Mobility for IPv4
charter-ietf-mip4-08

IP mobility support for IPv4 nodes (hosts and routers) is specified in
RFC3344. RFC 3344 mobility allows a node to continue using its
"permanent" home address as it moves around the Internet. The Mobile
IP protocols support transparency above the IP layer, including
maintenance of active TCP connections and UDP port bindings. Besides
the basic Mobile IPv4 (MIPv4) protocols, several other drafts deal
with concerns such as optimization, security, extensions, AAA support,
and deployment issues.

MIPv4 is currently being deployed on a wide basis (e.g., in cdma2000
networks). The scope of the deployment is on a fairly large scale and
accordingly, the MIP4 WG will focus on deployment issues and on
addressing known deficiencies and shortcomings in the protocol that
have come up as a result of deployment experience. Specifically, the
working group will complete the work items to facilitate interactions
with AAA environments, interactions with enterprise environments when
MIPv4 is used therein, and updating existing protocol specifications
in accordance with deployment needs and advancing those protocols that
are on the standards track.

Work expected to be done by the MIP4 WG as proposed by this charter is
as follows:

1. MIPv4 has been a Proposed Standard for several years. It has been
   adopted by other standard development organizations and has been
   deployed commercially. One of the next steps for the WG is to advance
   the protocol to draft standard status. As part of advancing base
   Mobile IP specifications to Draft Standard, the MIPv4 NAI RFC (2794)
   will be revised to reflect implementation experience.

2. The WG will complete the MIB specifications for the Mobile IPv4
   base protocol and the UDP tunneling extension.

3. A requirements document for RADIUS MIP4 support was previously
   completed and published as RFC 5030. Based on these requirements,
   the WG will complete the specification of MIPv4 RADIUS
   attributes, solicit feedback from the RADEXT WG, adjust, and submit
   this for publication. Note that the work may require extensions to the
   RADIUS attribute space which will be handled outside the MIP4 WG.

4. Like fixed nodes, mobile nodes sometimes need to be dynamically
   configured with parameters such as DNS server IP addresses. Previous
   work in the WG proposed to put a generic container for host configuration
   options into Mobile IPv4 signaling. However, it may be easier for
   mobile nodes to implement the already existing DHCP specification,
   and to run DHCP over the tunnel established with an initial registration.
   The WG will take on a draft describing any modifications to Mobile IPv4
   that may be needed to facilitate this mode of operation, and submit
   for publication as a Proposed Standard or Best Current Practice as
   appropriate.

5. The proliferation of devices with multiple interface technologies
   and the desire to use each interface for the type of traffic most
   appropriate to it (even simultaneously with other interfaces active at
   the same time) has led to requirements for supporting multiple
   simultaneous tunnels between the Home Agent and Mobile Node. The WG
   will adopt and take to publication as an Experimental RFC one draft that
   describes how to manage such tunnels and how to direct traffic to use
   the appropriate tunnel when multiple choices are available. This work
   will be coordinated with similar Mobile IPv6 work ongoing in the mext
   working group. In particular, we will strive to converge on a consistent
   set of architectural decisions (such as which entities are responsible
   for signaling flow-to-tunnel bindings) and we will share protocol
   definitions wherever practical (such as the layout of packet flow
   filters).

6. The WG has published a basic Network Mobility (NEMO) specification
   as RFC 5177. The WG has taken up an extension to NEMO that will
   allow for dynamic home network prefix allocation to a moving network.
   The WG will finish work on this draft and publish as a Proposed
   Standard.

7. Route optimization has been the focus of a large amount of effort
   in the Mobile IPv6 WG. For Mobile IPv4, however, the usage case is
   less clear due to a variety of factors, including the inability to
   modify already deployed correspondent nodes. Recently a specific
   use case has been proposed involving route optimization for a more
   closed network where modifications are made to site routers and a
   centralized Home Agent to enable offloading of traffic from the
   Home Agent. The WG will take on and publish a draft on this topic
   as a Experimental RFC.

8. The use of GRE tunneling with Mobile IPv4 enables support for
   multiple overlapping private address spaces within the same mobility
   agent. However, to distinguish flows from two different mobile nodes
   that happen to share the same (private) IP address, the GRE Key field
   needs to be populated with a unique identifier that will enable the
   mobility agent to demultiplex the flows. The value used for the Key
   needs to be signaled at the time of tunnel establishment, which means
   a new Mobile IPv4 extension is needed for this purpose. The WG will
   take on an publish a draft on this topic as a Proposed Standard.

9. Support for multicast and broadcast packets in Mobile IPv4
   as specified in RFC 3024 currently requires encapsulated delivery
   style for all packets. This leads to inefficiencies on the
   MN-to-FA link because even unicast packets must be encapsulated.
   Eliminating this inefficiency is possible if there is a mechanism
   to negotiate a mode of operation where only multicast/broadcast
   packets are encapsulated, while unicast packets can use direct
   delivery style. The WG will take on a draft to solve this
   problem and publish as a Proposed Standard.