Subject: WG Review: Multiple InterFaces (mif)

From: IESG Secretary <[email-masked]>
Date: Tue, 14 Apr 2009 13:00:02 -0700 (PDT)

A new IETF working group has been proposed in the Internet Area.  The IESG
has not made any determination as yet.  The following draft charter was
submitted, and is provided for informational purposes only.  Please send
your comments to the IESG mailing list ([email-masked]) by Tuesday, April
21, 2009.

Multiple InterFaces (mif)
------------------------------------------------
Last Modified: 2009-04-02

Current Status: Proposed Working Group

Chair(s):
TBD

Internet Area Director(s):
Ralph Droms <[email-masked]>
Jari Arkko <[email-masked]>

Internet Area Advisor:
TBD

Mailing Lists:
General Discussion: [email-masked]
To Subscribe: https://www.ietf.org/mailman/listinfo/mif
Archive: http://www.ietf.org/mail-archive/web/mif

Description of Working Group:

Many hosts have the ability to connect to multiple networks
simultaneously. This can happen over multiple physical network
interfaces, a combination of physical and virtual interfaces (VPNs or
tunnels), or even through multiple default routers being on the same
link. For instance, current laptops and smartphones typically have
multiple access network interfaces.

A host connected to multiple networks has to make decisions about
default router selection, address selection, DNS server selection,
choice of interface for packet transmission, and the treatment of
configuration information received from the various networks. Some
configuration objects are global to the node, some are local to the
interface, and some are related to a particular prefix. Various issues
arise when multiple configuration objects that are global to the node
are received on different interfaces. At best, decisions about these
matters have an efficiency effect. At worst, they have more significant
effects such as security impacts, or even lead to communication not
being possible at all.

A number of operating systems have implemented various techniques to
deal with multiple interfaces. Some devices employ only one interface at
a time and some allow per-host configuration of preferences between the
interfaces but still use just one at a time. Other systems allow
per-application preferences or implement sophisticated policy managers
that can be configured by users or controlled externally.

The purpose of the MIF working group is to describe the issues
surrounding the use of multiple interfaces on hosts, document existing
practice, and make recommendations about best current practice. The WG
shall employ and refer to existing IETF work in this area, including,
for instance, strong/weak models (RFC 1122), address selection (RFC
3484), DHCP mechanisms, Router Advertisement mechanisms, and DNS
recommendations. The focus of the working group should be on documenting
the system level effects to host IP stacks and identification of gaps
between the existing IETF recommendations and existing practice. The
working group shall address both IPv4 and IPv6 as well as stateless and
stateful configuration.

Network discovery and selection on lower layers as defined by RFC 5113
is out of scope. Also, the group shall not develop new protocol or
policy mechanisms; recommendations and gap analysis from the group are
solely based on existing solutions. The group shall not assume any
software beyond basic IP protocol support on its peers or in network
nodes. No work will be done to enable traffic flows to move from one
interface to another. The group recognizes existing work on mechanisms
that require peer or network support for moving traffic flows such as
RFC 5206, RFC 4980 and the use of multiple care-of addresses in Mobile
IPv6. This group does not work on or impact such mechanisms.

Once the group has completed its work items, the IETF can make an
informed decision about rechartering the working group to define new
mechanisms or asking other, specialized working groups (such as DHC or
6MAN) to deal with specific issues.

Milestones:

May 2009 WG chartered
July 2009 Initial draft on problem statement adopted by the WG
September 2009 Initial draft on existing practices adopted by the WG
Jan 2010 Initial best current practices draft adopted by the WG
March 2010 Problem statement draft submitted to the IESG for publication
as an Informational RFC
July 2010 Existing practices draft submitted to the IESG for publication
as an Informational RFC
September 2010 Best current practices draft submitted to the IESG for
publication as a BCP
October 2010 Recharter or close