draft-ietf-nemo-ro-space-analysis-00.txt   draft-ietf-nemo-ro-space-analysis-01.txt 
NEMO Working Group C. Ng NEMO Working Group C. Ng
Internet-Draft Panasonic Singapore Labs Internet-Draft Panasonic Singapore Labs
Expires: March 4, 2006 F. Zhao Expires: April 27, 2006 F. Zhao
UC Davis UC Davis
M. Watari M. Watari
KDDI R&D Labs KDDI R&D Labs
P. Thubert P. Thubert
Cisco Systems Cisco Systems
August 31, 2005 October 24, 2005
Network Mobility Route Optimization Solution Space Analysis Network Mobility Route Optimization Solution Space Analysis
draft-ietf-nemo-ro-space-analysis-00 draft-ietf-nemo-ro-space-analysis-01
Status of this Memo Status of this Memo
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Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2005). Copyright (C) The Internet Society (2005).
Abstract Abstract
With current Network Mobility (NEMO) Basic Support, all With current Network Mobility (NEMO) Basic Support, all
communications to and from Mobile Network Nodes must go through the communications to and from Mobile Network Nodes must go through the
MRHA tunnel when the mobile network is away. This results in MRHA tunnel when the mobile network is away. This results in
increased length of packet route and increased packet delay in most increased length of packet route and increased packet delay in most
cases. To overcome these limitations, one might have to turn to cases. To overcome these limitations, one might have to turn to
Route Optimization (RO) for NEMO. This memo documents various types Route Optimization (RO) for NEMO. This memo documents various types
of Route Optimization in NEMO, and explores the benefits and of Route Optimization in NEMO, and explores the benefits and
tradeoffs in different aspects of NEMO Route Optimization. tradeoffs in different aspects of NEMO Route Optimization.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 4
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . 4 1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . 4
2. Benefits of NEMO Route Optimization . . . . . . . . . . . . . 5 2. Benefits of NEMO Route Optimization . . . . . . . . . . . . . 5
3. Different Scenarios of NEMO Route Optimization . . . . . . . . 7 3. Different Scenarios of NEMO Route Optimization . . . . . . . . 7
3.1 Basic NEMO Route Optimization . . . . . . . . . . . . . . 7 3.1. Basic NEMO Route Optimization . . . . . . . . . . . . . . 7
3.2 Nested Mobility Optimization . . . . . . . . . . . . . . . 9 3.2. Nested Mobility Optimization . . . . . . . . . . . . . . . 9
3.2.1 Decreasing the number of Home Agents on the path . . . 9 3.2.1. Decreasing the Number of Home Agents on the Path . . . 9
3.2.2 Decreasing the number of tunnels . . . . . . . . . . . 9 3.2.2. Decreasing the Number of Tunnels . . . . . . . . . . . 9
3.3 Infrastructure based Optimization . . . . . . . . . . . . 10 3.3. Infrastructure based Optimization . . . . . . . . . . . . 10
3.4 Intra-NEMO Optimization . . . . . . . . . . . . . . . . . 10 3.4. Intra-NEMO Optimization . . . . . . . . . . . . . . . . . 10
4. Issues of NEMO Route Optimization . . . . . . . . . . . . . . 12 4. Issues of NEMO Route Optimization . . . . . . . . . . . . . . 12
4.1 Additional Signaling Overhead . . . . . . . . . . . . . . 12 4.1. Additional Signaling Overhead . . . . . . . . . . . . . . 12
4.2 Increased Protocol Complexity and Processing Load . . . . 12 4.2. Increased Protocol Complexity and Processing Load . . . . 12
4.3 Increased Delay during Handoff . . . . . . . . . . . . . . 13 4.3. Increased Delay during Handoff . . . . . . . . . . . . . . 13
4.4 New Functionalities . . . . . . . . . . . . . . . . . . . 13 4.4. New Functionalities . . . . . . . . . . . . . . . . . . . 13
4.5 Detection of New Functionalities . . . . . . . . . . . . . 14 4.5. Detection of New Functionalities . . . . . . . . . . . . . 14
4.6 Scalability . . . . . . . . . . . . . . . . . . . . . . . 14 4.6. Scalability . . . . . . . . . . . . . . . . . . . . . . . 15
4.7 Mobility Transparency and Location Privacy . . . . . . . . 15 4.7. Mobility Transparency and Location Privacy . . . . . . . . 15
4.8 Security Consideration . . . . . . . . . . . . . . . . . . 15 4.8. Security Consideration . . . . . . . . . . . . . . . . . . 15
5. Analysis of Solution Space . . . . . . . . . . . . . . . . . . 16 4.9. Support of Legacy Nodes . . . . . . . . . . . . . . . . . 16
5.1 Which Entities are Involved? . . . . . . . . . . . . . . . 16 5. Analysis of Solution Space . . . . . . . . . . . . . . . . . . 17
5.1.1 Mobile Network Node and Correspondent Node . . . . . . 16 5.1. Which Entities are Involved? . . . . . . . . . . . . . . . 17
5.1.2 Mobile Router and Correspondent Node . . . . . . . . . 17 5.1.1. Mobile Network Node and Correspondent Node . . . . . . 17
5.1.3 Mobile Router and Correspondent Router . . . . . . . . 17 5.1.2. Mobile Router and Correspondent Node . . . . . . . . . 18
5.1.4 Entities in the Infrastructure . . . . . . . . . . . . 17 5.1.3. Mobile Router and Correspondent Router . . . . . . . . 18
5.2 Who and When to Initiate Route Optimization? . . . . . . . 18 5.1.4. Entities in the Infrastructure . . . . . . . . . . . . 19
5.3 How to Detect Route Optimization Capability? . . . . . . . 19 5.2. Who and When to Initiate Route Optimization? . . . . . . . 19
5.4 How is Identity Represented? . . . . . . . . . . . . . . . 19 5.3. How to Detect Route Optimization Capability? . . . . . . . 20
5.5 How is Identity Bound to Location? . . . . . . . . . . . . 20 5.4. How is Address of Mobile Network Node Represented? . . . . 21
5.5.1 Binding to the Location of Parent Mobile Router . . . 20 5.5. How is Mobile Network Node's Address Bound to Location? . 21
5.5.2 Binding to a Sequence of Locations of Upstream 5.5.1. Binding to the Location of Parent Mobile Router . . . 22
Mobile Routers . . . . . . . . . . . . . . . . . . . . 23 5.5.2. Binding to a Sequence of Locations of Upstream
5.5.3 Binding to the Location of Root Mobile Router . . . . 24 Mobile Routers . . . . . . . . . . . . . . . . . . . . 24
5.6 How is Signaling Performed? . . . . . . . . . . . . . . . 26 5.5.3. Binding to the Location of Root Mobile Router . . . . 25
5.7 How is Data Transmitted? . . . . . . . . . . . . . . . . . 27 5.6. How is Signaling Performed? . . . . . . . . . . . . . . . 27
5.8 What are the Security Considerations? . . . . . . . . . . 28 5.7. How is Data Transmitted? . . . . . . . . . . . . . . . . . 28
5.8.1 Security Considerations of Identity-Location 5.8. What are the Security Considerations? . . . . . . . . . . 29
Binding . . . . . . . . . . . . . . . . . . . . . . . 28 5.8.1. Security Considerations of Address Binding . . . . . . 29
5.8.2 End-to-End Integrity . . . . . . . . . . . . . . . . . 29 5.8.2. End-to-End Integrity . . . . . . . . . . . . . . . . . 31
5.8.3 Location Privacy . . . . . . . . . . . . . . . . . . . 30 5.8.3. Location Privacy . . . . . . . . . . . . . . . . . . . 31
6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 31 6. Conclusion . . . . . . . . . . . . . . . . . . . . . . . . . . 33
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 31 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 33
8. Security Considerations . . . . . . . . . . . . . . . . . . . 31 8. Security Considerations . . . . . . . . . . . . . . . . . . . 33
9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 31 9. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 33
10. References . . . . . . . . . . . . . . . . . . . . . . . . . 32 10. References . . . . . . . . . . . . . . . . . . . . . . . . . . 34
10.1 Normative References . . . . . . . . . . . . . . . . . . . 32 10.1. Normative References . . . . . . . . . . . . . . . . . . . 34
10.2 Informative References . . . . . . . . . . . . . . . . . . 32 10.2. Informative References . . . . . . . . . . . . . . . . . . 34
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . 34 Appendix A. Change Log . . . . . . . . . . . . . . . . . . . . . 38
A. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 36 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 39
Intellectual Property and Copyright Statements . . . . . . . . 37 Intellectual Property and Copyright Statements . . . . . . . . . . 40
1. Introduction 1. Introduction
Network Mobility Route Optimization Problem Statement [1] describes Network Mobility Route Optimization Problem Statement [1] describes
operational limitations and overheads incurred in a deployment of operational limitations and overheads incurred in a deployment of
Network Mobility (NEMO) Basic Support [2], which could be alleviated Network Mobility (NEMO) Basic Support [2], which could be alleviated
by a set of NEMO Route Optimization techniques to be defined. For by a set of NEMO Route Optimization techniques to be defined. For
this purpose of NEMO, the term "Route Optimization" is accepted in a this purpose of NEMO, the term "Route Optimization" is accepted in a
broader sense than already defined for IPv6 Host Mobility in [3], to broader sense than already defined for IPv6 Host Mobility in [3], to
loosely refer to any approach that optimizes the transmission of loosely refer to any approach that optimizes the transmission of
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It is expected for readers to be familiar with general terminologies It is expected for readers to be familiar with general terminologies
related to mobility in [3] and [4], and NEMO related terms defined in related to mobility in [3] and [4], and NEMO related terms defined in
[5]. In addition, it is beneficial to keep in mind the design [5]. In addition, it is beneficial to keep in mind the design
requirements of NEMO [6]. A point to note is that since this requirements of NEMO [6]. A point to note is that since this
document discusses aspects of Route Optimization, the readers may document discusses aspects of Route Optimization, the readers may
assume that a mobile network or a mobile host is away when they are assume that a mobile network or a mobile host is away when they are
mentioned throughout this document, unless it is explicitly specified mentioned throughout this document, unless it is explicitly specified
that they are at home. that they are at home.
