draft-ietf-nemo-ro-space-analysis-03.txt   rfc4889.txt 
NEMO Working Group C. Ng Network Working Group C. Ng
Internet-Draft Panasonic Singapore Labs Request for Comments: 4889 Panasonic Singapore Labs
Intended status: Informational F. Zhao Category: Informational F. Zhao
Expires: March 19, 2007 UC Davis UC Davis
M. Watari M. Watari
KDDI R&D Labs KDDI R&D Labs
P. Thubert P. Thubert
Cisco Systems Cisco Systems
September 15, 2006
Network Mobility Route Optimization Solution Space Analysis Network Mobility Route Optimization Solution Space Analysis
draft-ietf-nemo-ro-space-analysis-03
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Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
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 Mobile Router and Home Agent (MRHA) tunnel when the mobile network is
increased length of packet route and increased packet delay in most away. This results in increased length of packet route and increased
cases. To overcome these limitations, one might have to turn to packet delay in most cases. To overcome these limitations, one might
Route Optimization (RO) for NEMO. This memo documents various types have to turn to Route Optimization (RO) for NEMO. This memo
of Route Optimization in NEMO, and explores the benefits and documents various types of Route Optimization in NEMO and explores
tradeoffs in different aspects of NEMO Route Optimization. the benefits and tradeoffs in different aspects of NEMO Route
Optimization.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 3
2. Benefits of NEMO Route Optimization . . . . . . . . . . . . . 5 2. Benefits of NEMO Route Optimization . . . . . . . . . . . . . 4
3. Different Scenarios of NEMO Route Optimization . . . . . . . . 7 3. Different Scenarios of NEMO Route Optimization . . . . . . . . 6
3.1. Non-Nested NEMO Route Optimization . . . . . . . . . . . . 7 3.1. Non-Nested NEMO Route Optimization . . . . . . . . . . . . 6
3.2. Nested Mobility Optimization . . . . . . . . . . . . . . . 9 3.2. Nested Mobility Optimization . . . . . . . . . . . . . . . 8
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 . . . 8
3.2.2. Decreasing the Number of Tunnels . . . . . . . . . . . 10 3.2.2. Decreasing the Number of Tunnels . . . . . . . . . . . 9
3.3. Infrastructure based Optimization . . . . . . . . . . . . 10 3.3. Infrastructure-Based Optimization . . . . . . . . . . . . 9
3.4. Intra-NEMO Optimization . . . . . . . . . . . . . . . . . 11 3.4. Intra-NEMO Optimization . . . . . . . . . . . . . . . . . 10
4. Issues of NEMO Route Optimization . . . . . . . . . . . . . . 13 4. Issues of NEMO Route Optimization . . . . . . . . . . . . . . 11
4.1. Additional Signaling Overhead . . . . . . . . . . . . . . 13 4.1. Additional Signaling Overhead . . . . . . . . . . . . . . 11
4.2. Increased Protocol Complexity and Processing Load . . . . 14 4.2. Increased Protocol Complexity and Processing Load . . . . 12
4.3. Increased Delay during Handoff . . . . . . . . . . . . . . 14 4.3. Increased Delay during Handoff . . . . . . . . . . . . . . 12
4.4. Extending Nodes with New Functionalities . . . . . . . . . 14 4.4. Extending Nodes with New Functionalities . . . . . . . . . 13
4.5. Detection of New Functionalities . . . . . . . . . . . . . 16 4.5. Detection of New Functionalities . . . . . . . . . . . . . 14
4.6. Scalability . . . . . . . . . . . . . . . . . . . . . . . 16 4.6. Scalability . . . . . . . . . . . . . . . . . . . . . . . 14
4.7. Mobility Transparency . . . . . . . . . . . . . . . . . . 16 4.7. Mobility Transparency . . . . . . . . . . . . . . . . . . 14
4.8. Location Privacy . . . . . . . . . . . . . . . . . . . . . 16 4.8. Location Privacy . . . . . . . . . . . . . . . . . . . . . 15
4.9. Security Consideration . . . . . . . . . . . . . . . . . . 17 4.9. Security Consideration . . . . . . . . . . . . . . . . . . 15
4.10. Support of Legacy Nodes . . . . . . . . . . . . . . . . . 17 4.10. Support of Legacy Nodes . . . . . . . . . . . . . . . . . 15
5. Analysis of Solution Space . . . . . . . . . . . . . . . . . . 18 5. Analysis of Solution Space . . . . . . . . . . . . . . . . . . 16
5.1. Which Entities are Involved? . . . . . . . . . . . . . . . 18 5.1. Which Entities Are Involved? . . . . . . . . . . . . . . . 16
5.1.1. Mobile Network Node and Correspondent Node . . . . . . 18 5.1.1. Mobile Network Node and Correspondent Node . . . . . . 16
5.1.2. Mobile Router and Correspondent Node . . . . . . . . . 19 5.1.2. Mobile Router and Correspondent Node . . . . . . . . . 17
5.1.3. Mobile Router and Correspondent Router . . . . . . . . 19 5.1.3. Mobile Router and Correspondent Router . . . . . . . . 17
5.1.4. Entities in the Infrastructure . . . . . . . . . . . . 20 5.1.4. Entities in the Infrastructure . . . . . . . . . . . . 18
5.2. Who and When to Initiate Route Optimization? . . . . . . . 20 5.2. Who Initiates Route Optimization? When? . . . . . . . . . 18
5.3. How to Detect Route Optimization Capability? . . . . . . . 21 5.3. How Is Route Optimization Capability Detected? . . . . . . 19
5.4. How is the Address of Mobile Network Node Represented? . . 22 5.4. How is the Address of the Mobile Network Node
5.5. How is Mobile Network Node's Address Bound to Location? . 22 Represented? . . . . . . . . . . . . . . . . . . . . . . . 20
5.5.1. Binding to the Location of Parent Mobile Router . . . 23 5.5. How Is the Mobile Network Node's Address Bound to
5.5.2. Binding to a Sequence of Locations of Upstream Location? . . . . . . . . . . . . . . . . . . . . . . . . 20
Mobile Routers . . . . . . . . . . . . . . . . . . . . 25 5.5.1. Binding to the Location of Parent Mobile Router . . . 21
5.5.3. Binding to the Location of Root Mobile Router . . . . 26 5.5.2. Binding to a Sequence of Upstream Mobile Routers . . . 23
5.6. How is Signaling Performed? . . . . . . . . . . . . . . . 28 5.5.3. Binding to the Location of Root Mobile Router . . . . 24
5.7. How is Data Transmitted? . . . . . . . . . . . . . . . . . 29 5.6. How Is Signaling Performed? . . . . . . . . . . . . . . . 26
5.8. What are the Security Considerations? . . . . . . . . . . 30 5.7. How Is Data Transmitted? . . . . . . . . . . . . . . . . . 27
5.8.1. Security Considerations of Address Binding . . . . . . 30 5.8. What Are the Security Considerations? . . . . . . . . . . 28
5.8.2. End-to-End Integrity . . . . . . . . . . . . . . . . . 32 5.8.1. Security Considerations of Address Binding . . . . . . 28
5.8.3. Location Privacy . . . . . . . . . . . . . . . . . . . 32 5.8.2. End-to-End Integrity . . . . . . . . . . . . . . . . . 30
6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 34 5.8.3. Location Privacy . . . . . . . . . . . . . . . . . . . 30
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 34 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 31
8. Security Considerations . . . . . . . . . . . . . . . . . . . 34 7. Security Considerations . . . . . . . . . . . . . . . . . . . 32
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 34 8. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 32
10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 35 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 32
10.1. Normative References . . . . . . . . . . . . . . . . . . . 35 9.1. Normative References . . . . . . . . . . . . . . . . . . . 32
10.2. Informative References . . . . . . . . . . . . . . . . . . 35 9.2. Informative References . . . . . . . . . . . . . . . . . . 33
Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 40
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 42
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. The
this purpose of NEMO, the term "Route Optimization" is accepted in a term "Route Optimization" is used in a broader sense than already
broader sense than already defined for IPv6 Host Mobility in [3], to defined for IPv6 Host Mobility in [3] to loosely refer to any
loosely refer to any approach that optimizes the transmission of approach that optimizes the transmission of packets between a Mobile
packets between a Mobile Network Node and a Correspondent Node. 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. The scope of the solutions, Optimization-related problems for NEMO. The scope of the solutions,
the benefits, and the impacts to the existing implementations and the benefits, and the impacts to the existing implementations and
deployments are analyzed. This work should serve as a foundation for deployments are analyzed. This work should serve as a foundation for
the NEMO WG to decide where to focus its Route Optimization effort, the NEMO WG to decide where to focus its Route Optimization effort,
with a deeper understanding of the relative strength and weaknesses with a deeper understanding of the relative strengths and weaknesses
of each approach. of each approach.
It should be beneficial for readers to keep in mind the design It should be beneficial for readers to keep in mind the design
requirements of NEMO [4]. A point to note is that since this requirements of NEMO [4]. A point to note is that since this
document discusses aspects of Route Optimization, the reader may document discusses aspects of Route Optimization, the reader 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 It is expected that readers are familiar with terminologies related
to mobility in [3] and [5], and NEMO related terms defined in [6]. to mobility in [3] and [5], and NEMO-related terms defined in [6].
In addition, the following Route Optimization specific terms are used In addition, the following Route Optimization-specific terms are used
in this document: in this document:
Correspondent Router (CR) Correspondent Router (CR)
This refers to the router which is capable of terminating a Route This refers to the router that 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 that 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
NEMO Route Optimization addresses the problems discussed in [1]. NEMO Route Optimization addresses the problems discussed in [1].
