draft-ietf-netlmm-nohost-ps-00.txt   draft-ietf-netlmm-nohost-ps-01.txt 
J. Kempf, J. Kempf,Editor
Editor
Internet Draft K. Leung Internet Draft K. Leung
Document: draft-ietf-netlmm-nohost-ps-00.txt P. Roberts Document: draft-ietf-netlmm-nohost-ps-01.txt P. Roberts
K. Nishida K. Nishida
G. Giaretta G. Giaretta
M. Liebsch M. Liebsch
Expires: August, 2006 Feburary, 2006 Expires: October, 2006 April, 2006
Problem Statement for IP Local Mobility Problem Statement for IP Local Mobility
(draft-ietf-netlmm-nohost-ps-00.txt) (draft-ietf-netlmm-nohost-ps-01.txt)
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware have been applicable patent or other IPR claims of which he or she is aware have been
or will be disclosed, and any of which he or she becomes aware will be or will be disclosed, and any of which he or she becomes aware will be
disclosed, in accordance with Section 6 of BCP 79. disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Task Force Internet-Drafts are working documents of the Internet Engineering Task Force
(IETF), its areas, and its working groups. Note that other groups may also (IETF), its areas, and its working groups. Note that other groups may also
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Abstract Abstract
In this document, the well-known problem of localized mobility management In this document, the well-known problem of localized mobility management
for IP link handover is given a fresh look. After a short discussion of the for IP link handover is given a fresh look. After a short discussion of the
problem and a couple of scenarios, the principal shortcomings of existing problem and a couple of scenarios, the principal shortcomings of existing
solutions are discussed. solutions are discussed.
Table of Contents Table of Contents
1.0 Introduction.....................................................2 1.0 Introduction.....................................................2
2.0 The Local Mobility Problem.......................................3 2.0 The Local Mobility Problem.......................................4
3.0 Scenarios for Localized Mobility Management......................6 3.0 Scenarios for Localized Mobility Management......................6
4.0 Most Serious Problems with Existing Solutions....................6 4.0 Problems with Existing Solutions.................................7
5.0 Security Considerations..........................................8 5.0 Security Considerations..........................................9
6.0 Author Information...............................................8 6.0 Author Information...............................................9
7.0 Informative References...........................................9 7.0 Informative References..........................................10
8.0 IPR Statements...................................................9 8.0 IPR Statements..................................................10
9.0 Disclaimer of Validity..........................................10 9.0 Disclaimer of Validity..........................................11
10.0 Copyright Notice................................................10 10.0 Copyright Notice................................................11
1.0 Introduction 1.0 Introduction
Localized mobility management has been the topic of much work in the IETF Localized mobility management has been the topic of much work in the IETF
for some time, and it may seem as if little remains to be said on the topic. for some time, and it may seem as if little remains to be said on the topic.
The experimental protocols developed from previous work, namely FMIPv6 [1] The experimental protocols developed from previous work, namely FMIPv6 [1]
and HMIPv6[2], involve host-based solutions that mimic to a greater or and HMIPv6[2], involve host-based solutions that mimic to a greater or
lesser extent the approach taken by Mobile IPv6 [3] for global mobility lesser extent the approach taken by Mobile IPv6 [3] for global mobility
management. However, recent developments in the IETF and the WLAN management. However, recent developments in the IETF and the WLAN
infrastructure market suggest that it may be time to take a fresh look at infrastructure market suggest that it may be time to take a fresh look at
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Localized Mobility Management Localized Mobility Management
Localized Mobility Management is a generic term for protocols dealing Localized Mobility Management is a generic term for protocols dealing
with IP mobility management confined within the access network. with IP mobility management confined within the access network.
Localized mobility management signaling is not routed outside the Localized mobility management signaling is not routed outside the
access network, although a handover may trigger Global Mobility access network, although a handover may trigger Global Mobility
Management signaling. Localized mobility management protocols exploit Management signaling. Localized mobility management protocols exploit
the locality of movement by confining movement related changes to the the locality of movement by confining movement related changes to the
access network. access network.
