draft-ietf-nemo-ro-space-analysis-01.txt   draft-ietf-nemo-ro-space-analysis-02.txt 
NEMO Working Group C. Ng NEMO Working Group C. Ng
Internet-Draft Panasonic Singapore Labs Internet-Draft Panasonic Singapore Labs
Expires: April 27, 2006 F. Zhao Expires: August 14, 2006 F. Zhao
UC Davis UC Davis
M. Watari M. Watari
KDDI R&D Labs KDDI R&D Labs
P. Thubert P. Thubert
Cisco Systems Cisco Systems
October 24, 2005 February 10, 2006
Network Mobility Route Optimization Solution Space Analysis Network Mobility Route Optimization Solution Space Analysis
draft-ietf-nemo-ro-space-analysis-01 draft-ietf-nemo-ro-space-analysis-02
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2006).
Abstract Abstract
With current Network Mobility (NEMO) Basic Support, all With current Network Mobility (NEMO) Basic Support, all
communications to and from Mobile Network Nodes must go through the communications to and from Mobile Network Nodes must go through the
MRHA tunnel when the mobile network is away. This results in MRHA tunnel when the mobile network is away. This results in
increased length of packet route and increased packet delay in most increased length of packet route and increased packet delay in most
cases. To overcome these limitations, one might have to turn to cases. To overcome these limitations, one might have to turn to
Route Optimization (RO) for NEMO. This memo documents various types Route Optimization (RO) for NEMO. This memo documents various types
of Route Optimization in NEMO, and explores the benefits and of Route Optimization in NEMO, and explores the benefits and
tradeoffs in different aspects of NEMO Route Optimization. tradeoffs in different aspects of NEMO Route Optimization.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Benefits of NEMO Route Optimization . . . . . . . . . . . . . 5 2. Benefits of NEMO Route Optimization . . . . . . . . . . . . . 5
3. Different Scenarios of NEMO Route Optimization . . . . . . . . 7 3. Different Scenarios of NEMO Route Optimization . . . . . . . . 7
3.1. Basic NEMO Route Optimization . . . . . . . . . . . . . . 7 3.1. Non-Nested NEMO Route Optimization . . . . . . . . . . . . 7
3.2. Nested Mobility Optimization . . . . . . . . . . . . . . . 9 3.2. Nested Mobility Optimization . . . . . . . . . . . . . . . 9
3.2.1. Decreasing the Number of Home Agents on the Path . . . 9 3.2.1. Decreasing the Number of Home Agents on the Path . . . 9
3.2.2. Decreasing the Number of Tunnels . . . . . . . . . . . 9 3.2.2. Decreasing the Number of Tunnels . . . . . . . . . . . 10
3.3. Infrastructure based Optimization . . . . . . . . . . . . 10 3.3. Infrastructure based Optimization . . . . . . . . . . . . 10
3.4. Intra-NEMO Optimization . . . . . . . . . . . . . . . . . 10 3.4. Intra-NEMO Optimization . . . . . . . . . . . . . . . . . 11
4. Issues of NEMO Route Optimization . . . . . . . . . . . . . . 12 4. Issues of NEMO Route Optimization . . . . . . . . . . . . . . 13
4.1. Additional Signaling Overhead . . . . . . . . . . . . . . 12 4.1. Additional Signaling Overhead . . . . . . . . . . . . . . 13
4.2. Increased Protocol Complexity and Processing Load . . . . 12 4.2. Increased Protocol Complexity and Processing Load . . . . 14
4.3. Increased Delay during Handoff . . . . . . . . . . . . . . 13 4.3. Increased Delay during Handoff . . . . . . . . . . . . . . 14
4.4. New Functionalities . . . . . . . . . . . . . . . . . . . 13 4.4. Extending Nodes with New Functionalities . . . . . . . . . 14
4.5. Detection of New Functionalities . . . . . . . . . . . . . 14 4.5. Detection of New Functionalities . . . . . . . . . . . . . 16
4.6. Scalability . . . . . . . . . . . . . . . . . . . . . . . 15 4.6. Scalability . . . . . . . . . . . . . . . . . . . . . . . 16
4.7. Mobility Transparency and Location Privacy . . . . . . . . 15 4.7. Mobility Transparency . . . . . . . . . . . . . . . . . . 16
4.8. Security Consideration . . . . . . . . . . . . . . . . . . 15 4.8. Location Privacy . . . . . . . . . . . . . . . . . . . . . 16
4.9. Support of Legacy Nodes . . . . . . . . . . . . . . . . . 16 4.9. Security Consideration . . . . . . . . . . . . . . . . . . 17
5. Analysis of Solution Space . . . . . . . . . . . . . . . . . . 17 4.10. Support of Legacy Nodes . . . . . . . . . . . . . . . . . 17
5.1. Which Entities are Involved? . . . . . . . . . . . . . . . 17 5. Analysis of Solution Space . . . . . . . . . . . . . . . . . . 18
5.1.1. Mobile Network Node and Correspondent Node . . . . . . 17 5.1. Which Entities are Involved? . . . . . . . . . . . . . . . 18
5.1.2. Mobile Router and Correspondent Node . . . . . . . . . 18 5.1.1. Mobile Network Node and Correspondent Node . . . . . . 18
5.1.3. Mobile Router and Correspondent Router . . . . . . . . 18 5.1.2. Mobile Router and Correspondent Node . . . . . . . . . 19
5.1.4. Entities in the Infrastructure . . . . . . . . . . . . 19 5.1.3. Mobile Router and Correspondent Router . . . . . . . . 19
5.2. Who and When to Initiate Route Optimization? . . . . . . . 19 5.1.4. Entities in the Infrastructure . . . . . . . . . . . . 20
5.3. How to Detect Route Optimization Capability? . . . . . . . 20 5.2. Who and When to Initiate Route Optimization? . . . . . . . 20
5.4. How is Address of Mobile Network Node Represented? . . . . 21 5.3. How to Detect Route Optimization Capability? . . . . . . . 21
5.5. How is Mobile Network Node's Address Bound to Location? . 21 5.4. How is the Address of Mobile Network Node Represented? . . 22
5.5.1. Binding to the Location of Parent Mobile Router . . . 22 5.5. How is Mobile Network Node's Address Bound to Location? . 22
5.5.1. Binding to the Location of Parent Mobile Router . . . 23
5.5.2. Binding to a Sequence of Locations of Upstream 5.5.2. Binding to a Sequence of Locations of Upstream
Mobile Routers . . . . . . . . . . . . . . . . . . . . 24 Mobile Routers . . . . . . . . . . . . . . . . . . . . 25
5.5.3. Binding to the Location of Root Mobile Router . . . . 25 5.5.3. Binding to the Location of Root Mobile Router . . . . 26
5.6. How is Signaling Performed? . . . . . . . . . . . . . . . 27 5.6. How is Signaling Performed? . . . . . . . . . . . . . . . 28
5.7. How is Data Transmitted? . . . . . . . . . . . . . . . . . 28 5.7. How is Data Transmitted? . . . . . . . . . . . . . . . . . 29
5.8. What are the Security Considerations? . . . . . . . . . . 29 5.8. What are the Security Considerations? . . . . . . . . . . 30
5.8.1. Security Considerations of Address Binding . . . . . . 29 5.8.1. Security Considerations of Address Binding . . . . . . 30
5.8.2. End-to-End Integrity . . . . . . . . . . . . . . . . . 31 5.8.2. End-to-End Integrity . . . . . . . . . . . . . . . . . 32
5.8.3. Location Privacy . . . . . . . . . . . . . . . . . . . 31 5.8.3. Location Privacy . . . . . . . . . . . . . . . . . . . 32
6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 33 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 34
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34
8. Security Considerations . . . . . . . . . . . . . . . . . . . 33 8. Security Considerations . . . . . . . . . . . . . . . . . . . 34
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 34 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35
10.1. Normative References . . . . . . . . . . . . . . . . . . . 34 10.1. Normative References . . . . . . . . . . . . . . . . . . . 35
10.2. Informative References . . . . . . . . . . . . . . . . . . 34 10.2. Informative References . . . . . . . . . . . . . . . . . . 35
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 38 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42
Intellectual Property and Copyright Statements . . . . . . . . . . 40 Intellectual Property and Copyright Statements . . . . . . . . . . 43
1. Introduction 1. Introduction
Network Mobility Route Optimization Problem Statement [1] describes Network Mobility Route Optimization Problem Statement [1] describes
operational limitations and overheads incurred in a deployment of operational limitations and overheads incurred in a deployment of
Network Mobility (NEMO) Basic Support [2], which could be alleviated Network Mobility (NEMO) Basic Support [2], which could be alleviated
by a set of NEMO Route Optimization techniques to be defined. For by a set of NEMO Route Optimization techniques to be defined. For
this purpose of NEMO, the term "Route Optimization" is accepted in a this purpose of NEMO, the term "Route Optimization" is accepted in a
broader sense than already defined for IPv6 Host Mobility in [3], to broader sense than already defined for IPv6 Host Mobility in [3], to
loosely refer to any approach that optimizes the transmission of loosely refer to any approach that optimizes the transmission of
packets between a Mobile Network Node and a Correspondent Node. packets between a Mobile Network Node and a Correspondent Node.
Solutions that would fit that general description were continuously Solutions that would fit that general description were continuously
proposed since the early days of NEMO, even before the Working Group proposed since the early days of NEMO, even before the Working Group
was formed. Based on that long standing stream of innovation, this was formed. Based on that long standing stream of innovation, this
document classifies, at a generic level, the solution space of the document classifies, at a generic level, the solution space of the
possible approaches that could be taken to solve the Route possible approaches that could be taken to solve the Route
Optimization related problems for NEMO. Optimization related problems for NEMO. The scope of the solutions,
the benefits, and the impacts to the existing implementations and
The scope of the solutions, the benefits, and the impacts to the deployments are analyzed. This work should serve as a foundation for
existing implementations and deployments are analyzed. This work the NEMO WG to decide where to focus its Route Optimization effort,
should serve as a foundation for the NEMO WG to decide where to focus with a deeper understanding of the relative strength and weaknesses
its Route Optimization effort, with a deeper understanding of the of each approach.
relative strength and weaknesses of each approach.
It is expected for readers to be familiar with general terminologies It should be beneficial for readers to keep in mind the design
related to mobility in [3] and [4], and NEMO related terms defined in requirements of NEMO [4]. A point to note is that since this
[5]. In addition, it is beneficial to keep in mind the design document discusses aspects of Route Optimization, the reader may
requirements of NEMO [6]. A point to note is that since this
document discusses aspects of Route Optimization, the readers may
assume that a mobile network or a mobile host is away when they are assume that a mobile network or a mobile host is away when they are
mentioned throughout this document, unless it is explicitly specified mentioned throughout this document, unless it is explicitly specified
that they are at home. that they are at home.
1.1. Terminology 1.1. Terminology
It is expected for readers to be familiar with terminologies related
to mobility in [3] and [5], and NEMO related terms defined in [6].
In addition, the following Route Optimization specific terms are used
in this document:
Correspondent Router (CR) Correspondent Router (CR)
This refers to the entity which is capable of terminating a Route This refers to the router which is capable of terminating a Route
Optimization session on behalf of a Correspondent Node. Optimization session on behalf of a Correspondent Node.
Correspondent Entity (CE) Correspondent Entity (CE)
This refers to the entity which a Mobile Router or Mobile Network This refers to the entity which a Mobile Router or Mobile Network
Node attempts to establish a Route Optimization session with. Node attempts to establish a Route Optimization session with.
Depending on the Route Optimization approach, the Correspondent Depending on the Route Optimization approach, the Correspondent
Entity maybe a Correspondent Node or Correspondent Router. Entity maybe a Correspondent Node or Correspondent Router.
2. Benefits of NEMO Route Optimization 2. Benefits of NEMO Route Optimization
To address the problems discussed in [1], one can incorporate Route NEMO Route Optimization addresses the problems discussed in [1].
Optimization into NEMO. Although a standardized NEMO Route Although a standardized NEMO Route Optimization solution has yet to
Optimization solution has yet to materialize, one can expect it to materialize, one can expect it to show some of the following
show some of the following benefits: benefits:
o Shorter Delay o Shorter Delay
Route Optimization involves the selection and utilization of a Route Optimization involves the selection and utilization of a
lesser cost (thus generally shorter and faster) route to be taken lesser cost (thus generally shorter and faster) route to be taken
for traffic between a Mobile Network Node and its Correspondent for traffic between a Mobile Network Node and its Correspondent
Node. Hence, Route Optimization should improve the latency of the Node. Hence, Route Optimization should improve the latency of the
data traffic between the two end nodes. This may possibly in turn data traffic between the two end nodes. This may possibly in turn
lead to better overall Quality of Service characteristics, such as lead to better overall Quality of Service characteristics, such as
reduced jitter and packet loss. reduced jitter and packet loss.
skipping to change at page 6, line 12 skipping to change at page 6, line 12
efficiency from the viewpoints of buffering and transport efficiency from the viewpoints of buffering and transport
protocols. protocols.
o Reduced Processing Delay o Reduced Processing Delay
In a nested mobile network, the application of Route Optimization In a nested mobile network, the application of Route Optimization
may eliminate the need of multiple encapsulations required by NEMO may eliminate the need of multiple encapsulations required by NEMO
Basic Support, which may result in less processing delay at the Basic Support, which may result in less processing delay at the
points of encapsulation and decapsulation. points of encapsulation and decapsulation.
o Avoiding the Bottleneck in Home Network o Avoiding Bottleneck in the Home Network
NEMO Route Optimization allows traffic to by-pass the Home Agents. NEMO Route Optimization allows traffic to by-pass the Home Agents.
