2.5.2 IP Routing for Wireless/Mobile Hosts (mobileip)

NOTE: This charter is a snapshot of the 51st IETF Meeting in London, England. It may now be out-of-date. Last Modified: 31-Jul-01


Phil Roberts <proberts@megisto.com>
Basavaraj Patil <basavaraj.patil@nokia.com>

Routing Area Director(s):

Rob Coltun <rcoltun@redback.com>
Abha Ahuja <ahuja@wibh.net>

Routing Area Advisor:

Abha Ahuja <ahuja@wibh.net>

Mailing Lists:

General Discussion:mobile-ip@sunroof.eng.sun.com
To Subscribe: mobile-ip-request@sunroof.eng.sun.com
In Body: (un)subscribe
Archive: http://playground.sun.com/mobile-ip/

Description of Working Group:

The Mobile IP Working Group has developed routing support to permit IP nodes (hosts and routers) using either IPv4 or IPv6 to seamlessly "roam" among IP subnetworks and media types. The Mobile IP method supports transparency above the IP layer, including the maintenance of active TCP connections and UDP port bindings. Where this level of transparency is not required, solutions such as DHCP and dynamic DNS updates may be adequate and techniques such as Mobile IP not needed.

The WG moving forward will focus on deployment issues in Mobile IP and provide appropriate protocol solutions to address known deficiencies and shortcomings. For example, the wireless/cellular industry is considering using Mobile IP as one technique for IP mobility for wireless data. The working group will endeavor to gain an understanding of data service in cellular systems such as GPRS, UMTS, CDMA2000, and interact with other standards bodies that are trying to adopt and deploy Mobile IP WG protocols in these contexts. In order to provide a complete solution and a set of protocols that can be used as a roadmap for widespread deployment, the following work needs to be accomplished by this WG. In the near term, the WG needs to work on:

- Use of NAIs to identify mobile users/nodes.

- Specifying how Mobile IP should use AAA functionality to support inter-domain and intra-domain mobility.

- Develop solutions for IPv4 private address spaces for the scenarios needed for deployment.

- Documenting any requirements specific to cellular/wireless networks.

In the longer term, the WG needs to address:

- QoS in the mobile IP environment using diff-serv and/or int-serv/RSVP.

- Location Privacy.

The Working Group will ensure that solutions proposed for these problem domains are suitable for IPv4 and IPv6 respectively.

Goals and Milestones:



Review and approve the charter, making any changes deemed necessary.



Post an Internet-Draft documenting the Mobile Hosts protocol.



Review the charter of the Mobile IP Working Group for additional work required to facilitate non-host mobility.



Submit the IPv4 Mobile Host Protocol to the IESG as a Proposed Standard.



Submit the IPv6 Mobile Host Protocol to the IESG as a Proposed Standard.



Submit Internet-Draft for NAI support in Mobile IP to IESG for consideration as a Proposed Standard.



Review security framework requirements for Mobile IP.



Review solutions and submit drafts for mobility in private address spaces.



Supply AAA requirements for Mobile IP to the AAA Working Group

Sep 00


Submit the IPv4 Mobile IP Protocol to the IESG for consideration as a Draft Standard.

Oct 00


Review the WG charter and update as needed.

Dec 00


Develop an access technology independent method for supporting low latency handover between access points within an administrative domain or across administrative domains.

Jul 01


Review QoS in a Mobile IP enabled network.

Aug 01


Submit Mobile IPv6 MIB to IESG for consideration as a Proposed Standard.

Request For Comments:






Applicability Statement for IP Mobility Support



Minimal Encapsulation within IP



IP Encapsulation within IP



IP Mobility Support



The Definitions of Managed Objects for IP Mobility Support using SMIv2



Sun's SKIP Firewall Traversal for Mobile IP



Mobile IP Network Access Identifier Extension for IPv4



Mobile IP Authentication, Authorization, and Accounting Requirements



Mobile IP Challenge/Response Extensions



Reverse Tunneling for Mobile IP, revised



Mobile IP Vendor/Organization-Specific Extensions

Current Meeting Report

Mobile IP WG meeting minutes for IETF51
Session 1

August 6th, 2001 (1930-2200)
Reported by : Jayshree Bharatia

Document Status :
- draft-ietf-mobileip-mier-07.txt (submitted)
- draft-ietf-mobileip-gnaie-04.txt (submitted)
- draft-ietf-mobileip-3g wireless-ext-06.txt (being updated based on IESG feedback)
- draft-ietf-mobileip-rfc2002-bis-06.txt (being updated based on IESG feedback)
- draft-ietf-mobileip-gen-key-00.txt (WG last call expired Friday 7/20 hopefully submitted)
- draft-ietf-mobileip-aaa-key-07.txt (to be submitted Friday 7/20)
- draft-ietf-mobileip-qos-requirements-00.txt (WG last call expired 7/25)
- draft-ietf-mobileip-reg-tunnel-04.txt (being updated)
- draft-ietf-mobileip-optim-10.txt (past WG last call, sitting on it until MIP v6 issues resolved)