Localized Mobility Management Protocol
A protocol that supports localized mobility management.
Global Mobility Protocol Global Mobility Protocol
A Global Mobility Protocol is a mobility protocol used by the mobile A Global Mobility Protocol is a mobility protocol used by the mobile
node to change the global, end-to-end routing of packets when movement node to change the global, end-to-end routing of packets when movement
causes a topology change and thus invalidates a global unicast address causes a topology change and thus invalidates a global unicast address
on the local IP link currently in active use by the mobile node. The on the local IP link currently in active use by the mobile node. The
Global Mobility Protocol allows the mobile node to maintain a mapping Global Mobility Protocol may also allow the mobile node to maintain a
between a permanent rendezvous or home address and a temporary care-of mapping between a permanent address and a temporary address on the
address for rendezvous with nodes that want to initiate a connection, local network for rendezvous with nodes that want to initiate a
and it may also provide direct routing through the rendezvous node connection. Typically, this protocol will be Mobile IPv6 [1] but it
and/or optimized routing directly between correspondent nodes and the
local address. Typically, this protocol will be Mobile IPv6 [1] but it
could also be HIP [4] or Mobike [5] (Note: although Mobike is not could also be HIP [4] or Mobike [5] (Note: although Mobike is not
considered a mobility management protocol in general, for purposes of considered a mobility management protocol in general, for purposes of
this document, it will be so considered because it manages the address this document, it will be so considered because it manages the address
map and routing between a fixed VPN endpoint address and a changing map and routing between a fixed VPN endpoint address and a changing
local address). local address).
Global Mobility Anchor Point Global Mobility Anchor Point
A node in the network where the mobile node has its fixed home address A node in the network where the mobile node maintains a permanent
that maintains the mapping between the home address and care-of address address and a mapping between the permanent address and the local
for purposes of rendezvous and possibly traffic forwarding. For Mobile temporary address where the mobile node happens to be currently
IPv6 [1], this is the home agent. For HIP [4], this is the rendezvous located. The Global Mobility Anchor Point may be used for purposes of
server. For Mobike [5], this is the VPN tunnel gateway in the home rendezvous and possibly traffic forwarding. For Mobile IPv6 [1], this
network. is the home agent. For HIP [4], this may be the rendezvous server. For
Mobike [5], this is the VPN tunnel gateway in the home network.
Intra-Link Mobility Intra-Link Mobility
Intra-Link Mobility is mobility between wireless access points within Intra-Link Mobility is mobility between wireless access points within
an IP Link. Typically, this kind of mobility only involves Layer 2 an IP Link. Typically, this kind of mobility only involves Layer 2
mechanisms, so Intra-Link Mobility is often called Layer 2 mobility. No mechanisms, so Intra-Link Mobility is often called Layer 2 mobility. No
IP link configuration is required upon movement since the link does not IP link configuration is required upon movement since the link does not
change, but some IP signaling may be required for the mobile node to change, but some IP signaling may be required for the mobile node to
confirm whether or not the change of wireless access point also confirm whether or not the change of wireless access point also
resulted in a change of IP link. If the IP link consists of a single resulted in a change of IP link. If the IP link consists of a single
access point/router combination, then this type of mobility is access point/router combination, then this type of mobility is
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an IP Link. Typically, this kind of mobility only involves Layer 2 an IP Link. Typically, this kind of mobility only involves Layer 2
mechanisms, so Intra-Link Mobility is often called Layer 2 mobility. No mechanisms, so Intra-Link Mobility is often called Layer 2 mobility. No
IP link configuration is required upon movement since the link does not IP link configuration is required upon movement since the link does not
change, but some IP signaling may be required for the mobile node to change, but some IP signaling may be required for the mobile node to
confirm whether or not the change of wireless access point also confirm whether or not the change of wireless access point also
resulted in a change of IP link. If the IP link consists of a single resulted in a change of IP link. If the IP link consists of a single
access point/router combination, then this type of mobility is access point/router combination, then this type of mobility is
typically absent. See Figure 1. typically absent. See Figure 1.