1.1 Terminology 1.1. Terminology
Correspondent Router (CR) Correspondent Router (CR)
This refers to the entity which is capable of terminating a Route This refers to the entity which is capable of terminating a Route
Optimization session on behalf of a Correspondent Node. Optimization session on behalf of a Correspondent Node.
Correspondent Agent (CA) Correspondent Entity (CE)
This refers to the entity which a Mobile Router or Mobile Network This refers to the entity which a Mobile Router or Mobile Network
Node attempts to establish a Route Optimization session with. Node attempts to establish a Route Optimization session with.
Depending on the Route Optimization approach, the Correspondent Depending on the Route Optimization approach, the Correspondent
Agent maybe a Correspondent Node or Correspondent Router. Entity maybe a Correspondent Node or Correspondent Router.
2. Benefits of NEMO Route Optimization 2. Benefits of NEMO Route Optimization
To address the problems discussed in [1], one can incorporate Route To address the problems discussed in [1], one can incorporate Route
Optimization into NEMO. Although a standardized NEMO Route Optimization into NEMO. Although a standardized NEMO Route
Optimization solution has yet to materialize, one can expect it to Optimization solution has yet to materialize, one can expect it to
show some of the following benefits: show some of the following 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
least cost (thus generally shorter and faster) route to be taken lesser cost (thus generally shorter and faster) route to be taken
for traffic between a Mobile Network Node and its Correspondent for traffic between a Mobile Network Node and its Correspondent
Node. Hence, Route Optimization should improve the latency of the Node. Hence, Route Optimization should improve the latency of the
data traffic between the two end nodes. This may possibly in turn data traffic between the two end nodes. This may possibly in turn
lead to better overall Quality of Services characteristics, such lead to better overall Quality of Service characteristics, such as
as reduced jitter and packet loss. reduced 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
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otherwise. otherwise.
o Avoid the Security Policy Issue o Avoid the Security Policy Issue
Security policy may forbid Mobile Routers from tunneling traffic Security policy may forbid Mobile Routers from tunneling traffic
of Visiting Mobile Nodes into the home network of Mobile Router. of Visiting Mobile Nodes into the home network of Mobile Router.
Route Optimization can be used to avoid this issue by forwarding Route Optimization can be used to avoid this issue by forwarding
traffic from Visiting Mobile Nodes directly to their destination traffic from Visiting Mobile Nodes directly to their destination
without going through the home network of the Mobile Router. without going through the home network of the Mobile Router.
o Avoid the Instability and Deadlock It should however be taken into consideration that a Route
Optimization mechanism may not be an appropriate solution since
the Mobile Router may still be held responsible for illegal
traffic sent from its Mobile Network Nodes even when Route
Optimization is used. In addition, there can be a variety of
different policies which might cause a conflict with the
deployment of Route Optimization for Visiting Mobile Nodes. Being
a policy issue, solving this with a protocol at the policy plane
might be more appropriate.
[1] described a potential deadlock situation when a Home Agent is o Avoid the Instability and Stalemate
[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 deadlock situations by directly forwarding traffic upstream. such stalemate situations by directly forwarding traffic upstream.
However, it should be noted that certain Route Optimization
schemes may require signaling packets to be first routed via the
Home Agent before an optimized route can be established. In such
cases, a Route Optimization solution cannot avoid the stalemate.
3. Different Scenarios of NEMO Route Optimization 3. Different Scenarios of NEMO Route Optimization
There are multiple proposals for providing various forms of Route There are multiple proposals for providing various forms of Route
Optimization in the NEMO context. In the following sub-sections, we Optimization in the NEMO context. In the following sub-sections, we
describe the different scenarios which would require a Route describe the different scenarios which would require a Route
Optimization mechanism and list the potential solutions which have Optimization mechanism and list the potential solutions which have
been proposed in that area. been proposed in that area.
3.1 Basic NEMO Route Optimization 3.1. Basic NEMO Route Optimization
We start off with a scenario where nesting of Mobile Routers is not We start off with a scenario where nesting of Mobile Routers is not
considered, and Route Optimization is initiated and performed between considered, and Route Optimization is initiated and performed between
a Mobile Router and its peer Mobile Router, also known as a a Mobile Router and its peer Mobile Router, also known as a
Correspondent Router. Such solutions are often posed with a Correspondent Router. Such solutions are often posed with a
requirement to leave the Mobile Network Nodes untouched, as with the requirement to leave the Mobile Network Nodes untouched, as with the
NEMO Basic Support protocol, and therefore Mobile Routers handle the NEMO Basic Support protocol, and therefore Mobile Routers handle the
optimization management on behalf of the Mobile Network Nodes. Thus, optimization management on behalf of the Mobile Network Nodes. Thus,
providing Route Optimization for Visiting Mobile Node is often out of providing Route Optimization for Visiting Mobile Node is often out of
scope for such scenario because such interaction would require scope for such scenario because such interaction would require
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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 of the Mobile
Router and is aware of the mobile network prefix(es) managed by Router and is aware of the mobile network prefix(es) managed by
the Mobile Router. The Correspondent Router can thus intercept the Mobile Router. The Correspondent Router can thus intercept
packets going to the mobile network, and forward them to the packets going to the mobile network, and forward them to the
Mobile Router over the established tunnel. Mobile Router over the established tunnel.
A straight-forward approach to Route Optimization in NEMO is for the A straight-forward 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
Agent. 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 Agent. The Correspondent Agent having received the Correspondent Entity. The Correspondent Entity having received the
binding update, can then set up a bi-directional tunnel with the binding update, can then set up a bi-directional tunnel with the
Mobile Router at the current care-of address of the Mobile Router, Mobile Router at the current care-of address of the Mobile Router,
and inject a route to its routing table so that packets destined for and inject a route to its routing table so that packets destined for
addresses in the mobile network prefix will be routed through the bi- addresses in the mobile network prefix will be routed through the bi-
directional tunnel. directional tunnel.
Examples of this approach include Optimized Route Cache (ORC) [7] and Examples of this approach include Optimized Route Cache (ORC) [7] and
Path Control Header (PCH) [8]. Path Control Header (PCH) [8].
3.2 Nested Mobility Optimization 3.2. Nested Mobility Optimization
Optimization in Nested Mobility targets scenarios where a nesting of Optimization in Nested Mobility targets scenarios where a nesting of
mobility management protocols is created (i.e. Mobile IPv6 enabled mobility management protocols is created (i.e. Mobile IPv6 enabled
host inside a mobile network or multiple Mobile Routers that attach host inside a mobile network or multiple Mobile Routers that attach
behind one another creating a nested mobile network). Note that behind one another creating a nested mobile network). Note that
because Mobile IPv6 defines its own Route Optimization mechanism in because Mobile IPv6 defines its own Route Optimization mechanism in
its base protocol suite as a standard, collaboration with this and its base protocol suite as a standard, collaboration with this and
NEMO brings various complexity. NEMO brings various complexity.
There are two main aspects in providing optimization for Nested There are two main aspects in providing optimization for Nested
Mobility and they are discussed in the following sub-sections. Mobility and they are discussed in the following sub-sections.
3.2.1 Decreasing the number of Home Agents on the path 3.2.1. Decreasing the Number of Home Agents on the Path
The aim is to remove the sub-optimality of paths caused by multiple The aim is to remove the sub-optimality of paths caused by multiple
tunnels established between multiple Mobile Nodes and their Home tunnels established between multiple Mobile Nodes and their Home
Agents. Such a solution will seek to minimize the number of Home Agents. Such a solution will seek to minimize the number of Home
Agents along the path, possibly by bypassing some of the Home Agents along the path, possibly by bypassing some of the Home
Agent(s) from the original path. Unlike the scenario where no Agent(s) from the original path. Unlike the scenario where no
nesting is formed and only a single Home Agent exists along the path, nesting is formed and only a single Home Agent exists along the path,
bypassing one of the many Home Agents can still be effective. bypassing one of the many Home Agents can still be effective.