Apart from having a more direct route, this also avoids routing Apart from having a more direct route, this also avoids routing
traffic via the home network, which may be a potential bottleneck traffic via the home network, which may be a potential bottleneck
otherwise. otherwise.
o Avoid the Security Policy Issue o Avoid the Security Policy Issue
Security policy may forbid Mobile Routers from tunneling traffic Security policy may forbid a Mobile Router from tunneling traffic
of Visiting Mobile Nodes into the home network of Mobile Router. of Visiting Mobile Nodes into the home network of the Mobile
Route Optimization can be used to avoid this issue by forwarding Router. Route Optimization can be used to avoid this issue by
traffic from Visiting Mobile Nodes directly to their destination forwarding traffic from Visiting Mobile Nodes directly to their
without going through the home network of the Mobile Router. destinations without going through the home network of the Mobile
Router.
It should however be taken into consideration that a Route It should however be taken into consideration that a Route
Optimization mechanism may not be an appropriate solution since Optimization mechanism may not be an appropriate solution since
the Mobile Router may still be held responsible for illegal the Mobile Router may still be held responsible for illegal
traffic sent from its Mobile Network Nodes even when Route traffic sent from its Mobile Network Nodes even when Route
Optimization is used. In addition, there can be a variety of Optimization is used. In addition, there can be a variety of
different policies which might cause a conflict with the different policies which might conflict with the deployment of
deployment of Route Optimization for Visiting Mobile Nodes. Being Route Optimization for Visiting Mobile Nodes. Being a policy
a policy issue, solving this with a protocol at the policy plane issue, solving this with a protocol at the policy plane might be
might be more appropriate. more appropriate.
o Avoid the Instability and Stalemate o Avoid the Instability and Stalemate
[1] described a potential stalemate situation when a Home Agent is [1] described a potential stalemate situation when a Home Agent is
nested within a Mobile Network. Route Optimization may circumvent nested within a Mobile Network. Route Optimization may circumvent
such stalemate situations by directly forwarding traffic upstream. such stalemate situations by directly forwarding traffic upstream.
However, it should be noted that certain Route Optimization However, it should be noted that certain Route Optimization
schemes may require signaling packets to be first routed via the schemes may require signaling packets to be first routed via the
Home Agent before an optimized route can be established. In such Home Agent before an optimized route can be established. In such
cases, a Route Optimization solution cannot avoid the stalemate. cases, a Route Optimization solution cannot avoid the stalemate.
3. Different Scenarios of NEMO Route Optimization 3. Different Scenarios of NEMO Route Optimization
There are multiple proposals for providing various forms of Route There are multiple proposals for providing various forms of Route
Optimization in the NEMO context. In the following sub-sections, we Optimization in the NEMO context. In the following sub-sections, we
describe the different scenarios which would require a Route describe the different scenarios which would require a Route
Optimization mechanism and list the potential solutions which have Optimization mechanism and list the potential solutions which have
been proposed in that area. been proposed in that area.
3.1. Basic NEMO Route Optimization 3.1. Non-Nested NEMO Route Optimization
We start off with a scenario where nesting of Mobile Routers is not
considered, and Route Optimization is initiated and performed between
a Mobile Router and its peer Mobile Router, also known as a
Correspondent Router. Such solutions are often posed with a
requirement to leave the Mobile Network Nodes untouched, as with the
NEMO Basic Support protocol, and therefore Mobile Routers handle the
optimization management on behalf of the Mobile Network Nodes. Thus,
providing Route Optimization for Visiting Mobile Node is often out of
scope for such scenario because such interaction would require
extensions to the Mobile IPv6 protocol. This scenario is illustrated
in Figure 1.
HAofCR ********************************** HAofMR
#*# #*#
#*# #*# +---------------------+
#*# #*# | LEGEND |
#*# #*# +---------------------+
#*# ############### #*# | #: Tunnel |
CR ooooooooooooooo MR | *: NEMO Basic route |
| ############### | | o: Optimized route |
MNN2 MNN1 +---------------------+
Figure 1: MR-CR Optimization
This form of optimization can carry traffic for both directions
identically:
o MNN1 to/from MNN2
The Mobile Router locates the Correspondent Router, establishes a
tunnel with that Correspondent Router and sets up a route to the
Mobile Network Node via the Correspondent Router over the tunnel.
Traffic to the Mobile Networks Nodes would no longer flow through
the Home Agents.
From the definition of Correspondent Router, it does not limit itself The Non-Nested NEMO Route Optimization involves a Mobile Router
to be mobile, but can also be an entity within the fixed sending binding information to a Correspondent Entity. It does not
infrastructure with similar functionalities. As long as the involve nesting of Mobile Routers nor Visiting Mobile Nodes. The
Correspondent Router is located "closer" to the Correspondent Node Correspondent Entity can be a Correspondent Node or a Correspondent
than the Home Agent of the Mobile Router, the route between Mobile Router. The interesting case is when the Correspondent Entity is a
Network Node and the Correspondent Node can be said to be optimized. Correspondent Router. With the use of Correspondent Router, Route
For this purpose, Correspondent Routers may be deployed to provide an Optimization session is terminated at the Correspondent Router on
optimal route as illustrated in Figure 2. behalf of the Correspondent Node. As long as the Correspondent
Router is located "closer" to the Correspondent Node than the Home
Agent of the Mobile Router, the route between Mobile Network Node and
the Correspondent Node can be said to be optimized. For this
purpose, Correspondent Routers may be deployed to provide an optimal
route as illustrated in Figure 1.
************************** HAofMR ************************** HAofMR
* #*# * #*#
* #*# +---------------------+ * #*# +---------------------+
CN #*# | LEGEND | CN #*# | LEGEND |
o #*# +---------------------+ o #*# +---------------------+
o ############### #*# | #: Tunnel | o ############### #*# | #: Tunnel |
CR ooooooooooooooo MR | *: NEMO Basic route | CR ooooooooooooooo MR | *: NEMO Basic route |
############### | | o: Optimized route | ############### | | o: Optimized route |
MNN +---------------------+ MNN +---------------------+
Figure 2: MR-CR Optimization Figure 1: MR-CR Optimization
This form of optimization can carry traffic both directions identical This form of optimization can carry traffic in both directions or
to the previous example in Figure 1, or independently for the 2 independently for the 2 directions of traffic:
directions of traffic:
o From MNN to CN o From MNN to CN
The Mobile Router locates the Correspondent Router, establishes a The Mobile Router locates the Correspondent Router, establishes a
tunnel with that Correspondent Router and sets up a route to the tunnel with that Correspondent Router and sets up a route to the
Correspondent Node via the Correspondent Router over the tunnel. Correspondent Node via the Correspondent Router over the tunnel.
Traffic to the Correspondent Node would no longer flow through the Traffic to the Correspondent Node would no longer flow through the
Home Agent anymore. Home Agent anymore.
o From CN to MNN o From CN to MNN
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Entity. This can be viewed as a logical extension to NEMO Basic Entity. This can be viewed as a logical extension to NEMO Basic
Support, where the Mobile Router would send binding updates Support, where the Mobile Router would send binding updates
containing one or more Mobile Network Prefix options to the containing one or more Mobile Network Prefix options to the
Correspondent Entity. The Correspondent Entity having received the Correspondent Entity. The Correspondent Entity having received the
binding update, can then set up a bi-directional tunnel with the binding update, can then set up a bi-directional tunnel with the
Mobile Router at the current care-of address of the Mobile Router, Mobile Router at the current care-of address of the Mobile Router,
and inject a route to its routing table so that packets destined for and inject a route to its routing table so that packets destined for
addresses in the mobile network prefix will be routed through the bi- addresses in the mobile network prefix will be routed through the bi-
directional tunnel. directional tunnel.
Examples of this approach include Optimized Route Cache (ORC) [7] and The definition of Correspondent Router does not limit it to be a
Path Control Header (PCH) [8]. fixed router. Here we consider the case where the Correspondent
Router is a Mobile Router. Thus Route Optimization is initiated and
performed between a Mobile Router and its peer Mobile Router. Such
solutions are often posed with a requirement to leave the Mobile
Network Nodes untouched, as with the NEMO Basic Support protocol, and
therefore Mobile Routers handle the optimization management on behalf
of the Mobile Network Nodes. Thus, providing Route Optimization for
Visiting Mobile Node is often out of scope for such scenario because
such interaction would require extensions to the Mobile IPv6
protocol. This scenario is illustrated in Figure 2.
HAofCR ********************************** HAofMR
#*# #*#
#*# #*# +---------------------+
#*# #*# | LEGEND |
#*# #*# +---------------------+
#*# ############### #*# | #: Tunnel |
CR ooooooooooooooo MR | *: NEMO Basic route |
| ############### | | o: Optimized route |
MNN2 MNN1 +---------------------+
Figure 2: MR-CR Optimization
This form of optimization can carry traffic for both directions
identically:
o MNN1 to/from MNN2
The Mobile Router locates the Correspondent Router, establishes a
tunnel with that Correspondent Router and sets up a route to the
Mobile Network Node via the Correspondent Router over the tunnel.
Traffic to the Mobile Networks Nodes would no longer flow through
the Home Agents.
Examples of this approach include Optimized Route Cache (ORC) [7][8]
and Path Control Header (PCH) [9].
3.2. Nested Mobility Optimization 3.2. Nested Mobility Optimization
Optimization in Nested Mobility targets scenarios where a nesting of Optimization in Nested Mobility targets scenarios where a nesting of
mobility management protocols is created (i.e. Mobile IPv6 enabled mobility management protocols is created (i.e. Mobile IPv6 enabled
host inside a mobile network or multiple Mobile Routers that attach host inside a mobile network or multiple Mobile Routers that attach
behind one another creating a nested mobile network). Note that behind one another creating a nested mobile network). Note that
because Mobile IPv6 defines its own Route Optimization mechanism in because Mobile IPv6 defines its own Route Optimization mechanism in
its base protocol suite as a standard, collaboration with this and its base protocol suite as a standard, collaboration between this and
NEMO brings various complexity. NEMO protocols brings various complexities.
There are two main aspects in providing optimization for Nested There are two main aspects in providing optimization for Nested
Mobility and they are discussed in the following sub-sections. Mobility and they are discussed in the following sub-sections.
3.2.1. Decreasing the Number of Home Agents on the Path 3.2.1. Decreasing the Number of Home Agents on the Path
The aim is to remove the sub-optimality of paths caused by multiple The aim is to remove the sub-optimality of paths caused by multiple
tunnels established between multiple Mobile Nodes and their Home tunnels established between multiple Mobile Nodes and their Home
Agents. Such a solution will seek to minimize the number of Home Agents. Such a solution will seek to minimize the number of Home
Agents along the path, possibly by bypassing some of the Home Agents along the path, by bypassing some of the Home Agent(s) from
Agent(s) from the original path. Unlike the scenario where no the original path. Unlike the scenario where no nesting is formed
nesting is formed and only a single Home Agent exists along the path, and only a single Home Agent exists along the path, bypassing one of
bypassing one of the many Home Agents can still be effective. the many Home Agents can still be effective.
Solutions for Nested Mobility scenarios can usually be divided into Solutions for Nested Mobility scenarios can usually be divided into
two cases based on whether the nesting involves Mobile IPv6 hosts or two cases based on whether the nesting involves Mobile IPv6 hosts or
only involves Mobile Routers. Since Mobile IPv6 defines its own only involves Mobile Routers. Since Mobile IPv6 defines its own
Route Optimization mechanism, providing optimal path for such hosts Route Optimization mechanism, providing optimal path for such hosts
will require interaction with the protocol and may require an will require interaction with the protocol and may require an
altering of the messages exchanged during the Return Routability altering of the messages exchanged during the Return Routability
procedure with the Correspondent Node. procedure with the Correspondent Node.
Example of this approach include Reverse Routing Header (RRH) [9]. Example of this approach include Reverse Routing Header (RRH) [10].
3.2.2. Decreasing the Number of Tunnels 3.2.2. Decreasing the Number of Tunnels
The aim is to reduce the amplification effect of nested tunnels due The aim is to reduce the amplification effect of nested tunnels due
to the nesting of tunnels between the Visiting Mobile Node and its to the nesting of tunnels between the Visiting Mobile Node and its
Home Agent within the tunnel between the parent Mobile Router and the Home Agent within the tunnel between the parent Mobile Router and the
parent Mobile Router's Home Agent. Such a solution will seek to parent Mobile Router's Home Agent. Such a solution will seek to
minimize the number of tunnels possibly by collapsing the amount of minimize the number of tunnels possibly by collapsing the amount of
tunnels required through some form of signaling between Mobile Nodes, tunnels required through some form of signaling between Mobile Nodes,
or between Mobile Nodes and their Home Agents, or by using routing or between Mobile Nodes and their Home Agents, or by using routing
headers to route packets through a discovered path. These limit the headers to route packets through a discovered path. These limit the
consequences of the amplification effect of nested tunnels, and at consequences of the amplification effect of nested tunnels, and at
best, the performance of a nested mobile network will be the same as best, the performance of a nested mobile network will be the same as
though there were no nesting at all. though there were no nesting at all.
