draft-ietf-dmm-requirements-01.txt   draft-ietf-dmm-requirements-02.txt 
Network Working Group H. Chan (Ed.) Network Working Group H. Chan (Ed.)
Internet-Draft Huawei Technologies Internet-Draft Huawei Technologies
Intended status: Informational July 12, 2012 Intended status: Informational September 7, 2012
Expires: January 13, 2013 Expires: March 11, 2013
Requirements of distributed mobility management Requirements for Distributed Mobility Management
draft-ietf-dmm-requirements-01 draft-ietf-dmm-requirements-02
Abstract Abstract
The traditional hierarchical structure of cellular networks has led This document defines the requirements for Distributed Mobility
to deployment models which are heavily centralized. Mobility Management (DMM) in IPv6 deployments. The traditionally hierarchical
management with centralized mobility anchoring in existing structure of cellular networks has led to deployment models which are
hierarchical mobile networks is quite prone to suboptimal routing and in practice centralized. Mobility management with logically
issues related to scalability. Centralized functions present a centralized mobility anchoring in current mobile networks is prone to
single point of failure, and inevitably introduce longer delays and suboptimal routing and raises scalability issues. Such centralized
higher signaling loads for network operations related to mobility functions can lead to single points of failure and inevitably
management. This document defines the requirements for distributed introduce longer delays and higher signaling loads for network
mobility management for IPv6 deployment. The objectives are to match operations related to mobility management. The objective is to
the mobility deployment with the current trend in network evolution, enhance mobility management in order to meet the primary goals in
to improve scalability, to avoid single point of failure, to enable network evolution, i.e., improve scalability, avoid single points of
transparency to upper layers only when needed, etc. The distributed failure, enable transparent mobility support to upper layers only
mobility management also needs to be compatible with existing network when needed, and so on. Distributed mobility management must be
deployments and end hosts, and be secured. secure and compatible with existing network deployments and end
hosts.
Status of this Memo Status of this Memo
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This Internet-Draft will expire on January 13, 2013. This Internet-Draft will expire on March 11, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2012 IETF Trust and the persons identified as the
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Conventions used in this document . . . . . . . . . . . . . . 5 2. Conventions used in this document . . . . . . . . . . . . . . 5
2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5 2.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 5
3. Centralized versus distributed mobility management . . . . . . 5 3. Centralized versus distributed mobility management . . . . . . 5
3.1. Centralized mobility management . . . . . . . . . . . . . 6 3.1. Centralized mobility management . . . . . . . . . . . . . 6
3.2. Distributed mobility management . . . . . . . . . . . . . 6 3.2. Distributed mobility management . . . . . . . . . . . . . 7
4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 8 4. Requirements . . . . . . . . . . . . . . . . . . . . . . . . . 7
4.1. Distributed deployment . . . . . . . . . . . . . . . . . . 8 4.1. Distributed deployment . . . . . . . . . . . . . . . . . . 8
4.2. Transparency to Upper Layers when needed . . . . . . . . . 9 4.2. Transparency to Upper Layers when needed . . . . . . . . . 9
4.3. IPv6 deployment . . . . . . . . . . . . . . . . . . . . . 10 4.3. IPv6 deployment . . . . . . . . . . . . . . . . . . . . . 10
4.4. Compatibility . . . . . . . . . . . . . . . . . . . . . . 10 4.4. Existing mobility protocols . . . . . . . . . . . . . . . 10
4.5. Existing mobility protocols . . . . . . . . . . . . . . . 11 4.5. Compatibility . . . . . . . . . . . . . . . . . . . . . . 10
4.6. Security considerations . . . . . . . . . . . . . . . . . 11 4.6. Security considerations . . . . . . . . . . . . . . . . . 11
5. Security Considerations . . . . . . . . . . . . . . . . . . . 12 5. Security Considerations . . . . . . . . . . . . . . . . . . . 11
6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12 6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7. Co-authors and Contributors . . . . . . . . . . . . . . . . . 12 7. Co-authors and Contributors . . . . . . . . . . . . . . . . . 12
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 13 8.1. Normative References . . . . . . . . . . . . . . . . . . . 13
8.2. Informative References . . . . . . . . . . . . . . . . . . 13 8.2. Informative References . . . . . . . . . . . . . . . . . . 13
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
In the past decade a fair number of mobility protocols have been In the past decade a fair number of mobility protocols have been
standardized. Although the protocols differ in terms of functions standardized [RFC6275] [RFC5944] [RFC5380] [RFC6301] [RFC5213].
and associated message format, we can identify a few key common Although the protocols differ in terms of functions and associated
features: message formats, we can identify a few key common features:
presence of a centralized mobility anchor providing global a centralized mobility anchor providing global reachability and an
reachability and an always-on experience; always-on experience to the user;
extensions to optimize handover performance while users roam extensions to the base protocols to optimize handover performance
across wireless cells; while users roam across wireless cells; and
extensions to enable the use of heterogeneous wireless interfaces extensions to enable the use of heterogeneous wireless interfaces
for multi-mode terminals (e.g. cellular phones). for multi-mode terminals (e.g. smartphones).