2.0 The Local Mobility Problem 2.0 The Local Mobility Problem
The local mobility problem is restricted to providing IP mobility management The local mobility problem is restricted to providing IP mobility management
for mobile nodes within an access network. An access network consists of a for mobile nodes within an access network. The access network aggregation
group of access routers connected to wired or wireless access points on the routers function as an access network gateway, although in this case, there
downlink side and a wired IP core through one or more aggregation routers on is no specialized routing protocol and the routers function as a standard IP
the side that is routed toward the border router and the Internet. The routed network. This is illustrated in Figure 1, where the aggregation
aggregation routers function as an access network gateway, although in this routers are designated as "AggR". Transitions between service providers in
case, there is no specialized routing protocol and the routers function as a separate autonomous systems or across broader topological "boundaries"
standard IP routed network. This is illustrated in Figure 1, where the within the same service provider are excluded.
aggregation routers are designated as "AggR". Transitions between service
providers in separate autonomous systems or across broader topological
"boundaries" within the same service provider are excluded.
Figure 1 depicts the scope of local mobility in comparison to global Figure 1 depicts the scope of local mobility in comparison to global
mobility. The Aggregation Routers AggR A1 and B1 are gateways to the access mobility. The Aggregation Routers AggR A1 and B1 are gateways to the access
network. The Access Routers AR A1 and A2 are in Access Network A, B1 is in network. The Access Routers AR A1 and A2 are in Access Network A, B1 is in
Access Network B. Note that it is possible to have additional aggregation Access Network B. Note that it is possible to have additional aggregation
routers between AggR A1 and AggR B1 and the access routers if the access routers between AggR A1 and AggR B1 and the access routers if the access
network is large. Access Points AP A1 through A3 are in Access Network A, B1 network is large. Access Points AP A1 through A3 are in Access Network A, B1
and B2 are in Access Network B. Other Aggregation Routers, Access Routers, and B2 are in Access Network B. Other Aggregation Routers, Access Routers,
and Access Points are also possible. The figure implies a star topology for and Access Points are also possible. The figure implies a star topology for
the access network deployment, and the star topology is the primary one of the access network deployment, and the star topology is the primary one of
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of the access networks is depends on deployment considerations. Mobility of the access networks is depends on deployment considerations. Mobility
between two access points under the same access router constitutes Intra- between two access points under the same access router constitutes Intra-
link mobility, and is typically handled by Layer 2 mobility protocols (if link mobility, and is typically handled by Layer 2 mobility protocols (if
there is only one access point/cell per access router, then intra-link there is only one access point/cell per access router, then intra-link
mobility may be lacking). Between these two lies local mobility. Local mobility may be lacking). Between these two lies local mobility. Local
mobility occurs when a mobile node moves between two access points connected mobility occurs when a mobile node moves between two access points connected
to two different access routers. to two different access routers.
Global mobility protocols allow a mobile node to maintain reachability when Global mobility protocols allow a mobile node to maintain reachability when
a change between access routers occurs, by updating the address mapping a change between access routers occurs, by updating the address mapping
between the home address and care-of address at the global mobility anchor between the permanent address and temporary local address at the global
point, or even end to end by changing the care-of address directly at the mobility anchor point, or even end to end by changing the temporary local
correspondent node. A global mobility management protocol can therefore be address directly at the node with which the mobile node is corresponding. A
used between access routers for handling local mobility. However, there are global mobility management protocol can therefore be used between access
three well-known problems involved in using a global mobility protocols for routers for handling local mobility. However, there are three well-known
every transition between access routers. Briefly, they are: problems involved in using a global mobility protocols for every transition
between access routers. Briefly, they are:
1) Update latency. If the global mobility anchor point and/or 1) Update latency. If the global mobility anchor point and/or
correspondent node (for route optimized traffic) is at some distance correspondent node (for route optimized traffic) is at some distance
from the mobile node's access network, the global mobility update may from the mobile node's access network, the global mobility update may
require a considerable amount of time, during which time packets require a considerable amount of time, during which time packets
continue to be routed to the old care-of address and are essentially continue to be routed to the old temporary local address and are
dropped. essentially dropped.