Examples of this approach include the Reverse Routing Header (RRH) Examples of this approach include the Reverse Routing Header (RRH)
[9], Access Router Option (ARO) [10], and Nested Path Info (NPI) [10], Access Router Option (ARO) [11], and Nested Path Info (NPI)
[11]. [12].
3.3. Infrastructure based Optimization 3.3. Infrastructure based Optimization
An infrastructure based optimization is an approach where An infrastructure based optimization is an approach where
optimization is carried out fully in the infrastructure. One example optimization is carried out fully in the infrastructure. One example
is to make use of mobile anchor points (MAP) in HMIPv6 [12] to is to make use of Mobility Anchor Points (MAP) such as defined in
optimize routes between themselves. Another example is to make use HMIPv6 [13] to optimize routes between themselves. Another example
of the global HAHA protocol [13]. In this case, proxy Home Agents is to make use of proxy Home Agent such as defined in the global HAHA
are distributed in the infrastructure and Mobile Routers bind to the protocol [14]. A proxy Home Agent acts as a Home Agent for the
closest proxy. The proxy, in turn, performs a primary binding with a Mobile Node, and acts as a Mobile Node for the Home Agent,
real Home Agent for that Mobile Router. Then, the proxy might Correspondent Node, Correspondent Router, and other proxies. In
establish secondary bindings with other Home Agents or proxies in the particular, the proxy Home Agent terminates the MRHA tunnel and the
associated encryption, extracts the packets, and re-encapsulates them
to the destination. In this case, proxy Home Agents are distributed
in the infrastructure and each Mobile Router binds to the closest
proxy. The proxy, in turn, performs a primary binding with a real
Home Agent for that Mobile Router. Then, the proxy might establish
secondary bindings with other Home Agents or proxies in the
infrastructure, in order to improve the end-to-end path. In this infrastructure, in order to improve the end-to-end path. In this
case, the proxies discover each other, establish a tunnel and case, the proxies discover each other using some form of Next Hop
exchange the relevant mobile network prefix information in the form Resolution Protocol, establish a tunnel and exchange the relevant
of explicit prefix routes. mobile network prefix information in the form of explicit prefix
routes.
Alternatively, another approach is to use prefix delegation. Here, Alternatively, another approach is to use prefix delegation. Here,
each Mobile Router in a nested mobile network is delegated a mobile each Mobile Router in a nested mobile network is delegated a mobile
network prefix from the access router using DHCP Prefix Delegation network prefix from the access router using DHCP Prefix Delegation
[14]. Each Mobile Router also autoconfigures its care-of address [15]. Each Mobile Router also autoconfigures its care-of address
from this delegated prefix. In this way, the care-of addresses of from this delegated prefix. In this way, the care-of addresses of
each Mobile Router are all from an aggregatable address space each Mobile Router are all formed from an aggregatable address space
starting from the access router. This may be used to eliminate the starting from the access router. This may be used to eliminate the
multiple tunnels caused by nesting of Mobile Nodes. multiple tunnels caused by nesting of Mobile Nodes.
3.4. Intra-NEMO Optimization 3.4. Intra-NEMO Optimization
A Route Optimization solution may seek to improve the communications A Route Optimization solution may seek to improve the communications
between two Mobile Network Nodes within a nested mobile network. between two Mobile Network Nodes within a nested mobile network.
This would avoid traffic being injected out of the nested mobile This would avoid traffic being injected out of the nested mobile
network and route them within the nested mobile network. An example network and route them within the nested mobile network. An example
will be the optimized route taken between MNN1 and MNN2 of Figure 3 will be the optimized route taken between MNN1 and MNN2 of Figure 3
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MNN1 MNN1
Figure 3: An example of nested Mobile Network Figure 3: An example of nested Mobile Network
One may be able to extend a well-designed NEMO Route Optimization for One may be able to extend a well-designed NEMO Route Optimization for
"Nested Mobility Optimization" (see Section 3.2) to provide for such "Nested Mobility Optimization" (see Section 3.2) to provide for such
kind of Intra-NEMO optimization, where, for example in Figure 3, MNN1 kind of Intra-NEMO optimization, where, for example in Figure 3, MNN1
is treated as a Correspondent Node by MR5/MNN2, and MNN2 is treated is treated as a Correspondent Node by MR5/MNN2, and MNN2 is treated
as a Correspondent Node by MR3/MNN1. as a Correspondent Node by MR3/MNN1.
Another possibility is for the "Basic NEMO Route Optimization" Another possibility is for the "Non-Nested NEMO Route Optimization"
technique (see Section 3.1) to be applied here. Using the same technique (see Section 3.1) to be applied here. Using the same
example of communication between MNN1 and MNN2, both MR3 and MR2 can example of communication between MNN1 and MNN2, both MR3 and MR2 can
treat MR5 as Correspondent Routers for MNN2, and MR5 treats MR3 and treat MR5 as Correspondent Routers for MNN2, and MR5 treats MR3 and
MR2 as Correspondent Routers for MNN1. An example of this approach MR2 as Correspondent Routers for MNN1. An example of this approach
is [15] which have Mobile Routers announce their Mobile Network is [16] which has the Mobile Routers announce their Mobile Network
Preifxes to other Mobile Routers in the same nested Mobile Network. Prefixes to other Mobile Routers in the same nested Mobile Network.
Yet another approach is to flatten any nested Mobile Network so that Yet another approach is to flatten any nested Mobile Network so that
all nested Mobile Network Nodes appear to be virtually on the same all nested Mobile Network Nodes appear to be virtually on the same
link. Examples of such approaches include delegating a single prefix link. Examples of such approaches include delegating a single prefix
to the nested Mobile Network, having Mobile Routers to perform to the nested Mobile Network, having Mobile Routers to perform
Neighbor Discovery on behalf of their Mobile Network Nodes, and Neighbor Discovery on behalf of their Mobile Network Nodes, and
exposing a single prefix over the entire mobile network using a exposing a single prefix over the entire mobile network using a
Mobile Ad-Hoc (MANET) protocol. Mobile Ad-Hoc (MANET) protocol. In particular, it might prove useful
to develop a new type of MANET, specialized for the NEMO problem, a
MANET for NEMO (MANEMO). The MANEMO will optimize the formation of
the nested NEMO and maintain inner connectivity, whether a connection
to the infrastructure can be established or not.
4. Issues of NEMO Route Optimization 4. Issues of NEMO Route Optimization
Although Route Optimization can bring benefits as described in Although Route Optimization can bring benefits as described in
Section 2, the scenarios described in Section 3 do so with some Section 2, the scenarios described in Section 3 do so with some
tradeoffs. This section explores some general issues that may impact tradeoffs. This section explores some general issues that may impact
a NEMO Route Optimization mechanism. a NEMO Route Optimization mechanism.
4.1. Additional Signaling Overhead 4.1. Additional Signaling Overhead
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messages, a NEMO Route Optimization procedure may take a longer time messages, a NEMO Route Optimization procedure may take a longer time
to finish its handoff than that in NEMO Basic Support. This may to finish its handoff than that in NEMO Basic Support. This may
exacerbate the overall delay during handoffs and further cause exacerbate the overall delay during handoffs and further cause
performance degradation of the applications running on Mobile Network performance degradation of the applications running on Mobile Network
Nodes. Nodes.
Another NEMO specific delay during handoff is that in a nested mobile Another NEMO specific delay during handoff is that in a nested mobile
network, a child Mobile Network Node may need to detect or be network, a child Mobile Network Node may need to detect or be
notified of the handoff of its parent Mobile Router so that it can notified of the handoff of its parent Mobile Router so that it can
begin signaling its own Correspondent Entities. Apart from the begin signaling its own Correspondent Entities. Apart from the
compromise of mobility awareness and location privacy, this mechanism compromise of mobility transparency and location privacy (see
also increases the delay during handoffs. Section 4.7 and Section 4.8), this mechanism also increases the delay
during handoffs.
Some of the solutions for Mobile IPv6, such as Fast Handoff for Some of the solutions for Mobile IPv6, such as Fast Handoff for
Mobile IPv6 [16], may be able to alleviate the increase in handoff Mobile IPv6 [17], may be able to alleviate the increase in handoff
delay. delay.
4.4. New Functionalities 4.4. Extending Nodes with New Functionalities
In order to support NEMO Route Optimization, some nodes need to be In order to support NEMO Route Optimization, some nodes need to be
changed or upgraded. Smaller number of nodes required to be changed changed or upgraded. Smaller number of nodes required to be changed
will allow for easier adoption of NEMO Route Optimization solution in will allow for easier adoption of NEMO Route Optimization solution in
the Internet and create less impact on existing Internet the Internet and create less impact on existing Internet
infrastructure. The number and the types of nodes involved with new infrastructure. The number and the types of nodes involved with new
functionalities also affect how much of the route is optimized. In functionalities also affect how much of the route is optimized. In
addition, it may also be beneficial to reuse existing protocols (such addition, it may also be beneficial to reuse existing protocols (such
as Mobile IPv6) as much as possible. as Mobile IPv6) as much as possible.
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maintained by a single node (such as the Mobile Router), this would maintained by a single node (such as the Mobile Router), this would
means that the single node has to keep track of the states of all means that the single node has to keep track of the states of all
route optimization sessions. This may leads to scalability issues route optimization sessions. This may leads to scalability issues
especially when that single node is a mobile device with limited especially when that single node is a mobile device with limited
memory and processing resources. memory and processing resources.
A similar scalability issue may be faced by Correspondent Entity as A similar scalability issue may be faced by Correspondent Entity as
well if it maintains many route optimized sessions on behalf of well if it maintains many route optimized sessions on behalf of
Correspondent Node(s) with a large number of Mobile Routers. Correspondent Node(s) with a large number of Mobile Routers.
4.7. Mobility Transparency and Location Privacy 4.7. Mobility Transparency
One advantage of NEMO Basic Support is that the Correspondent Nodes One advantage of NEMO Basic Support is that the Mobile Network Nodes
and Mobile Network Nodes need not be aware of the actual location and need not be aware of the actual location and mobility of the mobile
mobility of the mobile network. With Route Optimization, it might be network. With some approaches for Route Optimization, it might be
necessary to reveal the point of attachment of the Mobile Router to necessary to reveal the point of attachment of the Mobile Router to
other nodes, such as the Mobile Network Nodes or their Correspondent the Mobile Network Nodes. This may mean a tradeoff between mobility
Nodes. This may mean a tradeoff between location privacy [17] (and transparency and Route Optimization.
mobility transparency) and Route Optimization.
4.8. Location Privacy
Without Route Optimization, the Correspondent Nodes are not aware of
the actual location and mobility of the mobile network and its Mobile
Network Nodes. To achieve Route Optimization, it might be necessary
to reveal the point of attachment of the Mobile Router to the
Correspondent Nodes. This may mean a tradeoff between location
privacy [18] and Route Optimization.
In Mobile IPv6, a mobile node can decide whether or not to perform In Mobile IPv6, a mobile node can decide whether or not to perform
Route Optimization with a given Correspondent Node. Thus, the mobile Route Optimization with a given Correspondent Node. Thus, the mobile
node is in control of whether to trade location privacy for an node is in control of whether to trade location privacy for an
optimized route. In NEMO Route Optimization, if the decision to optimized route. In NEMO Route Optimization, if the decision to
perform Router Optimization is made by the Mobile Router, it will be perform Router Optimization is made by the Mobile Router, it will be
difficult for Mobile Network Nodes to control the decision of having difficult for Mobile Network Nodes to control the decision of having
this tradeoff. this tradeoff.
4.8. Security Consideration 4.9. Security Consideration
As Mobile Router and Home Agent usually belong to the same As Mobile Router and Home Agent usually belong to the same
administration domain, it is likely that there exists a security administration domain, it is likely that there exists a security
association between them, which is leveraged by NEMO Basic Support to association between them, which is leveraged by NEMO Basic Support to
conduct the home binding update in a secure way. However, NEMO Route conduct the home binding update in a secure way. However, NEMO Route
Optimization usually involves nodes from different domains (for Optimization usually involves nodes from different domains (for
example, Mobile Router and Correspondent Entity), thus the existence example, Mobile Router and Correspondent Entity), thus the existence
of such a security association is not a valid assumption in many of such a security association is not a valid assumption in many
deployment scenarios. Thus the security protection of NEMO Route deployment scenarios. Thus the security protection of NEMO Route
Optimization signaling message is considered as "weaker" than that in Optimization signaling message is considered as "weaker" than that in
NEMO Basic Support. It is expected that some additional security NEMO Basic Support. It is expected that some additional security
mechanisms are needed to achieve the same or similar level of mechanisms are needed to achieve the same or similar level of
security as in NEMO Basic Support. security as in NEMO Basic Support.
When considering security issues of NEMO Route Optimization, it might When considering security issues of NEMO Route Optimization, it might
be useful to keep in mind some of the security issues considered when be useful to keep in mind some of the security issues considered when
Mobile IPv6 Route Optimization was designed as documented in [18]. Mobile IPv6 Route Optimization was designed as documented in [19].
