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docName="draft-chan-dmm-requirements-01">
<front>
<title abbrev="DMM-Reqs">
Requirements of distributed mobility management
</title>
<author initials="H" surname="Chan (Ed.)"
fullname="H Anthony Chan (editor)">
<organization>Huawei Technologies</organization>
<address>
<postal>
<street>5340 Legacy Dr. Building 3, Plano, TX 75024, USA</street>
<street>Email: h.a.chan@ieee.org</street>
<street>-</street>
<street>Dapeng Liu</street>
<street>China Mobile</street>
<street>Unit2, 28 Xuanwumenxi Ave, Xuanwu District,
Beijing 100053, China</street>
<street>Email: liudapeng@chinamobile.com</street>
<street>-</street>
<street>Pierrick Seite</street>
<street>France Telecom - Orange</street>
<street>4, rue du Clos Courtel, BP 91226,
Cesson-Sevigne 35512, France</street>
<street>Email: pierrick.seite@orange-ftgroup.com</street>
<street>-</street>
<street>Hidetoshi Yokota</street>
<street>KDDI Lab</street>
<street>2-1-15 Ohara, Fujimino, Saitama, 356-8502 Japan</street>
<street>Email: yokota@kddilabs.jp</street>
<street>-</street>
<street>Charles E. Perkins</street>
<street>Huawei Technologies</street>
<street>Email: charliep@computer.org</street>
<street>-</street>
<street>Jouni Korhonen</street>
<street>Nokia Siemens Networks</street>
<street>Email: jouni.korhonen@nsn.com</street>
<street>-</street>
<street>Melia Telemaco</street>
<street>Alcatel-Lucent Bell Labs</street>
<street>Email: telemaco.melia@alcatel-lucent.com</street>
<street>-</street>
<street>Elena Demaria</street>
<street>Telecom Italia</street>
<street>via G. Reiss Romoli, 274, TORINO, 10148, Italy</street>
<street>Email: elena.demaria@telecomitalia.it</street>
<street>-</street>
<street>Jong-Hyouk Lee</street>
<street>RSM Department, Telecom Bretagne</street>
<street>Cesson-Sevigne, 35512, France</street>
<street>Email: jh.lee@telecom-bretagne.eu</street>
<street>-</street>
<street>Tricci So</street>
<street>ZTE</street>
<street>Email: tso@zteusa.com</street>
<street>-</street>
<street>Carlos J. Bernardos</street>
<street>Universidad Carlos III de Madrid</street>
<street>Av. Universidad, 30, Leganes, Madrid 28911, Spain</street>
<street>Email: cjbc@it.uc3m.es</street>
<street>-</street>
<street>Peter McCann</street>
<street>Huawei Technologies</street>
<street>Email: PeterMcCann@huawei.com</street>
<street>-</street>
<street>Seok Joo Koh</street>
<street>Kyungpook National University, Korea</street>
<street>Email: sjkoh@knu.ac.kr</street>
<street>-</street>
<street>Wen Luo</street>
<street>ZTE</street>
<street>No.68, Zijinhua RD,Yuhuatai District, Nanjing, Jiangsu 210012, China</street>
<street>Email: luo.wen@zte.com.cn</street>
<street>-</street>
</postal>
</address>
</author>
<date month="June" year="2012"></date>
<area></area>
<workgroup></workgroup>
<abstract>
<t>
The traditional hierarchical structure of cellular networks
has led to deployment models which are heavily centralized.
Mobility management with centralized mobility anchoring
in existing hierarchical mobile networks
is quite prone to suboptimal routing
and issues related to scalability.
Centralized functions present a single point of failure,
and inevitably introduce longer delays
and higher signaling loads
for network operations related to mobility management.
This document defines the requirements
for distributed mobility management
for IPv6 deployment.
The objectives are
to match the mobility deployment
with the current trend in network evolution,
to improve scalability,
to avoid single point of failure,
to enable transparency to upper layers
only when needed,
etc.
The distributed mobility management also needs
to be compatible with
existing network deployments and end hosts,
and be secured.
</t>
</abstract>
</front>
<middle>
<section anchor="intro" title="Introduction">
<t>
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:
<list>
<t>
presence of a centralized mobility anchor
providing global reachability and an always-on experience;
</t>
<t>
extensions to optimize handover performance
while users roam across wireless cells;
</t>
<t>
extensions to enable
the use of heterogeneous wireless interfaces
for multi-mode terminals
(e.g. cellular phones).
</t>
</list>
</t>
<t>
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 point, among other tasks,
ensures reachability
of forwarding of packets
destined to or sent from the mobile device.
Most of the deployed architectures today
have a small number of centralized anchors
managing the traffic of millions of mobile subscribers.
Compared with a distributed approach,
a centralized approach
is likely to have several issues or limitations
affecting performance and scalability,
which require costly network dimensioning
and engineering to resolve.
</t>
<t>
To optimize handovers from the perspective of mobile nodes,
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 signaling overhead.
Unfortunately today we witness difficulties
in getting such protocols deployed,
often leading to sub-optimal choices.
</t>
<t>
Moreover, the availability of multi-mode devices
and the possibility of
using several network interfaces simultaneously
have motivated the development
of more new protocol extensions.
