Subject: WG Review: Behavior Engineering for Hindrance Avoidance (behave)

From: The IESG <[email-masked]>
Date: Fri, 17 Sep 2004 11:31:03 -0400

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 ([email-masked]) by September 24.

Behavior Engineering for Hindrance Avoidance (behave)
=====================================================

Current Status: Proposed Working Group

DESCRIPTION:

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 deployment.
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:
draft-jennings-midcom-stun-results
draft-audet-nat-behave
RFC 3489
draft-ford-midcom-p2p

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