Although a standardized NEMO Route Optimization solution has yet to Although a standardized NEMO Route Optimization solution has yet to
materialize, one can expect it to show some of the following materialize, one can expect it to 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 in turn lead to
lead to better overall Quality of Service characteristics, such as better overall Quality of Service characteristics, such as reduced
reduced jitter and packet loss. jitter and packet loss.
o Reduced Consumption of Overall Network Resources o Reduced Consumption of Overall Network Resources
Through the selection of a shorter route, the total link Through the selection of a shorter route, the total link
utilization for all links used by traffic between the two end utilization for all links used by traffic between the two end
nodes should be much lower than that used if Route Optimization is nodes should be much lower than that used if Route Optimization is
not carried out. This would result in a lighter network load with not carried out. This would result in a lighter network load with
reduced congestion. reduced congestion.
o Reduced Susceptibility to Link Failure o Reduced Susceptibility to Link Failure
skipping to change at page 5, line 45 skipping to change at page 4, line 45
conceivably utilize a smaller number of links between the two end conceivably utilize a smaller number of links between the two end
nodes. Hence, the probability of a loss of connectivity due to a nodes. Hence, the probability of a loss of connectivity due to a
single point of failure at a link should be lower as compared to single point of failure at a link should be lower as compared to
the longer non-optimized route. the longer non-optimized route.
o Greater Data Efficiency o Greater Data Efficiency
Depending on the actual solution for NEMO Route Optimization, the Depending on the actual solution for NEMO Route Optimization, the
data packets exchanged between two end nodes may not require as data packets exchanged between two end nodes may not require as
many levels of encapsulation as that in NEMO Basic Support. This many levels of encapsulation as that in NEMO Basic Support. This
would mean less packet overheads, and higher data efficiency. In would mean less packet overheads and higher data efficiency. In
particular, avoiding packet fragmentation that may be induced by particular, avoiding packet fragmentation that may be induced by
the multiple levels of tunneling is critical for end-to-end the multiple levels of tunneling is critical for end-to-end
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 for multiple encapsulations required by
Basic Support, which may result in less processing delay at the NEMO Basic Support, which may result in less processing delay at
points of encapsulation and decapsulation. the points of encapsulation and decapsulation.
o Avoiding Bottleneck in the Home Network o Avoiding a Bottleneck in the Home Network
NEMO Route Optimization allows traffic to by-pass the Home Agents. NEMO Route Optimization allows traffic to bypass 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 a Mobile Router from tunneling traffic Security policy may forbid a Mobile Router from tunneling traffic
of Visiting Mobile Nodes into the home network of the Mobile of Visiting Mobile Nodes into the home network of the Mobile
Router. Route Optimization can be used to avoid this issue by Router. Route Optimization can be used to avoid this issue by
forwarding traffic from Visiting Mobile Nodes directly to their forwarding traffic from Visiting Mobile Nodes directly to their
destinations without going through the home network of the Mobile destinations without going through the home network of the Mobile
Router. Router.
It should however be taken into consideration that a Route However, it should 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 conflict with the deployment of different policies that might conflict with the deployment of
Route Optimization for Visiting Mobile Nodes. Being a policy Route Optimization for Visiting Mobile Nodes. Being a policy
issue, solving this with a protocol at the policy plane might be issue, solving this with a protocol at the policy plane 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 that would require a Route
Optimization mechanism and list the potential solutions which have Optimization mechanism and list the potential solutions that have
been proposed in that area. been proposed in that area.
3.1. Non-Nested NEMO Route Optimization 3.1. Non-Nested NEMO Route Optimization
The Non-Nested NEMO Route Optimization involves a Mobile Router The Non-Nested NEMO Route Optimization involves a Mobile Router
sending binding information to a Correspondent Entity. It does not sending binding information to a Correspondent Entity. It does not
involve nesting of Mobile Routers nor Visiting Mobile Nodes. The involve nesting of Mobile Routers or Visiting Mobile Nodes. The
Correspondent Entity can be a Correspondent Node or a Correspondent Correspondent Entity can be a Correspondent Node or a Correspondent
Router. The interesting case is when the Correspondent Entity is a Router. The interesting case is when the Correspondent Entity is a
Correspondent Router. With the use of Correspondent Router, Route Correspondent Router. With the use of Correspondent Router, Route
Optimization session is terminated at the Correspondent Router on Optimization session is terminated at the Correspondent Router on
behalf of the Correspondent Node. As long as the Correspondent behalf of the Correspondent Node. As long as the Correspondent
Router is located "closer" to the Correspondent Node than the Home Router is located "closer" to the Correspondent Node than the Home
Agent of the Mobile Router, the route between Mobile Network Node and Agent of the Mobile Router, the route between Mobile Network Node and
the Correspondent Node can be said to be optimized. For this the Correspondent Node can be said to be optimized. For this
purpose, Correspondent Routers may be deployed to provide an optimal purpose, Correspondent Routers may be deployed to provide an optimal
route as illustrated in Figure 1. route as illustrated in Figure 1.
skipping to change at page 7, line 42 skipping to change at page 6, line 42
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 1: MR-CR Optimization Figure 1: MR-CR Optimization
This form of optimization can carry traffic in both directions or This form of optimization can carry traffic in both directions or
independently for the 2 directions of traffic: independently for the two 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
The Correspondent Router is on the path of the traffic from the The Correspondent Router is on the path of the traffic from the
Correspondent Node to the Home Agent. In addition, it has an Correspondent Node to the Home Agent. In addition, it has an
established tunnel with the current care-of address of the Mobile established tunnel with the current Care-of Address (CoA) of the
Router and is aware of the mobile network prefix(es) managed by Mobile Router and is aware of the Mobile Network Prefix(es)
the Mobile Router. The Correspondent Router can thus intercept managed by the Mobile Router. The Correspondent Router can thus
packets going to the mobile network, and forward them to the intercept packets going to the mobile network, and forward them to
Mobile Router over the established tunnel. the Mobile Router over the established tunnel.
A straight-forward approach to Route Optimization in NEMO is for the A straightforward approach to Route Optimization in NEMO is for the
Mobile Router to attempt Route Optimization with a Correspondent Mobile Router to attempt Route Optimization with a Correspondent
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.
The definition of Correspondent Router does not limit it to be a The definition of Correspondent Router does not limit it to be a
fixed router. Here we consider the case where the Correspondent fixed router. Here we consider the case where the Correspondent
Router is a Mobile Router. Thus Route Optimization is initiated and Router is a Mobile Router. Thus, Route Optimization is initiated and
performed between a Mobile Router and its peer Mobile Router. Such performed between a Mobile Router and its peer Mobile Router. Such
solutions are often posed with a requirement to leave the Mobile solutions are often posed with a requirement to leave the Mobile
Network Nodes untouched, as with the NEMO Basic Support protocol, and Network Nodes untouched, as with the NEMO Basic Support protocol, and
therefore Mobile Routers handle the optimization management on behalf therefore Mobile Routers handle the optimization management on behalf
of the Mobile Network Nodes. Thus, providing Route Optimization for of the Mobile Network Nodes. Thus, providing Route Optimization for
Visiting Mobile Node is often out of scope for such scenario because a Visiting Mobile Node is often out of scope for such a scenario
such interaction would require extensions to the Mobile IPv6 because such interaction would require extensions to the Mobile IPv6
protocol. This scenario is illustrated in Figure 2. protocol. This scenario is illustrated in Figure 2.
HAofCR ********************************** HAofMR HAofCR ********************************** HAofMR
#*# #*# #*# #*#
#*# #*# +---------------------+ #*# #*# +---------------------+
#*# #*# | LEGEND | #*# #*# | LEGEND |
#*# #*# +---------------------+ #*# #*# +---------------------+
#*# ############### #*# | #: Tunnel | #*# ############### #*# | #: Tunnel |
CR ooooooooooooooo MR | *: NEMO Basic route | CR ooooooooooooooo MR | *: NEMO Basic route |
| ############### | | o: Optimized route | | ############### | | o: Optimized route |
MNN2 MNN1 +---------------------+ MNN2 MNN1 +---------------------+
Figure 2: MR-CR Optimization Figure 2: MR-MR Optimization
This form of optimization can carry traffic for both directions This form of optimization can carry traffic for both directions
identically: identically:
o MNN1 to/from MNN2 o MNN1 to/from MNN2
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
Mobile Network Node via the Correspondent Router over the tunnel. Mobile Network Node via the Correspondent Router over the tunnel.
Traffic to the Mobile Networks Nodes would no longer flow through Traffic to the Mobile Networks Nodes would no longer flow through
the Home Agents. the Home Agents.
Examples of this approach include Optimized Route Cache (ORC) [7][8] Examples of this approach include Optimized Route Cache (ORC) [7][8]
and Path Control Header (PCH) [9]. 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 between this and its base protocol suite as a standard, collaboration between this and
NEMO protocols brings various complexities. 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, by bypassing some of the Home Agent(s) from Agents along the path, by bypassing some of the Home Agent(s) from
the original path. Unlike the scenario where no nesting is formed the original path. Unlike the scenario where no nesting is formed
and only a single Home Agent exists along the path, bypassing one of and only a single Home Agent exists along the path, 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 an optimal path for such
will require interaction with the protocol and may require an hosts 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) [10]. An 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)
[10], Access Router Option (ARO) [11], and Nested Path Info (NPI) [10], Access Router Option (ARO) [11], and Nested Path Info (NPI)
[12]. [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 Mobility Anchor Points (MAP) such as defined in is to make use of Mobility Anchor Points (MAPs) such as defined in
HMIPv6 [13] to optimize routes between themselves. Another example HMIPv6 [13] to optimize routes between themselves. Another example
is to make use of proxy Home Agent such as defined in the global HAHA is to make use of proxy Home Agent such as defined in the global Home
protocol [14]. A proxy Home Agent acts as a Home Agent for the Agent to Home Agent (HAHA) protocol [14]. A proxy Home Agent acts as
Mobile Node, and acts as a Mobile Node for the Home Agent, a Home Agent for the Mobile Node, and acts as a Mobile Node for the
Correspondent Node, Correspondent Router, and other proxies. In Home Agent, Correspondent Node, Correspondent Router, and other
particular, the proxy Home Agent terminates the MRHA tunnel and the proxies. In particular, the proxy Home Agent terminates the MRHA
associated encryption, extracts the packets, and re-encapsulates them tunnel and the associated encryption, extracts the packets, and re-
to the destination. In this case, proxy Home Agents are distributed encapsulates them to the destination. In this case, proxy Home
in the infrastructure and each Mobile Router binds to the closest Agents are distributed in the infrastructure and each Mobile Router
proxy. The proxy, in turn, performs a primary binding with a real binds to the closest proxy. The proxy, in turn, performs a primary
Home Agent for that Mobile Router. Then, the proxy might establish binding with a real Home Agent for that Mobile Router. Then, the
secondary bindings with other Home Agents or proxies in the proxy might establish secondary bindings with other Home Agents or
infrastructure, in order to improve the end-to-end path. In this proxies in the infrastructure, in order to improve the end-to-end
case, the proxies discover each other using some form of Next Hop path. In this case, the proxies discover each other using some form
Resolution Protocol, establish a tunnel and exchange the relevant of Next Hop Resolution Protocol, establish a tunnel and exchange the
mobile network prefix information in the form of explicit prefix relevant Mobile Network Prefix information in the form of explicit
routes. 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
[15]. 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 formed 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 is the optimized route taken between MNN1 and MNN2 in Figure 3 below.
below.