Moving MIPv4 to draft standard - Charles Perkins
Charlie Perkins provided current status and reasoning of why RFC2002 should move toward draft standards from its current status as proposed standards. He mentioned that multiple interoperability tests have been performed and there has been significant deployment exist today. The following implemented options were pointed out:

- 'R' bit in the agent advertisement => may be superseded by AAA work

- Prefix length extension in agent advertisement => never implemented and not interoperated

- 'S' bit in registration request message => haven't shown interoperability, refers to simultaneous registration with separate COAs

As per 2002Bis-o6 draft, Mobile IP implementations should include HMAC-MD5 as one of the additional authentication algorithms. This algorithm is used for producing and verifying the authentication data in Mobile IP registration messages. If the requirement of using HMAC-MD5 is mandated, it may take six more months before draft moves for the last call. He insisted that the working group should influence this decision. The alternative suggested was to remove this portion from the 2002Bis draft and progress the draft for the proposed standards. It was pointed out by Thomas Narten that it is not required to have implementation of HMAC-MD5 in order to progress toward proposed standards. In the end it was decided that the decision would be taken based on the further WG mailing list discussion.

Mobile IP v6 security update - Phil Roberts

The discussion was based on MIPv6 protocol and the requirements for a security solution discussed in draft draft-team-mobileip-mipv6-sec-reqts-00.txt. It was mentioned by Raj that the draft has an approval from security ADs and pointed out a couple of outstanding items like implementation and usage of IPSec. The current goal is to progress MIPv6 draft to PS by the end of year 2001.

The current proposals that specify alternative solutions for the binding update problem are:
- draft-thomas-mobileip-ha-cookies-00.txt
- draft-perkins-bake-01.txt
- draft-montenegro-sucv-01.txt

The intent is to have an agreed upon solution that is acceptable to the security area directors and meets the requirements specified in the requirements I-D.

Further discussion lead to whether Routing Optimization should be a part of this draft and its impact on 3GPP2 work.

Mobile IP v6 other changes - Charles Perkins

Charlie brought up the issue related to authentication data passed with a binding update destination option. The working group comments received on this topic were that it is currently unclear in the draft on how IPSec can be used and how to handle potential IPSec problems. Also the issue with piggybacking IPSec on binding update data is still open. The further discussions on ESP vs AH may be continue on the mailing list. It seems home agent discovery may need some more work but other than this, the draft may be ready for the WG last call.

Low Latency Handover - Karim El-Malki

Short update of the draft-ietf-mobileip-lowlatency-handoffs-v4-01.txt presented by Karim. It seems draft discusses mainly three handoff techniques, pre-registration, post-registration and combined of the above two. This draft is completed and may be ready for the last WG call. The discussion lead toward using trigger defined from mayfolks-l2-trigger draft rather than defining separate subset specific to this work. Co-chair pointed out that by doing this, there might be a problem of introducing dependency. No decision was made in the meeting on this issue.

Fast Handover - Gopal Dometty

Gopal presented updates on draft-ietf-mobileip-fast-mipv6-01.txt. As per this draft, the mobile node can initiate a handover while it still has L2 connectivity to the current access router and about to move to a new access router. It seems there are some minor editorial changes made to this draft. He claimed that L2 and L3 are decoupled. Pat pointed out that access point is nothing but the foreign agent and hence it will have L3 address. Gopal pointed out that L3 information is generally obtained from L2. There is no agent advertisement involved here and hence may reduce delay. Also old CoA is reused.

BETH - James Kempf

James provided brief overview of BETH. He mentioned that BETH defines extension to the Fast Mobile IPv6 handover protocol described in draft-ietf-mobileip-fastmipv6-01.txt that reduces the amount of L3 latency in Mobile IPv6 handover to zero. It also removes routing loop problem. There were many questions raised by the group like how the new AR detects when the MN has an operational new CoA and tunnel tear down is started; bicasting is specified but the smoothing is not well understood; this draft may be dealing with rare cases only; for certain type of radio links the solution provided by this draft may not work etc.

The proposed plan is to incorporate BETH into the FMIPv6 specification as another way for achieving fast handoff. The scheme currently existing in the low-latency (v4) will also be aligned with the BETh proposal.

