Subject: [PWE3] Danny McPherson's Rtg-Dir review of draft-ietf-pwe3-p2mp-pw-requirements

From: "Adrian Farrel" <[email-masked]>
Date: Mon, 31 Mar 2014 17:27:44 +0100

draft-ietf-pwe3-p2mp-pw-requirements

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 comments that you
receive, and strive to resolve them through discussion or by updating the draft
as appropriate.  
 
Document: http://tools.ietf.org/html/draft-ietf-pwe3-p2mp-pw-requirements-07

Reviewer: Danny McPherson
Review Date: March 31, 2014
Intended Status: Informational

Document Overview: This document presents a set of requirements and a framework
for providing a P2MP PWs over MPLS PSNs.  A P2MP PW is a mechanism that emulates
the essential attributes of a P2MP telecommunications service such as a P2MP ATM
VC over a PSN.  The I-D describes the general architecture for P2MP PWs with a
reference model, discusses data encapsulation, and outlines specific
requirements for setup and maintenance of P2MP PWs, with a focus only on
Single-Segment PWs.  This version was lasted updated in February of 2014,
although it has existed as a PWE3 WG document since March 2009, and as an
individual contribution (draft-jounay-pwe3-p2mp-pw-requirements) since February
of 2007.  Among other applications, it provides primitives that can be employed
for Virtual Private LAN and Virtual Private Multicast services, such as those
specified in the L2VPN WG.

I have no substantial concerns with this document.  There are several comments
and nits below. 

1. I am not sure if from an IPR perspective the claims regarding IPR that
apparently no longer apply to this version of the document need to be explicitly
acknowledged as such by the relevant co-authors?

Nits
===

General:

1. Only single-segment PWs are addressed, not multi-segment PWs.  I understand
why this is the case currently although I wonder if the requirement akin to "a
single NMS" such as provided in S.4 should be conveyed forward?  I suppose it
should simply be out of scope.

2. In order to align with descriptive text in S3.1 it might be useful if the
Reference Model in Figure 1 depicted where root and leaf PEs reside in the
topology, and perhaps also that multiple CEs could be downstream from a single
leaf PE (the latter point Farrel made in his AD review as well, IIRC).

---
S 3.2: 

-
A single P2MP PSN tunnel MUST be able to serve more than one P2MP PW traffic in
an aggregated way, i.e., multiplexing

-
"not destined to Leaf PE at the service layer." reads a bit odd and ambiguous,
might use a bit of expansion.  

---
S 3.4.6: 

-
"In the example depicted below, a standby P2MP PW is used to protect the active
P2MP."  -- might consider adding a "PW" after the last P2MP in this sentence.

-
It might be useful to identify the "leaf" and "root" layer in Figure 3 & 4 as
well.