Subject: Protocol Action: IP Mobility Support for IPv4, revised to Proposed Standard

From: The IESG <[email-masked]>
Date: Mon, 29 Oct 2001 13:23:08 -0500

The IESG has approved the Internet-Draft 'IP Mobility Support for IPv4,
revised' <draft-ietf-mobileip-rfc2002-bis-08.txt> as a Proposed
Standard, replacing RFC2002.

This document is the product of the IP Routing for Wireless/Mobile
Hosts Working Group. The IESG contact persons are Abha Ahuja and Rob
Coltun.

Technical Summary
 
RFC2002 specifies a protocol to support transparent routing of IP
datagrams to mobile nodes in the Internet in a seamless manner. Mobile
node have two adddress: a Home Address that corresponds to its point
of attachment when it resides at home, and a care-of address that
reflects its current point of attachment as it moves around the
Internet. The protocol provides for registering the care-of address
with the mobile node's home agent.  The home agent then intercepts
packets intended for the mobile node (at its home address) and tunnels
them to the care-of address.  After arriving at the end of the tunnel,
each datagram is then delivered to the mobile node.

This document clarifies RFC 2002 in response to implementation
experience and interoperability testing. The document was originally
intended to be largely compatable with 2002. However, the text in RFC
2002 describing the authentication option was seriously flawed and
incorrect. In addition, RFC 2002 specified using a prefix-suffix form
of MD5, which is now viewed to have vulnerabilities compared with
alternatives. This document mandates the use of HMAC-MD5, with a
recommendation to also implement the earlier authentication method if
interoperability with existing implementations is an issue.

Working Group Summary
---------------------

The WG supports this document. Indeed, it is expected that this
document (with only minor changes) will be ready to advance to Draft
Standard shortly. Mandating the use of HMAC-MD5 as the default
authentication method did generate some concerns. But the concerns
were not of a technical nature (there is agreement to move to
HMAC-MD5). Rather, the concern was that mandating HMAC-MD5 meant that
existing implementations would not automatically be in compliance with
this document.

Protocol Quality
----------------

Multiple interoperability tests have been done with various
implementations on the original RFC2002 spec. The changes in the new
I-D do not change the protocol in a significant manner. The changes
are based on experience gained and also new developments in the Mobile
IP WG, such as the use of the NAI as the identifier, hence not
requiring the MN to have a permanently assigned address.

This document has been reviewed by Thomas Narten for the IESG.