Solutions for Nested Mobility scenarios can usually be divided into Solutions for Nested Mobility scenarios can usually be divided into
two cases based on whether the nesting involves Mobile IPv6 hosts or two cases based on whether the nesting involves Mobile IPv6 hosts or
only involves Mobile Routers. Since Mobile IPv6 defines its own only involves Mobile Routers. Since Mobile IPv6 defines its own
Route Optimization mechanism, providing optimal path for such hosts Route Optimization mechanism, providing optimal path for such hosts
will require interaction with the protocol and may require an will require interaction with the protocol and may require an
altering of the messages exchanged during the Return Routability altering of the messages exchanged during the Return Routability
procedure with the Correspondent Node. procedure with the Correspondent Node.
Examples of this approach include MIRON [9] and Reverse Routing Example of this approach include Reverse Routing Header (RRH) [9].
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.
Example includes the Reverse Routing Header (RRH) [10], Access Router Examples of this approach include the Reverse Routing Header (RRH)
Option (ARO) [11], and Nested Path Info (NPI) [12]. [9], Access Router Option (ARO) [10], and Nested Path Info (NPI)
[11].
3.3 Infrastructure based Optimization 3.3. Infrastructure based Optimization
An infrastructure based optimization is an approach where An infrastructure based optimization is an approach where
optimization is carried out fully in the infrastructure. One example optimization is carried out fully in the infrastructure. One example
is to make use of mobile anchor points (MAP) in HMIPv6 [13] to is to make use of mobile anchor points (MAP) in HMIPv6 [12] to
optimize routes between themselves. Another example is to make use optimize routes between themselves. Another example is to make use
of the global HAHA protocol [14]. In this case, proxy Home Agents of the global HAHA protocol [13]. In this case, proxy Home Agents
are distributed in the infrastructure and Mobile Routers bind to the are distributed in the infrastructure and Mobile Routers bind to the
closest proxy. The proxy, in turn, performs a primary binding with a closest proxy. The proxy, in turn, performs a primary binding with a
real Home Agent for that Mobile Router. Then, the proxy might real Home Agent for that Mobile Router. Then, the proxy might
establish secondary bindings with other Home Agents or proxies in the establish secondary bindings with other Home Agents or proxies in the
infrastructure, in order to improve the end-to-end path. In this infrastructure, in order to improve the end-to-end path. In this
case, the proxies discover each other, establish a tunnel and case, the proxies discover each other, establish a tunnel and
exchange the relevant mobile network prefix information in the form exchange the relevant mobile network prefix information in the form
of explicit prefix routes. of explicit prefix routes.
Alternatively, another approach is to use prefix delegation. Here, Alternatively, another approach is to use prefix delegation. Here,
each Mobile Router in a nested mobile network is delegated a mobile each Mobile Router in a nested mobile network is delegated a mobile
network prefix from the access router using DHCP Prefix Delegation network prefix from the access router using DHCP Prefix Delegation
[15]). Each Mobile Router also autoconfigures its care-of address [14]. Each Mobile Router also autoconfigures its care-of address
from this delegated prefix. In this way, the care-of addresses of from this delegated prefix. In this way, the care-of addresses of
each Mobile Router are all from an aggregatable address space each Mobile Router are all from an aggregatable address space
starting from the access router. This may be used to eliminate the starting from the access router. This may be used to eliminate the
multiple tunnels caused by nesting of Mobile Nodes. multiple tunnels caused by nesting of Mobile Nodes.
3.4 Intra-NEMO Optimization 3.4. Intra-NEMO Optimization
A Route Optimization solution may seek to improve the communications A Route Optimization solution may seek to improve the communications
between two Mobile Network Nodes within a nested mobile network. between two Mobile Network Nodes within a nested mobile network.
This would avoid traffic being injected out of the nested mobile This would avoid traffic being injected out of the nested mobile
network and route them within the nested mobile network. An example network and route them within the nested mobile network. An example
will be the optimized route taken between MNN1 and MNN2 of Figure 3 will be the optimized route taken between MNN1 and MNN2 of Figure 3
below. below.
+--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+ +--------+
| MR2_HA | | MR3_HA | | MR4_HA | | MR5_HA | | MR2_HA | | MR3_HA | | MR4_HA | | MR5_HA |
skipping to change at page 11, line 34 skipping to change at page 11, line 34
MNN2 | MR3 | MNN3 MNN2 | MR3 | MNN3
+---+---+ +---+---+
| |
----+---- ----+----
MNN1 MNN1
Figure 3: An example of nested Mobile Network Figure 3: An example of nested Mobile Network
One may be able to extend a well-designed NEMO Route Optimization for One may be able to extend a well-designed NEMO Route Optimization for
"Nested Mobility Optimization" (see Section 3.2) to provide for such "Nested Mobility Optimization" (see Section 3.2) to provide for such
kind of Intra-NEMO optimization, where, for example in Figure 3, kind of Intra-NEMO optimization, where, for example in Figure 3, MNN1
MNN1 is treated as a Correspondent Node from the perspective of MR5/ is treated as a Correspondent Node by MR5/MNN2, and MNN2 is treated
MNN2, and MNN2 is treated as a Correspondent Node from the view of as a Correspondent Node by MR3/MNN1.
MR3/MNN1.
Another possibility is for the "Basic NEMO Route Optimization" Another possibility is for the "Basic 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. MR2 as Correspondent Routers for MNN1. An example of this approach
is [15] which have Mobile Routers announce their Mobile Network
Preifxes to other Mobile Routers in the same nested Mobile Network.
Yet another approach is to flatten any nested Mobile Network so that Yet another approach is to flatten any nested Mobile Network so that
all nested Mobile Network Nodes appear to be virtually on the same all nested Mobile Network Nodes appear to be virtually on the same
link. Examples of such approaches include delegating a single prefix link. Examples of such approaches include delegating a single prefix
to the nested Mobile Network, having Mobile Routers to perform to the nested Mobile Network, having Mobile Routers to perform
Neighbor Discovery on behalf of their Mobile Network Nodes, and Neighbor Discovery on behalf of their Mobile Network Nodes, and
exposing a single prefix over the entire mobile network using a exposing a single prefix over the entire mobile network using a
Mobile Ad-Hoc (MANET) protocol. Mobile Ad-Hoc (MANET) protocol.
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 does 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 height
especially to the resource-scarce mobile node which typically has especially to the resource-scarce mobile node which typically has
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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.
4.2 Increased Protocol Complexity and Processing Load Even so, the amount of signaling required might be overwhelming,
since a large mobile network (such as those deployed on a train or
plane) may potentially have a large number of flows with a large
number of Correspondent Nodes. This might suggest a need to have
some adaptive behavior that depends on the amount of signaling
required versus the effort needed to tunnel home.
4.2. Increased Protocol Complexity and Processing Load
It is expected for NEMO Route Optimization to be more complicated It is expected for NEMO Route Optimization to 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.
4.3 Increased Delay during Handoff 4.3. Increased Delay during Handoff
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 Agents. Apart from the begin signaling its own Correspondent Entities. Apart from the
compromise of mobility awareness and location privacy, this mechanism compromise of mobility awareness and location privacy, this mechanism
also increases the delay during handoffs. also increases the delay during handoffs.
4.4 New Functionalities Some of the solutions for Mobile IPv6, such as Fast Handoff for
Mobile IPv6 [16], may be able to alleviate the increase in handoff
delay.
4.4. New Functionalities
In order to support NEMO Route Optimization, some nodes need to be In order to support NEMO Route Optimization, some nodes need to be
changed or upgraded. Smaller number of nodes required to be changed changed or upgraded. Smaller number of nodes required to be changed
will allow for easier adoption of NEMO Route Optimization solution in will allow for easier adoption of NEMO Route Optimization solution in
the Internet and create less impact on existing Internet the Internet and create less impact on existing Internet
infrastructure. The number and the types of nodes involved with new infrastructure. The number and the types of nodes involved with new
functionalities also affect how much of the route is optimized. functionalities also affect how much of the route is optimized. In
addition, it may also be beneficial to reuse existing protocols (such
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:
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.
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Correspondent Node. This might mean that only those Correspondent Correspondent Node. This might mean that only those Correspondent
Nodes that are modified can enjoy the benefits of Route Nodes that are modified can enjoy the benefits of Route
Optimization. Optimization.
o Correspondent Routers o Correspondent Routers
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 if
support of the new functionalities are available. Furthermore, it support of the new functionalities are available. Furthermore, it
might be advantageous to have a graceful fall back procedure if the might be advantageous to have a graceful fall back procedure if the
required functionalities are unavailable. 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 means that the single node has to keep track of the states of all
route optimization sessions. This may leads to scalability issues route optimization sessions. This may leads to scalability issues
especially when that single node is a mobile device with limited especially when that single node is a mobile device with limited
memory and processing resources. memory and processing resources.
A similar scalability issue may be faced by Correspondent Agent as A similar scalability issue may be faced by Correspondent Entity as
well if it maintains many route optimized sessions on behalf of well if it maintains many route optimized sessions on behalf of
Correspondent Node(s) with a large number of Mobile Routers. Correspondent Node(s) with a large number of Mobile Routers.