FMIPv6 Implementation experience report - Rajeev Koodli

Rajeev provided brief summery of FMIPv6 implementation experience. Handovers are all network initiated using UNIX based router, LINUX MN on 11 Mbps WLAN. The following issues were identified

- What destination address to use in the F-BU? It was confirmed by group that global IP address should be used instead of local address as suggested by current specifications

- Creating binding cache entry on previous access router (after receiving Hack and after sending F-Back to the old link). It was concluded that this is implementation specific and doesn't really have any protocol impact.

- What source address to use when sending F-BU from newer AR?

- Issues may be related to sending of F-NA (including only one IP address suffices). The group provided comments that it is essential to know both Hack and F-Back.

- When to change default router? There are two options proposed: after receiving proxy PA (may be not) or after actually attaching to the new link (the new AR).

Handover Smoothing - Phil Roberts

Phil pointed out that smoothing is currently part of low latency draft (draft-ietf-mobileip-lowlatency-handoffs-v4-01.txt) along with simultaneous binding and currently it is not supported in FMIPv6. The current proposal is to add handover smoothing to the FMIPv6 draft and remove it from the low latency draft. The following comments/proposals were received from the group

- FMIPv6 and smoothing may be defined as optional

- Bicasting may be treated as implementation specific.

- Bicasting is a useful feature needed for handovers

- There may be lot more work involved in removing smoothing from the low latency draft

- Bicasting is meant for achieving fast handovers and not necessarily for the handover smoothing

Discussion on smoothing vs bicasting and buffering. It was determined that smoothing has a larger scope than either bicasting and/or buffering and should be considered as a separate work item.

However for the fast handoff work a consensus call was done to determine if bicasting should be included as part of the FMIPv6 specification.

The final consensus was to move bicasting to a separate document for both the v4 and v6 fast handoff drafts.

Session 2

August 7th, 2001 (1700-1800)
Reported by : Basavaraj Patil

Consensus call for including bicasting in the fast handoff document was not very clear at the previous meeting. Clarified the question requiring consensus. The consensus call essentially was to see if people wanted to see bicasting as another option within the fast handoff specification. Consensus reached: Separate bicasting from fast handoff.

LMM Requirements - Carl Williams

Carl presented the major issues that have been raised on the Mobile IP mailing list since the last IETF[50] w.r.t LMM. The draft with Carl as the editor captures the requirements for an LMM solution. Discussion focused around obtaining consensus on the requirements and also to clarify the issues that have been previously discussed. One major issue that continues to persist is the one dealing with the levels of hierarchy. A long discussion on the pros and cons of single vs multiple levels of hierarchy ensued.

Since there was no conclusion on levels of hierarchy, it was decided that Carl would work with some of the interested people on this topic to arrive at some consensus. This should be documented in the next revision of the requirements document.

Mobile Network Suppport - Thierry Ernst

Thierry Ernst presented the draft on support for mobile networks and routers for IPv6 using Mobile IPv6.

Obviously this topic needs to be investigated more as it raised more questions than answers at this time. Basavaraj mentioned that the work does fit into the Mobile IP WG as the charter does not limit the scope to just mobile hosts. There were some concerns about stepping into MANET boundaries.

Erik Nordmark mentioned that the issue of authorization for mobile networks is a hard problem to solve and hence suggested that more work needs to be done in this area.

Opinions on the need for this work being done in the MIP WG were expressed by many people.

Conclusion was that more work needs to be done in this area. This draft is a good starting point and could be used to investigate the issues raised by Thierry in his presentation.

Nat Support in Mobile IPv4 - Henrik Levkowetz

A small group of WG members who are interested in having MIPv4 work in networks using NATs met the previous day. Conclusion reached at this meeting was that Mobile iPv4 does not currently work very well in a NAT world and scenarios where support for MIPv4 with NATs is required were discussed.

Henrik presented the conclusions of the discussion and the need for a solution for Mobile IPv4 over NATs.

Most WG members agreed that this work is important for MIPv4 deployment. A discussion list will be setup to discuss the scenarios and requirements for NAT support in MIPv4. The WG will make a decision regarding the inclusion of supporting NATs as a WG item at a later time [i.e after the scenarios and requirements draft are done].

Mobile IP Component Redundancy - Gopal Dometty

This could not be presented due to a lack of time.

Other MIP issues - Basavaraj Patil

Discussion item was skipped due to a lack of time.


Network Mobility Support
in IPv6

Fast MIPv6 Handoff
NAT Traversal Scenario
Place your BET!
Document Status
Handover Smoothing
Redundancy in Mobile IP Agents

Low Latency MIPv4 Handoffs
Localized Mobility Management Requirements For IPv6
FMIPv6 Implementation Issues
MIP v6 Security Status