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
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