2) Signaling overhead. The amount of signaling required when a mobile 2) Signaling overhead. The amount of signaling required when a mobile
node moves from one IP link to another can be quite extensive, node moves from one IP link to another can be quite extensive,
including all the signaling required to configure an IP address on the including all the signaling required to configure an IP address on the
new link and global mobility protocol signaling back into the network new link and global mobility protocol signaling back into the network
for changing the home to care-of address mapping. The signaling volume for changing the permanent to temporary local address mapping. The
may negatively impact wireless bandwidth usage and real time service signaling volume may negatively impact wireless bandwidth usage and
performance. real time service performance.
3) Location privacy. The change in care-of address as the mobile node 3) Location privacy. The change in temporary local address as the mobile
moves exposes the mobile node's topological location to correspondents node moves exposes the mobile node's topological location to
and potentially to eavesdroppers. An attacker that can assemble a correspondents and potentially to eavesdroppers. An attacker that can
mapping between subnet prefixes in the mobile node's access network assemble a mapping between subnet prefixes in the mobile node's access
and geographical locations can determine exactly where the mobile node network and geographical locations can determine exactly where the
is located. This can expose the mobile node's user to threats on their mobile node is located. This can expose the mobile node's user to
location privacy. threats on their location privacy.
These problems suggest that a protocol to localize the management of These problems suggest that a protocol to localize the management of
topologically small movements is preferable to using a global mobility topologically small movements is preferable to using a global mobility
management protocol on each IP link move. In addition to these problems, management protocol on each IP link move. In addition to these problems,
localized mobility management can provide a measure of local control, so localized mobility management can provide a measure of local control, so
mobility management can be tuned for specialized local conditions. Note also mobility management can be tuned for specialized local conditions. Note also
that if localized mobility management is provided, it is not strictly that if localized mobility management is provided, it is not strictly
required for a mobile node to support a global mobility management protocol required for a mobile node to support a global mobility management protocol
since movement within a restricted IP access network can still be since movement within a restricted IP access network can still be
accommodated. Without such support, however, a mobile node experiences a accommodated. Without such support, however, a mobile node experiences a
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UWB and Bluetooth, are designed for low power, short range operation. For UWB and Bluetooth, are designed for low power, short range operation. For
such protocols, extremely small picocells become more practical. Although such protocols, extremely small picocells become more practical. Although
picocells do not necessarily imply "pico IP links", wireless sensors and picocells do not necessarily imply "pico IP links", wireless sensors and
other advanced applications may end up making such picocellular type other advanced applications may end up making such picocellular type
networks node-dense, requiring subnets that cover small geographical areas, networks node-dense, requiring subnets that cover small geographical areas,
such as a single room. The ability to aggregate many subnets under a such as a single room. The ability to aggregate many subnets under a
localized mobility management scheme can help reduce the amount of IP localized mobility management scheme can help reduce the amount of IP
signaling required on IP link movement. signaling required on IP link movement.
4.0 Problems with Existing Solutions 4.0 Problems with Existing Solutions
Existing solutions for localized mobility management fall into three Existing solutions for localized mobility management fall into three
classes: classes:
1) Interoperable IP level protocols that require changes to the mobile node's 1) Interoperable IP level protocols that require changes to the mobile node's
IP stack and handle localized mobility management as a service provided to IP stack and handle localized mobility management as a service provided to
the host by the access network, the mobile node by the access network,
2) Link specific or proprietary protocols that handle localized mobility for 2) Link specific or proprietary protocols that handle localized mobility for
any mobile node but only for a specific type of link layer, namely 802.11 any mobile node but only for a specific type of link layer, namely 802.11
running on an 802.3 wired network backhaul. running on an 802.3 wired network backhaul.
3) Use of a standard IGP such as OSPF or IS-IS to distribute host routes, and 3) Use of a standard IGP such as OSPF or IS-IS to distribute host routes, and
updating the host routes when the mobile node moves. updating the host routes when the mobile node moves.