4.9. Support of Legacy Nodes 4.10. Support of Legacy Nodes
NEMO Basic Support is designed so that all legacy Mobile Network NEMO Basic Support is designed so that all legacy Mobile Network
Nodes (such as those who are not aware of the mobility of the network Nodes (such as those who are not aware of the mobility of the network
they are in, and those that do not understand any mobility protocols) they are in, and those that do not understand any mobility protocols)
can still reach and be reached from the Internet. Some Route can still reach and be reached from the Internet. Some Route
Optimization shcemes, however, require that all Mobile Routers to Optimization schemes, however, require that all Mobile Routers to
implement the same Route Optimization scheme in order for them to implement the same Route Optimization scheme in order for them to
operate. For instance, a nested Mobile Router may not be able to operate. Thus, a nested Mobile Router may not be able to achieve
achieve Route Optimization if it is attached to a legacy Local Fixed Route Optimization if it is attached to a legacy Local Fixed Router.
Router.
5. Analysis of Solution Space 5. Analysis of Solution Space
As described in Section 3, there are various different approaches to As described in Section 3, there are various different approaches to
achieve Route Optimization in Network Mobility Support. In this achieve Route Optimization in Network Mobility Support. In this
section, we attempt to analyze the vast solution space of NEMO Route section, we attempt to analyze the vast solution space of NEMO Route
optimization by asking the following questions: optimization by asking the following questions:
1. Which entities are involved? 1. Which entities are involved?
2. Who and when to initiate signaling? 2. Who and when to initiate signaling?
3. How to detect Route Optimization capabilities? 3. How to detect Route Optimization capabilities?
4. How is address of Mobile Network Node represented? 4. How is the address of Mobile Network Node represented?
5. How is address of Mobile Network Node bound to location of mobile 5. How is the address of Mobile Network Node bound to location of
network? mobile network?
6. How is signaling done? 6. How is signaling performed?
7. How is data transmitted? 7. How is data transmitted?
8. What are the security considerations? 8. What are the security considerations?
5.1. Which Entities are Involved? 5.1. Which Entities are Involved?
There are many combinations of entities involved in Route There are many combinations of entities involved in Route
Optimization. When considering the role each entity plays in Route Optimization. When considering the role each entity plays in Route
Optimization, one has to bear in mind the considerations described in Optimization, one has to bear in mind the considerations described in
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5.1.1. Mobile Network Node and Correspondent Node 5.1.1. Mobile Network Node and Correspondent Node
A Mobile Network Node can establish Route Optimization with its A Mobile Network Node can establish Route Optimization with its
Correspondent Node, possibly the same way as a Mobile Node Correspondent Node, possibly the same way as a Mobile Node
establishes Route Optimization with its Correspondent Node in Mobile establishes Route Optimization with its Correspondent Node in Mobile
IPv6. This would achieve the most optimal route, since the entire IPv6. This would achieve the most optimal route, since the entire
end-to-end path is optimized. However, there might be scalability end-to-end path is optimized. However, there might be scalability
issues since both the Mobile Network Node and the Correspondent Node issues since both the Mobile Network Node and the Correspondent Node
may need to maintain many Route Optimization sessions. In addition, may need to maintain many Route Optimization sessions. In addition,
new functionalities would be required for both the Mobile Network new functionalities would be required for both the Mobile Network
Node and Correspondent Node. Node and Correspondent Node. For the Mobile Network Node, it needs
to be able to manage its mobility, and possibly be aware of the
mobility of its upstream Mobile Router(s). For the Correspondent
Node, it needs to be able to maintain the bindings sent by the Mobile
Network Nodes.
5.1.2. Mobile Router and Correspondent Node 5.1.2. Mobile Router and Correspondent Node
Alternatively, Mobile Router can establish Route Optimization with a Alternatively, the Mobile Router can establish Route Optimization
Correspondent Node on behalf of the Mobile Network Node. Since the with a Correspondent Node on behalf of the Mobile Network Node.
Mobile Router is merely one hop away from the Mobile Network Node, Since all packets to and from the Mobile Network Node must transit
this effectively achieves an optimal route for the entire end-to-end the Mobile Router, this effectively achieves an optimal route for the
path as well. Compared with Section 5.1.1, the scalability issue entire end-to-end path as well. Compared with Section 5.1.1, the
here may be remedied since it is possible for Correspondent Node to scalability issue here may be remedied since it is possible for
maintain only one session with Mobile Router if it communicates with Correspondent Node to maintain only one session with the Mobile
many Mobile Network Nodes associated with Mobile Router. Router if it communicates with many Mobile Network Nodes associated
Furthermore, with Mobile Router handling Route Optimization, there is with the same Mobile Router. Furthermore, with the Mobile Router
no need for Mobile Network Nodes to implement new functionalities. handling Route Optimization, there is no need for Mobile Network
However, new functionality is likely to be required on the Nodes to implement new functionalities. However, new functionality
Correspondent Node. An additional point of consideration is the is likely to be required on the Correspondent Node. An additional
amount of state information the Mobile Router is required to point of consideration is the amount of state information the Mobile
maintain. Traditionally, it has been generally avoided to have state Router is required to maintain. Traditionally, it has been generally
information in the routers to increase proportionally with the number avoided to have state information in the routers to increase
of pairs of communicating peers. proportionally with the number of pairs of communicating peers.
5.1.3. Mobile Router and Correspondent Router 5.1.3. Mobile Router and Correspondent Router
Approaches involving Mobile Routers and Correspondent Routers are Approaches involving Mobile Routers and Correspondent Routers are
described in Section 3.1. The advantage of this approach is that no described in Section 3.1. The advantage of this approach is that no
additional functionality is required for the Correspondent Node and additional functionality is required for the Correspondent Node and
Mobile Network Nodes. In addition, location privacy is relatively Mobile Network Nodes. In addition, location privacy is relatively
preserved, since the current location of the mobile network is only preserved, since the current location of the mobile network is only
revealed to the Correspondent Router and not to the Correspondent revealed to the Correspondent Router and not to the Correspondent
Node (please refer to Section 5.8.3 for more discussions). Node (please refer to Section 5.8.3 for more discussions).
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5.1.4. Entities in the Infrastructure 5.1.4. Entities in the Infrastructure
Approaches using entities in the infrastructure are described in Approaches using entities in the infrastructure are described in
Section 3.3. The advantages of this approach include firstly not Section 3.3. The advantages of this approach include firstly not
requiring new functionalities to be implemented on the Mobile Network requiring new functionalities to be implemented on the Mobile Network
Nodes and Correspondent Nodes, and secondly having most of the Nodes and Correspondent Nodes, and secondly having most of the
complexity shifted to nodes in the infrastructure. However, one main complexity shifted to nodes in the infrastructure. However, one main
issue with this approach is how the Mobile Router can detect the issue with this approach is how the Mobile Router can detect the
presence of such entities, and why the Mobile Router should trust presence of such entities, and why the Mobile Router should trust
these entities. This may be easily addressed if such entity is a these entities. This may be easily addressed if such entity is a
Home Agent of the Mobile Router (such as in global HAHA [13]). Home Agent of the Mobile Router (such as in global HAHA [14]).
Another concern is that the resulting path may not be a true Another concern is that the resulting path may not be a true
optimized one, since it depends on the relative positions of the optimized one, since it depends on the relative positions of the
infrastructure entities with respect to the mobile network and the infrastructure entities with respect to the mobile network and the
Correspondent Node. Correspondent Node.
5.2. Who and When to Initiate Route Optimization? 5.2. Who and When to Initiate Route Optimization?
Having determined the entities involved in the Route Optimization in Having determined the entities involved in the Route Optimization in
the previous sub-section, the next question is which of these the previous sub-section, the next question is which of these
entities should initiate the Route Optimization session. Usually, entities should initiate the Route Optimization session. Usually,
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the initiator to attempt Route Optimization with the Correspondent the initiator to attempt Route Optimization with the Correspondent
Entity. Depending on the protocol specifics, the initiator may Entity. Depending on the protocol specifics, the initiator may
receive (i) a reply from the Correspondent Entity indicating its receive (i) a reply from the Correspondent Entity indicating its
capability, (ii) an error message from the Correspondent Entity, or capability, (ii) an error message from the Correspondent Entity, or
(iii) no response from the Correspondent Entity within a certain time (iii) no response from the Correspondent Entity within a certain time
period. This serves as an indication of whether the Correspondent period. This serves as an indication of whether the Correspondent
Entity supports the required functionality to establish Route Entity supports the required functionality to establish Route
Optimization or not. This form of detection may incur additional Optimization or not. This form of detection may incur additional
delay as a penalty when the Correspondent Entity does not have Route delay as a penalty when the Correspondent Entity does not have Route
Optimization capability, especially when the Route Optimization Optimization capability, especially when the Route Optimization
mechanism is using in-band-signalling. mechanism is using in-band-signaling.
When the Correspondent Entity is not the Correspondent Node but a When the Correspondent Entity is not the Correspondent Node but a
Correspondent Router, an immediate question is how its presence can Correspondent Router, an immediate question is how its presence can
be detected. One approach is for the initiator to send an Internet be detected. One approach is for the initiator to send an Internet
Control Message Protocol (ICMP) message containing the address of the Control Message Protocol (ICMP) message containing the address of the
Correspondent Node to a well-known anycast address reserved for all Correspondent Node to a well-known anycast address reserved for all
Correspondent Routers [7]. Only the Correspondent Router that is Correspondent Routers [7][8]. Only the Correspondent Router that is
capable of terminating Route Optimization session on behalf of the capable of terminating Route Optimization session on behalf of the
Correspondent Node will respond. Another way is to insert a Router Correspondent Node will respond. Another way is to insert a Router
Alert Option (RAO) to a packet sent to the Correspondent Node [8]. Alert Option (RAO) to a packet sent to the Correspondent Node [9].
Any Correspondent Router en route will process the Router Alert Any Correspondent Router en route will process the Router Alert
Option, and send a response to the Mobile Router. Option, and send a response to the Mobile Router.
Both approaches need to consider the possibility of multiple Both approaches need to consider the possibility of multiple
Correspondent Routers responding to the initiator, and both Correspondent Routers responding to the initiator, and both
approaches will generate additional traffic or processing load to approaches will generate additional traffic or processing load to
other routers. Furthermore, both approaches have yet to consider how other routers. Furthermore, both approaches have yet to consider how
the initiator can verify the authenticity of the Correspondent the initiator can verify the authenticity of the Correspondent
Routers that responded. Routers that responded.
5.4. How is Address of Mobile Network Node Represented? 5.4. How is the Address of Mobile Network Node Represented?
Normally, Route Optimization would mean that a binding between the Normally, Route Optimization would mean that a binding between the
address of Mobile Network Node and the location of the mobile network address of a Mobile Network Node and the location of the mobile
is registered at the Correspondent Entity. Before exploring into network is registered at the Correspondent Entity. Before exploring
different ways of binding (see Section 5.5), one must first ask how into different ways of binding (see Section 5.5), one must first ask
the address of the Mobile Network Node is represented. Basically, how the address of the Mobile Network Node is represented.
there are two ways to represent the Mobile Network Node's address: Basically, there are two ways to represent the Mobile Network Node's
address:
o inferred by the use of Mobile Network Prefix, or o inferred by the use of the Mobile Network Prefix, or
o explicitly specifying the address of Mobile Network Node. o explicitly specifying the address of the Mobile Network Node.
Using the Mobile Network Prefix would usually mean that the initiator Using the Mobile Network Prefix would usually mean that the initiator
is the Mobile Router, and has the benefit of binding numerous Mobile is the Mobile Router, and has the benefit of binding numerous Mobile
Network Nodes with one signaling. However, it also means that if Network Nodes with one signaling. However, it also means that if
location privacy is compromised, the location privacy of an entire location privacy is compromised, the location privacy of an entire
Mobile Network Prefix will be compromised. Mobile Network Prefix would be compromised.
On the other hand, using the Mobile Network Node's address would mean On the other hand, using the Mobile Network Node's address would mean
that the initiator is either the Mobile Network Node itself, or the that the initiator is either the Mobile Network Node itself, or the
Mobile Router is initiating Route Optimization on behalf of the Mobile Router is initiating Route Optimization on behalf of the
Mobile Network Node. Initiation by the Mobile Network Node itself Mobile Network Node. Initiation by the Mobile Network Node itself
means that the Mobile Network Node must have new functionalities means that the Mobile Network Node must have new functionalities
implemented, while initiation by the Mobile Router means that the implemented, while initiation by the Mobile Router means that the
Mobile Router must maintain some Route Optimization states for each Mobile Router must maintain some Route Optimization states for each
Mobile Network Node. Mobile Network Node.
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In order for route to be optimized, it is generally necessary for the In order for route to be optimized, it is generally necessary for the
Correspondent Entity to create a binding between the address and the Correspondent Entity to create a binding between the address and the
location of the Mobile Network Node. This can be done in the location of the Mobile Network Node. This can be done in the
following ways: following ways:
o binding the address to the location of the parent Mobile Router; o binding the address to the location of the parent Mobile Router;
o binding the address to a sequence of locations of upstream Mobile o binding the address to a sequence of locations of upstream Mobile
Routers; and Routers; and
o binding the address to the location of the root Mobile Router o binding the address to the location of the root Mobile Router
These will be described in the following sub-sections. These are described in the following sub-sections.