4.7 Mobility Transparency and Location Privacy 4.7. Mobility Transparency and Location Privacy
One advantage of NEMO Basic Support is that the Correspondent Nodes One advantage of NEMO Basic Support is that the Correspondent Nodes
and Mobile Network Nodes need not be aware of the actual location and and Mobile Network Nodes need not be aware of the actual location and
mobility of the mobile network. With Route Optimization, it might be mobility of the mobile network. With Route Optimization, it might be
necessary to reveal the point of attachment of the Mobile Router to necessary to reveal the point of attachment of the Mobile Router to
other nodes, such as the Mobile Network Nodes or their Correspondent other nodes, such as the Mobile Network Nodes or their Correspondent
Nodes. This may mean a tradeoff between location privacy [16] (and Nodes. This may mean a tradeoff between location privacy [17] (and
mobility transparency) and Route Optimization. mobility transparency) and Route Optimization.
In Mobile IPv6, a mobile node can decide whether or not to perform In Mobile IPv6, a mobile node can decide whether or not to perform
Route Optimization with a given Correspondent Node. Thus, the mobile Route Optimization with a given Correspondent Node. Thus, the mobile
node is in control of whether to trade location privacy for an node is in control of whether to trade location privacy for an
optimized route. In NEMO Route Optimization, if the decision to optimized route. In NEMO Route Optimization, if the decision to
perform Router Optimization is made by the Mobile Router, it will be perform Router Optimization is made by the Mobile Router, it will be
difficult for Mobile Network Nodes to control the decision of having difficult for Mobile Network Nodes to control the decision of having
this tradeoff. this tradeoff.
4.8 Security Consideration 4.8. 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 Agent), thus the existence example, Mobile Router and Correspondent Entity), thus the existence
of such a security association is not a valid assumption in many of such a security association is not a valid assumption in many
deployment scenarios. Thus the security protection of NEMO Route deployment scenarios. Thus the security protection of NEMO Route
Optimization signaling message is considered as "weaker" than that in Optimization signaling message is considered as "weaker" than that in
NEMO Basic Support. It is expected that some additional security NEMO Basic Support. It is expected that some additional security
mechanisms are needed to achieve the same or similar level of mechanisms are needed to achieve the same or similar level of
security as in NEMO Basic Support. security as in NEMO Basic Support.
When considering security issues of NEMO Route Optimization, it might When considering security issues of NEMO Route Optimization, it might
be useful to keep in mind some of the security issues considered when be useful to keep in mind some of the security issues considered when
Mobile IPv6 Route Optimization was designed as documented in [17]. Mobile IPv6 Route Optimization was designed as documented in [18].
4.9. Support of Legacy Nodes
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
they are in, and those that do not understand any mobility protocols)
can still reach and be reached from the Internet. Some Route
Optimization shcemes, however, require that all Mobile Routers to
implement the same Route Optimization scheme in order for them to
operate. For instance, a nested Mobile Router may not be able to
achieve 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 and when to initiate signaling?
3. How to detect Route Optimization capabilities? 3. How to detect Route Optimization capabilities?
4. How is identity represented? 4. How is address of Mobile Network Node represented?
5. How is identity bound to location? 5. How is address of Mobile Network Node bound to location of mobile
network?
6. How is signaling done? 6. How is signaling done?
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 subsections:
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
A Mobile Network Node can establish Route Optimization with its A Mobile Network Node can establish Route Optimization with its
Correspondent Node, possibly the same way as a Mobile Node Correspondent Node, possibly the same way as a Mobile Node
establishes Route Optimization with its Correspondent Node in Mobile establishes Route Optimization with its Correspondent Node in Mobile
IPv6. This would achieve the most optimal route, since the entire IPv6. This would achieve the most optimal route, since the entire
end-to-end path is optimized. However, there might be scalability end-to-end path is optimized. However, there might be scalability
issues since both the Mobile Network Node and the Correspondent Node issues since both the Mobile Network Node and the Correspondent Node
may need to maintain many Route Optimization sessions. In addition, may need to maintain many Route Optimization sessions. In addition,
new functionalities are required for both the Mobile Network Node and new functionalities would be required for both the Mobile Network
Correspondent Node. Node and Correspondent Node.
5.1.2 Mobile Router and Correspondent Node 5.1.2. Mobile Router and Correspondent Node
Alternatively, Mobile Router can establish Route Optimization with a Alternatively, Mobile Router can establish Route Optimization with a
Correspondent Node on behalf of the Mobile Network Node. Since the Correspondent Node on behalf of the Mobile Network Node. Since the
Mobile Router is merely one hop away from the Mobile Network Node, Mobile Router is merely one hop away from the Mobile Network Node,
this effectively achieves an optimal route for the entire end-to-end this effectively achieves an optimal route for the entire end-to-end
path as well. Compared with Section 5.1.1, the scalability issue path as well. Compared with Section 5.1.1, the scalability issue
here may be remedied since it is possible for Correspondent Node to here may be remedied since it is possible for Correspondent Node to
maintain only one session with Mobile Router if it communicates with maintain only one session with Mobile Router if it communicates with
many Mobile Network Nodes associated with Mobile Router. many Mobile Network Nodes associated with Mobile Router.
Furthermore, with Mobile Router handling Route Optimization, there is Furthermore, with Mobile Router handling Route Optimization, there is
no need for Mobile Network Nodes to implement new functionalities. no need for Mobile Network Nodes to implement new functionalities.
However, new functionality is likely to be required on the However, new functionality is likely to be required on the
Correspondent Node. Correspondent Node. An additional point of consideration is the
amount of state information the Mobile Router is required to
maintain. Traditionally, it has been generally avoided to have state
information in the routers to increase proportionally with the number
of pairs of communicating peers.
5.1.3 Mobile Router and Correspondent Router 5.1.3. Mobile Router and Correspondent Router
Approaches involving Mobile Routers and Correspondent Routers are Approaches involving Mobile Routers and Correspondent Routers are
described in Section 3.1. The advantage of this approach is that no described in Section 3.1. The advantage of this approach is that no
additional functionality is required for the Correspondent Node and additional functionality is required for the Correspondent Node and
Mobile Network Nodes. In addition, location privacy is relatively Mobile Network Nodes. In addition, location privacy is relatively
preserved, since the current location of the mobile network is only preserved, since the current location of the mobile network is only
revealed to the Correspondent Router and not to the Correspondent revealed to the Correspondent Router and not to the Correspondent
Node (please refer to Section 5.8.3 for more discussions). Node (please refer to Section 5.8.3 for more discussions).
Furthermore, if the Mobile Router and Correspondent Router exchange Furthermore, if the Mobile Router and Correspondent Router exchange
prefix information, this approach may scale well since a single Route prefix information, this approach may scale well since a single Route
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in the mobile network, and any Correspondent Node managed by the in the mobile network, and any Correspondent Node managed by the
Correspondent Router. 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.
5.1.4 Entities in the Infrastructure A deployment consideration with respect to the use of Correspondent
Router is the location of the Correspondent Router relative to the
Correspondent Node. On one hand, deploying the Correspondent Router
nearer to the Correspondent Node would result in a more optimal path.
On the other hand, a Correspondent Router that is placed further away
from the Correspondent Node can perform Route Optimization on behalf
of more Correspondent Nodes.
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). Another Home Agent of the Mobile Router (such as in global HAHA [13]).
concern is that the resulting path may not be a true optimized one, Another concern is that the resulting path may not be a true
since it depends on the relative positions of the infrastructure optimized one, since it depends on the relative positions of the
entities with respect to the mobile network and the Correspondent infrastructure entities with respect to the mobile network and the
Node. Correspondent Node.
5.2 Who and When to Initiate Route Optimization? 5.2. Who and When to Initiate Route Optimization?
Usually, the node that is mobile (i.e. Mobile Network Node or Mobile Having determined the entities involved in the Route Optimization in
Router) is in the best position to detect its mobility. Thus, in the previous sub-section, the next question is which of these
general, it is better for the mobile node to initiate the Route entities should initiate the Route Optimization session. Usually,
Optimization session in order to handle the topology changes in any the node that is moving (i.e. Mobile Network Node or Mobile Router)
kind of mobility pattern and achieve the optimized route promptly. is in the best position to detect its mobility. Thus, in general, it
However, when the mobile node is within a nested mobile network, the is better for the mobile node to initiate the Route Optimization
detection of the mobility may need to be conveyed to the nested session in order to handle the topology changes in any kind of
Mobile Network Node. This might incur longer signaling delay as mobility pattern and achieve the optimized route promptly. However,
discussed in Section 4.3. 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
the nested Mobile Network Node. This might incur longer signaling
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 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 Agent 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 Agent 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 is likely to be sent whenever there is topological changes.
The discussion in Section 4.1 should be considered. In addition, a The discussion in Section 4.1 should be considered. In addition, a
Lifetime value is often used to indicate the period of validity for Lifetime value is often used to indicate the period of validity for
the Route Optimization session. Signaling messages would have to be the Route Optimization session. Signaling messages would have to be
sent before the Lifetime value expires in order to maintain the Route sent before the Lifetime value expires in order to maintain the Route
Optimization session. The choice of Lifetime value needs to balance Optimization session. The choice of Lifetime value needs to balance
between different considerations. On one hand, a short Lifetime between different considerations. On one hand, a short Lifetime
value would increase the amount of signaling overhead. On the other value would increase the amount of signaling overhead. On the other
hand, a long Lifetime value may expose the Correspondent Agent to the hand, a long Lifetime value may expose the Correspondent Entity to
risk of having an obsolete binding cache entry, which creates an the risk of having an obsolete binding cache entry, which creates an
opportunity for an attacker to exploit. opportunity for an attacker to exploit.