The presence of the centralized mobility anchor allows a mobile The presence of the centralized mobility anchor allows a mobile node
device to be reachable when it is not connected to its home domain. to remain reachable when it is not connected to its home domain. The
The anchor point, among other tasks, ensures reachability of anchor point, among other tasks, ensures connectivity by forwarding
forwarding of packets destined to or sent from the mobile device. packets destined to, or sent from, the mobile node. In practice,
Most of the deployed architectures today have a small number of most of the deployed architectures today have a small number of
centralized anchors managing the traffic of millions of mobile centralized anchors managing the traffic of millions of mobile nodes.
subscribers. Compared with a distributed approach, a centralized Compared with a distributed approach, a centralized approach is
approach is likely to have several issues or limitations affecting likely to have several issues or limitations affecting performance
performance and scalability, which require costly network and scalability, which require costly network dimensioning and
dimensioning and engineering to resolve. engineering to resolve.
To optimize handovers from the perspective of mobile nodes, the base To optimize handovers from the perspective of mobile nodes, the base
protocols have been extended to efficiently handle packet forwarding protocols have been extended to efficiently handle packet forwarding
between the previous and new points of attachment. These extensions between the previous and new points of attachment. These extensions
are necessary when applications impose stringent requirements in are necessary when applications have stringent requirements in terms
terms of delay. Notions of localization and distribution of local of delay. Notions of localization and distribution of local agents
agents have been introduced to reduce signaling overhead. have been introduced to reduce signaling overhead [Paper-
Unfortunately today we witness difficulties in getting such protocols Distributed.Centralized.Mobility]. Unfortunately, today we witness
deployed, often leading to sub-optimal choices. difficulties in getting such protocols deployed, resulting in sub-
optimal choices for the network operators.
Moreover, the availability of multi-mode devices and the possibility Moreover, the availability of multi-mode devices and the possibility
of using several network interfaces simultaneously have motivated the of using several network interfaces simultaneously have motivated the
development of more new protocol extensions. Deployment is further development of even more protocol extensions to add more capabilities
complicated with so many extensions. to the base protocol. In the end, deployment is further complicated
with the multitude of extensions.
Mobile users are, more than ever, consuming Internet content; such Mobile users are, more than ever, consuming Internet content; such
traffic imposes new requirements on mobile core networks for data traffic imposes new requirements on mobile core networks for data
traffic delivery. When the traffic demand exceeds available traffic delivery. When the traffic demand exceeds available
capacity, service providers need to implement new strategies such as capacity, service providers need to implement new strategies such as
selective traffic offload (e.g. 3GPP work items LIPA/SIPTO) through selective traffic offload (e.g. 3GPP work items LIPA/SIPTO
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.
When demand exceeds capacity, both offloading and CDN techniques [TS.23829]) through alternative access networks (e.g. WLAN) [Paper-
could benefit from the development of mobile architectures with fewer Mobile.Data.Offloading]. Moreover, the presence of content providers
levels of routing hierarchy introduced into the data path by the closer to the mobile/fixed Internet Service Providers network
mobility management system. This trend in network flattening is requires taking into account local Content Delivery Networks (CDNs)
reinforced by a shift in users traffic behavior, aimed at increasing while providing mobility services.
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.
While deploying [Paper-Locating.User] today's mobile networks, When demand exceeds capacity, both traffic offloading and CDN
service providers face new challenges. More often than not, mobile mechanisms could benefit from the development of mobile architectures
devices remain attached to the same point of attachment. Specific IP with fewer levels of routing hierarchy introduced into the data path
mobility management support is not required for applications that by the mobility management system. This trend towards so-called
launch and complete while the mobile device is connected to the same "flat networks" is reinforced by a shift in user traffic behavior.
point of attachment. However, the mobility support has been designed In particular, there is an increase in direct communications among
to be always on and to maintain the context for each mobile peers in the same geographical area. Distributed mobility management
subscriber as long as they are connected to the network. This can in a truly flat mobile architecture would anchor the traffic closer
result in a waste of resources and ever-increasing costs for the to the point of attachment of the user, overcoming the suboptimal
service provider. Infrequent mobility and intelligence of many route stretch of a centralized mobility scheme.
applications suggest that mobility can be provided dynamically, thus
simplifying the context maintained in the different nodes of the While deploying today's mobile networks, service providers face new
mobile network. challenges. Mobility patterns indicate that, more often than not,
mobile nodes remain attached to the same point of attachment for
considerable periods of time [Paper-Locating.User] . Therefore it is
not uncommon to observe that specific IP mobility management support
is not required for applications that launch and complete their
sessions while the mobile node is connected to the same point of
attachment. However, currently, IP mobility support is designed for
always-on operation, maintaining all parameters of the context for
each mobile subscriber for 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 node mobility coupled
with application intelligence suggest that mobility can be provided
selectively, thus simplifying the context maintained in the different
nodes of the mobile network.