Deployment is further complicated with so many extensions.
</t>
<t>
Mobile users are, more than ever,
consuming Internet content;
such traffic imposes new requirements
on mobile core networks for data traffic delivery.
When the 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.
</t>
<t>
When demand exceeds capacity,
both offloading and CDN techniques
could benefit from the development of mobile architectures
with fewer levels of routing hierarchy
introduced into the data path
by the mobility management system.
This trend in network flattening is reinforced
by a shift in users traffic behavior,
aimed at increasing direct communications among peers
in the same geographical area.
Distributed mobility management
in a truly flat mobile architecture
would anchor the traffic
closer to the point of attachment of the user
and overcome the suboptimal routing issues
of a centralized mobility scheme.
</t>
<t>
While deploying
[Paper-Locating.User]
today's mobile networks,
service providers face new challenges.
More often than not,
mobile devices
remain attached to the same point of attachment.
Specific IP mobility management support
is not required for applications
that launch and complete
while the mobile device is 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.
</t>
<t>
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 agents 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 agents 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 topologically distant anchors.
</t>
<t>
Considering the above,
the distributed mobility management working group
is chartered with the following tasks:
<list>
<t>
Define the problem statement of
distributed mobility management
and identity the requirements
for a distributed mobility management solution.
</t>
<t>
Document practices for the deployment
of existing mobility protocols
in a distributed
mobility management environment.
</t>
<t>
Identify the limitations
in the current practices
with respect to
providing the expected functionality.
</t>
<t>
If limitations are identified
as part of the above deliverable,
specify extensions to existing protocols
that removes these limitations
within a distributed
mobility management environment.
</t>
</list>
</t>
<t>
This document describes
the motivations of distributed mobility management
and the proposed work in Section 1.1.
Section 1.2 summarizes the problems
with centralized IP mobility management
compared with distributed and dynamic mobility management,
which is elaborated in Section 4.
The requirements to address these problems
are given in Section 5.
A companion document
[I-D.yokota-dmm-scenario]
discusses the use case scenarios.
</t>
<t>
Much of the problems explained in this document
together with the contents in
[I-D.yokota-dmm-scenario]
have been merged and elaborated
into the following review paper:
[Paper-Distributed.Mobility.Review].
</t>
</section>
<section title="Conventions used in this document">
<t>
The key words "MUST", "MUST NOT",
"REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL"
in this document are to be interpreted as described
in <xref target="RFC2119" />.
</t>
</section>
<section
title="Centralized versus distributed mobility management">
<t>
Mobility management functions
may be implemented at different layers
of the network protocol stack.
At the IP (network) layer,
they may reside in the network or in the mobile node.
In particular,
a network-based solution resides in the network only.
It therefore enables mobility for existing hosts
and network applications
which are already in deployment but lack mobility support.
</t>
<t>
At the IP layer,
a mobility management protocol to achieve session continuity
is typically based on the principle
of distinguishing between identifier and routing address
and maintaining a mapping between them.
With Mobile IP,
the home address serves as an identifier of the device
whereas the care-of-address takes the role of routing address,
and the binding between them
is maintained at the mobility anchor,
i.e., the home agent.
If packets can be continuously delivered
to a mobile device at its home address,
then all sessions using that home address can be preserved
even though the routing or care-of address changes.
</t>
<t>
The next two subsections explain centralized and distributed
mobility management functions in the network.
</t>
<section title="Centralized mobility management">
<t>
With centralized mobility management,
the mapping information between the stable node identifier
and the changing IP address of a mobile node (MN)
is kept at a centralized mobility anchor.
Packets destined to an MN are routed via this anchor.
In other words,
such mobility management systems are centralized
in both the control plane and the data plane.
</t>
<t>
Many existing mobility management deployments
make use of centralized mobility anchoring
in a hierarchical network architecture,
as shown in Figure 1.
Examples of such centralized mobility anchors
are the home agent (HA) and local mobility anchor (LMA)
in Mobile IPv6 <xref target="RFC6275"/>
and Proxy Mobile IPv6 <xref target="RFC5213"/>, respectively.
Current mobile networks
such as the Third Generation Partnership Project (3GPP)
UMTS networks, CDMA networks,
and 3GPP Evolved Packet System (EPS) networks
also employ centralized mobility management,
with Gateway GPRS Support Node (GGSN)
and Serving GPRS Support Node (SGSN)
in the 3GPP UMTS hierarchical network
and with Packet data network Gateway (P-GW)
and Serving Gateway (S-GW) in the 3GPP EPS network.
</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
UMTS 3GPP SAE MIP/PMIP
+------+ +------+ +------+
| GGSN | | P-GW | |HA/LMA|
+------+ +------+ +------+
/\ /\ /\
/ \ / \ / \
/ \ / \ / \
/ \ / \ / \
/ \ / \ / \
+------+ +------+ +------+ +------+ +------+ +------+
| SGSN | | SGSN | | S-GW | | S-GW | |FA/MAG| |FA/MAG|
+------+ +------+ +------+ +------+ +------+ +------+
]]></artwork>
<postamble></postamble>
</figure>
<t>Figure 1. Centralized mobility management.