5.3 How to Detect Route Optimization Capability? 5.3. How to Detect Route Optimization Capability?
The question here is how the initiator of Route Optimization knows if The question here is how the initiator of Route Optimization knows if
the Correspondent Agent supports the functionality required to the Correspondent Entity supports the functionality required to
established a Route Optimization session. The usual method is for 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
Agent. Depending on the protocol specifics, the initiator may Entity. Depending on the protocol specifics, the initiator may
receive (i) a reply from the Correspondent Agent indicating its receive (i) a reply from the Correspondent Entity indicating its
capability, (ii) an error message from the Correspondent Agent, or capability, (ii) an error message from the Correspondent Entity, or
(iii) no response from the Correspondent Agent within a certain time (iii) no response from the Correspondent Entity within a certain time
period. This serves as an indication of whether the Correspondent period. This serves as an indication of whether the Correspondent
Agent supports the required functionality to establish Route Entity supports the required functionality to establish Route
Optimization or not. This form of detection may incur additional Optimization or not. This form of detection may incur additional
delay as a penalty when the Correspondent Agent does not have Route delay as a penalty when the Correspondent Entity does not have Route
Optimization capability. Optimization capability, especially when the Route Optimization
mechanism is using in-band-signalling.
When the Correspondent Agent is not the Correspondent Node but a When the Correspondent Entity is not the Correspondent Node but a
Correspondent Router, a more immediate question is how to detect its Correspondent Router, an immediate question is how its presence can
presence. One way to approach this is for the initiator to send an be detected. One approach is for the initiator to send an Internet
Internet Control Message Protocol (ICMP) message containing the Control Message Protocol (ICMP) message containing the address of the
address of the Correspondent Node to a well-known anycast address Correspondent Node to a well-known anycast address reserved for all
reserved for all Correspondent Routers [7]. Only the Correspondent Correspondent Routers [7]. Only the Correspondent Router that is
Router that is capable of terminating Route Optimization session on capable of terminating Route Optimization session on behalf of the
behalf of the Correspondent Node will respond. Another way is to Correspondent Node will respond. Another way is to insert a Router
insert a Router Alert Option (RAO) to a packet sent to the Alert Option (RAO) to a packet sent to the Correspondent Node [8].
Correspondent Node [8]. Any Correspondent Router en route will Any Correspondent Router en route will process the Router Alert
process the Router Alert Option, and send a response to the Mobile Option, and send a response to the Mobile Router.
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 Identity Represented? 5.4. How is Address of Mobile Network Node Represented?
Normally, Route Optimization would mean that a binding between the Normally, Route Optimization would mean that a binding between the
Mobile Network Node's identity and location is registered at the address of Mobile Network Node and the location of the mobile network
Correspondent Agent. Before exploring into different ways of binding is registered at the Correspondent Entity. Before exploring into
location to identity (see Section 5.5), one must first ask how the different ways of binding (see Section 5.5), one must first ask how
identity of the Mobile Network Node is represented. Basically, there the address of the Mobile Network Node is represented. Basically,
are two ways to represent the Mobile Network Node's identity: there are two ways to represent the Mobile Network Node's address:
o implicitly, by the use of Mobile Network Prefix, or o inferred by the use of Mobile Network Prefix, or
o explicitly, by the use of the address of Mobile Network Node. o explicitly specifying the address of Mobile Network Node.
Using the Mobile Network Prefix would usually mean the initiator is Using the Mobile Network Prefix would usually mean that the initiator
the Mobile Router, and has the benefit of binding numerous Mobile is the Mobile Router, and has the benefit of binding numerous Mobile
Network Nodes with one signaling. However, it also means that if Network Nodes with one signaling. However, it also means that if
location privacy is compromised, the location privacy of an entire location privacy is compromised, the location privacy of an entire
Mobile Network Prefix will be compromised. Mobile Network Prefix will be compromised.
On the other hand, using the Mobile Network Node's address would mean On the other hand, using the Mobile Network Node's address would mean
that the initiator is either the Mobile Network Node itself, or the that the initiator is either the Mobile Network Node itself, or the
Mobile Router is initiating Route Optimization on behalf of the Mobile Router is initiating Route Optimization on behalf of the
Mobile Network Node. Initiation by the Mobile Network Node itself Mobile Network Node. Initiation by the Mobile Network Node itself
means that the Mobile Network Node must have new functionalities means that the Mobile Network Node must have new functionalities
implemented, while initiation by the Mobile Router means that the implemented, while initiation by the Mobile Router means that the
Mobile Router must maintain some Route Optimization states for each Mobile Router must maintain some Route Optimization states for each
Mobile Network Node. Mobile Network Node.
5.5 How is Identity Bound to Location? 5.5. How is 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 Agent to create a binding between the identity 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 identity to the location of the parent Mobile Router; o binding the address to the location of the parent Mobile Router;
o binding the identity to a sequence of locations of upstream Mobile o binding the address to a sequence of locations of upstream Mobile
Routers; and Routers; and
o binding the identity to the location of the root Mobile Router o binding the address to the location of the root Mobile Router
These will be described in the following sub-sections. These will be 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 identity 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 Agent would know how to reach parent Mobile Router, the Correspondent Entity would know how to
the Mobile Network Node via the current location of the parent Mobile reach the Mobile Network Node via the current location of the parent
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 Agent. or more Mobile Network Prefix options to the Correspondent Entity.
The Correspondent Agent having received the Binding Update, can The Correspondent Entity having received the Binding Update, can
then set up a bi-directional tunnel with the Mobile Router at the then set up a bi-directional tunnel with the Mobile Router at the
current care-of address of the Mobile Router, and inject a route current care-of address of the Mobile Router, and inject a route
to its routing table so that packets destined for addresses in the to its routing table so that packets destined for addresses in the
mobile network prefix will be routed through the bi-directional mobile network prefix will be routed through the bi-directional
tunnel. tunnel.
Note that in this case, the identity 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 Agent, thus allowing the its Mobile Router to the Correspondent Entity, thus allowing the
Correspondent Agent to establish a binding between the identity 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 [10].
o Mobile Router as a Proxy o Mobile Router as a Proxy
Another approach is for the parent Mobile Router to act as a Another approach is for the parent Mobile Router to act as a
"proxy" for its Mobile Network Nodes. In this case, the Mobile "proxy" for its Mobile Network Nodes. In this case, the Mobile
Router uses standard Mobile IPv6 Route Optimization procedure to Router uses standard Mobile IPv6 Route Optimization procedure to
bind the address of a Mobile Network Node to the Mobile Router's bind the address of a Mobile Network Node to the Mobile Router's
care-of address. care-of address. For instance, when the Mobile Network Node is a
Local Fixed Node without Mobile IPv6 Route Optimization
o Mobile Router as a Transparent Proxy functionality, the Mobile Router may initiate teh Return
Routability procedure with a Correspondent Node on behalf of the
Local Fixed Node. An example of such an approach would be [19].
A somewhat similar approach involves the Mobile Router On the other hand, if the Mobile Network Node is a Visiting Mobile
transparently altering packets transmitted with Mobile IPv6 Route Node, it might be necessary for the Visiting Mobile Node to
Optimization (such as altering messages exchanged during the delegate the rights of Route Optimization signaling to the Mobile
return routability procedure between a Visiting Mobile Node and Router (see [20] for an example of such delegation). With this
its Correspondent Node), so that packets sent from Correspondent delegation, either the Visiting Mobile Network Node or the Mobile
Node to the Visiting Mobile Node will be routed to the care-of Router can initiate the Return Routability procedure with the
address of the Mobile Router once Route Optimization is Correspondent Node. For the case where the Return Routability
established (such as [9]). This should be contrasted against procedure is initiated by the Visiting Mobile Node, the Mobile
"Mobile Router as a Proxy". Here, the Mobile Router relies on the Router will have to transparently alters content of the Return
Visiting Mobile Node to start the Return Routability procedure, Routability signaling messages so that packets sent from the
and alters the contents of the messages in Return Routability Correspondent Node to the Visiting Node will be routed to the
procedure to achieve Route Optimization. Whereas in "Mobile care-of address of the Mobile Router once Route Optimization is
Router as a Proxy", the Mobile Router initiates the Return established. The case where the Return Routability procedure is
Routability procedure on its own. initiated by the Mobile Router is similar to the case where the
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 Agent 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
Agent, as the Correspondent Agent may need to perform multiple Entity, as the Correspondent Entity may need to perform multiple
binding cache look-ups before it can construct the complete route. binding cache look-ups before it can construct the complete route.
