Subject: [manet] New Version Notification for draft-ietf-manet-smf-06

From: IETF I-D Submission Tool <[email-masked]>
Date: Mon, 19 Nov 2007 08:41:46 -0500

A new version of I-D, draft-ietf-manet-smf-06.txt has been successfuly submitted by Joseph Macker and posted to the IETF repository.

Filename:	 draft-ietf-manet-smf
Revision:	 06
Title:		 Simplified Multicast Forwarding for MANET
Creation_date:	 2007-11-17
WG ID:		 manet
Number_of_pages: 47

Abstract:
This document describes a Simplified Multicast Forwarding (SMF)
mechanism that provides basic IP multicast forwarding suitable for
wireless mesh and mobile ad hoc network (MANET) use.  SMF specifies
techniques for multicast duplicate packet detection (DPD) to assist
the forwarding process.  SMF also specifies DPD maintenance and
checking operations consistent with both IPv4 and IPv6.  SMF takes
advantage of reduced relay sets for efficient MANET multicast
forwarding within a mesh topology and the document describes protocol
interaction with a number of approaches.  Candidate algorithms for
selecting reduced relay sets and related discussion is provided in
the Appendices.  Basic issues relating to the operation of multicast
MANET border routers are discussed but ongoing work remains in this
area beyond the scope of this document.

The IETF Secretariat.

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From: Bruce M Simpson <[email-masked]>
Date: Thu, 29 Nov 2007 00:16:41 +0000

I am a bit disappointed that the current I-D for MANET SMF has no 
provision for the encapsulation of MANET SMF datagrams in IPv4.

My points:
 * ip_id is only 16 bits wide, making its usefulness limited in large 
MANET topologies.
  * Both BSD and Linux may be configured to randomize the ip_id field as 
a defensive measure against IP host fingerprinting.
 * Choosing ip_id as a tag for the histogram based duplicate packet 
detection requires that NAT routers on the path examine ip_id, in 
addition to being examined by any software multicast forwarding plane 
implementation.
 * Encapsulation considerably simplifies implementation within existing 
software multicast forwarding planes, again, re: BSD and Linux.
 * The overhead of demux and rewrite of BSD mbufs or Linux skbufs is 
likely to be the same, i.e. O(n), for ip_id versus an encapsulation header.
 * For multicast flows between PIM domains and MANET domains, the 
overhead of prepending such encapsulation at the gateway is very likely 
to be within acceptable performance limits.

I would therefore encourage you to consider the benefits of allowing the 
use of encapsulation in SMF viz the above points.

Kind regards
BMS