</t>
</section>
<section title="Distributed mobility management">
<t>Mobility management functions may also be distributed
to multiple locations in different networks
as shown in Figure 2,
so that a mobile node in any of these networks
may be served by a closeby mobility function (MF).
</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
+------+ +------+ +------+ +------+
| MF | | MF | | MF | | MF |
+------+ +------+ +------+ +------+
|
----
| MN |
----
]]></artwork>
<postamble></postamble>
</figure>
<t>Figure 2. Distributed mobility management.
</t>
<t>
Mobility management may be partially distributed,
i.e., only the data plane is distributed,
or fully distributed
where both the data plane and control plane are distributed.
These different approaches are described in detail in
[I-D.yokota-dmm-scenario].
</t>
<t>
[Paper-New.Perspective] discusses
some initial steps towards a clear definition
of what mobility management may be,
to assist in better developing distributed architecture.
[Paper-Characterization.Mobility.Management]
analyses current mobility solutions
and proposes an initial decoupling of mobility management
into well-defined functional blocks,
identifying their interactions,
as well as a potential grouping,
which later can assist
in deriving more flexible mobility management architectures.
According to the split functional blocks,
this paper proposes three ways
into which mobility management functional blocks
can be groups, as an initial way
to consider a better distribution:
location and handover management,
control and data plane,
user and access perspective.
</t>
<t>
A distributed mobility management scheme is proposed in
[Paper-Distributed.Dynamic.Mobility]
for future flat IP architecture consisting of access nodes.
The benefits of this design
over centralized mobility management
are also verified through simulations in
[Paper-Distributed.Centralized.Mobility].
</t>
<t>
Before designing new mobility management protocols
for a future flat IP architecture,
one should first ask
whether the existing mobility management protocols
that have already been deployed
for the hierarchical mobile networks
can be extended to serve the flat IP architecture.
MIPv4 has already been deployed in 3GPP2 networks,
and PMIPv6 has already been adopted in WiMAX Forum
and in 3GPP standards.
Using MIP or PMIP
for both centralized and distributed architectures
would ease the migration of the current mobile networks
towards a flat architecture.
It has therefore been proposed to adapt MIP or PMIPv6
to achieve distributed mobility management
by using a distributed mobility anchor architecture.
</t>
<t>
In
[Paper-Migrating.Home.Agents],
the HA functionality is copied to many locations.
The HoA of all MNs are anycast addresses,
so that a packet destined to the HoA
from any corresponding node (CN)
from any network
can be routed via the nearest copy of the HA.
In addition,
distributing the function of HA
using a distributed hash table structure is proposed in
[Paper-Distributed.Mobility.SAE].
A lookup query to the hash table
will retrieve the location information of an MN is stored.
</t>
<t>
In
[Paper-Distributed.Mobility.PMIP],
only the mobility routing (MR) function
is duplicated and distributed in many locations.
The location information for any MN
that has moved to a visited network
is still centralized
and kept at a location management (LM) function
in the home network of the MN.
The LM function at different networks
constitutes a distributed database system
of all the MNs
that belong to any of these networks
and have moved to a visited network.
The location information is maintained
in the form of a hierarchy:
the LM at the home network,
the CoA of the MR of the visited network,
and then the CoA to reach the MN in the visited network.
The LM in the home network
keeps a binding of the HoA of the MN
to the CoA of the MR of the visited network.
The MR keeps the binding of the HoA of the MN
to the CoA of the MN in the case of MIP,
or the proxy-CoA of the Mobile Access Gateway (MAG)
serving the MN in the case of PMIP.
</t>
<t>
[I-D.jikim-dmm-pmip]
discusses two distributed mobility control schemes
using the PMIP protocol:
Signal-driven PMIP (S-PMIP)
and Signal-driven Distributed PMIP (SD-PMIP).
S-PMIP is a partially distributed scheme,
in which the control plane
(using a Proxy Binding Query to get the Proxy-CoA of the MN)
is separate from the data plane,
and the optimized data path
is directly between the CN and the MN.
SD-PMIP is a fully distributed scheme,
in which the Proxy Binding Update is not performed,
and instead each MAG will multicast
a Proxy Binding Query message
to all of the MAGs in its local PMIP domain
to retrieve the Proxy-CoA of the MN.
</t>
</section>
</section>
<section title="Problem statement">
<t>
This section identifies problems and limitations
of centralized mobility approaches,
and compares against possible distributed approaches.
A few other related problems
that may not be specific to the centralized approach
are also described.
</t>
<!-- PS1 -->
<section title="Non-optimal routes">
<t>
<list style='format PS%d:' counter="PS_count">
<t>
Routing via a centralized anchor
often results in a longer route,
and the problem is especially manifested
when accessing a local or cache server
of a Content Delivery Network (CDN).
</t>
</list>
Figure 3 shows two cases of non-optimized routes.
</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
MIP/PMIP
+------+
|HA/LMA|
+------+
/\ \ \ +---+
/ \ \ \ |CDN|
/ \ \ \ +---+
/ \ \ \ |
/ \ \ \ |
+------+ +------+ +------+ +------+
|FA/MAG| |FA/MAG| |FA/MAG| |FA/MAG|
+------+ +------+ +------+ +------+
| |
---- ----
| CN | | MN |
---- ----
]]></artwork>
<postamble></postamble>
</figure>
<t>Figure 3. Non-optimized route
when communicating with a CN
and when accessing a local or cache server
of a CDN.