Other than increasing the complexity of the Correspondent Agent, Other than increasing the complexity of the Correspondent Entity,
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 Agent. 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 Agent, the delay from the reach and be processed by the Correspondent Entity, the delay from
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 Agent 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 Upstream Mobile Router", new functionality is required
at the Correspondent Agent, whereas "Mobile Router as a Proxy" and at the Correspondent Entity, whereas "Mobile Router as a Proxy" keeps
"Mobile Router as a Transparent Proxy" keeps the functionality of the the functionality of the Correspondent Entity to be the same as a
Correspondent Agent to be the same as a Mobile IPv6 Correspondent Mobile IPv6 Correspondent Node. However, this is done at an expense
Node. However, this is done at an expense of the Mobile Routers, of the Mobile Routers, since in "Mobile Router as a Proxy", the
since in "Mobile Router as a Proxy" and "Mobile Router as a Mobile Router must maintain state information for every Route
Transparent Proxy", the Mobile Router must maintain state information Optimization session its Mobile Network Nodes have. Furthermore, in
for every Route Optimization session its Mobile Network Nodes have. some cases, the Mobile Router needs to look beyond the standard IPv6
Furthermore, for "Mobile Router as a Transparent Proxy", the Mobile headers for ingress and egress packets, and alter the packet contents
Router needs to look beyond the standard IPv6 headers for ingress and appropriately.
egress packets, and alter the packet contents appropriately.
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 requirements 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 Agent 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 Agent need not store one complete route per Mobile the Correspondent Entity need not store one complete route per Mobile
Network Node when it is having Route Optimizations sessions with Network Node when it is having Route Optimizations sessions with
multiple Mobile Network Nodes from the same mobile network. multiple Mobile Network Nodes from the same mobile network.
5.5.2 Binding to a Sequence of Locations of Upstream Mobile Routers 5.5.2. Binding to a Sequence of Locations of Upstream Mobile Routers
For a nested Mobile Network Node, it might be more worth while to For a nested Mobile Network Node, it might be more worthwhile to bind
bind its identity 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 Agent 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 [9] and
and [12]. [11].
Different from Section 5.5.1, this approach constructs the complete Different from Section 5.5.1, this approach constructs the complete
route to a specific Mobile Network Node at the mobile network side, route to a specific Mobile Network Node at the mobile network side,
thus offering the opportunity to reduce the signaling overhead. thus offering the opportunity to reduce the signaling overhead.
Since the complete route is conveyed to the Correspondent Agent in a Since the complete route is conveyed to the Correspondent Entity in a
single transmission, it is possible to reduce the delay from the time single transmission, it is possible to reduce the delay from the time
an optimized route is changed till the time the change is registered an optimized route is changed till the time the change is registered
on the Correspondent Agent to its minimum. on the Correspondent Entity to its minimum.
One question that immediately comes to the mind is how the Mobile One question that immediately comes to the mind is how the Mobile
Network Node gets hold of the sequence of locations of its upstream Network Node gets hold of the sequence of locations of its upstream
Mobile Routers. This is usually achieved by having such information Mobile 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 used in [9] where upstream Mobile Routers insert their current
point of attachment into a Reverse Routing Header embedded within a point of attachment into a Reverse Routing Header embedded within a
packet sent by the Mobile Network Node. This may raise security packet sent by the Mobile Network Node. This may raise security
concerns that will be discussed later in Section 5.8.2. concerns that will be discussed later in Section 5.8.2.
In order for a Correspondent Agent to bind the identity 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
Agent. The Correspondent Agent 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 Agent 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 to existing Network. In addition, some amount of modifications or extension to
protocols is also required, such as a new type of IPv6 routing existing protocols is also required, such as a new type of IPv6
header, or new options in Router Advertisement messages. routing header, or new options in Router Advertisement messages.
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 identity of the Mobile Network Node A third approach is to bind the address of the Mobile Network Node to
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 Agent needs to forward packet to the Whenever the Correspondent Entity needs to forward packet to the
Mobile Network Node, it only needs to forward the packet to this Mobile Network Node, it only needs to forward the packet to this
point of attachment. The mobile network will figure out how to point of attachment. The mobile network will figure out how to
forward the packet to the Mobile Network Node by itself. This kind forward the packet to the Mobile Network Node by itself. This kind
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 Agent that Mobile Network, so that it seems to the Correspondent Entity that
every node in the Mobile Network is attached to the Internet at the every node in the Mobile Network is attached to the Internet at the
same network segment. same network segment.
There are various approaches to achieve this: There are various approaches to achieve this:
o Prefix Delegation o Prefix Delegation
Here, each Mobile Router in a nested mobile network is delegated a Here, each Mobile Router in a nested mobile network is delegated a
Mobile Network Prefix from the access router (such as using DHCP Mobile Network Prefix from the access router (such as using DHCP
Prefix Delegation [15]). Each Mobile Router also autoconfigures Prefix Delegation [14]). Each Mobile Router also autoconfigures
its care-of address from this delegated prefix. In this way, the its care-of address from this delegated prefix. In this way, the
care-of addresses of Mobile Routers are all from an aggregatable care-of addresses of Mobile Routers are all from an aggregatable
address space starting from the access router. Mobile Network address space starting from the access router. Mobile Network
Nodes with Mobile IPv6 functionality may also autoconfigure its Nodes with Mobile IPv6 functionality may also autoconfigure its
care-of address from this delegated prefix, and use standard care-of address from this delegated prefix, and use standard
Mobile IPv6 mechanism to bind its home address to this care-of Mobile IPv6 mechanism to bind its home address to this care-of
address. address.
Examples of this approach includes [18] and [19]. Examples of this approach includes [21] and [22].
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 Agents. Updates to their Correspondent Entities.
o Neighbor Discovery Proxy o Neighbor Discovery Proxy
This approach (such as [20]) achieves Route Optimization by having This approach (such as [23]) achieves Route Optimization by having
Mobile Routers to act as a Neighbor Discovery [21] proxy for its Mobile Routers to act as a Neighbor Discovery [24] proxy for its
Mobile Network Nodes. Mobile Router will configure a care-of Mobile Network Nodes. Mobile Router will configure a care-of
address from the network prefix advertised by its access router, address from the network prefix advertised by its access router,
and also relay this prefix to its subnets. When a Mobile Network and also relay this prefix to its subnets. When a Mobile Network
Node configures an address from this prefix, the Mobile Router Node configures an address from this prefix, the Mobile Router
will act as a Neighbor Discovery proxy on its behalf. In this will act as a Neighbor Discovery proxy on its behalf. In this
way, the entire mobile network and its access network form a 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 Agents, it will also cause a burst Updates to their Correspondent Entities, it will also cause a
of Duplicate Address Discovery messages to be exchanged between burst of Duplicate Address Discovery messages to be exchanged
the mobile network and the access network. between the mobile network and the access network. Furthermore,
route optimization for Local Fixed Nodes is not possible without
new functionalities implemented on the Local Fixed Nodes.
o Hierarchical Registrations o Hierarchical Registrations
Hierarchical Registration involves Mobile Network Nodes (including Hierarchical Registration involves Mobile Network Nodes (including
nested Mobile Routers) to register itself with either their parent nested Mobile Routers) to register itself with either their parent
Mobile Routers, or the root Mobile Router itself. After 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 Agents, Network Nodes are tunneled directly to the Correspondent Entities,
thus avoiding nested tunneling. thus avoiding nested tunneling.
One form of such approach uses the principle of Hierarchical One form of such approach uses the principle of Hierarchical
Mobile IPv6 [13], where the root Mobile Router acts as a Mobility Mobile IPv6 [12], where the root Mobile Router acts as a Mobility
Anchor Point. It is also possible for each parent Mobile Router Anchor Point. It is also possible for each parent Mobile Router
to act as Mobility Anchor Points for their child Mobile Routers, to act as Mobility Anchor Points for their child Mobile Routers,
thus forming a hierarchy of Mobility Anchor Points. One can also thus forming a hierarchy of Mobility Anchor Points. One can also
view these Mobility Anchor Points as local Home Agents, thus view these Mobility Anchor Points as local Home Agents, thus
forming a cascade of mobile Home Agents. In this way, each Mobile forming a cascade of mobile Home Agents. In this way, each Mobile
Router terminates its tunnel at its parent Mobile Router. Hence, Router terminates its tunnel at its parent Mobile Router. Hence,
although there are equal number of tunnels as the level of although there are equal number of tunnels as the level of
nesting, there is no tunnel encapsulated within another. nestings, there is no tunnel encapsulated within another.
Examples of this approach includes [22] and [23]. Examples of this approach includes [25] and [26].
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 packets forwarding between nodes in the same hoc routing for packet-forwarding between nodes in the same mobile
mobile network. An approach of doing so might involve a router network. An approach of doing so might involve a router acting as
acting as a gateway for connecting nodes in the mobile network to a gateway for connecting nodes in the mobile network to the global
the global Internet. All nodes in the mobile network would Internet. All nodes in the mobile network would configure their
configure their care-of addresses from one or more prefixes care-of addresses from one or more prefixes advertised by that
advertised by that gateway, while their parent Mobile Routers use gateway, while their parent Mobile Routers use Mobile Ad-hoc
Mobile Ad-hoc routing to forward packets to that gateway or other routing to forward packets to that gateway or other destinations
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 Agent. 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 [9]. 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 Agent network topology can be rapidly propagated to the Correspondent
as long as there is a continuous stream of data to be transmitted. Entity as long as there is a continuous stream of data to be
However, this might incur a substantial overhead on the data packets. transmitted. However, this might incur a substantial overhead on the
Off-plane signaling, on the other hand, sends signaling messages data packets. Off-plane signaling, on the other hand, sends
independently from the data packet. This has the advantage of signaling messages independently from the data packet. This has the
reducing the signaling overhead in situations where there are advantage of reducing the signaling overhead in situations where
relatively less topological changes to the mobile network. However, there are relatively less topological changes to the mobile network.
data packets transmission maybe disrupted while off-plane signaling However, data packets transmission may be disrupted while off-plane
takes place. signaling takes place.
