Re: [MEXT] the future of the MEXT working group

[h chan <[e-mail]>]

The DMM design team consisting of people from initially 8 (and later more) major operators and vendors had worked on DMM from over a year ago. It was also open to anyone and had later been joined by more people from more both industry and academia. In the past, the activities from this team (such as dmm discussion group and a couple of dmm meetings in Prague and in Quebec City) had been considered individual activities not part of the mext WG. As the mext WG is now re-chartered into DMM WG and has used the charter statement from the team as candidate input to the re-charter statement, is it reasonable to consider incorporating the work from this team into the DMM WG? It is of cause open to more suggestions and inputs from anyone as it had always been in the past.

The following 2 documents were the initial outputs from the team:
Problem statement: draft-chan-distributed-mobility-ps-
Use cases: draft-yokota-dmm-scenario-00
and a charter statement

The majority of the charter statement can be found in the introduction charter of the above problem statement from over a year ago.
This charter statement from this team is now being used by Jari as input to the re-charter to the WG.

In the last dmm meeting in July, work had already started in drafting the requirements, and an initial draft has also been produced in one session of the above ps draft, which had taken the discussions into account and had closely relate the requirements to address the problem statements.

In addition, the contents from the above documents had largely been used and improved in the following journal paper so that they had also been reviewed through the journal publication process:

"Distributed and Dynamic Mobility Management in Mobile Internet: Current Approaches and Issues," Journal of Communications, vol. 6, no. 1, pp. 4-15, Feb 2011.

I especially point out the above because they are the team work of many people resulting from a lot of efforts as well as using extensive discussions in emails (design team and then dmm mailing list) and in meetings.

I have not mentioned many other drafts on dmm from many other authors here.

Also, the earlier discussions in the dmm mailing list had caused the mext WG to not hold mext meeting in Quebec City with the reason that there was not enough interest in dmm. If the mext WG is to rename to dmm WG, are we going to use the dmm mailing list in future?

H Anthony Chan, Fellow IEEE

From: [e-mail] [mailto:[e-mail]] On Behalf Of Jari Arkko
Sent: Friday, October 28, 2011 8:21 PM
To: [e-mail]
Subject: Re: [MEXT] the future of the MEXT working group

And a follow-up on the charter. I'm describing a couple of different takes on what the new charter could be. Comments and alternative proposals are welcome. This is what the current charter says about DMM:
  The working group will also work on operational considerations on
  setting up Mobile IPv6 networks so that traffic is distributed
  in an optimal way, for instance by using existing protocol mechanisms
  to select the closest home agents for new clients.

  Oct 2011 - Submit I-D 'Operational considerations for distributed use of Mobile IPv6' for publication as Informational.

Which is admittedly a bit short, but is also very concrete and achievable, if we work on it. I got another proposal from Hui Deng that extended this a bit, including going beyond mere operational considerations.
In the past decade a fair number of mobility protocols have been standardized. Although the protocols differ in terms of functions and associated message format, we can identify a few key common features:
presence of a centralized mobility anchor providing global reachability and an always-on experience
extensions to optimize handover performance while users roam across wireless cells
extensions to enable the use of heterogeneous wireless interfaces for multi-mode terminals (e.g. cellular phones)
The presence of the centralized mobility anchor allows a mobile device to be reachable when it is not connected to its home domain. The anchor, among other tasks, ensures forwarding of packets destined to or sent from the mobile device. As such, most of the deployed architectures today have a small number of centralized anchors managing the traffic of millions of mobile subscribers.

To optimize handovers for mobile users, the base protocols have been extended to efficiently handle packet forwarding between the previous and new points of attachment. These extensions are necessary when applications impose stringent requirements in terms of delay. Notions of localization and distribution of local agents have been introduced to reduce signalling overhead. Unfortunately today we witness difficulties in getting such protocols deployed, often leading to sub-optimal choices. Moreover, all the availability of multi-mode devices and the possibility to use several network interfaces simultaneously have motivated the development of more new protocol extensions.

Mobile users are, more than ever, consuming Internet content, and impose new requirements on mobile core networks for data traffic delivery. When this traffic demand exceeds available capacity, service providers need to implement new strategies such as selective traffic offload (e.g. 3GPP work items LIPA/SIPTO) through alternative access networks (e.g. WLAN). Moreover, the localization of content providers closer to the Mobile/Fixed Internet Service Providers network requires taking into account local Content Delivery Networks (CDNs) while providing mobility services.

As long as demand exceeds capacity, both offloading and CDN techniques could benefit from the development of more flat mobile architectures (i.e., fewer levels of routing hierarchy introduced into the data path by the mobility management system). This view is reinforced by the shift in users' traffic behaviour, aimed at increasing direct communications among peers in the same geographical area. The development of truly flat mobile architectures would result in anchoring the traffic closer to point of attachment of the user and overcoming the suboptimal routing issues of a centralized mobility scheme.

While deploying today's mobile networks, service providers face new challenges. More often than not, mobile devices remain attached to the same point of attachment, in which case specific IP mobility management support is not required for applications that launch and complete while connected to the same point of attachment. However, the mobility support has been designed to be always on and to maintain the context for each mobile subscriber as long as they are connected to the network. This can result in a waste of resources and ever-increasing costs for the service provider. Infrequent mobility and intelligence of many applications suggest that mobility can be provided dynamically, thus simplifying the context maintained in the different nodes of the mobile network.

The proposed charter will address two complementary aspects of mobility management procedures: the distribution of mobility anchors to achieve a more flat design and the dynamic activation/deactivation of mobility protocol support as an enabler to distributed mobility management. The former has the goal of positioning mobility anchors (HA, LMA) closer to the user; ideally, these mobility anchors could be collocated with the first hop router. The latter, facilitated by the distribution of mobility anchors, aims at identifying when mobility must be activated and identifying sessions that do not impose mobility management -- thus reducing the amount of state information to be maintained in the various mobility anchors of the mobile network. The key idea is that dynamic mobility management relaxes some constraints while also repositioning mobility anchors; it avoids the establishment of non optimal tunnels between two anchors topologically distant.

Considering the above, the working group will:

Define the problem statement and associated requirements for distributed mobility management. This work aims at defining the problem space and identifies the key functional requirements.

Produce a gap analysis mapping the above requirements against existing solutions.

Give best practices for the deployment of existing mobility protocols in a distributed mobility management and describe limitations of each such approach.

Describe extensions, if needed, to current mobility protocols for their application in distributed mobility architectures

Comments?

Jari