2.3.12 Multiple Interfaces (mif)

NOTE: This charter is a snapshot of the 76th IETF Meeting in Hiroshima, Japan. It may now be out-of-date.

Last Modified: 2009-10-19


Margaret Wasserman <mrw@lilacglade.org>
Hui Deng <denghui02@hotmail.com>

Internet Area Director(s):

Ralph Droms <rdroms@cisco.com>
Jari Arkko <jari.arkko@piuha.net>

Internet Area Advisor:

Jari Arkko <jari.arkko@piuha.net>

Mailing Lists:

General Discussion: mif@ietf.org
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 attach to multiple networks
simultaneously. This can happen over multiple physical network
interfaces, a combination of physical and virtual interfaces (VPNs or
tunnels), or even indirectly through multiple default routers being on
the same link. For instance, current laptops and smartphones typically
have multiple access network interfaces.

A host attached 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
contradictory 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 attachments to multiple networks. 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 of
attaching to multiple networks on hosts and document existing practice.
The group shall also analyze the impacts and effectiveness of these
existing mechanisms. 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), ICE and other mechanisms higher layers can
use for address selection, 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.

Goals and Milestones:

Done  WG chartered
Done  Initial draft on problem statement adopted by the WG
Done  Initial draft on existing practices adopted by the WG
Dec 2009  Initial draft on analysis of existing practices adopted by the WG
Mar 2010  Problem statement draft submitted to the IESG for publication as an Informational RFC
Jul 2010  Existing practices draft submitted to the IESG for publication as an Informational RFC
Sep 2010  Analysis draft submitted to the IESG for publication as an Informational RFC
Oct 2010  Recharter or close


  • draft-ietf-mif-problem-statement-01.txt
  • draft-ietf-mif-current-practices-00.txt

    No Request For Comments

    Meeting Minutes


    MIF Agenda IETF76
    MIF Problem Statement IETF76
    MIF Current Practices IETF76
    Starting MIF Analysis Work
    Socket API Extension for MIF
    Multi-Homing Extensions for PMIPv6
    Inter-Technology Handoff for PMIPv6
    MPTCP and MIF