The DMM charter addresses two complementary aspects of mobility The DMM charter addresses two complementary aspects of mobility
management procedures: the distribution of mobility anchors to management procedures: the distribution of mobility anchors towards a
achieve a more flat design and the dynamic activation/deactivation of more flat network and the dynamic activation/deactivation of mobility
mobility protocol support as an enabler to distributed mobility protocol support as an enabler to distributed mobility management.
management. The former has the goal of positioning mobility anchors The former aims at positioning mobility anchors (HA, LMA) closer to
(HA, LMA) closer to the user; ideally, these mobility agents could be the user; ideally, mobility agents could be collocated with the
collocated with the first hop router. The latter, facilitated by the first-hop router. The latter, facilitated by the distribution of
distribution of mobility anchors, aims at identifying when mobility mobility anchors, aims at identifying when mobility support must be
must be activated and identifying sessions that do not impose activated and identifying sessions that do not require mobility
mobility management -- thus reducing the amount of state information management support -- thus reducing the amount of state information
to be maintained in the various mobility agents of the mobile that must be maintained in various mobility agents of the mobile
network. The key idea is that dynamic mobility management relaxes network. The key idea is that dynamic mobility management relaxes
some constraints so that it may avoid the establishment of non- some of the constraints of previously-standardized mobility
optimal tunnels between two topologically distant anchors. management solutions and, by doing so, it can avoid the establishment
of non-optimal tunnels between two topologically distant anchors.
This document describes the motivations of distributed mobility Given this motivational background in this section, this document
management in Section 1. Section 3 compares distributed mobility compares distributed mobility management with centralized mobility
management with centralized mobility management. The requirements to management in Section 3. The requirements to address these problems
address these problems are given in Section 4. are given in Section 4. Finally, security considerations are
discussed in Section 5.
The problem statement and the use cases [I-D.yokota-dmm-scenario] can The problem statement and the use cases [I-D.yokota-dmm-scenario] can
be found in the following review paper: [Paper- be found in [Paper-Distributed.Mobility.Review].
Distributed.Mobility.Review].
2. Conventions used in this document 2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL","SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in [RFC2119]. document are to be interpreted as described in [RFC2119].
2.1. Terminology 2.1. Terminology
All the general mobility-related terms and their acronyms used in All the general mobility-related terms and their acronyms used in
this document are to be interpreted as defined in the Mobile IPv6 this document are to be interpreted as defined in the Mobile IPv6
base specification [RFC6275], in the Proxy mobile IPv6 specification base specification [RFC6275], in the Proxy mobile IPv6 specification
[RFC5213], and in Mobility Related Terminology [RFC3753]. These [RFC5213], and in Mobility Related Terminology [RFC3753]. These
terms include mobile node (MN), correspondent node (CN), home agent terms include the following: mobile node (MN), correspondent node
(HA), local mobility anchor (LMA), mobile access gateway (MAG), and (CN), and home agent (HA) as per [RFC6275]; local mobility anchor
context. (LMA) and mobile access gateway (MAG) as per [RFC5213], and context
as per [RFC3753].
In addition, this draft introduces the following term. In addition, this draft introduces the following term.
Mobility context Mobility context
is the collection of information required to provide mobility is the collection of information required to provide mobility
support for a given mobile node. management support for a given mobile node.
3. Centralized versus distributed mobility management 3. Centralized versus distributed mobility management
Mobility management functions may be implemented at different layers Mobility management functions may be implemented at different layers
of the network protocol stack. At the IP (network) layer, they may of the protocol stack. At the IP (network) layer, they may reside in
reside in the network or in the mobile node. In particular, a the network or in the mobile node. In particular, a network-based
network-based solution resides in the network only. It therefore solution resides in the network only. It therefore enables mobility
enables mobility for existing hosts and network applications which for existing hosts and network applications which are already in
are already in deployment but lack mobility support. deployment but lack mobility support.
At the IP layer, a mobility management protocol to achieve session At the IP layer, a mobility management protocol supporting session
continuity is typically based on the principle of distinguishing continuity is typically based on the principle of distinguishing
between identifier and routing address and maintaining a mapping between identifier and routing address and maintaining a mapping
between them. With Mobile IP, the home address serves as an between the two. In Mobile IP, the home address serves as an
identifier of the device whereas the care-of-address takes the role identifier of the device whereas the care-of-address (CoA) takes the
of routing address, and the binding between them is maintained at the role of the routing address. The binding between these two is
mobility anchor, i.e., the home agent. If packets can be maintained at the home agent (mobility anchor). If packets can be
continuously delivered to a mobile device at its home address, then continuously delivered to a mobile node at its home address, then all
all sessions using that home address can be preserved even though the sessions using that home address are unaffected even though the
routing or care-of address changes. routing address (CoA) changes.
The next two subsections explain centralized and distributed mobility The next two subsections explain centralized and distributed mobility
management functions in the network. management functions in the network.
3.1. Centralized mobility management 3.1. Centralized mobility management
With centralized mobility management, the mapping information between In centralized mobility management, the mapping information between
the stable node identifier and the changing IP address of a mobile the persistent node identifier and the changing IP address of a
node (MN) is kept at a centralized mobility anchor. Packets destined mobile node (MN) is kept at a single mobility anchor. At the same
to an MN are routed via this anchor. In other words, such mobility time, packets destined to the MN are routed via this anchor. In
management systems are centralized in both the control plane and the other words, such mobility management systems are centralized in both
data plane. the control plane and the data plane.
