping for
IPv6'.

Introduction: there are a few places where the text refers to a 'target
LDP session'. It isn't clear if this means the src/dst of the LDP session
that an LSP ping echo request message is targeting (hence target is ok) or
if it really means the 'targeted LDP session', which is what this type of
LDP session is normally referred as. Please clarify.

Figure 1 and Figure 2 titles. These are not new FEC types for IPv4 and
IPv6, but rather new target FEC stack sub-TLVs. I would help readability
to modify the titles accordingly.

---

From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Sat, 24 Nov 2012 16:20:15 +0000

Hi Matthew,

Many thanks for your review! Please find some follow-ups inline.

> Switched Path (LSP) Ping for Pseudowire FECs Advertised over IPv6".

This is a really good comment -- I agree completely.

Essentially, we are defining LSP Ping Target FEC Stack sub-TLVs for IPv6 LDP, which include the LDP PW FECs and the PE addresses -- only the latter being of course IP version dependent.

I like the updated title suggestion. We should also update the short_title from "IPv6 PW LSP Ping", suggesting "LSP Ping for PWs over IPv6" -- but open to further suggestions.

> call them the LSPs used for each direction of an MPLS PW.

Sure.

> the draft headers could be clarified to something like 'PW LSP Ping for

Ack on both. Agreed.

> LDP session is normally referred as. Please clarify.

There is a little bit of potential ambiguity, yes, although frankly it could be either. For the case though that there are two PEs back-to-back and we'd have a link instead of targeted LDP adjacency, I prefer to only refer to "target" and to clear the ambiguity we can just remove "target" and leave "LDP Session" (which is what RFC 4447 uses).

> to modify the titles accordingly.

Yes, but this is not only in the Figure titles. We could replace all occurrences of 'IPv4 "FEC 128" Pseudowire' with say '"FEC 128" Pseudowire - IPv4' or similar.

Thoughts?

Thanks,

-- Carlos.

---

From: "Bocci, Matthew (Matthew)" <[email-masked]>
Date: Mon, 26 Nov 2012 14:53:24 +0100

Hi Carlos,

On 24/11/2012 16:20, "Carlos Pignataro (cpignata)" <[email-masked]>
wrote:

>On Nov 21, 2012, at 11:12 AM, "Bocci, Matthew (Matthew)"
><[email-masked]> wrote:
>
>> Hello,
>> 
>Essentially, we are defining LSP Ping Target FEC Stack sub-TLVs for IPv6
>LDP, which include the LDP PW FECs and the PE addresses -- only the
>latter being of course IP version dependent.
>
>I like the updated title suggestion. We should also update the
>short_title from "IPv6 PW LSP Ping", suggesting "LSP Ping for PWs over
>IPv6" -- but open to further suggestions.
>
>> 
>There is a little bit of potential ambiguity, yes, although frankly it
>could be either. For the case though that there are two PEs back-to-back
>and we'd have a link instead of targeted LDP adjacency, I prefer to only
>refer to "target" and to clear the ambiguity we can just remove "target"
>and leave "LDP Session" (which is what RFC 4447 uses).

Fine with me.

>Yes, but this is not only in the Figure titles. We could replace all
>occurrences of 'IPv4 "FEC 128" Pseudowire' with say '"FEC 128" Pseudowire
>- IPv4' or similar.

Agreed. I think that should include the names used in the IANA registries.

Regards

Matthew

---

From: "Carlos Pignataro (cpignata)" <[email-masked]>
Date: Mon, 26 Nov 2012 14:53:10 +0000

Hi Matthew,

Ack -- thanks again for the review.

-- Carlos.