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| MR2_HA | | MR3_HA | | MR4_HA | | MR5_HA | | MR2_HA | | MR3_HA | | MR4_HA | | MR5_HA |
+------+-+ +---+----+ +---+----+ +-+------+ +------+-+ +---+----+ +---+----+ +-+------+
\ | | / \ | | /
+--------+ +------------------------------+ +--------+ +------------------------------+
| MR1_HA |----| Internet |-----CN | MR1_HA |----| Internet |-----CN
+--------+ +--------------+---------------+ +--------+ +--------------+---------------+
| |
+----+----+ +----+----+
skipping to change at page 11, line 41 skipping to change at page 10, line 40
| MR5 | | MR2 | | MR4 | | MR5 | | MR2 | | MR4 |
+---+---+ +---+---+ +---+---+ +---+---+ +---+---+ +---+---+
| | | | | |
---+--- +---+---+ ---+--- ---+--- +---+---+ ---+---
MNN2 | MR3 | MNN3 MNN2 | MR3 | MNN3
+---+---+ +---+---+
| |
----+---- ----+----
MNN1 MNN1
Figure 3: An example of nested Mobile Network Figure 3: An Example of a 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 "Non-Nested 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 [16] which has the Mobile Routers announce their Mobile Network is [16], which has the Mobile Routers announce their Mobile Network
Prefixes 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. In particular, it might prove useful Mobile Ad-Hoc (MANET) protocol. In particular, it might prove useful
to develop a new type of MANET, specialized for the NEMO problem, a to develop a new type of MANET, specialized for the NEMO problem, a
MANET for NEMO (MANEMO). The MANEMO will optimize the formation of MANET for NEMO (MANEMO). The MANEMO will optimize the formation of
the nested NEMO and maintain inner connectivity, whether a connection the nested NEMO and maintain inner connectivity, whether or not a
to the infrastructure can be established or not. connection to the infrastructure can be established.
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
The nodes involved in performing Route Optimization would be expected The nodes involved in performing Route Optimization would be expected
to exchange additional signaling messages in order to establish Route to exchange additional signaling messages in order to establish Route
Optimization. The required amount of signaling depends on the Optimization. The required amount of signaling depends on the
solution, but is likely to exceed the amount required in the home solution, but is likely to exceed the amount required in the home
binding update procedure defined in NEMO Basic Support. The amount Binding Update procedure defined in NEMO Basic Support. The amount
of signaling is likely to increase with the increasing number of of signaling is likely to increase with the increasing number of
Mobile Network Nodes and/or Correspondent Nodes, and may be amplified Mobile Network Nodes and/or Correspondent Nodes, and may be amplified
with nesting of mobile networks. It may scale to unacceptable height with nesting of mobile networks. It may scale to unacceptable
especially to the resource-scarce mobile node which typically has heights, especially to the resource-scarce mobile node, which
limited power, memory and processing capacity. typically has limited power, memory, and processing capacity.
This may lead to an issue that impacts NEMO Route Optimization, known This may lead to an issue that impacts NEMO Route Optimization, known
as the phenomenon of "Binding Update Storm", or more generally, as the phenomenon of "Binding Update Storm", or more generally,
"Signaling Storm". This occurs when a change in point of attachment "Signaling Storm". This occurs when a change in point of attachment
of the mobile network is accompanied with a sudden burst of signaling of the mobile network is accompanied with a sudden burst of signaling
messages, resulting in temporary congestion, packet delays or even messages, resulting in temporary congestion, packet delays, or even
packet loss. This effect will be especially significant for wireless packet loss. This effect will be especially significant for wireless
environment where bandwidth is relatively limited. environment where bandwidth is relatively limited.
It is possible to moderate the effect of Signaling Storm by It is possible to moderate the effect of Signaling Storm by
incorporating mechanisms such as spreading the transmissions burst of incorporating mechanisms such as spreading the transmissions burst of
signaling messages over a longer period of time, or aggregating the signaling messages over a longer period of time, or aggregating the
signaling messages. signaling messages.
Even so, the amount of signaling required might be overwhelming, Even so, the amount of signaling required might be overwhelming,
since a large mobile network (such as those deployed on a train or since large mobile networks (such as those deployed on a train or
plane) may potentially have a large number of flows with a large plane) may potentially have a large number of flows with a large
number of Correspondent Nodes. This might suggest a need to have number of Correspondent Nodes. This might suggest a need to have
some adaptive behavior that depends on the amount of signaling some adaptive behavior that depends on the amount of signaling
required versus the effort needed to tunnel home. required versus the effort needed to tunnel home.
4.2. Increased Protocol Complexity and Processing Load 4.2. Increased Protocol Complexity and Processing Load
It is expected for NEMO Route Optimization to be more complicated It is expected that NEMO Route Optimization will be more complicated
than NEMO Basic Support. Thus, complexity of nodes that are required than NEMO Basic Support. Thus, complexity of nodes that are required
to incorporate new functionalities to support NEMO Route Optimization to incorporate new functionalities to support NEMO Route Optimization
would be higher than those required to provide NEMO Basic Support. would be higher than those required to provide NEMO Basic Support.
Coupled with the increased complexity, nodes that are involved in the Coupled with the increased complexity, nodes that are involved in the
establishment and maintenance of Route Optimization will have to bear establishment and maintenance of Route Optimization will have to bear
the increased processing load. If such nodes are mobile, this may the increased processing load. If such nodes are mobile, this may
prove to be a significant cost due to the limited power and prove to be a significant cost due to the limited power and
processing resources such devices usually have. processing resources such devices usually have.
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Due to the diversity of locations of different nodes that Mobile Due to the diversity of locations of different nodes that Mobile
Network Node may signal with and the complexity of NEMO Route Network Node may signal with and the complexity of NEMO Route
Optimization procedure that may cause several rounds of signaling Optimization procedure that may cause several rounds of signaling
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 transparency and location privacy (see compromise of mobility transparency and location privacy (see
Section 4.7 and Section 4.8), this mechanism also increases the delay Section 4.7 and Section 4.8), this mechanism also increases the delay
during handoffs. during handoffs.
Some of the solutions for Mobile IPv6, such as Fast Handoff for Some of the solutions for Mobile IPv6, such as Fast Handovers for
Mobile IPv6 [17], 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. Extending Nodes with 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 the NEMO Route Optimization
the Internet and create less impact on existing Internet solution in 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.
Possible nodes that may be required to change include: Possible nodes that may be required to change include the following:
o Local Fixed Nodes o Local Fixed Nodes
It may prove to be difficult to introduce new functionalities at It may prove to be difficult to introduce new functionalities at
Local Fixed Nodes, since by definition, any IPv6 node can be a Local Fixed Nodes, since by definition, any IPv6 node can be a
Local Fixed Node. This might mean that only those Local Fixed Local Fixed Node. This might mean that only those Local Fixed
Nodes that are modified can enjoy the benefits of Route Nodes that are modified can enjoy the benefits of Route
Optimization. Optimization.
o Visiting Mobile Nodes o Visiting Mobile Nodes
Visiting Mobile Nodes in general should already implement Mobile Visiting Mobile Nodes in general should already implement Mobile
IPv6 functionalities, and since Mobile IPv6 is a relatively new IPv6 functionalities, and since Mobile IPv6 is a relatively new
standard, there is still a considerable window to allow mobile standard, there is still a considerable window to allow mobile
devices to implement new functionalities. devices to implement new functionalities.
o Mobile Routers o Mobile Routers
It is expected for Mobile Routers to implement new functionalities It is expected that Mobile Routers will implement new
in order to support route optimization. functionalities in order to support Route Optimization.
o Access Routers o Access Routers
Some approaches require access routers, or nodes in the access Some approaches require access routers, or nodes in the access
network, to implement some new functionalities. It may prove to network, to implement some new functionalities. It may prove to
be difficult to do so, since access routers, are in general, be difficult to do so, since access routers are, in general,
standard IPv6 routers. standard IPv6 routers.
o Home Agents o Home Agents
It is relatively easier for new functionalities to be implemented It is relatively easier for new functionalities to be implemented
in Home Agents. in Home Agents.
o Correspondent Nodes o Correspondent Nodes
It may prove to be difficult to introduce new functionalities at It may prove to be difficult to introduce new functionalities at
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Correspondent Routers are new entities introduced for the purpose Correspondent Routers are new entities introduced for the purpose
of Route Optimization, and therefore new functionalities can be of Route Optimization, and therefore new functionalities can be
defined as needed. defined as needed.