5.5.1. Binding to the Location of Parent Mobile Router 5.5.1. Binding to the Location of Parent Mobile Router
By binding the address of Mobile Network Node to the location of its By binding the address of Mobile Network Node to the location of its
parent Mobile Router, the Correspondent Entity would know how to parent Mobile Router, the Correspondent Entity would know how to
reach the Mobile Network Node via the current location of the parent reach the Mobile Network Node via the current location of the parent
Mobile Router. This can be done by: Mobile Router. This can be done by:
o Binding Update with Mobile Network Prefix o Binding Update with Mobile Network Prefix
This can be viewed as a logical extension to NEMO Basic Support, This can be viewed as a logical extension to NEMO Basic Support,
where the Mobile Router would send binding updates containing one where the Mobile Router would send binding updates containing one
or more Mobile Network Prefix options to the Correspondent Entity. or more Mobile Network Prefix options to the Correspondent Entity.
The Correspondent Entity having received the Binding Update, can The Correspondent Entity having received the Binding Update, can
then set up a bi-directional tunnel with the Mobile Router at the then set up a bi-directional tunnel with the Mobile Router at the
current care-of address of the Mobile Router, and inject a route current care-of address of the Mobile Router, and inject a route
to its routing table so that packets destined for addresses in the to its routing table so that packets destined for addresses in the
mobile network prefix will be routed through the bi-directional mobile network prefix would be routed through the bi-directional
tunnel. tunnel.
Note that in this case, the address of the Mobile Network Node is Note that in this case, the address of the Mobile Network Node is
implied by the Mobile Network Prefix (see Section 5.4). implied by the Mobile Network Prefix (see Section 5.4).
o Sending Information of Parent Mobile Router o Sending Information of Parent Mobile Router
This involves the Mobile Network Node sending the information of This involves the Mobile Network Node sending the information of
its Mobile Router to the Correspondent Entity, thus allowing the its Mobile Router to the Correspondent Entity, thus allowing the
Correspondent Entity to establish a binding between the address of Correspondent Entity to establish a binding between the address of
the Mobile Network Node to the location of the parent Mobile the Mobile Network Node to the location of the parent Mobile
Router. An example of such an approach would be [10]. Router. An example of such an approach would be [11].
o Mobile Router as a Proxy o Mobile Router as a Proxy
Another approach is for the parent Mobile Router to act as a Another approach is for the parent Mobile Router to act as a
"proxy" for its Mobile Network Nodes. In this case, the Mobile "proxy" for its Mobile Network Nodes. In this case, the Mobile
Router uses standard Mobile IPv6 Route Optimization procedure to Router uses standard Mobile IPv6 Route Optimization procedure to
bind the address of a Mobile Network Node to the Mobile Router's bind the address of a Mobile Network Node to the Mobile Router's
care-of address. For instance, when the Mobile Network Node is a care-of address. For instance, when the Mobile Network Node is a
Local Fixed Node without Mobile IPv6 Route Optimization Local Fixed Node without Mobile IPv6 Route Optimization
functionality, the Mobile Router may initiate teh Return functionality, the Mobile Router may initiate the Return
Routability procedure with a Correspondent Node on behalf of the Routability procedure with a Correspondent Node on behalf of the
Local Fixed Node. An example of such an approach would be [19]. Local Fixed Node. An example of such an approach would be
[20][21].
On the other hand, if the Mobile Network Node is a Visiting Mobile On the other hand, if the Mobile Network Node is a Visiting Mobile
Node, it might be necessary for the Visiting Mobile Node to Node, it might be necessary for the Visiting Mobile Node to
delegate the rights of Route Optimization signaling to the Mobile delegate the rights of Route Optimization signaling to the Mobile
Router (see [20] for an example of such delegation). With this Router (see [22] for an example of such delegation). With this
delegation, either the Visiting Mobile Network Node or the Mobile delegation, either the Visiting Mobile Network Node or the Mobile
Router can initiate the Return Routability procedure with the Router can initiate the Return Routability procedure with the
Correspondent Node. For the case where the Return Routability Correspondent Node. For the case where the Return Routability
procedure is initiated by the Visiting Mobile Node, the Mobile procedure is initiated by the Visiting Mobile Node, the Mobile
Router will have to transparently alters content of the Return Router will have to transparently alters content of the Return
Routability signaling messages so that packets sent from the Routability signaling messages so that packets sent from the
Correspondent Node to the Visiting Node will be routed to the Correspondent Node to the Visiting Node will be routed to the
care-of address of the Mobile Router once Route Optimization is care-of address of the Mobile Router once Route Optimization is
established. The case where the Return Routability procedure is established. The case where the Return Routability procedure is
initiated by the Mobile Router is similar to the case where the initiated by the Mobile Router is similar to the case where the
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the Correspondent Entity need not store one complete route per Mobile the Correspondent Entity need not store one complete route per Mobile
Network Node when it is having Route Optimizations sessions with Network Node when it is having Route Optimizations sessions with
multiple Mobile Network Nodes from the same mobile network. multiple Mobile Network Nodes from the same mobile network.
5.5.2. Binding to a Sequence of Locations of Upstream Mobile Routers 5.5.2. Binding to a Sequence of Locations of Upstream Mobile Routers
For a nested Mobile Network Node, it might be more worthwhile to bind For a nested Mobile Network Node, it might be more worthwhile to bind
its address to the sequence of points of attachment of upstream its address to the sequence of points of attachment of upstream
Mobile Routers. In this way, the Correspondent Entity can build a Mobile Routers. In this way, the Correspondent Entity can build a
complete sequence of points of attachment from a single transmission complete sequence of points of attachment from a single transmission
of the binding information. Examples using this approach are [9] and of the binding information. Examples using this approach are [10]
[11]. and [12].
Different from Section 5.5.1, this approach constructs the complete Different from Section 5.5.1, this approach constructs the complete
route to a specific Mobile Network Node at the mobile network side, route to a specific Mobile Network Node at the mobile network side,
thus offering the opportunity to reduce the signaling overhead. thus offering the opportunity to reduce the signaling overhead.
Since the complete route is conveyed to the Correspondent Entity in a Since the complete route is conveyed to the Correspondent Entity in a
single transmission, it is possible to reduce the delay from the time single transmission, it is possible to reduce the delay from the time
an optimized route is changed till the time the change is registered an optimized route is changed till the time the change is registered
on the Correspondent Entity to its minimum. on the Correspondent Entity to its minimum.
One question that immediately comes to the mind is how the Mobile One question that immediately comes to mind is how the Mobile Network
Network Node gets hold of the sequence of locations of its upstream Node gets hold of the sequence of locations of its upstream Mobile
Mobile Routers. This is usually achieved by having such information Routers. This is usually achieved by having such information
inserted as special options in the Router Advertisement messages inserted as special options in the Router Advertisement messages
advertised by upstream Mobile Routers. To do so, not only must a advertised by upstream Mobile Routers. To do so, not only must a
Mobile Router advertise its current location to its Mobile Network Mobile Router advertise its current location to its Mobile Network
Nodes, it must also relay information embedded in Router Nodes, it must also relay information embedded in Router
Advertisement messages it has received from its upstream Mobile Advertisement messages it has received from its upstream Mobile
Routers. This might imply a compromise of the mobility transparency Routers. This might imply a compromise of the mobility transparency
of a mobile network (see Section 4.7). In addition, it also means of a mobile network (see Section 4.7). In addition, it also means
that whenever an upstream Mobile Router changes its point of that whenever an upstream Mobile Router changes its point of
attachment, all downstream Mobile Network Nodes must perform Route attachment, all downstream Mobile Network Nodes must perform Route
Optimization signaling again, possibly leading to a "signaling storm" Optimization signaling again, possibly leading to a "signaling storm"
(see Section 4.1). (see Section 4.1).
A different method of conveying locations of upstream Mobile Routers A different method of conveying locations of upstream Mobile Routers
is used in [9] where upstream Mobile Routers insert their current is used in [10] where upstream Mobile Routers insert their current
point of attachment into a Reverse Routing Header embedded within a point of attachment into a Reverse Routing Header embedded within a
packet sent by the Mobile Network Node. This may raise security packet sent by the Mobile Network Node. This may raise security
concerns that will be discussed later in Section 5.8.2. concerns that will be discussed later in Section 5.8.2.
In order for a Correspondent Entity to bind the address of a Mobile In order for a Correspondent Entity to bind the address of a Mobile
Network Node to a sequence of locations of upstream Mobile Routers, Network Node to a sequence of locations of upstream Mobile Routers,
new functionalities need to be implemented on the Correspondent new functionalities need to be implemented on the Correspondent
Entity. The Correspondent Entity also needs to store the complete Entity. The Correspondent Entity also needs to store the complete
sequence of locations of upstream Mobile Routers for every Mobile sequence of locations of upstream Mobile Routers for every Mobile
Network Node. This may demand more memory compared to Section 5.5.1 Network Node. This may demand more memory compared to Section 5.5.1
if the same Correspondent Entity has a lot of Route Optimization if the same Correspondent Entity has a lot of Route Optimization
sessions with Mobile Network Nodes from the same nested Mobile sessions with Mobile Network Nodes from the same nested Mobile
Network. In addition, some amount of modifications or extension to Network. In addition, some amount of modifications or extension to
existing protocols is also required, such as a new type of IPv6 existing protocols is also required, such as a new type of IPv6
routing header, or new options in Router Advertisement messages. routing header, or a new option in Router Advertisement message.
5.5.3. Binding to the Location of Root Mobile Router 5.5.3. Binding to the Location of Root Mobile Router
A third approach is to bind the address of the Mobile Network Node to A third approach is to bind the address of the Mobile Network Node to
the location of the root Mobile Router, regardless of how deeply the location of the root Mobile Router, regardless of how deeply
nested the Mobile Network Node is within a nested Mobile Network. nested the Mobile Network Node is within a nested Mobile Network.
Whenever the Correspondent Entity needs to forward packet to the Whenever the Correspondent Entity needs to forward packet to the
Mobile Network Node, it only needs to forward the packet to this Mobile Network Node, it only needs to forward the packet to this
point of attachment. The mobile network will figure out how to point of attachment. The mobile network will figure out how to
forward the packet to the Mobile Network Node by itself. This kind forward the packet to the Mobile Network Node by itself. This kind
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Mobile Network, so that it seems to the Correspondent Entity that Mobile Network, so that it seems to the Correspondent Entity that
every node in the Mobile Network is attached to the Internet at the every node in the Mobile Network is attached to the Internet at the
same network segment. same network segment.
There are various approaches to achieve this: There are various approaches to achieve this:
o Prefix Delegation o Prefix Delegation
Here, each Mobile Router in a nested mobile network is delegated a Here, each Mobile Router in a nested mobile network is delegated a
Mobile Network Prefix from the access router (such as using DHCP Mobile Network Prefix from the access router (such as using DHCP
Prefix Delegation [14]). Each Mobile Router also autoconfigures Prefix Delegation [15]). Each Mobile Router also autoconfigures
its care-of address from this delegated prefix. In this way, the its care-of address from this delegated prefix. In this way, the
care-of addresses of Mobile Routers are all from an aggregatable care-of addresses of Mobile Routers are all from an aggregatable
address space starting from the access router. Mobile Network address space starting from the access router. Mobile Network
Nodes with Mobile IPv6 functionality may also autoconfigure its Nodes with Mobile IPv6 functionality may also autoconfigure its
care-of address from this delegated prefix, and use standard care-of address from this delegated prefix, and use standard
Mobile IPv6 mechanism to bind its home address to this care-of Mobile IPv6 mechanism to bind its home address to this care-of
address. address.
Examples of this approach includes [21] and [22]. Examples of this approach includes [23] and [24][25].
This approach has the advantage of keeping the implementations of This approach has the advantage of keeping the implementations of
Correspondent Nodes unchanged. However, it requires the access Correspondent Nodes unchanged. However, it requires the access
router (or some other entity within the access network) and Mobile router (or some other entity within the access network) and Mobile
Router to possess prefix delegation functionality, and also Router to possess prefix delegation functionality, and also
maintain information on what prefix is delegated to which node. maintain information on what prefix is delegated to which node.
How to efficiently assign a subset of Mobile Network Prefix to How to efficiently assign a subset of Mobile Network Prefix to
child Mobile Routers could be an issue because Mobile Network child Mobile Routers could be an issue because Mobile Network
Nodes may dynamically join and leave with an unpredictable Nodes may dynamically join and leave with an unpredictable
pattern. In addition, a change in the point of attachment of the pattern. In addition, a change in the point of attachment of the
root Mobile Router will also require every nested Mobile Router root Mobile Router will also require every nested Mobile Router
(and possibly Visiting Mobile Nodes) to change their care-of (and possibly Visiting Mobile Nodes) to change their care-of
addresses and delegated prefixes. These will cause a burst of addresses and delegated prefixes. These will cause a burst of
Binding Updates and prefix delegation activities where every Binding Updates and prefix delegation activities where every
Mobile Router and every Visiting Mobile Node start sending Binding Mobile Router and every Visiting Mobile Node start sending Binding
Updates to their Correspondent Entities. Updates to their Correspondent Entities.
