Last Call Review of draft-ietf-l2vpn-vpls-mcast-14
review-ietf-l2vpn-vpls-mcast-14-tsvdir-lc-black-2013-09-24-00

I've reviewed this document as part of the transport area directorate's
ongoing effort to review key IETF documents. These comments were written
primarily for the transport area directors, but are copied to the
document's authors for their information and to allow them to address
any issues raised. When done at the time of IETF Last Call, the authors
should consider this review together with any other last-call comments
they receive. Please always CC âtsv-dir at ietf.org if you reply to or
forward this review.

Document: draft-ietf-l2vpn-vpls-mcast-14
Reviewer: David L. Black
Review Date: September 23, 2012
IETF LC End Date: September 23, 2012

Summary: This draft is basically ready for publication, but has nits that
	should be fixed before publication.

This draft describes multicast optimizations for VPLS via use of MPLS
multicast distribution trees within the service provider (SP) network.

In general, the techniques in this draft are an improvement, as they
should typically result in reduction of SP network traffic required
to carry the same level of multicast traffic originating from the VPLS
edges.  I have reviewed primarily for transport-related topics; while
I don't have the expertise to review for MPLS and VPLS concerns, I'm
confident in the expertise of this author team in those technologies. 

I found a couple of items that are effectively editorial:

(1) The techniques in this draft appear to add an MPLS label to the
stack in order to identify the MPLS multicast tree.  Does that added
label raise any MTU concerns in practice?

(2) Two techniques used by this draft - replication of traffic within
a multicast tree, and flooding of traffic (section 14) - could be
employed as traffic amplifiers in denial of service attacks.  A short
discussion of this possibility and the applicability of countermeasures
described in this draft, RFC 4761 and/or RFC 4762 would be good to
add to the security considerations section.

Thanks,
--David
----------------------------------------------------
David L. Black, Distinguished Engineer
EMC Corporation, 176 South St., Hopkinton, MAÂ 01748
+1 (508) 293-7953ÂÂÂÂÂÂÂÂÂÂÂÂ FAX: +1 (508) 293-7786
david.black at emc.comÂÂÂÂÂÂÂ Mobile: +1 (978) 394-7754
----------------------------------------------------