Background and Motivation

   A multi-homed host has multiple network interfaces (physical and/or
   logical).  For example, a node may be connected to a wired Ethernet
   LAN, a 802.11 LAN, a 3G cell network, one or multiple VPN connections
   or one or multiple automatic or manual tunnels. Current laptops and
   smartphones typically have multiple access network interfaces. 

   RFC 1122 has speicified the strong model and the weak model for a 
   multi-homed host, the weak model has been widely implemented by the 
   major OSs, but it treat the source and destination of the connection
   as a host other than interfaces. Strong model recently has been 
   implemented in new OSs. Some mobile 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. 
   
   A multi-homed host receives node configuration information from each
   of its access networks.  Some configuration objects are global to the
   node, some are local to the interface.  Various issues arise when
   multiple configuration objects that are global to the node are
   received on the many interfaces the multi-homed host has.  Therefore,
   there is a need to define the appropriate behaviors of an IPv4 and IPv6
   host and understand the limitations, if there is any limitations set 
   by the current protocols. Note that the MIF deals with the usage of 
   active interfaces. This is different from the decision to bring up 
   these interfaces or the decision to attach a wireless interface to a 
   particular available radio network (see RFC 5113). Mechanisms related
   to these other decisions are outside the scope of MIF.
   
   Multi-homed MIF hosts do not assume any new software on its peers, or 
   any new network entity for routing traffic through. This makes MIF 
   different from Shim6, Mobile IPv6 multi-address extensions, and HIP. 
   MIF also does not provide any means for traffic flows to move from one 
   interface to another.

Proposed Work:
-------------

The proposed mif Working Group will focus on the following topics
relevant for multiple interfaces:

 Problem statement

   o A document describing the problems caused by the multiple 
   interfaces in the host. (Informational)

 Current Practices

   o What the current major host vendors do regarding to multiple 
   interfaces.(Informational)
 
 Merging of IP layer autoconfiguration:

   o A multi-homed host received IP layer autoconfiguration information
   across multiple access networks. Thus it need to merge all those
   configuration information. (Best Current Practice)

The BoF proposes to discuss the above items and gauge interest in
forming a working Group. There is already work in progress addressing
the identified problems, which is expected to be the starting point
for the deliverables. 

The proposed activity will be complementary to the existing IETF
Working Groups, notably the DHC,6MAN and MEXT WGs. 


Approximate Timeline for Deliverables:
-------------------------------------
    * April 2009 WG approved by IESG
    * 3H09 Submit problem statement I-D to IESG
    * 3H09 Submit current practices I-D to IESG
    * 1H10 Submit Merging of IP layer autoconfiguration I-D to IESG
    * 2H10 Recharter or close WG