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pattern. In addition, a change in the point of attachment of the pattern. In addition, a change in the point of attachment of the
root Mobile Router will also require every nested Mobile Router root Mobile Router will also require every nested Mobile Router
(and possibly Visiting Mobile Nodes) to change their care-of (and possibly Visiting Mobile Nodes) to change their care-of
addresses and delegated prefixes. These will cause a burst of addresses and delegated prefixes. These will cause a burst of
Binding Updates and prefix delegation activities where every Binding Updates and prefix delegation activities where every
Mobile Router and every Visiting Mobile Node start sending Binding Mobile Router and every Visiting Mobile Node start sending Binding
Updates to their Correspondent Entities. Updates to their Correspondent Entities.
o Neighbor Discovery Proxy o Neighbor Discovery Proxy
This approach (such as [23]) achieves Route Optimization by having This approach (such as [26][27]) achieves Route Optimization by
Mobile Routers to act as a Neighbor Discovery [24] proxy for its having Mobile Router to act as a Neighbor Discovery [28] proxy for
Mobile Network Nodes. Mobile Router will configure a care-of its Mobile Network Nodes. The Mobile Router will configure a
address from the network prefix advertised by its access router, care-of address from the network prefix advertised by its access
and also relay this prefix to its subnets. When a Mobile Network router, and also relay this prefix to its subnets. When a Mobile
Node configures an address from this prefix, the Mobile Router Network Node configures an address from this prefix, the Mobile
will act as a Neighbor Discovery proxy on its behalf. In this Router will act as a Neighbor Discovery proxy on its behalf. In
way, the entire mobile network and its access network form a this way, the entire mobile network and its access network form a
logical multilink subnet, thus eliminating any nesting. logical multilink subnet, thus eliminating any nesting.
This approach has the advantage of keeping the implementations of This approach has the advantage of keeping the implementations of
Correspondent Nodes unchanged. However, it requires the root Correspondent Nodes unchanged. However, it requires the root
Mobile Router to act as a Neighbor Discovery proxy for all the Mobile Router to act as a Neighbor Discovery proxy for all the
Mobile Network Nodes that are directly or indirectly attached to Mobile Network Nodes that are directly or indirectly attached to
it. This increases the processing load of the root Mobile Router. it. This increases the processing load of the root Mobile Router.
In addition, a change in the point of attachment of the root In addition, a change in the point of attachment of the root
Mobile Router will require every nested Mobile Router (and Mobile Router will require every nested Mobile Router (and
possibly Visiting Mobile Nodes) to change their care-of addresses. possibly Visiting Mobile Nodes) to change their care-of addresses.
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Mobile Router and every Visiting Mobile Node start sending Binding Mobile Router and every Visiting Mobile Node start sending Binding
Updates to their Correspondent Entities, it will also cause a Updates to their Correspondent Entities, it will also cause a
burst of Duplicate Address Discovery messages to be exchanged burst of Duplicate Address Discovery messages to be exchanged
between the mobile network and the access network. Furthermore, between the mobile network and the access network. Furthermore,
route optimization for Local Fixed Nodes is not possible without route optimization for Local Fixed Nodes is not possible without
new functionalities implemented on the Local Fixed Nodes. new functionalities implemented on the Local Fixed Nodes.
o Hierarchical Registrations o Hierarchical Registrations
Hierarchical Registration involves Mobile Network Nodes (including Hierarchical Registration involves Mobile Network Nodes (including
nested Mobile Routers) to register itself with either their parent nested Mobile Routers) to register themselves with either their
Mobile Routers, or the root Mobile Router itself. After parent Mobile Routers, or the root Mobile Router itself. After
registrations, Mobile Network Nodes would tunnel packets directly registrations, Mobile Network Nodes would tunnel packets directly
to the upstream Mobile Router they register with. At the root to the upstream Mobile Router they register with. At the root
Mobile Router, packets tunneled from sub-Mobile Routers or Mobile Mobile Router, packets tunneled from sub-Mobile Routers or Mobile
Network Nodes are tunneled directly to the Correspondent Entities, Network Nodes are tunneled directly to the Correspondent Entities,
thus avoiding nested tunneling. thus avoiding nested tunneling.
One form of such approach uses the principle of Hierarchical One form of such approach uses the principle of Hierarchical
Mobile IPv6 [12], where the root Mobile Router acts as a Mobility Mobile IPv6 [13], where the root Mobile Router acts as a Mobility
Anchor Point. It is also possible for each parent Mobile Router Anchor Point. It is also possible for each parent Mobile Router
to act as Mobility Anchor Points for their child Mobile Routers, to act as Mobility Anchor Points for their child Mobile Routers,
thus forming a hierarchy of Mobility Anchor Points. One can also thus forming a hierarchy of Mobility Anchor Points. One can also
view these Mobility Anchor Points as local Home Agents, thus view these Mobility Anchor Points as local Home Agents, thus
forming a cascade of mobile Home Agents. In this way, each Mobile forming a cascade of mobile Home Agents. In this way, each Mobile
Router terminates its tunnel at its parent Mobile Router. Hence, Router terminates its tunnel at its parent Mobile Router. Hence,
although there are equal number of tunnels as the level of although there are equal number of tunnels as the level of
nestings, there is no tunnel encapsulated within another. nestings, there is no tunnel encapsulated within another.
Examples of this approach includes [25] and [26]. Examples of this approach includes [29], [30] and [31][32].
An advantage of this approach is that the functionalities of the An advantage of this approach is that the functionalities of the
Correspondent Nodes are unchanged. Correspondent Nodes are unchanged.
o Mobile Ad-Hoc Routing o Mobile Ad-Hoc Routing
It is possible for nodes within a mobile network to use Mobile Ad- It is possible for nodes within a mobile network to use Mobile Ad-
hoc routing for packet-forwarding between nodes in the same mobile hoc routing for packet-forwarding between nodes in the same mobile
network. An approach of doing so might involve a router acting as network. An approach of doing so might involve a router acting as
a gateway for connecting nodes in the mobile network to the global a gateway for connecting nodes in the mobile network to the global
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One advantage that is common to all the approaches listed above is One advantage that is common to all the approaches listed above is
that local mobility of a Mobile Network Node within a nested Mobile that local mobility of a Mobile Network Node within a nested Mobile
Network is hidden from the Correspondent Entity. Network is hidden from the Correspondent Entity.
5.6. How is Signaling Performed? 5.6. How is Signaling Performed?
In general, Route Optimization signaling can be done either in-plane, In general, Route Optimization signaling can be done either in-plane,
off-plane, or both. In-plane signaling involves embedding signaling off-plane, or both. In-plane signaling involves embedding signaling
information into headers of data packets. A good example of in-plane information into headers of data packets. A good example of in-plane
signaling would be Reverse Routing Header [9]. Off-plane signaling signaling would be Reverse Routing Header [10]. Off-plane signaling
uses dedicated signaling packets rather than embedding signaling uses dedicated signaling packets rather than embedding signaling
information into headers of data packets. Proposals involving the information into headers of data packets. Proposals involving the
sending of Binding Updates fall into this category. sending of Binding Updates fall into this category.
The advantage of in-plane signaling is that any change in the mobile The advantage of in-plane signaling is that any change in the mobile
network topology can be rapidly propagated to the Correspondent network topology can be rapidly propagated to the Correspondent
Entity as long as there is a continuous stream of data to be Entity as long as there is a continuous stream of data to be
transmitted. However, this might incur a substantial overhead on the transmitted. However, this might incur a substantial overhead on the
data packets. Off-plane signaling, on the other hand, sends data packets. Off-plane signaling, on the other hand, sends
signaling messages independently from the data packet. This has the signaling messages independently from the data packet. This has the
advantage of reducing the signaling overhead in situations where advantage of reducing the signaling overhead in situations where
there are relatively less topological changes to the mobile network. there are relatively less topological changes to the mobile network.
However, data packets transmission may be disrupted while off-plane However, data packets transmission may be disrupted while off-plane
signaling takes place. signaling takes place.
An entirely different method of signaling makes use of upper layer An entirely different method of signaling makes use of upper layer
protocol to establish the bindings between the address of a Mobile protocols to establish the bindings between the address of a Mobile
Network Node and the location of the mobile network. Such binding Network Node and the location of the mobile network. Such binding
information can then be passed down to the IP layer to insert the information can then be passed down to the IP layer to insert the
appropriate entry in the Binding Cache or routing table. An example appropriate entry in the Binding Cache or routing table. An example
of such mechanism is [27] which uses the Session Initiation Protocol of such mechanism is [33] which uses the Session Initiation Protocol
(SIP) to relay binding information. (SIP) to relay binding information.
5.7. How is Data Transmitted? 5.7. How is Data Transmitted?
With Route Optimization established, one remaining question to be With Route Optimization established, one remaining question to be
answered is how data packets can be routed to follow the optimized answered is how data packets can be routed to follow the optimized
route. There are the following possible approaches: route. There are the following possible approaches:
o Encapsulations o Encapsulations
One way to route packets through the optimized path is to use IP- One way to route packets through the optimized path is to use IP-
in-IP encapsulations [28]. In this way, the original packet can in-IP encapsulations [34]. In this way, the original packet can
be tunneled to the location bound to the address of the Mobile be tunneled to the location bound to the address of the Mobile
Network Node using the normal routing infrastructure. Depending Network Node using the normal routing infrastructure. Depending
on how the location is bound to the address of Mobile Network on how the location is bound to the address of Mobile Network
Node, the number of encapsulations required might vary. Node, the number of encapsulations required might vary.
For instance, if the Correspondent Entity knows the full sequence For instance, if the Correspondent Entity knows the full sequence
of points of attachment, it might be necessary for there to be of points of attachment, it might be necessary for there to be
multiple encapsulations in order to forward the data packet multiple encapsulations in order to forward the data packet
through each point of attachment. This may lead to the need for through each point of attachment. This may lead to the need for
multiple tunnels and extra packet header overhead. It is possible multiple tunnels and extra packet header overhead. It is possible
to alleviate this by using Robust Header Compression techniques to alleviate this by using Robust Header Compression techniques
[29][30] to compress the multiple tunnel packet headers. [35][36] [37] to compress the multiple tunnel packet headers.
o Routing Headers o Routing Headers
A second way to route packets through the optimized path is to use A second way to route packets through the optimized path is to use
routing headers. This is useful especially for the case where the routing headers. This is useful especially for the case where the
Correspondent Entity knows the sequence of locations of upstream Correspondent Entity knows the sequence of locations of upstream
Mobile Routers, (see Section 5.5.2), since a routing header can Mobile Routers, (see Section 5.5.2), since a routing header can
contain multiple intermediate destinations. Each intermediate contain multiple intermediate destinations. Each intermediate
destination corresponds to a point of attachment bound to the destination corresponds to a point of attachment bound to the
address of the Mobile Network Node. address of the Mobile Network Node.
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This requires the use of a new Routing Header type, or possibly an This requires the use of a new Routing Header type, or possibly an
extension of the Type 2 Routing Header as defined by Mobile IPv6 extension of the Type 2 Routing Header as defined by Mobile IPv6
to contain multiple addresses instead of only one. to contain multiple addresses instead of only one.
o Routing Entries in Parent Mobile Routers o Routing Entries in Parent Mobile Routers
Yet another way is for parent Mobile Routers to install routing Yet another way is for parent Mobile Routers to install routing
entries in their routing table that will route Route Optimized entries in their routing table that will route Route Optimized
packets differently, most likely based on source address routing. packets differently, most likely based on source address routing.
This usually applies to approaches described in Section 5.5.3. This usually applies to approaches described in Section 5.5.3.
For instance, the Prefix Delegation approach [21][22] would For instance, the Prefix Delegation approach [23][24][25] would
require parent Mobile Routers to route packets differently if the require parent Mobile Routers to route packets differently if the
source address belongs to the prefix delegated from the access source address belongs to the prefix delegated from the access
network. network.
5.8. What are the Security Considerations? 5.8. What are the Security Considerations?
5.8.1. Security Considerations of Address Binding 5.8.1. Security Considerations of Address Binding
The most important security consideration in Route Optimization is The most important security consideration in Route Optimization is
certainly the security risks a Correspondent Entity is exposed to by certainly the security risks a Correspondent Entity is exposed to by
creating a binding between the address of a Mobile Network Node and creating a binding between the address of a Mobile Network Node and
the specified location(s) of the Mobile Network. Generally, it is the specified location(s) of the Mobile Network. Generally, it is
assumed that Correspondent Entity and Mobile Network Node do not assumed that Correspondent Entity and Mobile Network Node do not
share any pre-existing security association. However, the share any pre-existing security association. However, the
Correspondent Entity must have some ways of verifying the Correspondent Entity must have some ways of verifying the
authenticity of the binding specified, else it will be susceptible to authenticity of the binding specified, else it will be susceptible to
various attacks described in [18], such as snooping (sending packets various attacks described in [19], such as snooping (sending packets
meant for a Mobile Network Node to an attacker) or denial-of-service meant for a Mobile Network Node to an attacker) or denial-of-service
(flooding a victim with packets meant for a Mobile Network Node) (flooding a victim with packets meant for a Mobile Network Node)
attacks. attacks.