Many existing mobility management deployments make use of centralized Many existing mobility management deployments make use of centralized
mobility anchoring in a hierarchical network architecture, as shown mobility anchoring in a hierarchical network architecture, as shown
in Figure 1. Examples of such centralized mobility anchors are the in Figure 1. Examples of such centralized mobility anchors are the
home agent (HA) and local mobility anchor (LMA) in Mobile IPv6 home agent (HA) and local mobility anchor (LMA) in Mobile IPv6
[RFC6275] and Proxy Mobile IPv6 [RFC5213], respectively. Current [RFC6275] and Proxy Mobile IPv6 [RFC5213], respectively. Current
mobile networks such as the Third Generation Partnership Project cellular networks such as the Third Generation Partnership Project
(3GPP) UMTS networks, CDMA networks, and 3GPP Evolved Packet System (3GPP) UMTS networks, CDMA networks, and 3GPP Evolved Packet System
(EPS) networks also employ centralized mobility management, with (EPS) networks employ centralized mobility management too. In
Gateway GPRS Support Node (GGSN) and Serving GPRS Support Node (SGSN) particular, Gateway GPRS Support Node (GGSN) and Serving GPRS Support
in the 3GPP UMTS hierarchical network and with Packet data network Node (SGSN) in the 3GPP UMTS hierarchical network, and the Packet
Gateway (P-GW) and Serving Gateway (S-GW) in the 3GPP EPS network. data network Gateway (P-GW) and Serving Gateway (S-GW) in the 3GPP
EPS network, respectively, act as anchors in a hierarchy.
UMTS 3GPP SAE MIP/PMIP UMTS 3GPP SAE MIP/PMIP
+------+ +------+ +------+ +------+ +------+ +------+
| GGSN | | P-GW | |HA/LMA| | GGSN | | P-GW | |HA/LMA|
+------+ +------+ +------+ +------+ +------+ +------+
/\ /\ /\ /\ /\ /\
/ \ / \ / \ / \ / \ / \
/ \ / \ / \ / \ / \ / \
/ \ / \ / \ / \ / \ / \
/ \ / \ / \ / \ / \ / \
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| SGSN | | SGSN | | S-GW | | S-GW | |MN/MAG| |MN/MAG| | SGSN | | SGSN | | S-GW | | S-GW | |MN/MAG| |MN/MAG|
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
Figure 1. Centralized mobility management. Figure 1. Centralized mobility management.
3.2. Distributed mobility management 3.2. Distributed mobility management
Mobility management functions may also be distributed to multiple Mobility management functions may also be distributed to multiple
locations in different networks as shown in Figure 2, so that a networks as shown in Figure 2, so that a mobile node in any of these
mobile node in any of these networks may be served by a closeby networks may be served by a closeby mobility function (MF).
mobility function (MF).
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| MF | | MF | | MF | | MF | | MF | | MF | | MF | | MF |
+------+ +------+ +------+ +------+ +------+ +------+ +------+ +------+
| |
---- ----
| MN | | MN |
---- ----
Figure 2. Distributed mobility management. Figure 2. Distributed mobility management.
Mobility management may be partially distributed, i.e., only the data Mobility management may be partially or fully distributed. In the
plane is distributed, or fully distributed where both the data plane former case only the data plane is distributed. Fully distributed
and control plane are distributed. These different approaches are mobility management implies that both the data plane and the control
described in detail in [I-D.yokota-dmm-scenario]. plane are distributed. These different approaches are described in
detail in [I-D.yokota-dmm-scenario].
[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 grouped, as an initial
way to consider a better distribution: location and handover
management, control and data plane, user and access perspective.
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].
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.
In [Paper-Migrating.Home.Agents], the HA functionality is copied to A distributed mobility management scheme for future flat IP-based
many locations. The HoA of all MNs are anycast addresses, so that a mobile network architecture consisting of access nodes is proposed in
packet destined to the HoA from any corresponding node (CN) from any [Paper-Distributed.Dynamic.Mobility]. Its benefits over centralized
network can be routed via the nearest copy of the HA. In addition, mobility management are shown through simulations in [Paper-
[Paper-Distributed.Mobility.SAE] proposes to distribute the function Distributed.Centralized.Mobility]. Moreover, the (re)use and
of HA into many mobility agents (MAs) each serving a portion of MNs extension of existing protocols in the design of both fully
using a distributed hash table structure. A lookup to the hash table distributed mobility management [Paper-Migrating.Home.Agents] [Paper-
will point to the MA serving an MN. In [Paper- Distributed.Mobility.SAE] and partially distributed mobility
Distributed.Mobility.PMIP] and [Paper-Distributed.Mobility.MIP], only management [Paper-Distributed.Mobility.PMIP] [Paper-
the mobility routing (MR) function is duplicated and distributed in Distributed.Mobility.MIP] have been reported in the literature.
many locations. The location information for any MN that has moved Therefore, before designing new mobility management protocols for a
to a visited network is still centralized and kept at a location future flat IP architecture, it is recommended to first consider
management (LM) function in the home network of the MN. The LM whether existing mobility management protocols can be extended to
function at different networks constitutes a distributed database serve a flat IP architecture.
system of all the MNs that belong to any of these networks and have
moved to a visited network.