5.7 How is Data Transmitted? An entirely different method of signaling makes use of upper layer
protocol to establish the bindings between the address of a Mobile
Network Node and the location of the mobile network. Such binding
information can then be passed down to the IP layer to insert the
appropriate entry in the Binding Cache or routing table. An example
of such mechanism is [27] which uses the Session Initiation Protocol
(SIP) to relay binding information.
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 [24]. In this way, the original packet can in-IP encapsulations [28]. In this way, the original packet can
be tunneled to the location bound to the identity 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 identity, the number of on how the location is bound to the address of Mobile Network
encapsulations required might vary. Node, the number of encapsulations required might vary.
For instance, if the Correspondent Agent 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
[25][26] to compress the multiple tunnel packet headers. [29][30] 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 Agent 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
identity 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 [18][19] would For instance, the Prefix Delegation approach [21][22] 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 Identity-Location 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 Agent is exposed to by certainly the security risks a Correspondent Entity is exposed to by
creating a binding between the identity 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 Agent and Mobile Network Node do not share assumed that Correspondent Entity and Mobile Network Node do not
any pre-existing security association. However, the Correspondent share any pre-existing security association. However, the
Agent must have some ways of verifying the authenticity of the Correspondent Entity must have some ways of verifying the
binding specified, else it will be susceptible to various attacks authenticity of the binding specified, else it will be susceptible to
described in [17], such as snooping (sending packets meant for a various attacks described in [18], such as snooping (sending packets
Mobile Network Node to an attacker) or denial-of-service (flooding a meant for a Mobile Network Node to an attacker) or denial-of-service
victim with packets meant for a Mobile Network Node) attacks. (flooding a victim with packets meant for a Mobile Network Node)
attacks.
When the binding is performed between the identity 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 Agent. This also reasonable degree of assurance to the Correspondent Entity. This
allows the Correspondent Agent to re-use existing implementations. also allows the Correspondent Entity to re-use existing
But in other situations, an extension to the Return Routability implementations. But in other situations, an extension to the Return
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 Binding
Update containing Mobile Network Prefix information to Correspondent Update containing Mobile Network Prefix information to Correspondent
Agent (see Section 5.5.1). Although the Return Routability procedure Entity (see Section 5.5.1). Although the Return Routability
allows the Correspondent Agent to verify that the care-of and home procedure allows the Correspondent Entity to verify that the care-of
addresses of the Mobile Router are indeed collocated, it does not and home addresses of the Mobile Router are indeed collocated, it
allow the Correspondent Agent to verify the validity of the Mobile does not allow the Correspondent Entity to verify the validity of the
Network Prefix. If the Correspondent Agent accepts the binding Mobile Network Prefix. If the Correspondent Entity accepts the
without verification, it will be exposed to attacks where the binding without verification, it will be exposed to attacks where the
attacker tricks the Correspondent Agent into forwarding packets attacker tricks the Correspondent Entity into forwarding packets
destined for a mobile network to the attacker (snooping) or victim destined for a mobile network to the attacker (snooping) or victim
(DoS). [27] discusses this security threat further. (DoS). [31] 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 Agents. In approaches that involve the constrained to Correspondent Entities. In approaches that involve
Correspondent Routers (see Section 5.1.3), there have been the Correspondent Routers (see Section 5.1.3), there have been
suggestions for the Correspondent Router to advertise the network suggestions for the Correspondent Router to advertise the network
prefix(es) of Correspondent Nodes the Correspondent Router is capable prefix(es) of Correspondent Nodes the Correspondent Router is capable
of terminating Route Optimization on behalf of to Mobile Network of terminating Route Optimization on behalf of to Mobile Network
Nodes. In such cases, the Mobile Network Nodes also need a mechanism Nodes. In such cases, the Mobile Network Nodes also need a mechanism
to check the authenticity of such claims. Even if the Correspondent to check the authenticity of such claims. Even if the Correspondent
Routers do not advertise the network prefix, the Mobile Network Nodes Routers do not advertise the network prefix, the Mobile Network Nodes
also have the need to verify that the Correspondent Router is indeed also have the need to verify that the Correspondent Router is indeed
a valid Correspondent Router for a given Correspondent Node. 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 signaling of Route Optimization involves
sending the location of one or more upstream Mobile Routers. The sending the location of one or more upstream Mobile Routers. The
Correspondent Agent must also have the means to verify such Correspondent Entity must also have the means to verify such
information. Again, the standard Return Routability procedure is information. Again, the standard Return Routability procedure is
inadequate here. An extension such as attaching a routing header to inadequate here. An extension such as attaching a routing header to
the Care-of Test (CoT) message to verify the authenticity of the 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 Agents. The risk, however, is not confined to the Correspondent Entities. The
Mobile Network Nodes are also under the threat of receiving false Mobile Network Nodes are also under the threat of receiving false
information from their upstream Mobile Routers, which they might pass information from their upstream Mobile Routers, which they might pass
to the Correspondent Agents. There are some considerations that this to the Correspondent Entities. There are some considerations that
kind of on-path threat exists in the current Internet anyway this kind of on-path threat exists in the current Internet anyway
especially when no (or weak) end-to-end protection is used. especially when no (or weak) end-to-end protection is used.
All these concerns over the authenticity of addresses might suggest All these concerns over the authenticity of addresses might suggest
that perhaps a more radical and robust approach is necessary. This that perhaps a more radical and robust approach is necessary. This
is currently under extensive study in various Working Groups of the is currently under extensive study in various Working Groups of the
IETF, and many related documents might be of interest here, such as IETF, and many related documents might be of interest here. For
Securing Neighbor Discovery (SEND) [28], the use of Cryptographically instance, in Securing Neighbor Discovery (SEND) [32], the use of
Generated Addresses (CGA) [29], various enhancements to the Route Cryptographically Generated Addresses (CGA) [33] could be used to
Optimization scheme of Mobile IPv6 [30][31], and possibly Host establish the ownership of care-of adresses and network prefixes.
Identity Protocol (HIP) [32] with end-host mobility considerations [34] employs the Home Agent to check the signaling messages sent by
[33]. Mobile Routers to provide a way for Correspondent Entities to verify
the authenticity of Mobile Network Prefixes specified. [35] documents
various proposed enhancements to the Mobile IPv6 Route Optimization
mechanism which might be applied to NEMO Route Optimization as well,
such as [36] which allows the Correspondent Entity to authenticate a
certain operator's Home Agent by verifying the associated
certificate. The Host Identity Protocol (HIP) [37] with end-host
mobility considerations [38] may also be extended for NEMO Route
Optimization as well.
5.8.2 End-to-End Integrity In addition, interested readers might want to refer to [39] that
discussed the general problem of making Route Optimization in NEMO
secure and explored some possible solution schemes. There is also a
proposed mechanism for Mobile Network Node to delegate some rights to
their Mobile Routers in [20], which may be used to allow the Mobile
Routers to prove their authenticities to Correspondent Entities when
establishing Route Optimization sessions on behalf of the Mobile
Network Nodes.
In some of the approaches, such as "Mobile Router as a Proxy" and 5.8.2. End-to-End Integrity
"Mobile Router as a Transparent Proxy" in Section 5.5.1, the Mobile
Router sends messages using the Mobile Network Node's address as the In some of the approaches, such as "Mobile Router as a Proxy" in
source address. This is done mainly to achieve zero new Section 5.5.1, the Mobile Router sends messages using the Mobile
functionalities required at the Correspondent Agents and the Mobile Network Node's address as the source address. This is done mainly to
Network Nodes. However, adopting such a strategy may interfere with achieve zero new functionalities required at the Correspondent
existing or future protocols, most particularly security-related Entities and the Mobile Network Nodes. However, adopting such a
protocols. This is especially true for the "Mobile Router as a strategy may interfere with existing or future protocols, most
Transparent Proxy" approach, as it requires the Mobile Router to make particularly security-related protocols. This is especially true
changes to packets sent by Mobile Network Nodes. In a sense, these when the Mobile Router needs to make changes to packets sent by
approaches break the end-to-end integrity of packets. Mobile Network Nodes. In a sense, these approaches break the end-to-
end integrity of packets. A related concern is that this kind of
approach may also require the Mobile Router to inspect into packet
contents sent to/by Mobile Network Nodes. This may prove to be
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 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 draft currently does not consider the location privacy threats
caused by an on path eavesdropper. For more information on that caused by an on path eavesdropper. For more information on that
aspect, please refer to [16]. Instead, we consider the following aspect, please refer to [17]. Instead, we consider the following
three aspects to location privacy: three aspects to location privacy:
o Revelation of Location to Correspondent Agent 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
identity of the Mobile Network Node and the current location of address of the Mobile Network Node and the current location of the
the Mobile Network. It is thus inevitable that the location of Mobile Network. It is thus inevitable that the location of Mobile
Mobile Network Node be revealed to the Correspondent Agent. The Network Node be revealed to the Correspondent Entity. The concern
concern may be alleviated if the Correspondent Agent is not the may be alleviated if the Correspondent Entity is not the
Correspondent Node, since this implies that the actual traffic Correspondent Node, since this implies that the actual traffic
end-point (i.e. the Correspondent Node) would remain ignorant of end-point (i.e. the Correspondent Node) would remain ignorant of
the current location of the Mobile Network Node. the 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 identity 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 Agent. Whereas for network is revealed to the Correspondent Entity. Whereas for
approaches such as those described in Section 5.5.1 and approaches such as those described in Section 5.5.1 and
Section 5.5.2, more information (such as Mobile Network Prefixes Section 5.5.2, more information (such as Mobile Network Prefixes
and current locations of upstream Mobile Routers) is revealed. and current locations of upstream Mobile Routers) is revealed.