4.5. Detection of New Functionalities 4.5. Detection of New Functionalities
One issue that is related to the need for new functionalities as One issue that is related to the need for new functionalities as
described in Section 4.4 is the need to detect the existence of such described in Section 4.4 is the need to detect the existence of such
functionalities. In these cases, a detection mechanism might be functionalities. In these cases, a detection mechanism might be
helpful to allow the initiator of Route Optimization to detect if helpful to allow the initiator of Route Optimization to detect
support of the new functionalities are available. Furthermore, it whether support for the new functionalities is available.
might be advantageous to have a graceful fall back procedure if the Furthermore, it might be advantageous to have a graceful fall back
required functionalities are unavailable. procedure if the required functionalities are unavailable.
4.6. Scalability 4.6. Scalability
Given the same number of nodes, the number of route optimization Given the same number of nodes, the number of Route Optimization
sessions would usually be more than the number of NEMO Basic Support sessions would usually be more than the number of NEMO Basic Support
tunnels. If all route optimization sessions of a mobile network are tunnels. If all Route Optimization sessions of a mobile network are
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 mean 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 lead 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 a 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 a
Correspondent Node(s) with a large number of Mobile Routers. Correspondent Node(s) with a large number of Mobile Routers.
4.7. Mobility Transparency 4.7. Mobility Transparency
One advantage of NEMO Basic Support is that the Mobile Network Nodes One advantage of NEMO Basic Support is that the Mobile Network Nodes
need not be aware of the actual location and mobility of the mobile need not be aware of the actual location and mobility of the mobile
network. With some approaches for 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
the Mobile Network Nodes. This may mean a tradeoff between mobility the Mobile Network Nodes. This may mean a tradeoff between mobility
transparency and Route Optimization. transparency and Route Optimization.
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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.
4.9. 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. For this reason, the security protection of
Optimization signaling message is considered as "weaker" than that in NEMO Route Optimization signaling message is considered "weaker" than
NEMO Basic Support. It is expected that some additional security that in NEMO Basic Support. It is expected that some additional
mechanisms are needed to achieve the same or similar level of security mechanisms are needed to achieve the same or similar level
security as in NEMO Basic Support. of 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 [19]. Mobile IPv6 Route Optimization was designed as documented in [19].
4.10. 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 that are not aware of the mobility of the
they are in, and those that do not understand any mobility protocols) network they are in, and those that do not understand any mobility
can still reach and be reached from the Internet. Some Route protocols) can still reach and be reached from the Internet. Some
Optimization schemes, however, require that all Mobile Routers to Route Optimization schemes, however, require that all Mobile Routers
implement the same Route Optimization scheme in order for them to implement the same Route Optimization scheme in order for them to
operate. Thus, a nested Mobile Router may not be able to achieve operate. Thus, a nested Mobile Router may not be able to achieve
Route Optimization if it is attached to a legacy Local Fixed Router. Route Optimization if it is attached to a legacy Local Fixed 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 initiates Route Optimization? When?
3. How to detect Route Optimization capabilities? 3. How is Route Optimization capabilities detected?
4. How is the address of Mobile Network Node represented? 4. How is the address of the Mobile Network Node represented?
5. How is the address of Mobile Network Node bound to location of 5. How is the Mobile Network Node's address bound to location?
mobile network?
6. How is signaling performed? 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
Section 4.4 and Section 4.5. Below is a list of combinations to be Section 4.4 and Section 4.5. Below is a list of combinations to be
discussed in the following subsections: discussed in the following sub-sections:
o Mobile Network Node and Correspondent Node o Mobile Network Node and Correspondent Node
o Mobile Router and Correspondent Node o Mobile Router and Correspondent Node
o Mobile Router and Correspondent Router o Mobile Router and Correspondent Router
o Entities in the Infrastructure o Entities in the Infrastructure
5.1.1. Mobile Network Node and Correspondent Node 5.1.1. Mobile Network Node and Correspondent Node
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Node, it needs to be able to maintain the bindings sent by the Mobile Node, it needs to be able to maintain the bindings sent by the Mobile
Network Nodes. Network Nodes.
5.1.2. Mobile Router and Correspondent Node 5.1.2. Mobile Router and Correspondent Node
Alternatively, the Mobile Router can establish Route Optimization Alternatively, the Mobile Router can establish Route Optimization
with a Correspondent Node on behalf of the Mobile Network Node. with a Correspondent Node on behalf of the Mobile Network Node.
Since all packets to and from the Mobile Network Node must transit Since all packets to and from the Mobile Network Node must transit
the Mobile Router, this effectively achieves an optimal route for the the Mobile Router, this effectively achieves an optimal route for the
entire end-to-end path as well. Compared with Section 5.1.1, the entire end-to-end path as well. Compared with Section 5.1.1, the
scalability issue here may be remedied since it is possible for scalability issue here may be remedied since it is possible for the
Correspondent Node to maintain only one session with the Mobile Correspondent Node to maintain only one session with the Mobile
Router if it communicates with many Mobile Network Nodes associated Router if it communicates with many Mobile Network Nodes associated
with the same Mobile Router. Furthermore, with the Mobile Router with the same Mobile Router. Furthermore, with the Mobile Router
handling Route Optimization, there is no need for Mobile Network handling Route Optimization, there is no need for Mobile Network
Nodes to implement new functionalities. However, new functionality Nodes to implement new functionalities. However, new functionality
is likely to be required on the Correspondent Node. An additional is likely to be required on the Correspondent Node. An additional
point of consideration is the amount of state information the Mobile point of consideration is the amount of state information the Mobile
Router is required to maintain. Traditionally, it has been generally Router is required to maintain. Traditionally, it has been generally
avoided to have state information in the routers to increase avoided having state information in the routers to increase
proportionally with the number 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 these approaches is that
additional functionality is required for the Correspondent Node and no additional functionality is required for the Correspondent Node
Mobile Network Nodes. In addition, location privacy is relatively and Mobile Network Nodes. In addition, location privacy is
preserved, since the current location of the mobile network is only relatively preserved, since the current location of the mobile
revealed to the Correspondent Router and not to the Correspondent network is only revealed to the Correspondent Router and not to the
Node (please refer to Section 5.8.3 for more discussions). Correspondent Node (please refer to Section 5.8.3 for more
Furthermore, if the Mobile Router and Correspondent Router exchange discussions). Furthermore, if the Mobile Router and Correspondent
prefix information, this approach may scale well since a single Route Router exchange prefix information, this approach may scale well
Optimization session between the Mobile Router and Correspondent since a single Route Optimization session between the Mobile Router
Router can achieve Route Optimization between any Mobile Network Node and Correspondent Router can achieve Route Optimization between any
in the mobile network, and any Correspondent Node managed by the Mobile Network Node in the mobile network, and any Correspondent Node
Correspondent Router. managed by the Correspondent Router.
The main concern with this approach is the need for a mechanism to The main concern with this approach is the need for a mechanism to
allow the Mobile Router to detect the presence of the Correspondent allow the Mobile Router to detect the presence of the Correspondent
Router (see Section 5.3 for details), and its security impact. Both Router (see Section 5.3 for details), and its security impact. Both
the Mobile Router and the Correspondent Router need some means to the Mobile Router and the Correspondent Router need some means to
verify the validity of each other. This is discussed in greater verify the validity of each other. This is discussed in greater
detail in Section 5.8. detail in Section 5.8.
A deployment consideration with respect to the use of Correspondent A deployment consideration with respect to the use of Correspondent
Router is the location of the Correspondent Router relative to the Router is the location of the Correspondent Router relative to the
Correspondent Node. On one hand, deploying the Correspondent Router Correspondent Node. On one hand, deploying the Correspondent Router
nearer to the Correspondent Node would result in a more optimal path. nearer to the Correspondent Node would result in a more optimal path.
On the other hand, a Correspondent Router that is placed further away On the other hand, a Correspondent Router that is placed farther away
from the Correspondent Node can perform Route Optimization on behalf from the Correspondent Node can perform Route Optimization on behalf
of more Correspondent Nodes. of more Correspondent Nodes.
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 [14]). Home Agent of the Mobile Router (such as in the global Home Agent to
Another concern is that the resulting path may not be a true Home Agent protocol [14]). Another concern is that the resulting
optimized one, since it depends on the relative positions of the path may not be a true optimized one, since it depends on the
infrastructure entities with respect to the mobile network and the relative positions of the infrastructure entities with respect to the
Correspondent Node. mobile network and the Correspondent Node.
5.2. Who and When to Initiate Route Optimization? 5.2. Who Initiates Route Optimization? When?
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,
the node that is moving (i.e. Mobile Network Node or Mobile Router) the node that is moving (i.e., Mobile Network Node or Mobile Router)
is in the best position to detect its mobility. Thus, in general, it is in the best position to detect its mobility. Thus, in general, it
is better for the mobile node to initiate the Route Optimization is better for the mobile node to initiate the Route Optimization
session in order to handle the topology changes in any kind of session in order to handle the topology changes in any kind of
mobility pattern and achieve the optimized route promptly. However, mobility pattern and achieve the optimized route promptly. However,
when the mobile node is within a nested mobile network, the detection when the mobile node is within a nested mobile network, the detection
of the mobility of upstream Mobile Routers may need to be conveyed to of the mobility of upstream Mobile Routers may need to be conveyed to
the nested Mobile Network Node. This might incur longer signaling the nested Mobile Network Node. This might incur longer signaling
delay as discussed in Section 4.3. delay as discussed in Section 4.3.
Some solution may enable the node on the correspondent side to Some solution may enable the node on the correspondent side to
initiate Route Optimization session in certain situations. For initiate the Route Optimization session in certain situations. For
instance, when the Route Optimization state that is already instance, when the Route Optimization state that is already
established on the Correspondent Entity is about to expire but the established on the Correspondent Entity is about to expire but the
communication is still active, depending on the policy, the communication is still active, depending on the policy, the
Correspondent Entity may initiate a Route Optimization request with Correspondent Entity may initiate a Route Optimization request with
the mobile node side. the mobile node side.