4. Requirements 4. Requirements
After comparing distributed mobility management against centralized After comparing distributed mobility management against centralized
deployment in Section 3, this section states the requirements as deployment in Section 3, this section states the requirements as
follows: follows:
4.1. Distributed deployment 4.1. Distributed deployment
REQ1: Distributed deployment REQ1: Distributed deployment
IP mobility, network access and routing solutions provided by IP mobility, network access and routing solutions provided by
DMM MUST enable a distributed deployment of mobility DMM MUST enable distributed deployment for mobility management
management of IP sessions so that the traffic can be routed in of IP sessions so that traffic does not need to traverse
an optimal manner without traversing centrally deployed centrally deployed mobility anchors and thus can be routed in
mobility anchors. an optimal manner.
Motivation: The motivations of this requirement are to match Motivation: This requirement is motivated by current trends in
mobility deployment with current trend in network evolution: network evolution: (a) it is cost- and resource-effective to
more cost and resource effective to cache and distribute cache and distribute content by combining distributed mobility
contents when combining distributed anchors with caching anchors with caching systems (e.g., CDN); (b) the
systems (e.g., CDN); improve scalability; avoid single point significantly larger number of mobile nodes and flows call for
of failure; mitigate threats being focused on a centrally improved scalability; (c) single points of failure are avoided
deployed anchor, e.g., home agent and local mobility anchor. in a distributed system; (d) threats against centrally
deployed anchors, e.g., home agent and local mobility anchor,
are mitigated in a distributed system.
This requirement addresses the following problems PS1, PS2, PS3, and This requirement addresses problems PS1, PS2, PS3, and PS4 in the
PS4. following.
PS1: Non-optimal routes PS1: Non-optimal routes
Routing via a centralized anchor often results in a longer Routing via a centralized anchor often results in a longer
route, and the problem is especially manifested when accessing route. The problem is especially manifested when accessing a
a local or cache server of a Content Delivery Network (CDN). local server or servers of a Content Delivery Network (CDN).
PS2: Non-optimality in Evolved Network Architecture PS2: Divergence from other evolutionary trends in network
architecture
The centralized mobility management can become non-optimal as a Centralized mobility management can become non-optimal with a
network architecture evolves and becomes more flattened. flat network architecture.
PS3: Low scalability of centralized route and mobility context PS3: Low scalability of centralized route and mobility context
maintenance maintenance
Setting up such special routes and maintaining the mobility Setting up routes through a central anchor and maintaining
context for each MN is more difficult to scale in a centralized mobility context for each MN therein requires more resources is
design with a large number of MNs. Distributing the route more difficult to scale in a centralized design, thus reducing
maintenance function and the mobility context maintenance scalability. Distributing the route maintenance function and
function among different networks can be more scalable. the mobility context maintenance function among different
network entities can increase scalability.
PS4: Single point of failure and attack PS4: Single point of failure and attack
Centralized anchoring may be more vulnerable to single point of Centralized anchoring may be more vulnerable to single points
failure and attack than a distributed system. of failures and attacks than a distributed system. The impact
of a successful attack on a system with centralized mobility
management can be far greater as well.
4.2. Transparency to Upper Layers when needed 4.2. Transparency to Upper Layers when needed
REQ2: Transparency to Upper Layers when needed REQ2: Transparency to Upper Layers when needed
The DMM solutions MUST provide transparency above the IP layer DMM solutions MUST provide transparent mobility support above
when needed. Such transparency is needed, when the mobile the IP layer when needed. Such transparency is needed, for
hosts or entire mobile networks [RFC3963] change their point example, when, upon change of point of attachment to the
of attachment to the Internet, for the application flows that Internet, an application flow cannot cope with a change in the
cannot cope with a change of IP address. Otherwise the IP address. Otherwise, support for maintaining a stable home
support to maintain a stable home IP address or prefix during IP address or prefix during handovers may be declined.
handover may be declined.
Motivation: The motivation of this requirement is to enable Motivation: The motivation of this requirement is to enable
more efficient use of network resources and more efficient more efficient use of network resources and more efficient
routing by not maintaining a stable home IP address when there routing by not maintaining context at the mobility anchor when
is no such need. there is no such need.
This requirement addresses the problems PS5 as well as the other This requirement addresses the problems PS5 as well as the other
related problem O-PS1. related problem O-PS1.
PS5: Wasting resources to support mobile nodes not needing mobility PS5: Wasting resources to provide mobility support to nodes that do
support not need such support
IP mobility support is not always required. For example, some IP mobility support is not always required, and not every
applications do not need a stable IP address during handover, parameter of mobility context is always used. For example,
i.e., IP session continuity. Sometimes, the entire application some applications do not need a stable IP address during a
session runs while the terminal does not change the point of handover to maintain IP session continuity. Sometimes, the
attachment. In these situations that do not require IP entire application session runs while the terminal does not
mobility support, network resources are wasted when mobility change the point of attachment.
context is set up.