</t>
<t>
In the first case, the mobile node and the correspondent node
are close to each other
but are both far from the mobility anchor.
Packets destined to the mobile node
need to be routed via the mobility anchor,
which is not on the shortest path.
<!-- CEP: stopped here for now... -->
The second case involves a content delivery network (CDN).
A user may obtain content from a server,
such as when watching a video.
As such usage becomes more popular,
resulting in an increase in the core network traffic,
service providers may relieve the core network traffic
by placing these contents closer to the users
in the access network
in the form of cache or local CDN servers.
Yet as the MN is getting content
from a local or cache server of a CDN,
even though the server is close to the MN,
packets still need to go through the core network
to route via the mobility anchor
in the home network of the MN,
if the MN uses the HoA as its identifier.
</t>
<t>
In a distributed mobility management design,
one possibility is to have
mobility anchors distributed in different access networks
so that packets may be routed
via a nearby mobility anchor function,
as shown in Figure 4.
</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
+---+
|CDN|
+---+
|
|
+------+ +------+ +------+ +------+
| MF | | MF | | MF | | MF |
+------+ +------+ +------+ +------+
| |
---- ----
| CN | | MN |
---- ----
]]></artwork>
<postamble></postamble>
</figure>
<t>Figure 4.
Mobile node in any network is served
by a close by mobility function.
</t>
<t>
Due to the above limitation,
with the centralized mobility anchor design,
route optimization extensions to mobility protocols
are therefore needed.
Whereas the location privacy of each MN may be compromised
when the CoA of an MN is given to the CN,
those mobility protocol deployments
that lack such optimization extensions
will encounter non-optimal routes,
which affect the performance.
</t>
<t>
In contrast,
route optimization may be naturally
an integral part of a distributed mobility management design.
With the help of such intrinsic route optimization,
the data transmission delay will be reduced,
by which the data transmission throughputs can be enhanced.
Furthermore, the data traffic overhead at the mobility agents
such as the HA and the LMA
in the core network can be alleviated significantly.
</t>
</section>
<!-- PS2 -->
<section
title="Non-optimality in Evolved Network Architecture">
<t>
<list style='format PS%d:' counter="PS_count">
<t>
The centralized mobility management
can become non-optimal
as a network architecture evolves
and becomes more flattened.
</t>
</list>
Centralized mobility management
is currently deployed
to support the existing hierarchical mobile data networks.
It leverages on the hierarchical architecture.
However,
the volume of wireless data traffic
continues to increase exponentially.
The data traffic increase
would require costly capacity upgrade
of centralized architectures.
It is thus predictable
that the data traffic increase will soon overload
the centralized data anchor point,
e.g., the P-GW in 3GPP EPS.
In order to address this issue,
a trend in the evolution of mobile networks
is to distribute network functions
close to access networks.
These network functions can be the content servers
in a CDN,
and also the data anchor point.
</t>
<t>
Mobile networks have been evolving
from a hierarchical architecture
to a more flattened architecture.
In the 3GPP standards,
the GPRS network
has the hierarchy GGSN 每 SGSN 每 RNC 每 NB (Node B).
In 3GPP EPS networks,
the hierarchy is reduced to P-GW 每 S-GW 每 eNB (Evolved NB).
In some deployments,
the P-GW and the S-GW
are collocated to further reduce the hierarchy.
Reducing the hierarchy this way
reduces the number of different physical network elements
in the network,
contributing to easier system maintenance and lower cost.
As mobile networks become more flattened,
the centralized mobility management can become non-optimal.
Mobility management deployment
with distributed architecture
is then needed to support the more flattened network
and the CDN networks.
</t>
</section>
<!-- PS3 -->
<section title=
"Low scalability of centralized route and mobility context maintenance">
<t>
<list style='format PS%d:' counter="PS_count">
<t>
Setting up such special routes
and maintaining the mobility context
for each MN is more difficult to scale
in a centralized design with a large number of MNs.
Distributing the route maintenance function
and the mobility context maintenance function
among different networks can be more scalable.
</t>
</list>
Special routes are set up
to enable session continuity when a handover occurs.
Packets sent from the CN
need to be tunneled between the HA and FA in MIP
and between the LMA and MAG in PMIP.
However,
these network elements at the ends of the tunnel
are also routers
performing the regular routing tasks
for ordinary packets not involving a mobile node.
These ordinary packets need to be directly routed
according to the routing table in the routers
without tunneling.
Therefore,
the network must be able to distinguish
those packets requiring tunneling from the regular packets.
For each packet that requires tunneling owing to mobility,
the network will encapsulate it
with a proper outer IP header
with the proper source and destination IP addresses.
The network therefore
needs to maintain and manage the mobility context of each MN,
which is the relevant information
needed to characterize the mobility situation of that MN
to allow the network to distinguish
their packets from other packets
and to perform the required tunneling.
</t>
<t>
Setting up such special routes
and maintaining the mobility context for each MN
is more difficult to scale
in a centralized design with a large number of MNs.
Distributing the route maintenance function
and the mobility context maintenance function
among different networks can be more scalable.