There is also the question of when Route Optimization should be There is also the question of when Route Optimization should be
initiated. Because route optimization would certainly incur initiated. Because Route Optimization would certainly incur
tradeoffs of various forms, it might not be desirable for Route tradeoffs of various forms, it might not be desirable for Route
Optimization to be performed for any kind of traffic. This is, Optimization to be performed for any kind of traffic. This is,
however, implementation specific and policy driven. however, implementation specific and policy driven.
A related question is how often signaling messages should be sent to A related question is how often signaling messages should be sent to
maintain the Route Optimization session. Typically, signaling maintain the Route Optimization session. Typically, signaling
messages is likely to be sent whenever there is topological changes. messages are likely to be sent whenever there are topological
The discussion in Section 4.1 should be considered. In addition, a changes. The discussion in Section 4.1 should be considered. In
Lifetime value is often used to indicate the period of validity for addition, a Lifetime value is often used to indicate the period of
the Route Optimization session. Signaling messages would have to be validity for the Route Optimization session. Signaling messages
sent before the Lifetime value expires in order to maintain the Route would have to be sent before the Lifetime value expires in order to
Optimization session. The choice of Lifetime value needs to balance maintain the Route Optimization session. The choice of Lifetime
between different considerations. On one hand, a short Lifetime value needs to balance between different considerations. On one
value would increase the amount of signaling overhead. On the other hand, a short Lifetime value would increase the amount of signaling
hand, a long Lifetime value may expose the Correspondent Entity to overhead. On the other hand, a long Lifetime value may expose the
the risk of having an obsolete binding cache entry, which creates an Correspondent Entity to the risk of having an obsolete binding cache
opportunity for an attacker to exploit. entry, which creates an opportunity for an attacker to exploit.
5.3. How to Detect Route Optimization Capability? 5.3. How Is Route Optimization Capability Detected?
The question here is how the initiator of Route Optimization knows if The question here is how the initiator of Route Optimization knows
the Correspondent Entity supports the functionality required to whether the Correspondent Entity supports the functionality required
established a Route Optimization session. The usual method is for to established a Route Optimization session. The usual method is for
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 or not the
Entity supports the required functionality to establish Route Correspondent Entity supports the required functionality to establish
Optimization or not. This form of detection may incur additional Route Optimization. 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-signaling. 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][8]. 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 the Route Optimization session on behalf of
Correspondent Node will respond. Another way is to insert a Router the Correspondent Node will respond. Another way is to insert a
Alert Option (RAO) to a packet sent to the Correspondent Node [9]. Router Alert Option (RAO) into a packet sent to the Correspondent
Any Correspondent Router en route will process the Router Alert Node [9]. Any Correspondent Router en route will process the Router
Option, and send a response to the Mobile Router. Alert 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 the Address of Mobile Network Node Represented? 5.4. How is the Address of the 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 a Mobile Network Node and the location of the mobile address of a Mobile Network Node and the location of the mobile
network is registered at the Correspondent Entity. Before exploring network is registered at the Correspondent Entity. Before exploring
into different ways of binding (see Section 5.5), one must first ask different ways of binding (see Section 5.5), one must first ask how
how the address of the Mobile Network Node is represented. the address of the Mobile Network Node is represented. Basically,
Basically, there are two ways to represent the Mobile Network Node's there are two ways to represent the Mobile Network Node's address:
address:
o inferred by the use of the Mobile Network Prefix, or o inferred by the use of the Mobile Network Prefix, or
o explicitly specifying the address of the 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 would 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 either the initiator is 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.
5.5. How is Mobile Network Node's Address Bound to Location? 5.5. How Is the Mobile Network Node's Address Bound to Location?
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 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 are 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 would 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 [11]. 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 the standard Mobile IPv6 Route Optimization procedure
bind the address of a Mobile Network Node to the Mobile Router's to bind the address of a Mobile Network Node to the Mobile
care-of address. For instance, when the Mobile Network Node is a Router's Care-of Address. For instance, when the Mobile Network
Local Fixed Node without Mobile IPv6 Route Optimization Node is a Local Fixed Node without Mobile IPv6 Route Optimization
functionality, the Mobile Router may initiate the 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 Local Fixed Node. An example of such an approach would be
[20][21]. [20][21][22].
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 [22] for an example of such delegation). With this Router (see [23] 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 alter the 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
Mobile Network Node is a Local Fixed Node. Mobile Network Node is a Local Fixed Node.
For all of the approaches listed above, when the Mobile Network Node For all of the approaches listed above, when the Mobile Network Node
is deeply nested within a Mobile Network, the Correspondent Entity is deeply nested within a Mobile Network, the Correspondent Entity
would need to gather Binding Updates from all the upstream Mobile would need to gather Binding Updates from all the upstream Mobile
Routers in order to build the complete route to reach the Mobile Routers in order to build the complete route to reach the Mobile
Network Node. This increases the complexity of the Correspondent Network Node. This increases the complexity of the Correspondent
Entity, as the Correspondent Entity may need to perform multiple Entity, as the Correspondent Entity may need to perform multiple
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these approaches may incur extra signaling overhead and delay for a these approaches may incur extra signaling overhead and delay for a
nested Mobile Network Node. For instance, every Mobile Router on the nested Mobile Network Node. For instance, every Mobile Router on the
upstream of the Mobile Network Node needs to send Binding Updates to upstream of the Mobile Network Node needs to send Binding Updates to
the Correspondent Entity. If this is done by the upstream Mobile the Correspondent Entity. If this is done by the upstream Mobile
Routers independently, it may incur additional signaling overhead. Routers independently, it may incur additional signaling overhead.
Also, since each Binding Update takes a finite amount of time to Also, since each Binding Update takes a finite amount of time to
reach and be processed by the Correspondent Entity, the delay from reach and be processed by the Correspondent Entity, the delay from
the time an optimized route is changed till the time the change is the time an optimized route is changed till the time the change is
registered on the Correspondent Entity will increase proportionally registered on the Correspondent Entity will increase proportionally
with the number of Mobile Routers on the upstream of the Mobile with the number of Mobile Routers on the upstream of the Mobile
Network Node (i.e. the level of nesting of the Mobile Network Node). Network Node (i.e., the level of nesting of the Mobile Network Node).
For "Binding Update with Mobile Network Prefix" and "Sending For "Binding Update with Mobile Network Prefix" and "Sending
Information of Upstream Mobile Router", new functionality is required Information of Parent Mobile Router", new functionality is required
at the Correspondent Entity, whereas "Mobile Router as a Proxy" keeps at the Correspondent Entity, whereas "Mobile Router as a Proxy" keeps
the functionality of the Correspondent Entity to be the same as a the functionality of the Correspondent Entity the same as a Mobile
Mobile IPv6 Correspondent Node. However, this is done at an expense IPv6 Correspondent Node. However, this is done at an expense of the
of the Mobile Routers, since in "Mobile Router as a Proxy", the Mobile Routers, since in "Mobile Router as a Proxy", the Mobile
Mobile Router must maintain state information for every Route Router must maintain state information for every Route Optimization
Optimization session its Mobile Network Nodes have. Furthermore, in session its Mobile Network Nodes have. Furthermore, in some cases,
some cases, the Mobile Router needs to look beyond the standard IPv6 the Mobile Router needs to look beyond the standard IPv6 headers for
headers for ingress and egress packets, and alter the packet contents ingress and egress packets, and alter the packet contents
appropriately. appropriately (this may impact end-to-end integrity, see 5.8.2).
One advantage shared by all the approaches listed here is that only One advantage shared by all the approaches listed here is that only
mobility protocol is affected. In other words, no modification is mobility protocol is affected. In other words, no modification is
required on other existing protocols (such as Neighbor Discovery). required on other existing protocols (such as Neighbor Discovery).
There is also no additional requirements on existing infrastructure There is also no additional requirement on existing infrastructure
(such as the access network). (such as the access network).
In addition, having upstream Mobile Routers send Binding Updates In addition, having upstream Mobile Routers send Binding Updates
independently means that the Correspondent Entity can use the same independently means that the Correspondent Entity can use the same
binding cache entries of upstream Mobile Routers to construct the binding cache entries of upstream Mobile Routers to construct the
complete route to two Mobile Network Nodes that have common upstream complete route to two Mobile Network Nodes that have common upstream
Mobile Routers. This may translate to lower memory consumption since Mobile Routers. This may translate to lower memory consumption since
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 Optimization 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 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 [10] of the binding information. Examples using this approach are [10]
and [12]. 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,
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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 [10] where upstream Mobile Routers insert their current is (such as used in [10]) where upstream Mobile Routers insert their
point of attachment into a Reverse Routing Header embedded within a current point of attachment into a Reverse Routing Header embedded
packet sent by the Mobile Network Node. This may raise security within a packet sent by the Mobile Network Node. This may raise
concerns that will be discussed later in Section 5.8.2. security 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 a new option in Router Advertisement message. routing header or a new option in the 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 a 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
of approach can be viewed as flattening the structure of a nested of approach can be viewed as flattening the structure of a nested
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
Prefix Delegation [15]). Each Mobile Router also autoconfigures Dynamic Host Configuration Protocol (DHCP) Prefix Delegation
its care-of address from this delegated prefix. In this way, the [15]). Each Mobile Router also autoconfigures its Care-of Address
care-of addresses of Mobile Routers are all from an aggregatable from this delegated prefix. In this way, the Care-of Addresses of
address space starting from the access router. Mobile Network Mobile Routers are all from an aggregatable address space starting
Nodes with Mobile IPv6 functionality may also autoconfigure its from the access router. A Mobile Network Node with Mobile IPv6
care-of address from this delegated prefix, and use standard functionality may also autoconfigure its Care-of Address from this
Mobile IPv6 mechanism to bind its home address to this care-of delegated prefix, and use standard Mobile IPv6 mechanism's to bind
address. its Home Address to this Care-of Address.