For Solution 1, the following are specific problems: For Solution 1, the following are specific problems:
1) The host stack software requirement limits broad usage even if the 1) The host stack software requirement limits broad usage even if the
modifications are small. The success of WLAN switches indicates that modifications are small. The success of WLAN switches indicates that
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packets to drop. Since IGPs typically propagate routing updates through packets to drop. Since IGPs typically propagate routing updates through
flooding, the delay in host route propagation also limits the topological flooding, the delay in host route propagation also limits the topological
span of the localized mobility management domain. span of the localized mobility management domain.
3) Rapid movement by the mobile node faster than the rate at which flooding 3) Rapid movement by the mobile node faster than the rate at which flooding
can propagate host routes could lead to a cascading series of host route can propagate host routes could lead to a cascading series of host route
messages that never stabilize. messages that never stabilize.
Having an interoperable, standardized localized mobility management protocol Having an interoperable, standardized localized mobility management protocol
that is scalable to topologically large networks, but requires no host stack that is scalable to topologically large networks, but requires no host stack
involvement for localized mobility management is a highly desirable involvement for localized mobility management is a highly desirable
solution. solution. Mobility routing anchor points within the backbone network
maintain a collection of routes for individual mobile nodes. The routes
point to the access routers on which mobile nodes currently are located.
Packets for the mobile node are routed to and from the mobile node through
the mobility anchor point. When a mobile node moves from one access router
to another, the access routers send a route update to the mobility anchor
point. While some mobile node involvement is necessary and expected for
generic mobility functions such as movement detection and to inform the
access router about mobile node movement, no specific mobile node to network
protocol will be required for localized mobility management itself.
The advantages that this solution has over the Solutions 1 through 3 above
are as follows:
1) Compared with Solution 1, a network-based solution requires no localized
mobility management support on the mobile node and is independent of
global mobility management protocol, so it can be used with any or none
of the existing global mobility management protocols. The result is a
more modular mobility management architecture that better accommodates
changing technology and market requirements.
2) Compared with Solution 2, an IP level network-based localized mobility
management solution works for link protocols other than Ethernet, and for
wide area networks.
3) Compared with Solution 3, the framework described above for network-based
localized mobility management only requires the involvement of the access
routers and the mobility anchor. All other routers within the localized
mobility management domain do not need to handle host routes, making the
architecture more scalable. In addition, because updating the routes
requires communication between only two routers, propagation of routes on
handover is likely to be much faster.
5.0 Security Considerations 5.0 Security Considerations
Localized mobility management has certain security considerations, one of Localized mobility management has certain security considerations, one of
which - need for access network to mobile node security - was touched on in which - need for access network to mobile node security - was touched on in
this document. Existing localized mobility management solutions increase the this document. Existing localized mobility management solutions increase the
need for mobile node to access network signaling and provisioning of the need for mobile node to access network signaling and provisioning of the
mobile node with credentials without increasing the security beyond what is mobile node with credentials without increasing the security beyond what is
available if no localized mobility management solution is used. A more available if no localized mobility management solution is used. A more
complete discussion of the security requirements for localized mobility complete discussion of the security requirements for localized mobility
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TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT
LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT
INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS INFRINGE ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE. FOR A PARTICULAR PURPOSE.
10.0 Copyright Notice 10.0 Copyright Notice
Copyright (C) The Internet Society (2006). This document is subject to the Copyright (C) The Internet Society (2006). This document is subject to the
rights, licenses and restrictions contained in BCP 78, and except as set rights, licenses and restrictions contained in BCP 78, and except as set
forth therein, the authors retain all their rights. forth therein, the authors retain all their rights.
11.0 Changes in 01 (remove before publication)
- Added "revised" to those definitions in Section 1.1 that are revised
from RFC 3753.
- Changed "mobile host" to "mobile node" where the wireless device was
meant, to avoid confusion about whether mobile routers are supported.
- Added discussion in Section 4 of problems involving using a standard
IGP for host route distribution.
 End of changes. 18 change blocks. 
55 lines changed or deleted 85 lines changed or added

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