</t>
</section>
<!-- PS4 -->
<section title="Single point of failure and attack">
<t>
<list style='format PS%d:' counter="PS_count">
<t>
Centralized anchoring
may be more vulnerable
to single point of failure and attack
than a distributed system.
</t>
</list>
A centralized anchoring architecture
is generally more vulnerable
to a single point of failure or attack,
requiring duplication and backups of the support functions.
</t>
<t>
On the other hand,
a distributed mobility management architecture
has intrinsically mitigated the problem
to a local network which is then of a smaller scope.
In addition,
the availability of such functions in neighboring networks
has already provided the needed architecture
to support protection.
</t>
</section>
<!-- PS5 -->
<section
title="Wasting resources
to support mobile nodes not needing mobility support">
<t>
<list style='format PS%d:' counter="PS_count">
<t>
IP mobility support is not always required.
For example,
some applications do not need a stable IP address
during handover, i.e., IP session continuity.
Sometimes, the entire application session runs
while the terminal does not change the point of attachment.
In these situations that do not require IP mobility support,
network resources are wasted
when mobility context is set up.
</t>
</list>
The problem of centralized route
and mobility context maintenance
is aggravated
when the via routes are set up for many more MNs
that are not requiring IP mobility support.
On the one hand,
the network needs to provide mobility support
for the increasing number of mobile devices
because the existing mobility management
has been designed to always provide such support
as long as a mobile device is attached to the network.
On the other hand,
many nomadic users are connected to a network in an office
or meeting room. Such users will not move
for the entire network session.
It has been measured that over two-thirds of a
user mobility is local
[Paper-Locating.User].
In addition,
it is possible to have the intelligence
for applications to manage mobility
without needing help from the network.
Network resources are therefore wasted
to provide mobility support for the devices
that do not really need it at the moment.
</t>
<t>
It is necessary to dynamically set up the via routes
only for MNs that actually undergo handovers
and lack higher-layer mobility support.
With distributed mobility anchors,
such dynamic mobility management mechanism
may then also be distributed.
Therefore, dynamic mobility
and distributed mobility may complement each other
and may be integrated.
</t>
</section>
<section
title="Other related problems">
<t>
Other related problems that may not be specifically
owing to a centralized architecture
but are desirable to solve
are described in this subsection.
</t>
<!-- O-PS1 -->
<section title=
"Mobility signaling overhead with peer-to-peer communication">
<t>
<list style='format O-PS%d:' counter="O-PS_count">
<t>
Wasting resources when mobility signaling
(e.g., maintenance of the tunnel, keep alive, etc.)
is not turned off for peer-to-peer communication.
</t>
</list>
In peer-to-peer communications,
end users communicate by sending packets
directly addressed to each other's IP address.
However, they need to find each other's IP address first
through signaling in the network.
While different schemes for this purpose may be used,
MIP already has a mechanism to locate an MN
and may be used in this way.
In particular,
MIPv6 Route Optimization (RO) mode
enables a more efficient data packets exchange
than the bidirectional tunneling (BT) mode,
as shown in Figure 5.
</t>
<figure>
<preamble></preamble>
<artwork><![CDATA[
MIP/PMIP
+------+
|HA/LMA|
+------+
/\ \ \
/ \ \ \
/ \ \ \
/ \ \ \
/ \ \ \
+------+ +------+ +------+ +------+
|FA/MAG| |FA/MAG| |FA/MAG| |FA/MAG|
+------+ +------+ +------+ +------+
| |
---- ----
| MN |<--->| CN |
---- ----
]]></artwork>
<postamble></postamble>
</figure>
<t>Figure 5. Non-optimized route when communicating with CN
and when accessing local content.
</t>
<t>
This RO mode is expected to be used whenever possible
unless the MN is not interested
in disclosing its topological location,
i.e., the CoA, to the CN (e.g., for privacy reasons)
or some other network constraints are put in place.
However,
MIPv6 RO mode requires
exchanging a significant amount of signaling messages
in order to establish
and periodically refresh
a bidirectional security association (BSA)
between an MN and its CN.
While the mobility signaling exchange
impacts the overall handover latency,
the BSA is needed to authenticate the binding update
and acknowledgment messages
(note that the latter is not mandatory).
In addition,
the amount of mobility signaling messages increases further
when both endpoints are mobile.
</t>
<t>
A dynamic mobility management capability
that turns off these signaling when they are not needed
will enable the RO mode between two mobile endpoints
at minimum or no cost.
It will also reduce the handover latency
owing to the removal of the extra signaling.
These benefits for peer-to-peer communications
will encourage the adoption
and large-scale deployment of dynamic mobility management.
</t>
</section>
<!-- O-PS2 -->
<section title=
"Complicated deployment with too many variants and extensions of MIP">
<t>
<list style='format O-PS%d:' counter="O-PS_count">
<t>
Deployment is complicated
with many variants and extensions of MIP.
When introducing new functions
which may add to the complicity,
existing solutions are more vulnerable to break.