Examples of this approach includes [23] and [24][25]. Examples of this approach include [24], [25], and [26].
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.
o Neighbor Discovery Proxy o Neighbor Discovery Proxy
This approach (such as [26][27]) achieves Route Optimization by This approach (such as [27] and [28]) achieves Route Optimization
having Mobile Router to act as a Neighbor Discovery [28] proxy for by having the Mobile Router act as a Neighbor Discovery [29] proxy
its Mobile Network Nodes. The Mobile Router will configure a for its Mobile Network Nodes. The Mobile Router will configure a
care-of address from the network prefix advertised by its access Care-of Address from the network prefix advertised by its access
router, and also relay this prefix to its subnets. When a Mobile router, and also relay this prefix to its subnets. When a Mobile
Network Node configures an address from this prefix, the Mobile Network Node configures an address from this prefix, the Mobile
Router will act as a Neighbor Discovery proxy on its behalf. In Router will act as a Neighbor Discovery proxy on its behalf. In
this 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.
Not only will this cause a burst of Binding Updates where every Not only will this cause a burst of Binding Updates 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, 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 themselves with either their nested Mobile Routers) registering themselves with either their
parent 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 an approach uses the principle of Hierarchical
Mobile IPv6 [13], 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 its 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 numbers 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 [29], [30] and [31][32]. Examples of this approach include [30], [31], [32], and [33].
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
Internet. All nodes in the mobile network would configure their Internet. All nodes in the mobile network would configure their
care-of addresses from one or more prefixes advertised by that Care-of Addresses from one or more prefixes advertised by that
gateway, while their parent Mobile Routers use Mobile Ad-hoc gateway, while their parent Mobile Routers use Mobile Ad-hoc
routing to forward packets to that gateway or other destinations routing to forward packets to that gateway or other destinations
inside the mobile network. inside the mobile network.
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 [10]. 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 fewer topological changes to the mobile network.
However, data packets transmission may be disrupted while off-plane However, data packet 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
protocols 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 [33] which uses the Session Initiation Protocol of such a mechanism is [34], which uses the Session Initiation
(SIP) to relay binding information. Protocol (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 [34]. In this way, the original packet can in-IP encapsulations [35]. 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 the 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
[35][36] [37] to compress the multiple tunnel packet headers. [36][37][38] 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.
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 [23][24][25] would For instance, the Prefix Delegation approach [24][25][26] 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 the 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 [19], 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) (DoS) (flooding a victim with packets meant for a Mobile Network
attacks. Node) 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
implementations. But in other situations, an extension to the Return implementations. But in other situations, an extension to the Return
Routability procedure might be necessary. Routability procedure might be necessary.
For instance, consider the case where the Mobile Router sends Binding For instance, consider the case where the Mobile Router sends a
Update containing Mobile Network Prefix information to Correspondent Binding Update containing Mobile Network Prefix information to the
Entity (see Section 5.5.1). Although the Return Routability Correspondent Entity (see Section 5.5.1). Although the Return
procedure allows the Correspondent Entity to verify that the care-of Routability procedure allows the Correspondent Entity to verify that
and home addresses of the Mobile Router are indeed collocated, it the Care-of and Home Addresses of the Mobile Router are indeed
does not allow the Correspondent Entity to verify the validity of the collocated, it does not allow the Correspondent Entity to verify the
Mobile Network Prefix. If the Correspondent Entity accepts the validity of the Mobile Network Prefix. If the Correspondent Entity
binding without verification, it will be exposed to attacks where the accepts the binding without verification, it will be exposed to
attacker tricks the Correspondent Entity into forwarding packets attacks where the attacker tricks the Correspondent Entity into
destined for a mobile network to the attacker (snooping) or victim forwarding packets destined for a mobile network to the attacker
(DoS). [38] discusses this security threat further. (snooping) or victim (DoS); [39] 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 that the Correspondent Router is
of terminating Route Optimization on behalf of to Mobile Network capable of terminating Route Optimization on behalf of to Mobile
Nodes. In such cases, the Mobile Network Nodes also need a mechanism Network Nodes. In such cases, the Mobile Network Nodes also need a
to check the authenticity of such claims. Even if the Correspondent mechanism to check the authenticity of such claims. Even if the
Routers do not advertise the network prefix, the Mobile Network Nodes Correspondent Routers do not advertise the network prefix, the Mobile
also have the need to verify that the Correspondent Router is indeed Network Nodes also have the need to verify that the Correspondent
a valid Correspondent Router for a given Correspondent Node. Router is indeed a valid Correspondent Router for a given
Correspondent Node.
In Section 5.5.2, the signaling of Route Optimization involves In Section 5.5.2, the registration signaling involves sending the
sending the location of one or more upstream Mobile Routers. The information about one or more upstream Mobile Routers. The
Correspondent Entity must also have the means to verify such Correspondent Entity (or Home Agent) must also have the means to
information. Again, the standard Return Routability procedure is verify such information. Again, the standard Return Routability
inadequate here. An extension such as attaching a routing header to procedure as defined in [3] is inadequate here, as it is not designed
the Care-of Test (CoT) message to verify the authenticity of the to verify the reachability of an address over a series of upstream
routers. An extension such as attaching a routing header to the
Care-of Test (CoT) message to verify the authenticity of the
locations of upstream Mobile Routers is likely to be needed. The locations of upstream Mobile Routers is likely to be needed. The
risk, however, is not confined to the Correspondent Entities. The risk, however, is not confined to Correspondent Entities. The Mobile
Mobile Network Nodes are also under the threat of receiving false 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 Correspondent Entities (this also implies that Correspondent
this kind of on-path threat exists in the current Internet anyway Entities cannot rely on any security associations they have with the
especially when no (or weak) end-to-end protection is used. Mobile Network Nodes to establish the validity of address bindings).
There are some considerations that this kind of on-path threat exists
in the current Internet anyway 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) [39], the use of instance, in Secure Neighbor Discovery (SEND) [40], Cryptographically
Cryptographically Generated Addresses (CGA) [40] could be used to Generated Addresses (CGAs) [41] could be used to establish the
establish the ownership of care-of addresses and network prefixes. ownership of Care-of Addresses. [42] employs the Home Agent to check
[41] employs the Home Agent to check the signaling messages sent by the signaling messages sent by Mobile Routers to provide a way for
Mobile Routers to provide a way for Correspondent Entities to verify Correspondent Entities to verify the authenticity of Mobile Network
the authenticity of Mobile Network Prefixes specified. [42] documents Prefixes specified. [18] documents various proposed enhancements to
various proposed enhancements to the Mobile IPv6 Route Optimization the Mobile IPv6 Route Optimization mechanism that might be applied to
mechanism which might be applied to NEMO Route Optimization as well, NEMO Route Optimization as well, such as [43], which allows the
such as [43] which allows the Correspondent Entity to authenticate a Correspondent Entity to authenticate a certain operator's Home Agent
certain operator's Home Agent by verifying the associated by verifying the associated certificate. The Host Identity Protocol
certificate. The Host Identity Protocol (HIP) [44] with end-host (HIP) [44] with end-host mobility considerations [45] may be extended
mobility considerations [45] may also be extended for NEMO Route for NEMO Route Optimization as well.
Optimization as well.
In addition, interested readers might want to refer to [46] that In addition, interested readers might want to refer to [46], which
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 in [23] for Mobile Network Node to delegate some
their Mobile Routers in [22], which may be used to allow the Mobile rights to their Mobile Routers, 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
Entities and the Mobile Network Nodes. However, adopting such a Entities and the Mobile Network Nodes. However, adopting such a
strategy may interfere with existing or future protocols, most strategy may interfere with existing or future protocols, most
particularly security-related protocols. This is especially true particularly security-related protocols. This is especially true
when the Mobile Router needs to make changes to packets sent by when the Mobile Router needs to make changes to packets sent by
Mobile Network Nodes. In a sense, these approaches break the end-to- Mobile Network Nodes. In a sense, these approaches break the end-to-
end integrity of packets. A related concern is that this kind of end integrity of packets. A related concern is that this kind of
approach may also require the Mobile Router to inspect into packet approach may also require the Mobile Router to inspect the packet
contents sent to/by Mobile Network Nodes. This may prove to be contents sent to/by Mobile Network Nodes. This may prove to be
difficult or impossible if such contents are encrypted. difficult or impossible if such contents are encrypted.
