Subject: [netext] Fwd: DMM problem statement and scenario draft

From: liu dapeng <[email-masked]>
Date: Tue, 19 Oct 2010 16:15:08 +0800

---------- Forwarded message ----------
From: liu dapeng <[email-masked]>
Date: Tue, 19 Oct 2010 16:12:30 +0800
Subject: DMM problem statement and scenario draft
To: dmm <[email-masked]>
Cc: "charles.perkins" <[email-masked]>, yokota
<[email-masked]>, MELIA TELEMACO
<[email-masked]>, Wassim Haddad
<[email-masked]>, Anthony Chan <[email-masked]>,
"elena.demaria" <[email-masked]>, denghui02
<[email-masked]>, caozhen <[email-masked]>

Hello all,

After several weeks and many contributor's hard working, we finished
DMM problem statement and scenario draft:

http://tools.ietf.org/html/draft-chan-distributed-mobility-ps-00
http://tools.ietf.org/html/draft-yokota-dmm-scenario-00

Besides, we have the following introduction and initial work plan of DMM:

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Work plan proposal -- Distributed and Dynamic Mobility Management
==================================================

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 capactity, 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 [1] 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

[1] G. Kirby, "Locating the User", Communication International, 1995
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Please feel free to comment. Thanks.

Best Regards,
Dapeng Liu