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[802SEC] FW: [New-work] WG Review: Behavior Engineering for Hindrance Avoidance(behave)

802 WG Chairs,

FYI... The following new work item in the IETF may be of interest to
members of your working group.  Feel free to update them on this new
work item if it is appropriate.


-----Original Message-----
From: [] On
Behalf Of The IESG
Sent: Friday, September 17, 2004 8:23 AM
Subject: [New-work] WG Review: Behavior Engineering for Hindrance

A new IETF working group has been proposed in the Transport Area.  The
IESG has not made any determination as yet. The following description
was submitted, and is provided for informational purposes only. Please
send your comments to the IESG mailing list ( by September

Behavior Engineering for Hindrance Avoidance (behave)

Current Status: Proposed Working Group


Given the current near-universal deployment of NATs (Network Address
Translators) in the public Internet, the lack of standards for NAT
behavior has given rise to a crisis. While it is widely acknowledged
that NATs create problems for numerous Internet applications, our
inability to describe precisely what a NAT is or how it behaves leaves
us few solutions for compensating for the presence of NATs.

The behavior of NATs varies dramatically from one implementation to
another. As a result it is very difficult for applications to predict or
discover the behavior of these devices. Predicting and/or discovering
the behavior of NATs is important for designing application protocols
and NAT traversal technique that work reliably in existing networks.
This situation is especially problematic for end-to-end interactive
applications such as multiuser games and interactive multimedia.

NATs continue to proliferate and have seen an increasing rate of
IPv6 deployments can eliminate this problem, but there is a significant
interim period in which applications will need to work both in IPv4 NAT
environments and with the IPv6 to IPv4 transition mechanisms.

This working group proposes to generate requirements documents and best
current practices to enable NATs to function in as deterministic a
fashion as possible. It will consider what is broken by these devices
and document approaches for characterizing and testing them. The NAT
behavior practices will be application independent. The group will also
advise on how to develop applications that discover and reliably
function in environments with NATs that follow the best current
practices identified by this working group. The group will consider the
security implications (or non-implications) of these devices.

The work will be done with the goal of encouraging eventual migration to
IPv6 and compliance with the UNSAF [RFC 3424] considerations. It will
not encourage the proliferation of NATs.

The behavior that will be considered includes IP fragmentation and
parameters that impact ICMP, UDP, TCP, IGMP, MLD, and multicast. The
proposed WG will coordinate with v6ops, midcom and nsis. The work is
largely limited to examining various approaches that are already in use
today and providing suggestions about which ones are likely to work best
in the internet architecture.

Discussion will start from several existing drafts or RFCs, including:
RFC 3489

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