The concern over end-to-end integrity arises for the use of Reverse The concern over end-to-end integrity arises for the use of a Reverse
Routing Header (see Section 5.5.2) too, since Mobile Routers would Routing Header (see Section 5.5.2) too, since Mobile Routers would
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 document currently does not consider the location privacy
caused by an on path eavesdropper. For more information on that threats caused by an on-path eavesdropper. For more information on
aspect, please refer to [18]. Instead, we consider the following that aspect, please refer to [18]. Instead, we consider the
three aspects to location privacy: following 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 the
Network Node be revealed to the Correspondent Entity. The concern Mobile Network Node be revealed to the Correspondent Entity. The
may be alleviated if the Correspondent Entity is not the concern 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 end
end-point (i.e. the Correspondent Node) would remain ignorant of point (i.e., the Correspondent Node) would remain ignorant of the
the current location of the Mobile Network Node. current location of the Mobile Network Node.
o Degree of Revelation o Degree of Revelation
With network mobility, the degree of location exposure varies, With network mobility, the degree of location exposure varies,
especially when one considers nested mobile networks. For especially when one considers nested mobile networks. For
instance, for approaches that bind the address of the Mobile instance, for approaches that bind the address of the Mobile
Network Node to the location of the root Mobile Router (see Network Node to the location of the root Mobile Router (see
Section 5.5.3), only the topmost point of attachment of the mobile Section 5.5.3), only the topmost point of attachment of the mobile
network is revealed to the Correspondent Entity. Whereas for network is revealed to the Correspondent Entity. For approaches
approaches such as those described in Section 5.5.1 and such as those described in Section 5.5.1 and Section 5.5.2, more
Section 5.5.2, more information (such as Mobile Network Prefixes information (such as Mobile Network Prefixes and current locations
and current locations of upstream Mobile Routers) is revealed. of upstream Mobile Routers) is revealed. Techniques such as
exposing only locally-scoped addresses of intermediate upstream
mobile routers to Correspondent Entities may be used to reduce the
degree of revelation.
o Control of the Revelation o Control of the Revelation
When Route Optimization is initiated by the Mobile Network Node When Route Optimization is initiated by the Mobile Network Node
itself, it is in control of whether or not to sacrifice location itself, it is in control of whether or not to sacrifice location
privacy for an optimized route. However, if it is the Mobile privacy for an optimized route. However, if it is the Mobile
Router that initiates Route Optimization (e.g. "Binding Update Router that initiates Route Optimization (e.g., "Binding Update
with Mobile Network Prefix" and "Mobile Router as a Proxy" in with Mobile Network Prefix" and "Mobile Router as a Proxy" in
Section 5.5.1), then control is taken away from the Mobile Network Section 5.5.1), then control is taken away from the Mobile Network
Node. Additional signaling mechanism between the Mobile Network Node. An additional signaling mechanism between the Mobile
Node and its Mobile Router can be used in this case to prevent the Network Node and its Mobile Router can be used in this case to
Mobile Router from attempting Route Optimization for a given prevent the Mobile Router from attempting Route Optimization for a
traffic stream. given traffic stream.
6. Conclusion 6. Conclusion
The problem space of Route Optimization in the NEMO context is The problem space of Route Optimization in the NEMO context is
multifold and can be split into several work areas. It will be multifold and can be split into several work areas. It will be
critical, though, that the solution to a given piece of the puzzle be critical, though, that the solution to a given piece of the puzzle be
compatible and integrated smoothly with others. With this in mind, compatible and integrated smoothly with others. With this in mind,
this document attempts to present a detailed and in depth analysis of this document attempts to present a detailed and in-depth analysis of
the NEMO Route Optimization solution space by first describing the the NEMO Route Optimization solution space by first describing the
benefits a Route Optimization solution is expected to bring, then benefits a Route Optimization solution is expected to bring, then
illustrating the different scenarios in which a Route Optimization illustrating the different scenarios in which a Route Optimization
solution applies to, and next presenting some issues a Route solution applies, and next presenting some issues a Route
Optimization solution might face. We have also asked ourselves some Optimization solution might face. We have also asked ourselves some
of the basic questions about a Route Optimization solution. By of the basic questions about a Route Optimization solution. By
investigating different possible answers to these questions, we have investigating different possible answers to these questions, we have
explored different aspects to a Route Optimization solution. The explored different aspects to a Route Optimization solution. The
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. Security Considerations
This is an informational document and does not require any IANA
action.
8. Security Considerations
This is an informational document that analyzes 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 4.9 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 8. Acknowledgments
The authors wish to thank the co-authors of previous drafts from The authors wish to thank the co-authors of previous versions from
which this draft is derived: Marco Molteni, Paik Eun-Kyoung, Hiroyuki which this document is derived: Marco Molteni, Paik Eun-Kyoung,
Ohnishi, Felix Wu, and Souhwan Jung. In addition, sincere Hiroyuki 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 9. References
10.1. Normative References 9.1. Normative References
[1] Ng, C., Thubert, P., Watari, M., and F. Zhao, "Network Mobility [1] Ng, C., Thubert, P., Watari, M., and F. Zhao, "Network Mobility
Route Optimization Problem Statement", Route Optimization Problem Statement", RFC 4888, July 2007.
draft-ietf-nemo-ro-problem-statement-03 (work in progress),
September 2006.
[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] Ernst, T., "Network Mobility Support Goals and Requirements", [4] Ernst, T., "Network Mobility Support Goals and Requirements",
draft-ietf-nemo-requirements-05 (work in progress), RFC 4886, July 2007.
October 2005.
[5] Manner, J. and M. Kojo, "Mobility Related Terminology", [5] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004. RFC 3753, June 2004.
[6] Ernst, T. and H. Lach, "Network Mobility Support Terminology", [6] Ernst, T. and H-Y. Lach, "Network Mobility Support
draft-ietf-nemo-terminology-05 (work in progress), March 2006. Terminology", RFC 4885, July 2007.
10.2. Informative References 9.2. Informative References
[7] Wakikawa, R., Koshiba, S., Uehara, K., and J. Murai, "ORC: [7] Wakikawa, R., Koshiba, S., Uehara, K., and J. Murai, "ORC:
Optimized Route Cache Management Protocol for Network Optimized Route Cache Management Protocol for Network
Mobility", 10th International Conference on Telecommunications, Mobility", 10th International Conference on Telecommunications,
vol 2, pp 1194-1200, February 2003. vol 2, pp 1194-1200, February 2003.
[8] Wakikawa, R. and M. Watari, "Optimized Route Cache Protocol [8] Wakikawa, R. and M. Watari, "Optimized Route Cache Protocol
(ORC)", draft-wakikawa-nemo-orc-01 (work in progress), (ORC)", Work in Progress, November 2004.
November 2004.
[9] Na, J., Cho, S., Kim, C., Lee, S., Kang, H., and C. Koo, "Route [9] Na, J., Cho, S., Kim, C., Lee, S., Kang, H., and C. Koo, "Route
Optimization Scheme based on Path Control Header", Optimization Scheme based on Path Control Header", Work
draft-na-nemo-path-control-header-00 (work in progress), in Progress, April 2004.
April 2004.
[10] Thubert, P. and M. Molteni, "IPv6 Reverse Routing Header and [10] Thubert, P. and M. Molteni, "IPv6 Reverse Routing Header and
its application to Mobile Networks", its application to Mobile Networks", Work in Progress,
draft-thubert-nemo-reverse-routing-header-05 (work in February 2007.
progress), June 2004.
[11] 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", Work in Progress, July 2004.
draft-ng-nemo-access-router-option-01 (work in progress),
July 2004.
[12] Na, J., Cho, S., Kim, C., Lee, S., Kang, H., and C. Koo, [12] Na, J., Cho, S., Kim, C., Lee, S., Kang, H., and C. Koo,
"Secure Nested Tunnels Optimization using Nested Path "Secure Nested Tunnels Optimization using Nested Path
Information", draft-na-nemo-nested-path-info-00 (work in Information", Work in Progress, September 2003.
progress), September 2003.
[13] 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.
[14] Thubert, P., Wakikawa, R., and V. Devarapalli, "Global HA to HA [14] Thubert, P., Wakikawa, R., and V. Devarapalli, "Global HA to HA
protocol", draft-thubert-nemo-global-haha-01 (work in protocol", Work in Progress, September 2006.
progress), October 2005.
[15] 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.
[16] Baek, S., Yoo, J., Kwon, T., Paik, E., and M. Nam, "Routing [16] Baek, S., Yoo, J., Kwon, T., Paik, E., and M. Nam, "Routing
Optimization in the same nested mobile network", Optimization in the same nested mobile network", Work
draft-baek-nemo-nested-ro-00 (work in progress), October 2005. in Progress, October 2005.
[17] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068, [17] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068,
July 2005. July 2005.
[18] Koodli, R., "IP Address Location Privacy and Mobile IPv6: [18] Vogt, C. and J. Arkko, "A Taxonomy and Analysis of Enhancements
Problem Statement", draft-irtf-mobopts-location-privacy-ps-00 to Mobile IPv6 Route Optimization", RFC 4651, February 2007.
(work in progress), July 2005.
[19] Nikander, P., "Mobile IP version 6 Route Optimization Security [19] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E.
Design Background", draft-ietf-mip6-ro-sec-03 (work in Nordmark, "Mobile IP Version 6 Route Optimization Security
progress), May 2005. Design Background", RFC 4225, December 2005.
[20] Bernardos, C., Bagnulo, M., and M. Calderon, "MIRON: MIPv6 [20] Bernardos, C., Bagnulo, M., and M. Calderon, "MIRON: MIPv6
Route Optimization for NEMO", 4th Workshop on Applications and Route Optimization for NEMO", 4th Workshop on Applications and
Services in Wireless Network, Services in Wireless Network,
Online: http://www.it.uc3m.es/cjbc/papers/miron_aswn2004.pdf, Online: http://www.it.uc3m.es/cjbc/papers/miron_aswn2004.pdf,
August 2004. August 2004.
[21] Bernardos, C., Bagnulo, M., Calderon, M., and I. Soto, "Mobile [21] Calderon, M., Bernardos, C., Bagnulo, M., Soto, I., and A.
IPv6 Route Optimisation for Network Mobility (MIRON)", Oliva, "Design and Experimental Evaluation of a Route
draft-bernardos-nemo-miron-00 (work in progress), July 2005. Optimisation Solution for NEMO", IEEE Journal on Selected Areas
in Communications (J-SAC), vol 24, no 9, September 2006.
[22] Ylitalo, J., "Securing Route Optimization in NEMO", Workshop [22] Bernardos, C., Bagnulo, M., Calderon, M., and I. Soto, "Mobile
IPv6 Route Optimisation for Network Mobility (MIRON)", Work
in Progress, July 2005.
[23] 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.
[23] Perera, E., Hsieh, R., and A. Seneviratne, "Extended Network [24] Perera, E., Lee, K., Kim, H., and J. Park, "Extended Network
Mobility Support", draft-perera-nemo-extended-00 (work in Mobility Support", Work in Progress, July 2003.
progress), July 2003.
