Subject: Re: Last Call: <draft-ietf-mip4-gre-key-extension-04.txt> (GRE Key Extension for Mobile IPv4) to Proposed Standard

From: Pekka Savola <[email-masked]>
Date: Tue, 15 Mar 2011 11:45:20 +0200 (EET)

On Mon, 28 Feb 2011, The IESG wrote:
> The IESG has received a request from the Mobility for IPv4 WG (mip4) to
> consider the following document:
> - 'GRE Key Extension for Mobile IPv4'
>  <draft-ietf-mip4-gre-key-extension-04.txt> as a Proposed Standard

I've done an ops-dir review of draft-ietf-mip4-gre-key-extension-04.
The document defines procedures when using using GRE tunneling between
the mobile node or foreign agent and the home agent.  GRE Key extention is
used as for disambiguation purposes to handle overlapping address space.

The specification appears to be clear enough, though it is actually
specifying more than the document title suggests e.g. by adding MUST
requirements for all foreign agent implementations.

As a general comment, I suppose this is expected to be used in controlled
environments only, because UDP encapsulation is already defined and does not
(AFAIK) have these issues, and GRE is not expected to traverse NATs. As such
this does not seem to be a very long-term solution.

As an operational comment, I know many hardware GRE tunneling
implementations don't support GRE keying in hardware.  Maybe this is not a
concern here.

substantial issues
------------------

The document title is a bit misleading. This document not only specifies MIP
GRE key extension, but seems to be specifying how Foreign Agent (FA) MUST
act when either the foreign agent or mobile node wants to use GRE tunneling.
This document includes MUST requirements also for Foreign Agents that don't
implement GRE (S 4.1, fourth paragraph), and even if Key extension would
not be used (S 4.1-4.2).  As such, Updates: RFC3344 should be required.
(Or, now Updates: RFC5944)

In essence, this seems to actually be a more specific "Encapsulation with
MIP4" specification.

As a result, it would be nice if the scope of the document was laid out
more clearly.

Nits:
-----

  - Abstract is a bit verbose and mostly copy-paste from Introduction.
  - in S 4.1, reference [X.S0011-D] does not seem to exist in the references
    section.
  - RFC3344 has been obsoleted by RFC5944

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