</t>
</list>
Mobile IP,
which has primarily been deployed in a centralized manner
for the hierarchical mobile networks,
already has numerous variants and extensions
including PMIP, Fast MIP (FMIP)
<xref target="RFC4068"/>
<xref target="RFC4988"/>
, Proxy-based FMIP (PFMIP)
<xref target="RFC5949"/>
, hierarchical MIP (HMIP)
<xref target="RFC5380"/>
, Dual-Stack Mobile IP (DSMIP)
<xref target="RFC5454"/>
<xref target="RFC5555"/>
and there may be more to come.
These different modifications or extensions of MIP
have been developed over the years
owing to the different needs that are found afterwards.
Deployment can then become complicated,
especially when interoperability with different deployments
is an issue.
</t>
<t>
A desirable feature of mobility management
is to be able to work with network architectures
of both hierarchical networks and flattened networks,
so that the mobility management protocol
possesses enough flexibility to support different networks.
In addition, one goal of dynamic mobility management
is the capability to selectively turn on and off
mobility support
and certain mobility signaling.
Such flexibility in the design
is compatible with the goal
to integrate different mobility variants as options.
Some additional extensions to the base protocols
may then be needed to improve the integration
while avoiding existing functions to break.
</t>
</section>
</section>
</section>
<section title="Requirements">
<t>
After reviewing the problems and limitations
of centralized deployment in Section 4,
this section states
the requirements as follows:
</t>
<!-- REQ1 -->
<section
title="Distributed deployment">
<t>
<list style='format REQ%d:' counter="R_count">
<t>
Distributed deployment
<vspace blankLines="1" />
IP mobility, network access and routing solutions
provided by DMM
SHALL enable a distributed deployment
of mobility management of IP sessions
so that the traffic can be routed
in an optimal manner
without traversing
centrally deployed mobility anchors.
<vspace blankLines="1" />
Motivation:
The motivations of this requirement are
to match mobility deployment
with current trend in network evolution:
more cost and resource effective
to cache and distribute contents
when combining distributed anchors with caching systems
(e.g., CDN);
improve scalability;
avoid single point of failure;
mitigate threats
being focused on a centrally deployed anchor,
e.g., home agent and local mobility anchor.
</t>
</list>
</t>
<t>
This requirement addresses the problems
PS1, PS2, PS3, and PS4
explained in Section 4 above.
</t>
</section>
<!-- REQ2 -->
<section
title="Transparency to Upper Layers when needed">
<t>
<list style='format REQ%d:' counter="R_count">
<t>
Transparency to Upper Layers when needed
<vspace blankLines="1" />
The DMM solutions SHALL provide
transparency above the IP layer when needed.
Such transparency is needed,
when the mobile hosts
or entire mobile networks
change their point of attachment to the Internet,
for the application flows
that cannot cope with a change of IP address.
Otherwise the support
to maintain a stable home IP address or prefix
during handover may be declined.
<vspace blankLines="1" />
Motivation:
The motivation of this requirement is to
enable more efficient use of network resources
and more efficient routing
by not maintaining a stable IP home IP address
when there is no such need.
</t>
</list>
</t>
<t>
This requirement addresses the problems
PS5 as well as the other related problem O-PS1
which are explained in Section 4 above.
</t>
</section>
<!-- REQ3 -->
<section
title="IPv6 deployment">
<t>
<list style='format REQ%d:' counter="R_count">
<t>
IPv6 deployment
<vspace blankLines="1" />
The DMM solutions SHOULD target IPv6 as primary deployment
and SHOULD NOT be tailored specifically to support IPv4,
in particular in situations
where private IPv4 addresses and/or NATs are used.
<vspace blankLines="1" />
Motivation:
The motivation for this requirement is
to be inline with the general orientation of IETF.
Moreover,
DMM deployment is foreseen in mid-term/long-term,
hopefully in an IPv6 world.
It is also unnecessarily complex
to solve this problem for IPv4,
as we will not be able to use
some of the IPv6-specific features/tools.
</t>
</list>
</t>
</section>
<!-- REQ4 -->
<section
title="Compatibility">
<t>
<list style='format REQ%d:' counter="R_count">
<t>
Compatibility
<vspace blankLines="1" />
The DMM solution SHOULD be able to work
between trusted administrative domains
when allowed by the security measures
deployed between these domains.
Furthermore,
the DMM solution SHOULD
preserve backwards compatibility
with existing network deployment and end hosts.
For example,
depending on the environment in which dmm is deployed,
the dmm solutions
may need to be compatible
with other existing mobility protocols
that are deployed in that environment
or may need to be interoperable
with the network or the mobile hosts/routers
that do not support the dmm enabling protocol.
<vspace blankLines="1" />
Motivation: The motivation of this requirement is
to allow inter-domain operation
if desired and to preserve backwards compatibility
so that the existing networks and hosts
are not affected and do not break.
</t>
</list>
</t>
</section>
<!-- REQ5 -->
<section
title="Existing mobility protocols">
<t>
<list style='format REQ%d:' counter="R_count">
<t>
Existing mobility protocols
<vspace blankLines="1" />
A DMM solution SHOULD
first consider reusing
and extending the existing mobility protocols
before specifying new protocols.
<vspace blankLines="1" />
Motivation:
The purpose is to reuse the existing protocols first
before considering new protocols.