[24] Lee, K., Park, J., and H. Kim, "Route Optimization for Mobile [25] Lee, K., Park, J., and H. Kim, "Route Optimization for Mobile
Nodes in Mobile Network based on Prefix Delegation", 58th IEEE Nodes in Mobile Network based on Prefix Delegation", 58th IEEE
Vehicular Technology Conference, vol 3, pp 2035-2038, Vehicular Technology Conference, vol 3, pp 2035-2038,
October 2003. October 2003.
[25] Lee, K., Jeong, J., Park, J., and H. Kim, "Route Optimization [26] Lee, K., Jeong, J., Park, J., and H. Kim, "Route Optimization
for Mobile Nodes in Mobile Network based on Prefix for Mobile Nodes in Mobile Network based on Prefix Delegation",
Delegation", draft-leekj-nemo-ro-pd-02 (work in progress), Work in Progress, February 2004.
February 2004.
[26] Jeong, J., Lee, K., Park, J., and H. Kim, "Route Optimization [27] Jeong, J., Lee, K., Park, J., and H. Kim, "Route Optimization
based on ND-Proxy for Mobile Nodes in IPv6 Mobile Network", based on ND-Proxy for Mobile Nodes in IPv6 Mobile Network",
59th IEEE Vehicular Technology Conference, vol 5, pp 2461-2465, 59th IEEE Vehicular Technology Conference, vol 5, pp 2461-2465,
May 2004. May 2004.
[27] Jeong, J., Lee, K., Kim, H., and J. Park, "ND-Proxy based Route [28] Jeong, J., Lee, K., Kim, H., and J. Park, "ND-Proxy based Route
Optimization for Mobile Nodes in Mobile Network", Optimization for Mobile Nodes in Mobile Network", Work
draft-jeong-nemo-ro-ndproxy-02 (work in progress), in Progress, February 2004.
February 2004.
[28] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery [29] 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.
[29] Kang, H., Kim, K., Han, S., Lee, K., and J. Park, "Route [30] Kang, H., Kim, K., Han, S., Lee, K., and J. Park, "Route
Optimization for Mobile Network by Using Bi-directional Between Optimization for Mobile Network by Using Bi-directional Between
Home Agent and Top Level Mobile Router", Home Agent and Top Level Mobile Router", Work in Progress,
draft-hkang-nemo-ro-tlmr-00 (work in progress), June 2003. June 2003.
[30] Lee, D., Lim, K., and M. Kim, "Hierarchical FRoute Optimization [31] Lee, D., Lim, K., and M. Kim, "Hierarchical FRoute Optimization
for Nested Mobile Network", 18th Int'l Conf on Advance for Nested Mobile Network", 18th Int'l Conf on Advance
Information Networking and Applications, vol 1, pp 225-229, Information Networking and Applications, vol 1, pp 225-229,
2004. 2004.
[31] Takagi, Y., Ohnishi, H., Sakitani, K., Baba, K., and S. [32] Takagi, Y., Ohnishi, H., Sakitani, K., Baba, K., and S.
Shimojo, "Route Optimization Methods for Network Mobility with Shimojo, "Route Optimization Methods for Network Mobility with
Mobile IPv6", IEICE Trans. on Comms, vol E87-B, no 3, pp 480- Mobile IPv6", IEICE Trans. on Comms, vol E87-B, no 3, pp 480-
489, March 2004. 489, March 2004.
[32] Ohnishi, H., Sakitani, K., and Y. Takagi, "HMIP based Route [33] Ohnishi, H., Sakitani, K., and Y. Takagi, "HMIP based Route
optimization method in a mobile network", optimization method in a mobile network", Work in Progress,
draft-ohnishi-nemo-ro-hmip-00 (work in progress), October 2003. October 2003.
[33] Lee, C., Zheng, J., and C. HUang, "SIP-based Network Mobility [34] Lee, C., Zheng, J., and C. HUang, "SIP-based Network Mobility
(SIP-NEMO) Route Optimization", draft-ming-nemo-sipnemo-00 (SIP-NEMO) Route Optimization (RO)", Work in Progress,
(work in progress), October 2005. October 2006.
[34] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 [35] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6
Specification", RFC 2473, December 1998. Specification", RFC 2473, December 1998.
[35] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H., [36] 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.
[36] Jonsson, L-E., "RObust Header Compression (ROHC): Terminology [37] Jonsson, L-E., "RObust Header Compression (ROHC): Terminology
and Channel Mapping Examples", RFC 3759, April 2004. and Channel Mapping Examples", RFC 3759, April 2004.
[37] Minaburo, A., Paik, E., Toutain, L., and J. Bonnin, "ROHC [38] Minaburo, A., Paik, E., Toutain, L., and J. Bonnin, "ROHC
(Robust Header Compression) in NEMO network", (Robust Header Compression) in NEMO network", Work in Progress,
draft-minaburo-rohc-nemo-01 (work in progress), July 2005. July 2005.
[38] Ng, C. and J. Hirano, "Extending Return Routability Procedure [39] Ng, C. and J. Hirano, "Extending Return Routability Procedure
for Network Prefix (RRNP)", draft-ng-nemo-rrnp-00 (work in for Network Prefix (RRNP)", Work in Progress, October 2004.
progress), October 2004.
[39] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure [40] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005. Neighbor Discovery (SEND)", RFC 3971, March 2005.
[40] Aura, T., "Cryptographically Generated Addresses (CGA)", [41] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005. RFC 3972, March 2005.
[41] Zhao, F., "Extensions to Return Routability Test in MIP6", [42] Zhao, F., Wu, F., and S. Jung, "Extensions to Return
draft-zhao-mip6-rr-ext-01 (work in progress), February 2005. Routability Test in MIP6", Work in Progress, February 2005.
[42] Arkko, J. and C. Vogt, "A Taxonomy and Analysis of Enhancements
to Mobile IPv6 Route Optimization",
draft-irtf-mobopts-ro-enhancements-08 (work in progress),
May 2006.
[43] Bao, F., Deng, R., Qiu, Y., and J. Zhou, "Certificate-based [43] Bao, F., Deng, R., Qiu, Y., and J. Zhou, "Certificate-based
Binding Update Protocol (CBU)", Binding Update Protocol (CBU)", Work in Progress, March 2005.
draft-qiu-mip6-certificated-binding-update-03 (work in
progress), March 2005.
[44] Moskowitz, R., "Host Identity Protocol", draft-ietf-hip-base-06 [44] Moskowitz, R., Nikander, P., Jokela, P., and T. Henderson,
(work in progress), June 2006. "Host Identity Protocol", Work in Progress, April 2007.
[45] 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-04 (work in progress), Identity Protocol", Work in Progress, March 2007.
June 2006.
[46] 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
o draft-ietf-nemo-ro-space-analysis-03:
* Keepalive release
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:
* Changed the term "Correspondent Agent" to "Correspondent
Entity" [Issue #13]
* Added clarifying text to some benefits listed in Sect 2 [Issue
#14]
* Added clarifying text to Sect 4.1, 4.3 and 4.4 [Issues #5, #6,
#16]
* Added Section 4.9 [Issue #3]
* Added clarifying text to various parts of Sect 5 [Issues #7,
#8, #9, #11, and #16]
* Combined "MR as a Proxy" and "MR as a Transparent Proxy" in
Sect 5.5.1 [Issue #11]
* Changed the term "identity of MNN" to "address of MNN" in Sect
5.5 [Issue #12]
* Added text on signaling using upper layer protocols in Sect 5.6
* Added more security consideration to Sect 5.8 [Issue #15]
o draft-ietf-nemo-ro-space-analysis-00:
* Adapted from Sections 3, 4 & 5 of
'draft-thubert-nemo-ro-taxonomy-04.txt' into:
+ Section 3 - "Different Scenarios of NEMO Route Optimization"
+ Section 4 - "Issues of NEMO Route Optimization"
* Included various parts from 'draft-zhao-nemo-ro-ps-01.txt'
* Re-vamped Section 5 - "Analysis of Solution Space"
Authors' Addresses Authors' Addresses
Chan-Wah Ng Chan-Wah Ng
Panasonic Singapore Laboratories Pte Ltd Panasonic Singapore Laboratories Pte Ltd
Blk 1022 Tai Seng Ave #06-3530 Blk 1022 Tai Seng Ave #06-3530
Tai Seng Industrial Estate Tai Seng Industrial Estate, Singapore 534415
Singapore 534415
SG SG
Phone: +65 65505420 Phone: +65 65505420
Email: chanwah.ng@sg.panasonic.com EMail: chanwah.ng@sg.panasonic.com
Fan Zhao Fan Zhao
University of California Davis University of California Davis
One Shields Avenue One Shields Avenue
Davis, CA 95616 Davis, CA 95616
US US
Phone: +1 530 752 3128 Phone: +1 530 752 3128
Email: fanzhao@ucdavis.edu EMail: fanzhao@ucdavis.edu
Masafumi Watari Masafumi Watari
KDDI R&D Laboratories Inc. KDDI R&D Laboratories Inc.
2-1-15 Ohara 2-1-15 Ohara
Fujimino, Saitama 356-8502 Fujimino, Saitama 356-8502
JAPAN JAPAN
Email: watari@kddilabs.jp EMail: watari@kddilabs.jp
Pascal Thubert Pascal Thubert
Cisco Systems Technology Center Cisco Systems
Village d'Entreprises Green Side Village d'Entreprises Green Side
400, Avenue Roumanille 400, Avenue de Roumanille
Biot - Sophia Antipolis 06410 Batiment T3, Biot - Sophia Antipolis 06410
FRANCE FRANCE
Email: pthubert@cisco.com EMail: pthubert@cisco.com
Full Copyright Statement Full Copyright Statement
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors contained in BCP 78, and except as set forth therein, the authors
retain all their rights. retain all their rights.
This document and the information contained herein are provided on an This document and the information contained herein are provided on an
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Acknowledgment Acknowledgement
Funding for the RFC Editor function is provided by the IETF Funding for the RFC Editor function is currently provided by the
Administrative Support Activity (IASA). Internet Society.
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