O-PS1: Mobility signaling overhead with peer-to-peer communication O-PS1: Mobility signaling overhead with peer-to-peer communication
Wasting resources when mobility signaling (e.g., maintenance Wasting resources when mobility signaling (e.g., maintenance
of the tunnel, keep alive, etc.) is not turned off for peer- of the tunnel, keep alive, etc.) is not turned off for peer-
to-peer communication. to-peer communication. Peer-to-peer communications have
particular traffic patterns that often do not benefit from
mobility support from the network. Thus, the assoicated
mobility support signaling (e.g., maintenance of the tunnel,
keep alives, etc.) wastes network resources for no
application gain. In such a case, it is better to enable
mobility support selectively.
4.3. IPv6 deployment 4.3. IPv6 deployment
REQ3: IPv6 deployment REQ3: IPv6 deployment
The DMM solutions SHOULD target IPv6 as primary deployment and DMM solutions SHOULD target IPv6 as the primary deployment
SHOULD NOT be tailored specifically to support IPv4, in environment and SHOULD NOT be tailored specifically to support
particular in situations where private IPv4 addresses and/or IPv4, in particular in situations where private IPv4 addresses
NATs are used. and/or NATs are used.
Motivation: The motivation for this requirement is to be Motivation: This requirement is to be inline with the general
inline with the general orientation of IETF. Moreover, DMM orientation of IETF work. DMM deployment is foreseen in mid-
deployment is foreseen in mid-term/long-term, hopefully in an to long-term horizon, when IPv6 is expected to be far more
IPv6 world. It is also unnecessarily complex to solve this common than today. It is also unnecessarily complex to solve
problem for IPv4, as we will not be able to use some of the this problem for IPv4, as we will not be able to use some of
IPv6-specific features/tools. the IPv6-specific features/tools.
4.4. Compatibility 4.4. Existing mobility protocols
REQ4: Compatibility REQ4: Existing mobility protocols
The DMM solution SHOULD be able to work between trusted A DMM solution SHOULD first consider reusing and extending
administrative domains when allowed by the security measures IETF-standardized protocols before specifying new protocols.
deployed between these domains. Furthermore, the DMM solution
MUST be able to co-exist with existing network deployment and
end hosts so that the existing deployment can continue to be
supported. 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.
Motivation: The motivation of this requirement is to allow Motivation: Using IETF protocols is easier to deploy and to
inter-domain operation if desired and to preserve backwards update.
compatibility so that the existing networks and hosts are not
affected and do not break.
This requirement addresses the following other related problem O-PS2. 4.5. Compatibility
O-PS2: Complicated deployment with too many variants and extensions REQ5: Compatibility
of MIP
Deployment is complicated with many variants and extensions The DMM solution MUST be able to co-exist with existing
of MIP. When introducing new functions which may add to the network deployments and end hosts. For example, depending on
complexity, existing solutions are more vulnerable to break. the environment in which DMM is deployed, DMM solutions may
need to be compatible with other deployed mobility protocols
or may need to interoperate with a network or mobile hosts/
routers that do not support DMM protocols. Furthermore, a DMM
solution SHOULD work across different networks, possibly
operated as separate administrative domains, when allowed by
the trust relationship between them.
4.5. Existing mobility protocols Motivation: The motivations of this requirement are (1) to
preserve backwards compatibility so that existing networks and
hosts are not affected and continue to function as usual, and
(2) enable inter-domain operation if desired.
REQ5: Existing mobility protocols This requirement addresses the following related problem O-PS2.
A DMM solution SHOULD first consider reusing and extending the O-PS2: Complicated deployment with too many MIP variants and
existing mobility protocols before specifying new protocols. extensions
Motivation: The purpose is to reuse the existing protocols Deployment is complicated with many variants and extensions
first before considering new protocols. of MIP. When introducing new functions which may add to the
complexity, existing solutions are more vulnerable to break.
4.6. Security considerations 4.6. Security considerations
REQ6: Security considerations REQ6: Security considerations
The protocol solutions for DMM MUST consider security, for DMM protocol solutions MUST consider security aspects,
example authentication and authorization mechanisms that allow including confidentiality and integrity. Examples of aspects
a legitimate mobile host/router to access to the DMM service, to be considered are authentication and authorization
protection of signaling messages of the protocol solutions in mechanisms that allow a legitimate mobile host/router to use
terms of authentication, data integrity, and data the mobility support provided by the DMM solution; signaling
confidentiality, opt-in or opt-out data confidentiality to message protection in terms of authentication, encryption,
signaling messages depending on network environments or user etc.; data integrity and confidentiality; opt-in or opt-out
requirements. data confidentiality to signaling messages depending on
network environments or user requirements.