</t>
</list>
</t>
</section>
<!-- REQ6 -->
<section
title="Security considerations">
<t>
<list style='format REQ%d:' counter="R_count">
<t>
Security considerations
<vspace blankLines="1" />
The protocol solutions for DMM
SHALL consider security,
for example
authentication and authorization mechanisms
that allow a legitimate mobile host/router
to access to the DMM service,
protection of signaling messages
of the protocol solutions
in terms of authentication, data integrity,
and data confidentiality,
opti-in or opt-out data confidentiality
to signaling messages
depending on network environments
or user requirements.
<vspace blankLines="1" />
Motivation and problem statement:
Mutual authentication and authorization
between a mobile host/router and an access router
providing the DMM service to the mobile host/router
are required to prevent potential attacks
in the access network of the DMM service.
Otherwise, various attacks such as impersonation,
denial of service, man-in-the-middle attacks, etc.
are present to obtain illegitimate access
or to collapse the DMM service.
<vspace blankLines="1" />
Signaling messages are subject to various attacks
since these messages carry context of a mobile host/router.
For instance,
a malicious node can forge
and send a number of signaling messages
to redirect traffic to a specific node.
Consequently, the specific node is
under a denial of service attack,
whereas other nodes are not receiving their traffic.
As signaling messages travel over the Internet,
the end-to-end security is required.
</t>
</list>
</t>
</section>
</section>
<section anchor="security" title="Security Considerations">
<t>
Distributed mobility management (DMM)
requires two kinds of security considerations:
1) access network security
that only allows
a legitimate mobile host/router
to access the DMM service;
2) end-to-end security
that protects signaling messages
for the DMM service.
Access network security is required
between the mobile host/router
and the access network
providing the DMM service.
End-to-end security is required
between nodes
that participate in the DMM protocol.
</t>
<t>
It is necessary to provide sufficient defense
against possible security attacks,
or to adopt existing security mechanisms
and protocols
to provide sufficient security protections.
For instance,
EAP based authentication
can be used for access network security,
while IPsec can be used
for end-to-end security.
</t>
</section>
<section title="IANA Considerations">
<t>None</t>
</section>
<section title="Co-authors and Contributors">
<t>This problem statement document is a joint effort
among the following participants.
Each individual has made significant contributions
to this work.
</t>
<t>Dapeng Liu: liudapeng@chinamobile.com</t>
<t>Pierrick Seite: pierrick.seite@orange-ftgroup.com</t>
<t>Hidetoshi Yokota: yokota@kddilabs.jp</t>
<t>Charles E. Perkins: charliep@computer.org</t>
<t>Melia Telemaco: telemaco.melia@alcatel-lucent.com</t>
<t>Elena Demaria: elena.demaria@telecomitalia.it</t>
<t>Peter McCann: Peter.McCann@huawei.com</t>
<t>Wassim Michel Haddad: Wassam.Haddad@ericsson.com</t>
<t>Hui Deng: denghui@chinamobile.com</t>
<t>Tricci So: tso@zteusa.com</t>
<t>Jong-Hyouk Lee: jh.lee@telecom-bretagne.eu</t>
<t>Seok Joo Koh: sjkoh@knu.ac.kr</t>
</section>
</middle>
<back>
<references title="Normative References">
&rfc2119;
</references>
<references title="Informative References">
<?rfc include="reference.RFC.6275" ?>
<?rfc include="reference.RFC.5213" ?>
<?rfc include="reference.RFC.5380" ?>
<?rfc include="reference.RFC.4068" ?>
<?rfc include="reference.RFC.4988" ?>
<?rfc include="reference.RFC.5454" ?>
<?rfc include="reference.RFC.5555" ?>
<?rfc include="reference.RFC.5844" ?>
<?rfc include="reference.RFC.5949" ?>
<?rfc include="reference.RFC.3963" ?>
<reference anchor="I-D.yokota-dmm-scenario">
<front>
<title>Use case scenarios
for Distributed Mobility Management</title>
<author initials="H" surname="Yokota"
fullname="Hidetoshi Yokota">
<organization />
</author>
<author initials="P" surname="Seite"
fullname="Pierrick Seite">
<organization />
</author>
<author initials="E" surname="Demaria"
fullname="Elena Demaria">
<organization />
</author>
<author initials="Z" surname="Cao" fullname="Zhen Cao">
<organization />
</author>
<date day="18" month="October" year="2010" />
</front>
<seriesInfo name="Internet-Draft"
value="draft-yokota-dmm-scenario-00" />
<format type="TXT" target=
"http://www.ietf.org/internet-drafts/draft-yokota-dmm-scenario-00.txt"/>
</reference>
<reference anchor="I-D.ietf-netext-pd-pmip">
<front>
<title>Prefix Delegation for Proxy Mobile IPv6</title>
<author fullname="Xingyue Zhou" surname="Zhou" initials="X">
<organization/>
</author>
<author fullname="Jouni Korhonen" surname="Korhonen" initials="J">
<organization/>
</author>
<author fullname="Carl Williams" surname="Williams" initials="C">
<organization/>
</author>
<author fullname="Sri Gundavelli" surname="Gundavelli" initials="S">
<organization/>
</author>
<author fullname="Carlos Bernardos" surname="Bernardos" initials="C">
<organization/>
</author>
<date year="2012" day="12" month="March"/>
<abstract>
<t>Proxy Mobile IPv6 enables IP mobility for a host without requiring its participation in any mobility signaling, being the network responsible for managing IP mobility on behalf of the host. However, Proxy Mobile IPv6 does not support assigning a prefix to a router and managing its IP mobility. This document specifies an extension to Proxy Mobile IPv6 protocol for supporting network mobility using DHCPv6-based Prefix Delegation.
