Subject: [Gen-art] Gen-ART Last Call review of draft-ietf-l2tpext-keyed-ipv6-tunnel-07

From: Paul Kyzivat <[email-masked]>
Date: Wed, 26 Oct 2016 17:08:20 -0400

I am the assigned Gen-ART reviewer for this draft. The General Area 
Review Team (Gen-ART) reviews all IETF documents being processed by the 
IESG for the IETF Chair. Please treat these comments just like any other 
last call comments. For more information, please see the FAQ at 
<​http://wiki.tools.ietf.org/area/gen/trac/wiki/GenArtfaq>.

Document: draft-ietf-l2tpext-keyed-ipv6-tunnel-07
Reviewer: Paul Kyzivat
Review Date: 2016-10-26
IETF LC End Date: 2016-10-28
IESG Telechat date: 2016-11-03

Summary:

This draft is on the right track but has open issues, described in the 
review.

Issues:

Major: 0
Minor: 3
Nits:  0

(1) MINOR: General comment

As best I can understand, this draft provides a new alternative approach 
tunneling Ethernet over IPv6, that differs from L2TPv3 over IP in two 
key ways:

- it uniquely associates a tunnel with an IPv6 address, simplifying 
routing of arriving packets

- it does not use the L2TPv3 control plane, instead relying upon 
coordinated consistent configuration of the two ends of the tunnel.

As best I can tell, these two choices are independent of one another.

IMO this draft would be improved with a substantial discussion of why 
this new approach to tunneling, using these two features, is being 
offered as an alternative. This is mentioned very slightly in Section 1, 
but seems incomplete. What are the cons as well as the pros, and under 
what circumstances will the pros outweigh the cons?

(2) MINOR: Section 3:

There is no explanation of why 64-bit cookies are chosen and required. 
Is this because there is no mechanism for negotiation, so a fixed size 
is needed to define the packet format? Since coordinated configuration 
of the two ends is required wouldn't it be possible to allow the 
consistent configuration of the cookie size? Better explanation would be 
helpful.

(3) MINOR: Section 5:

The 2nd paragraph uses "recommended" (non-normative) while the 
subsequent paragraphs used "RECOMMENDED" (normative). Is this intentional?