When the binding is performed between the address of the Mobile When the binding is performed between the address of the Mobile
Network Node and one care-of address (possibly of the Mobile Router, Network Node and one care-of address (possibly of the Mobile Router,
see Section 5.5.1 and Section 5.5.3), the standard Return Routability see Section 5.5.1 and Section 5.5.3), the standard Return Routability
procedure specified in Mobile IPv6 might be sufficient to provide a procedure specified in Mobile IPv6 might be sufficient to provide a
reasonable degree of assurance to the Correspondent Entity. This reasonable degree of assurance to the Correspondent Entity. This
also allows the Correspondent Entity to re-use existing also allows the Correspondent Entity to re-use existing
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For instance, consider the case where the Mobile Router sends Binding For instance, consider the case where the Mobile Router sends Binding
Update containing Mobile Network Prefix information to Correspondent Update containing Mobile Network Prefix information to Correspondent
Entity (see Section 5.5.1). Although the Return Routability Entity (see Section 5.5.1). Although the Return Routability
procedure allows the Correspondent Entity to verify that the care-of procedure allows the Correspondent Entity to verify that the care-of
and home addresses of the Mobile Router are indeed collocated, it and home addresses of the Mobile Router are indeed collocated, it
does not allow the Correspondent Entity to verify the validity of the does not allow the Correspondent Entity to verify the validity of the
Mobile Network Prefix. If the Correspondent Entity accepts the Mobile Network Prefix. If the Correspondent Entity accepts the
binding without verification, it will be exposed to attacks where the binding without verification, it will be exposed to attacks where the
attacker tricks the Correspondent Entity into forwarding packets attacker tricks the Correspondent Entity into forwarding packets
destined for a mobile network to the attacker (snooping) or victim destined for a mobile network to the attacker (snooping) or victim
(DoS). [31] discusses this security threat further. (DoS). [38] discusses this security threat further.
The need to verify the validity of network prefixes is not The need to verify the validity of network prefixes is not
constrained to Correspondent Entities. In approaches that involve constrained to Correspondent Entities. In approaches that involve
the Correspondent Routers (see Section 5.1.3), there have been the Correspondent Routers (see Section 5.1.3), there have been
suggestions for the Correspondent Router to advertise the network suggestions for the Correspondent Router to advertise the network
prefix(es) of Correspondent Nodes the Correspondent Router is capable prefix(es) of Correspondent Nodes the Correspondent Router is capable
of terminating Route Optimization on behalf of to Mobile Network of terminating Route Optimization on behalf of to Mobile Network
Nodes. In such cases, the Mobile Network Nodes also need a mechanism Nodes. In such cases, the Mobile Network Nodes also need a mechanism
to check the authenticity of such claims. Even if the Correspondent to check the authenticity of such claims. Even if the Correspondent
Routers do not advertise the network prefix, the Mobile Network Nodes Routers do not advertise the network prefix, the Mobile Network Nodes
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Mobile Network Nodes are also under the threat of receiving false Mobile Network Nodes are also under the threat of receiving false
information from their upstream Mobile Routers, which they might pass information from their upstream Mobile Routers, which they might pass
to the Correspondent Entities. There are some considerations that to the Correspondent Entities. There are some considerations that
this kind of on-path threat exists in the current Internet anyway this kind of on-path threat exists in the current Internet anyway
especially when no (or weak) end-to-end protection is used. especially when no (or weak) end-to-end protection is used.
All these concerns over the authenticity of addresses might suggest All these concerns over the authenticity of addresses might suggest
that perhaps a more radical and robust approach is necessary. This that perhaps a more radical and robust approach is necessary. This
is currently under extensive study in various Working Groups of the is currently under extensive study in various Working Groups of the
IETF, and many related documents might be of interest here. For IETF, and many related documents might be of interest here. For
instance, in Securing Neighbor Discovery (SEND) [32], the use of instance, in Securing Neighbor Discovery (SEND) [39], the use of
Cryptographically Generated Addresses (CGA) [33] could be used to Cryptographically Generated Addresses (CGA) [40] could be used to
establish the ownership of care-of adresses and network prefixes. establish the ownership of care-of addresses and network prefixes.
[34] employs the Home Agent to check the signaling messages sent by [41] employs the Home Agent to check the signaling messages sent by
Mobile Routers to provide a way for Correspondent Entities to verify Mobile Routers to provide a way for Correspondent Entities to verify
the authenticity of Mobile Network Prefixes specified. [35] documents the authenticity of Mobile Network Prefixes specified. [42] documents
various proposed enhancements to the Mobile IPv6 Route Optimization various proposed enhancements to the Mobile IPv6 Route Optimization
mechanism which might be applied to NEMO Route Optimization as well, mechanism which might be applied to NEMO Route Optimization as well,
such as [36] which allows the Correspondent Entity to authenticate a such as [43] which allows the Correspondent Entity to authenticate a
certain operator's Home Agent by verifying the associated certain operator's Home Agent by verifying the associated
certificate. The Host Identity Protocol (HIP) [37] with end-host certificate. The Host Identity Protocol (HIP) [44] with end-host
mobility considerations [38] may also be extended for NEMO Route mobility considerations [45] may also be extended for NEMO Route
Optimization as well. Optimization as well.
In addition, interested readers might want to refer to [39] that In addition, interested readers might want to refer to [46] that
discussed the general problem of making Route Optimization in NEMO discussed the general problem of making Route Optimization in NEMO
secure and explored some possible solution schemes. There is also a secure and explored some possible solution schemes. There is also a
proposed mechanism for Mobile Network Node to delegate some rights to proposed mechanism for Mobile Network Node to delegate some rights to
their Mobile Routers in [20], which may be used to allow the Mobile their Mobile Routers in [22], which may be used to allow the Mobile
Routers to prove their authenticities to Correspondent Entities when Routers to prove their authenticities to Correspondent Entities when
establishing Route Optimization sessions on behalf of the Mobile establishing Route Optimization sessions on behalf of the Mobile
Network Nodes. Network Nodes.
5.8.2. End-to-End Integrity 5.8.2. End-to-End Integrity
In some of the approaches, such as "Mobile Router as a Proxy" in In some of the approaches, such as "Mobile Router as a Proxy" in
Section 5.5.1, the Mobile Router sends messages using the Mobile Section 5.5.1, the Mobile Router sends messages using the Mobile
Network Node's address as the source address. This is done mainly to Network Node's address as the source address. This is done mainly to
achieve zero new functionalities required at the Correspondent achieve zero new functionalities required at the Correspondent
skipping to change at page 31, line 42 skipping to change at page 32, line 46
insert new contents to the header of packets sent by downstream insert new contents to the header of packets sent by downstream
Mobile Network Nodes. This makes it difficult for Mobile Network Mobile Network Nodes. This makes it difficult for Mobile Network
Nodes to protect the end-to-end integrity of such information with Nodes to protect the end-to-end integrity of such information with
security associations. security associations.
5.8.3. Location Privacy 5.8.3. Location Privacy
Another security related concern is the issue of location privacy. Another security related concern is the issue of location privacy.
This draft currently does not consider the location privacy threats This draft currently does not consider the location privacy threats
caused by an on path eavesdropper. For more information on that caused by an on path eavesdropper. For more information on that
aspect, please refer to [17]. Instead, we consider the following aspect, please refer to [18]. Instead, we consider the following
three aspects to location privacy: three aspects to location privacy:
o Revelation of Location to Correspondent Entity o Revelation of Location to Correspondent Entity
Route optimization is achieved by creating a binding between the Route optimization is achieved by creating a binding between the
address of the Mobile Network Node and the current location of the address of the Mobile Network Node and the current location of the
Mobile Network. It is thus inevitable that the location of Mobile Mobile Network. It is thus inevitable that the location of Mobile
Network Node be revealed to the Correspondent Entity. The concern Network Node be revealed to the Correspondent Entity. The concern
may be alleviated if the Correspondent Entity is not the may be alleviated if the Correspondent Entity is not the
Correspondent Node, since this implies that the actual traffic Correspondent Node, since this implies that the actual traffic
skipping to change at page 33, line 30 skipping to change at page 34, line 30
intent of this work is to enhance our common understanding of the intent of this work is to enhance our common understanding of the
Route Optimization problem and solution space. Route Optimization problem and solution space.
7. IANA Considerations 7. IANA Considerations
This is an informational document and does not require any IANA This is an informational document and does not require any IANA
action. action.
8. Security Considerations 8. Security Considerations
This is an informational document that analyze the solution space of This is an informational document that analyzes the solution space of
NEMO Route Optimization. Security considerations of different NEMO Route Optimization. Security considerations of different
approaches are described in the relevant sections throughout this approaches are described in the relevant sections throughout this
document. Particularly, please refer to Section 4.8 for a brief document. Particularly, please refer to Section 4.9 for a brief
discussion of the security concern with respect to Route Optimization discussion of the security concern with respect to Route Optimization
in general, and Section 5.8 for a more detailed analysis of the in general, and Section 5.8 for a more detailed analysis of the
various Route Optimization approaches. various Route Optimization approaches.
9. Acknowledgments 9. Acknowledgments
The authors wish to thank the co-authors of previous drafts from The authors wish to thank the co-authors of previous drafts from
which this draft is derived: Marco Molteni, Paik Eun-Kyoung, Hiroyuki which this draft is derived: Marco Molteni, Paik Eun-Kyoung, Hiroyuki
Ohnishi, Felix Wu, and Souhwan Jung. In addition, sincere Ohnishi, Felix Wu, and Souhwan Jung. In addition, sincere
appreciation is also extended to Jari Arkko, Carlos Jesus Bernardos, appreciation is also extended to Jari Arkko, Carlos Jesus Bernardos,
Greg Daley, Thierry Ernst, T.J. Kniveton, Erik Nordmark, Alexandru Greg Daley, Thierry Ernst, T.J. Kniveton, Erik Nordmark, Alexandru
Petrescu, Hesham Soliman, Ryuji Wakikawa and Patrick Wetterwald for Petrescu, Hesham Soliman, Ryuji Wakikawa and Patrick Wetterwald for
their various contributions. their various contributions.
10. References 10. References
10.1. Normative References 10.1. Normative References
[1] Ng, C., "Network Mobility Route Optimization Problem Statement", [1] Ng, C., Thubert, P., Watari, M., and F. Zhao, "Network Mobility
draft-ietf-nemo-ro-problem-statement-01 (work in progress), Route Optimization Problem Statement",
October 2005. draft-ietf-nemo-ro-problem-statement-02 (work in progress),
December 2005.
[2] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, [2] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005. January 2005.
[3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in [3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004. IPv6", RFC 3775, June 2004.
[4] Manner, J. and M. Kojo, "Mobility Related Terminology", [4] Ernst, T., "Network Mobility Support Goals and Requirements",
RFC 3753, June 2004. draft-ietf-nemo-requirements-05 (work in progress),
October 2005.
[5] Ernst, T. and H. Lach, "Network Mobility Support Terminology", [5] Manner, J. and M. Kojo, "Mobility Related Terminology",
draft-ietf-nemo-terminology-03 (work in progress), RFC 3753, June 2004.
February 2005.
[6] Ernst, T., "Network Mobility Support Goals and Requirements", [6] Ernst, T. and H. Lach, "Network Mobility Support Terminology",
draft-ietf-nemo-requirements-04 (work in progress), draft-ietf-nemo-terminology-04 (work in progress), October 2005.
February 2005.
10.2. Informative References 10.2. Informative References
[7] Wakikawa, R., "Optimized Route Cache Protocol (ORC)", [7] Wakikawa, R., Koshiba, S., Uehara, K., and J. Murai, "ORC:
draft-wakikawa-nemo-orc-01 (work in progress), November 2004. Optimized Route Cache Management Protocol for Network
Mobility", 10th International Conference on Telecommunications,
vol 2, pp 1194-1200, February 2003.
[8] Na, J., "Route Optimization Scheme based on Path Control [8] Wakikawa, R. and M. Watari, "Optimized Route Cache Protocol
Header", draft-na-nemo-path-control-header-00 (work in (ORC)", draft-wakikawa-nemo-orc-01 (work in progress),
progress), April 2004. November 2004.
[9] Thubert, P. and M. Molteni, "IPv6 Reverse Routing Header and [9] Na, J., Cho, S., Kim, C., Lee, S., Kang, H., and C. Koo, "Route
Optimization Scheme based on Path Control Header",
draft-na-nemo-path-control-header-00 (work in progress),
April 2004.
[10] Thubert, P. and M. Molteni, "IPv6 Reverse Routing Header and
its application to Mobile Networks", its application to Mobile Networks",
draft-thubert-nemo-reverse-routing-header-05 (work in draft-thubert-nemo-reverse-routing-header-05 (work in
progress), June 2004. progress), June 2004.
[10] Ng, C. and T. Tanaka, "Securing Nested Tunnels Optimization [11] Ng, C. and T. Tanaka, "Securing Nested Tunnels Optimization
with Access Router Option", with Access Router Option",
draft-ng-nemo-access-router-option-01 (work in progress), draft-ng-nemo-access-router-option-01 (work in progress),
July 2004. July 2004.