Motivation and problem statement: Mutual authentication and Motivation: Mutual authentication and authorization between a
authorization between a mobile host/router and an access mobile host/router and an access router providing the DMM
router providing the DMM service to the mobile host/router are service to the mobile host/router are required to prevent
required to prevent potential attacks in the access network of potential attacks in the access network of the DMM service.
the DMM service. Otherwise, various attacks such as Various attacks such as impersonation, denial of service, man-
impersonation, denial of service, man-in-the-middle attacks, in-the-middle attacks, and so on, can be mounted against a DMM
etc. are present to obtain illegitimate access or to collapse service and need to be protected against.
the DMM service.
Signaling messages are subject to various attacks since these Signaling messages can be subject to various attacks since
messages carry context of a mobile host/router. For instance, they carry critical context information about a mobile node/
a malicious node can forge and send a number of signaling router. For instance, a malicious node can forge a number of
messages to redirect traffic to a specific node. signaling messages thus redirecting traffic from its
Consequently, the specific node is under a denial of service legitimate path. Consequently, the specific node is under a
attack, whereas other nodes are not receiving their traffic. denial of service attack, whereas other nodes do not receive
As signaling messages travel over the Internet, the end-to-end their traffic. As signaling messages may travel over the
security is required. Internet, end-to-end security could be required.
5. Security Considerations 5. Security Considerations
Distributed mobility management (DMM) requires two kinds of security Distributed mobility management (DMM) requires two kinds of security
considerations: 1) access network security that only allows a considerations: First, access network security that only allows a
legitimate mobile host/router to access the DMM service; 2) end-to- legitimate mobile host/router to access the DMM service; Second, end-
end security that protects signaling messages for the DMM service. to-end security that protects signaling messages for the DMM service.
Access network security is required between the mobile host/router Access network security is required between the mobile host/router
and the access network providing the DMM service. End-to-end and the access network providing the DMM service. End-to-end
security is required between nodes that participate in the DMM security is required between nodes that participate in the DMM
protocol. protocol.
It is necessary to provide sufficient defense against possible It is necessary to provide sufficient defense against possible
security attacks, or to adopt existing security mechanisms and security attacks, or to adopt existing security mechanisms and
protocols to provide sufficient security protections. For instance, protocols to provide sufficient security protections. For instance,
EAP based authentication can be used for access network security, EAP-based authentication can be used for access network security,
while IPsec can be used for end-to-end security. while IPsec can be used for end-to-end security.
6. IANA Considerations 6. IANA Considerations
None None
7. Co-authors and Contributors 7. Co-authors and Contributors
This problem statement document is a joint effort among the following This problem statement document is a joint effort among the following
participants. Each individual has made significant contributions to participants. Each individual has made significant contributions to
skipping to change at page 12, line 46 skipping to change at page 12, line 36
Hidetoshi Yokota: yokota@kddilabs.jp Hidetoshi Yokota: yokota@kddilabs.jp
Charles E. Perkins: charliep@computer.org Charles E. Perkins: charliep@computer.org
Melia Telemaco: telemaco.melia@alcatel-lucent.com Melia Telemaco: telemaco.melia@alcatel-lucent.com
Elena Demaria: elena.demaria@telecomitalia.it Elena Demaria: elena.demaria@telecomitalia.it
Peter McCann: Peter.McCann@huawei.com Peter McCann: Peter.McCann@huawei.com
Kostas Pentikousis: k.pentikousis@huawei.com
Tricci So: tso@zteusa.com Tricci So: tso@zteusa.com
Jong-Hyouk Lee: jh.lee@telecom-bretagne.eu Jong-Hyouk Lee: jh.lee@telecom-bretagne.eu
Jouni Korhonen: jouni.korhonen@nsn.com Jouni Korhonen: jouni.korhonen@nsn.com
Sri Gundavelli: sgundave@cisco.com Sri Gundavelli: sgundave@cisco.com
Carlos J. Bernardos: cjbc@it.uc3m.es Carlos J. Bernardos: cjbc@it.uc3m.es
Marco Liebsch: Marco.Liebsch@neclab.eu Marco Liebsch: Marco.Liebsch@neclab.eu
Wen Luo: luo.wen@zte.com.cn Wen Luo: luo.wen@zte.com.cn
Georgios Karagiannis: g.karagiannis@utwente.nl Georgios Karagiannis: g.karagiannis@utwente.nl
Julien Laganier: jlaganier@juniper.net Julien Laganier: jlaganier@juniper.net
Wassim Michel Haddad: Wassam.Haddad@ericsson.com Wassim Michel Haddad: Wassam.Haddad@ericsson.com
Alexandru Petrescu: alexandru.petrescu@gmail.com
Seok Joo Koh: sjkoh@knu.ac.kr Seok Joo Koh: sjkoh@knu.ac.kr
Dirk von Hugo: Dirk.von-Hugo@telekom.de Dirk von Hugo: Dirk.von-Hugo@telekom.de
Ahmad Muhanna: amuhanna@awardsolutions.com Ahmad Muhanna: amuhanna@awardsolutions.com
8. References 8. References
8.1. Normative References 8.1. Normative References
skipping to change at page 14, line 46 skipping to change at page 14, line 42
[Paper-Locating.User] [Paper-Locating.User]
Kirby, G., "Locating the User", Communication Kirby, G., "Locating the User", Communication
International, 1995. International, 1995.