</t>
</abstract>
</front>
<seriesInfo value="draft-ietf-netext-pd-pmip-02"
name="Internet-Draft"/>
<format type="TXT"
target="http://www.ietf.org/internet-drafts/draft-ietf-netext-pd-pmip-02.txt"/>
</reference>
<reference anchor="I-D.jikim-dmm-pmip">
<front>
<title>Use of Proxy Mobile IPv6 for
Distributed Mobility Control</title>
<author fullname="Ji Kim" surname="Kim" initials="J" >
<organization />
</author>
<author fullname="Seok Koh" surname="Koh" initials="S" >
<organization />
</author>
<author fullname="Hee Jung" surname="Jung" initials="H" >
<organization />
</author>
<author fullname="Youn-Hee Han" surname="Han" initials="Y" >
<organization />
</author>
<date year="2012" month="March" day="4" />
</front>
<seriesInfo
name="Internet-Draft" value="draft-jikim-dmm-pmip-00" />
<format type="TXT"
target=
"http://www.ietf.org/internet-drafts/draft-jikim-dmm-pmip-00.txt"
/>
</reference>
<reference anchor="Paper-Locating.User">
<front>
<title>Locating the User</title>
<author initials="G" surname="Kirby">
<organization />
</author>
<date year="1995" />
</front>
<seriesInfo name="" value="Communication International" />
</reference>
<reference anchor="Paper-Distributed.Dynamic.Mobility">
<front>
<title>A Distributed Dynamic Mobility Management Scheme
Designed for Flat IP Architectures</title>
<author initials="P" surname="Bertin">
<organization />
</author>
<author initials="S" surname="Bonjour">
<organization />
</author>
<author initials="J-M" surname="Bonnin">
<organization />
</author>
<date year="2008" />
</front>
<seriesInfo name=""
value="Proceedings of 3rd International Conference
on New Technologies, Mobility and Security (NTMS)" />
</reference>
<reference anchor="Paper-Distributed.Centralized.Mobility">
<front>
<title>A Distributed or Centralized Mobility</title>
<author initials="P" surname="Bertin">
<organization />
</author>
<author initials="S" surname="Bonjour">
<organization />
</author>
<author initials="J-M" surname="Bonnin">
<organization />
</author>
<date month="December" year="2009" />
</front>
<seriesInfo name=""
value="Proceedings of Global Communications Conference
(GlobeCom)" />
</reference>
<reference anchor="Paper-Migrating.Home.Agents">
<front>
<title>Migrating Home Agents
Towards Internet-scale Mobility Deployments</title>
<author initials="R" surname="Wakikawa">
<organization />
</author>
<author initials="G" surname="Valadon">
<organization />
</author>
<author initials="J" surname="Murai">
<organization />
</author>
<date month="December" year="2006" />
</front>
<seriesInfo name=""
value="Proceedings of the ACM 2nd CoNEXT Conference
on Future Networking Technologies" />
</reference>
<reference anchor="Paper-Distributed.Mobility.SAE">
<front>
<title>A Distributed IP Mobility Approach for 3G SAE</title>
<author initials="M" surname="Fisher">
<organization />
</author>
<author initials="F.U" surname="Anderson">
<organization />
</author>
<author initials="A" surname="Kopsel">
<organization />
</author>
<author initials="G" surname="Schafer">
<organization />
</author>
<author initials="M" surname="Schlager">
<organization />
</author>
<date year="2008" />
</front>
<seriesInfo name=""
value="Proceedings of the 19th International Symposium
on Personal, Indoor and Mobile Radio Communications (PIMRC)"
/>
</reference>
<reference anchor="Paper-Distributed.Mobility.Review">
<front>
<title>Distributed and Dynamic Mobility Management
in Mobile Internet: Current Approaches and Issues,
Journal of Communications, vol. 6, no. 1, pp. 4-15, Feb 2011.
</title>
<author initials="H" surname="Chan">
<organization />
</author>
<author initials="H" surname="Yokota">
<organization />
</author>
<author initials="J" surname="Xie">
<organization />
</author>
<author initials="P" surname="Seite">
<organization />
</author>
<author initials="D" surname="Liu">
<organization />
</author>
<date month="February" year="2011" />
</front>
<seriesInfo name=""
value="Proceedings of GlobeCom Workshop
on Seamless Wireless Mobility" />
</reference>
<reference anchor="Paper-Distributed.Mobility.PMIP">
<front>
<title>Proxy Mobile IP
with Distributed Mobility Anchors</title>
<author initials="H" surname="Chan">
<organization />
</author>
<date month="December" year="2010" />
</front>
<seriesInfo name=""
value="Proceedings of GlobeCom Workshop
on Seamless Wireless Mobility" />
</reference>
</references>
</back>
</rfc>
| PAFTECH AB 2003-2026 | 2026-04-24 08:37:36 |