[11] Na, J., "Secure Nested Tunnels Optimization using Nested Path [12] Na, J., Cho, S., Kim, C., Lee, S., Kang, H., and C. Koo,
"Secure Nested Tunnels Optimization using Nested Path
Information", draft-na-nemo-nested-path-info-00 (work in Information", draft-na-nemo-nested-path-info-00 (work in
progress), September 2003. progress), September 2003.
[12] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier, [13] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier,
"Hierarchical Mobile IPv6 Mobility Management (HMIPv6)", "Hierarchical Mobile IPv6 Mobility Management (HMIPv6)",
RFC 4140, August 2005. RFC 4140, August 2005.
[13] Thubert, P., "Global HA to HA protocol", [14] Thubert, P., Wakikawa, R., and V. Devarapalli, "Global HA to HA
draft-thubert-nemo-global-haha-01 (work in progress), protocol", draft-thubert-nemo-global-haha-01 (work in
October 2005. progress), October 2005.
[14] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host [15] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host
Configuration Protocol (DHCP) version 6", RFC 3633, Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003. December 2003.
[15] Baek, S., "Routing Optimization in the same nested mobile [16] Baek, S., Yoo, J., Kwon, T., Paik, E., and M. Nam, "Routing
network", draft-baek-nemo-nested-ro-00 (work in progress), Optimization in the same nested mobile network",
October 2005. draft-baek-nemo-nested-ro-00 (work in progress), October 2005.
[16] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068, [17] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068,
July 2005. July 2005.
[17] Koodli, R., "IP Address Location Privacy and Mobile IPv6: [18] Koodli, R., "IP Address Location Privacy and Mobile IPv6:
Problem Statement", draft-irtf-mobopts-location-privacy-ps-00 Problem Statement", draft-irtf-mobopts-location-privacy-ps-00
(work in progress), July 2005. (work in progress), July 2005.
[18] Nikander, P., "Mobile IP version 6 Route Optimization Security [19] Nikander, P., "Mobile IP version 6 Route Optimization Security
Design Background", draft-ietf-mip6-ro-sec-03 (work in Design Background", draft-ietf-mip6-ro-sec-03 (work in
progress), May 2005. progress), May 2005.
[19] Bernardos, C., "Mobile IPv6 Route Optimisation for Network [20] Bernardos, C., Bagnulo, M., and M. Calderon, "MIRON: MIPv6
Mobility (MIRON)", draft-bernardos-nemo-miron-00 (work in Route Optimization for NEMO", 4th Workshop on Applications and
progress), July 2005. Services in Wireless Network,
Online: http://www.it.uc3m.es/cjbc/papers/miron_aswn2004.pdf,
August 2004.
[20] Ylitalo, J., "Securing Route Optimization in NEMO", Workshop [21] Bernardos, C., Bagnulo, M., Calderon, M., and I. Soto, "Mobile
IPv6 Route Optimisation for Network Mobility (MIRON)",
draft-bernardos-nemo-miron-00 (work in progress), July 2005.
[22] Ylitalo, J., "Securing Route Optimization in NEMO", Workshop
of 12th Network and Distributed System Security Syposuim, NDSS of 12th Network and Distributed System Security Syposuim, NDSS
Workshop 2005, online: http://www.isoc.org/isoc/conferences/ Workshop 2005, online: http://www.isoc.org/isoc/conferences/
ndss/05/workshop/ylitalo.pdf, February 2005. ndss/05/workshop/ylitalo.pdf, February 2005.
[21] Perera, E., "Extended Network Mobility Support", [23] Perera, E., Hsieh, R., and A. Seneviratne, "Extended Network
draft-perera-nemo-extended-00 (work in progress), July 2003. Mobility Support", draft-perera-nemo-extended-00 (work in
progress), July 2003.
[22] Lee, K., "Route Optimization for Mobile Nodes in Mobile Network [24] Lee, K., Park, J., and H. Kim, "Route Optimization for Mobile
based on Prefix Delegation", draft-leekj-nemo-ro-pd-02 (work Nodes in Mobile Network based on Prefix Delegation", 58th IEEE
in progress), February 2004. Vehicular Technology Conference, vol 3, pp 2035-2038,
October 2003.
[23] Jeong, J., "ND-Proxy based Route Optimization for Mobile Nodes [25] Lee, K., Jeong, J., Park, J., and H. Kim, "Route Optimization
in Mobile Network", draft-jeong-nemo-ro-ndproxy-02 (work in for Mobile Nodes in Mobile Network based on Prefix
progress), February 2004. Delegation", draft-leekj-nemo-ro-pd-02 (work in progress),
February 2004.
[24] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery [26] Jeong, J., Lee, K., Park, J., and H. Kim, "Route Optimization
based on ND-Proxy for Mobile Nodes in IPv6 Mobile Network",
59th IEEE Vehicular Technology Conference, vol 5, pp 2461-2465,
May 2004.
[27] Jeong, J., Lee, K., Kim, H., and J. Park, "ND-Proxy based Route
Optimization for Mobile Nodes in Mobile Network",
draft-jeong-nemo-ro-ndproxy-02 (work in progress),
February 2004.
[28] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery
for IP Version 6 (IPv6)", RFC 2461, December 1998. for IP Version 6 (IPv6)", RFC 2461, December 1998.
[25] Kang, H., "Route Optimization for Mobile Network by Using Bi- [29] Kang, H., Kim, K., Han, S., Lee, K., and J. Park, "Route
directional Between Home Agent and Top Level Mobile Router", Optimization for Mobile Network by Using Bi-directional Between
Home Agent and Top Level Mobile Router",
draft-hkang-nemo-ro-tlmr-00 (work in progress), June 2003. draft-hkang-nemo-ro-tlmr-00 (work in progress), June 2003.
[26] Ohnishi, H., "HMIP based Route optimization method in a mobile [30] Lee, D., Lim, K., and M. Kim, "Hierarchical FRoute Optimization
network", draft-ohnishi-nemo-ro-hmip-00 (work in progress), for Nested Mobile Network", 18th Int'l Conf on Advance
October 2003. Information Networking and Applications, vol 1, pp 225-229,
2004.
[27] Lee, C., "SIP-based Network Mobility (SIP-NEMO) Route [31] Takagi, Y., Ohnishi, H., Sakitani, K., Baba, K., and S.
Optimization", draft-ming-nemo-sipnemo-00 (work in progress), Shimojo, "Route Optimization Methods for Network Mobility with
October 2005. Mobile IPv6", IEICE Trans. on Comms, vol E87-B, no 3, pp 480-
489, March 2004.
[28] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 [32] Ohnishi, H., Sakitani, K., and Y. Takagi, "HMIP based Route
optimization method in a mobile network",
draft-ohnishi-nemo-ro-hmip-00 (work in progress), October 2003.
[33] Lee, C., Zheng, J., and C. Huang, "SIP-based Network Mobility
(SIP-NEMO) Route Optimization", draft-ming-nemo-sipnemo-00
(work in progress), October 2005.
[34] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6
Specification", RFC 2473, December 1998. Specification", RFC 2473, December 1998.
[29] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H., [35] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H.,
Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le, K., Hannu, H., Jonsson, L-E., Hakenberg, R., Koren, T., Le, K.,
Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K., Wiebke, T., Liu, Z., Martensson, A., Miyazaki, A., Svanbro, K., Wiebke, T.,
Yoshimura, T., and H. Zheng, "RObust Header Compression (ROHC): Yoshimura, T., and H. Zheng, "RObust Header Compression (ROHC):
Framework and four profiles: RTP, UDP, ESP, and uncompressed", Framework and four profiles: RTP, UDP, ESP, and uncompressed",
RFC 3095, July 2001. RFC 3095, July 2001.
[30] Jonsson, L-E., "RObust Header Compression (ROHC): Terminology [36] Jonsson, L-E., "RObust Header Compression (ROHC): Terminology
and Channel Mapping Examples", RFC 3759, April 2004. and Channel Mapping Examples", RFC 3759, April 2004.
[31] Ng, C., "Extending Return Routability Procedure for Network [37] Minaburo, A., Paik, E., Toutain, L., and J. Bonnin, "ROHC
Prefix (RRNP)", draft-ng-nemo-rrnp-00 (work in progress), (Robust Header Compression) in NEMO network",
October 2004. draft-minaburo-rohc-nemo-01 (work in progress), July 2005.
[32] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure [38] Ng, C. and J. Hirano, "Extending Return Routability Procedure
for Network Prefix (RRNP)", draft-ng-nemo-rrnp-00 (work in
progress), October 2004.
[39] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005. Neighbor Discovery (SEND)", RFC 3971, March 2005.
[33] Aura, T., "Cryptographically Generated Addresses (CGA)", [40] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005. RFC 3972, March 2005.
[34] Zhao, F., "Extensions to Return Routability Test in MIP6", [41] Zhao, F., "Extensions to Return Routability Test in MIP6",
draft-zhao-mip6-rr-ext-01 (work in progress), February 2005. draft-zhao-mip6-rr-ext-01 (work in progress), February 2005.
[35] Arkko, J. and C. Vogt, "A Taxonomy and Analysis of Enhancements [42] Arkko, J. and C. Vogt, "A Taxonomy and Analysis of Enhancements
to Mobile IPv6 Route Optimization", to Mobile IPv6 Route Optimization",
draft-irtf-mobopts-ro-enhancements-03 (work in progress), draft-irtf-mobopts-ro-enhancements-04 (work in progress),
October 2005. October 2005.
[36] Bao, F., "Certificate-based Binding Update Protocol (CBU)", [43] Bao, F., Deng, R., Qiu, Y., and J. Zhou, "Certificate-based
Binding Update Protocol (CBU)",
draft-qiu-mip6-certificated-binding-update-03 (work in draft-qiu-mip6-certificated-binding-update-03 (work in
progress), March 2005. progress), March 2005.
[37] Moskowitz, R., "Host Identity Protocol", draft-ietf-hip-base-03 [44] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson,
(work in progress), June 2005. "Host Identity Protocol", draft-ietf-hip-base-04 (work in
progress), October 2005.
[38] Nikander, P., "End-Host Mobility and Multihoming with the Host [45] Henderson, T., "End-Host Mobility and Multihoming with the Host
Identity Protocol", draft-ietf-hip-mm-02 (work in progress), Identity Protocol", draft-ietf-hip-mm-02 (work in progress),
July 2005. July 2005.
[39] Calderon, M., Bernardos, C., Bagnulo, M., and I. Soto, [46] Calderon, M., Bernardos, C., Bagnulo, M., and I. Soto,
"Securing Route Optimization in NEMO", Third International "Securing Route Optimization in NEMO", Third International
Symposium on Modeling and Optimization in Mobile, Ad Hoc, and Symposium on Modeling and Optimization in Mobile, Ad Hoc, and
Wireless Networks, WIOPT 2005, pages 248-254, April 2005. Wireless Networks, WIOPT 2005, pages 248-254, April 2005.
Appendix A. Change Log Appendix A. Change Log
o draft-ietf-nemo-ro-space-analysis-02:
* Changed title of Sect 3.1 from "Basic NEMO Route Optimization"
to "Non-Nested NEMO Route Optimization"
* Added "Terminology" Sub-section [Issue #17]
* Modifications to Sect 3.1 and 5.1.1 [Issues #18, #20]
* Break "Mobility Transparency and Location Privacy" into Sect
4.7 and 4.8 [Issue #19]
* Updated References [Issue #21]
o draft-ietf-nemo-ro-space-analysis-01: o draft-ietf-nemo-ro-space-analysis-01:
* Changed the term "Correspondent Agent" to "Correspondent * Changed the term "Correspondent Agent" to "Correspondent
Entity" [Issue #13] Entity" [Issue #13]
* Added clarifying text to some benefits listed in Sect 2 [Issue * Added clarifying text to some benefits listed in Sect 2 [Issue
#14] #14]
* Added clarifying text to Sect 4.1, 4.3 and 4.4 [Issue #5, #6, * Added clarifying text to Sect 4.1, 4.3 and 4.4 [Issues #5, #6,
#16] #16]
* Added Section 4.9 [Issue #3] * Added Section 4.9 [Issue #3]
* Added clarifying text to various parts of Sect 5 [Issue #7, #8, * Added clarifying text to various parts of Sect 5 [Issues #7,
#9, #11, and #16] #8, #9, #11, and #16]
* Combined "MR as a Proxy" and "MR as a Transparent Proxy" in * Combined "MR as a Proxy" and "MR as a Transparent Proxy" in
Sect 5.5.1 [Issue #11] Sect 5.5.1 [Issue #11]
* Changed the term "identity of MNN" to "address of MNN" in Sect * Changed the term "identity of MNN" to "address of MNN" in Sect
5.5 [Issue #12] 5.5 [Issue #12]
* Added text on signaling using upper layer protocols in Sect 5.6 * Added text on signaling using upper layer protocols in Sect 5.6
* Added more security consideration to Sect 5.8 [Issue #15] * Added more security consideration to Sect 5.8 [Issue #15]
skipping to change at page 40, line 41 skipping to change at page 43, line 41
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED, ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement Copyright Statement
Copyright (C) The Internet Society (2005). This document is subject Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights. except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is currently provided by the
Internet Society. Internet Society.
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