[Paper-Migrating.Home.Agents] [Paper-Migrating.Home.Agents]
Wakikawa, R., Valadon, G., and J. Murai, "Migrating Home Wakikawa, R., Valadon, G., and J. Murai, "Migrating Home
Agents Towards Internet-scale Mobility Deployments", Agents Towards Internet-scale Mobility Deployments",
Proceedings of the ACM 2nd CoNEXT Conference on Future Proceedings of the ACM 2nd CoNEXT Conference on Future
Networking Technologies, December 2006. Networking Technologies, December 2006.
[Paper-Mobile.Data.Offloading]
Lee, K., Lee, J., Yi, Y., Rhee, I., and S. Chong, "Mobile
Data Offloading: How Much Can WiFi Deliver?", SIGCOMM
2010, 2010.
[RFC3753] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol", Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, January 2005. RFC 3963, January 2005.
[RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K., [RFC5213] Gundavelli, S., Leung, K., Devarapalli, V., Chowdhury, K.,
and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008. and B. Patil, "Proxy Mobile IPv6", RFC 5213, August 2008.
[RFC5380] Soliman, H., Castelluccia, C., ElMalki, K., and L.
Bellier, "Hierarchical Mobile IPv6 (HMIPv6) Mobility
Management", RFC 5380, October 2008.
[RFC5944] Perkins, C., "IP Mobility Support for IPv4, Revised",
RFC 5944, November 2010.
[RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support [RFC6275] Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", RFC 6275, July 2011. in IPv6", RFC 6275, July 2011.
[RFC6301] Zhu, Z., Wakikawa, R., and L. Zhang, "A Survey of Mobility
Support in the Internet", RFC 6301, July 2011.
[TS.23829]
3GPP, "Local IP Access and Selected IP Traffic Offload
(LIPA-SIPTO)", 3GPP TR 23.829 10.0.1, October 2011.
Author's Address Author's Address
H Anthony Chan (editor) H Anthony Chan (editor)
Huawei Technologies Huawei Technologies
5340 Legacy Dr. Building 3, Plano, TX 75024, USA 5340 Legacy Dr. Building 3, Plano, TX 75024, USA
Email: h.a.chan@ieee.org Email: h.a.chan@ieee.org
- -
Dapeng Liu Dapeng Liu
China Mobile China Mobile
Unit2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China Unit2, 28 Xuanwumenxi Ave, Xuanwu District, Beijing 100053, China
skipping to change at page 15, line 30 skipping to change at page 15, line 48
Pierrick Seite Pierrick Seite
France Telecom - Orange France Telecom - Orange
4, rue du Clos Courtel, BP 91226, Cesson-Sevigne 35512, France 4, rue du Clos Courtel, BP 91226, Cesson-Sevigne 35512, France
Email: pierrick.seite@orange-ftgroup.com Email: pierrick.seite@orange-ftgroup.com
- -
Hidetoshi Yokota Hidetoshi Yokota
KDDI Lab KDDI Lab
2-1-15 Ohara, Fujimino, Saitama, 356-8502 Japan 2-1-15 Ohara, Fujimino, Saitama, 356-8502 Japan
Email: yokota@kddilabs.jp Email: yokota@kddilabs.jp
- -
Charles E. Perkins
Huawei Technologies
Email: charliep@computer.org
-
Jouni Korhonen Jouni Korhonen
Nokia Siemens Networks Nokia Siemens Networks
Email: jouni.korhonen@nsn.com Email: jouni.korhonen@nsn.com
- -
Charles E. Perkins
Huawei Technologies
Email: charliep@computer.org
-
Melia Telemaco Melia Telemaco
Alcatel-Lucent Bell Labs Alcatel-Lucent Bell Labs
Email: telemaco.melia@alcatel-lucent.com Email: telemaco.melia@alcatel-lucent.com
- -
Elena Demaria Elena Demaria
Telecom Italia Telecom Italia
via G. Reiss Romoli, 274, TORINO, 10148, Italy via G. Reiss Romoli, 274, TORINO, 10148, Italy
Email: elena.demaria@telecomitalia.it Email: elena.demaria@telecomitalia.it
- -
Jong-Hyouk Lee Jong-Hyouk Lee
RSM Department, Telecom Bretagne RSM Department, Telecom Bretagne
Cesson-Sevigne, 35512, France Cesson-Sevigne, 35512, France
Email: jh.lee@telecom-bretagne.eu Email: jh.lee@telecom-bretagne.eu
- -
Kostas Pentikousis
Huawei Technologies
Carnotstr. 4 10587 Berlin, Germany
Email: k.pentikousis@huawei.com
-
Tricci So Tricci So
ZTE ZTE
Email: tso@zteusa.com Email: tso@zteusa.com
- -
Carlos J. Bernardos Carlos J. Bernardos
Universidad Carlos III de Madrid Universidad Carlos III de Madrid
Av. Universidad, 30, Leganes, Madrid 28911, Spain Av. Universidad, 30, Leganes, Madrid 28911, Spain
Email: cjbc@it.uc3m.es Email: cjbc@it.uc3m.es
- -
Peter McCann Peter McCann
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