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
skipping to change at page 31, line 11 skipping to change at page 33, line 11
Node and its Mobile Router can be used in this case to prevent the Node and its Mobile Router can be used in this case to prevent the
Mobile Router from attempting Route Optimization for a given Mobile Router from attempting Route Optimization for a given
traffic stream. 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 detail 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 to, 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.
skipping to change at page 31, line 34 skipping to change at page 33, line 34
This is an informational document and does not require any IANA This is an informational document and does not require any IANA
action. action.
8. Security Considerations 8. Security Considerations
This is an informational document that analyze the solution space of This is an informational document that analyze the solution space of
NEMO Route Optimization. Security considerations of different NEMO Route Optimization. Security considerations of different
approaches are described in the relevant sections throughout this approaches are described in the relevant sections throughout this
document. Particularly, please refer to Section 4.8 for a brief document. Particularly, please refer to Section 4.8 for a brief
discussion of the security concern in with respect to Route discussion of the security concern with respect to Route Optimization
Optimization in general, and Section 5.8 for a more detailed analysis in general, and Section 5.8 for a more detailed analysis of the
of the various Route Optimization approaches. various Route Optimization approaches.
9. Acknowledgments 9. Acknowledgments
The authors wish to thank the co-authors of previous drafts from The authors wish to thank the co-authors of previous drafts from
which this draft is derived: Marco Molteni, Paik Eun-Kyoung, Hiroyuki which this draft is derived: Marco Molteni, Paik Eun-Kyoung, Hiroyuki
Ohnishi, Felix Wu, and Souhwan Jung. In addition, sincere Ohnishi, Felix Wu, and Souhwan Jung. In addition, sincere
appreciation is also extended to Thierry Ernst, Greg Daley, Erik appreciation is also extended to Jari Arkko, Carlos Jesus Bernardos,
Nordmark, T.J. Kniveton, Alexandru Petrescu, Hesham Soliman, Ryuji Greg Daley, Thierry Ernst, T.J. Kniveton, Erik Nordmark, Alexandru
Wakikawa and Patrick Wetterwald for their various contributions. Petrescu, Hesham Soliman, Ryuji Wakikawa and Patrick Wetterwald for
their various contributions.
10. References 10. References
10.1 Normative References 10.1. Normative References
[1] Ng, C., "Network Mobility Route Optimization Problem Statement", [1] Ng, C., "Network Mobility Route Optimization Problem Statement",
draft-ietf-nemo-ro-problem-statement-00 (work in progress), draft-ietf-nemo-ro-problem-statement-01 (work in progress),
July 2005. October 2005.
[2] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert, [2] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. Thubert,
"Network Mobility (NEMO) Basic Support Protocol", RFC 3963, "Network Mobility (NEMO) Basic Support Protocol", RFC 3963,
January 2005. January 2005.
[3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in [3] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support in
IPv6", RFC 3775, June 2004. IPv6", RFC 3775, June 2004.
[4] Manner, J. and M. Kojo, "Mobility Related Terminology", [4] Manner, J. and M. Kojo, "Mobility Related Terminology",
RFC 3753, June 2004. RFC 3753, June 2004.
[5] Ernst, T. and H. Lach, "Network Mobility Support Terminology", [5] Ernst, T. and H. Lach, "Network Mobility Support Terminology",
draft-ietf-nemo-terminology-03 (work in progress), draft-ietf-nemo-terminology-03 (work in progress),
February 2005. February 2005.
[6] Ernst, T., "Network Mobility Support Goals and Requirements", [6] Ernst, T., "Network Mobility Support Goals and Requirements",
draft-ietf-nemo-requirements-04 (work in progress), draft-ietf-nemo-requirements-04 (work in progress),
February 2005. February 2005.
10.2 Informative References 10.2. Informative References
[7] Wakikawa, R., "Optimized Route Cache Protocol (ORC)", [7] Wakikawa, R., "Optimized Route Cache Protocol (ORC)",
draft-wakikawa-nemo-orc-01 (work in progress), November 2004. draft-wakikawa-nemo-orc-01 (work in progress), November 2004.
[8] Na, J., "Route Optimization Scheme based on Path Control [8] Na, J., "Route Optimization Scheme based on Path Control
Header", draft-na-nemo-path-control-header-00 (work in Header", draft-na-nemo-path-control-header-00 (work in
progress), April 2004. progress), April 2004.
[9] Bernardos, C., "Mobile IPv6 Route Optimisation for Network [9] Thubert, P. and M. Molteni, "IPv6 Reverse Routing Header and
Mobility (MIRON)", draft-bernardos-nemo-miron-00 (work in
progress), July 2005.
[10] Thubert, P. and M. Molteni, "IPv6 Reverse Routing Header and
its application to Mobile Networks", its application to Mobile Networks",
draft-thubert-nemo-reverse-routing-header-05 (work in draft-thubert-nemo-reverse-routing-header-05 (work in
progress), June 2004. progress), June 2004.
[11] Ng, C. and T. Tanaka, "Securing Nested Tunnels Optimization [10] Ng, C. and T. Tanaka, "Securing Nested Tunnels Optimization
with Access Router Option", with Access Router Option",
draft-ng-nemo-access-router-option-01 (work in progress), draft-ng-nemo-access-router-option-01 (work in progress),
July 2004. July 2004.
[12] Na, J., "Secure Nested Tunnels Optimization using Nested Path [11] Na, J., "Secure Nested Tunnels Optimization using Nested Path
Information", draft-na-nemo-nested-path-info-00 (work in Information", draft-na-nemo-nested-path-info-00 (work in
progress), September 2003. progress), September 2003.
[13] Soliman, H., Castelluccia, C., El Malki, K., and L. Bellier, [12] 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., "Global HA to HA protocol", [13] Thubert, P., "Global HA to HA protocol",
draft-thubert-nemo-global-haha-00 (work in progress), draft-thubert-nemo-global-haha-01 (work in progress),
October 2004. October 2005.
[15] Droms, R. and O. Troan, "IPv6 Prefix Options for DHCPv6", [14] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host
draft-troan-dhcpv6-opt-prefix-delegation-01 (work in progress), Configuration Protocol (DHCP) version 6", RFC 3633,
May 2002. December 2003.
[16] Koodli, R., "IP Address Location Privacy and Mobile IPv6: [15] Baek, S., "Routing Optimization in the same nested mobile
network", draft-baek-nemo-nested-ro-00 (work in progress),
October 2005.
[16] Koodli, R., "Fast Handovers for Mobile IPv6", RFC 4068,
July 2005.
[17] Koodli, R., "IP Address Location Privacy and Mobile IPv6:
Problem Statement", draft-irtf-mobopts-location-privacy-ps-00 Problem Statement", draft-irtf-mobopts-location-privacy-ps-00
(work in progress), July 2005. (work in progress), July 2005.
[17] Nikander, P., "Mobile IP version 6 Route Optimization Security [18] Nikander, P., "Mobile IP version 6 Route Optimization Security
Design Background", draft-ietf-mip6-ro-sec-03 (work in Design Background", draft-ietf-mip6-ro-sec-03 (work in
progress), May 2005. progress), May 2005.
[18] Perera, E., "Extended Network Mobility Support", [19] Bernardos, C., "Mobile IPv6 Route Optimisation for Network
Mobility (MIRON)", draft-bernardos-nemo-miron-00 (work in
progress), July 2005.
[20] Ylitalo, J., "Securing Route Optimization in NEMO", Workshop
of 12th Network and Distributed System Security Syposuim, NDSS
Workshop 2005, online: http://www.isoc.org/isoc/conferences/
ndss/05/workshop/ylitalo.pdf, February 2005.
[21] Perera, E., "Extended Network Mobility Support",
draft-perera-nemo-extended-00 (work in progress), July 2003. draft-perera-nemo-extended-00 (work in progress), July 2003.
[19] Lee, K., "Route Optimization for Mobile Nodes in Mobile Network [22] Lee, K., "Route Optimization for Mobile Nodes in Mobile Network
based on Prefix Delegation", draft-leekj-nemo-ro-pd-02 (work based on Prefix Delegation", draft-leekj-nemo-ro-pd-02 (work
in progress), February 2004. in progress), February 2004.
[20] Jeong, J., "ND-Proxy based Route Optimization for Mobile Nodes [23] Jeong, J., "ND-Proxy based Route Optimization for Mobile Nodes
in Mobile Network", draft-jeong-nemo-ro-ndproxy-02 (work in in Mobile Network", draft-jeong-nemo-ro-ndproxy-02 (work in
progress), February 2004. progress), February 2004.
[21] Narten, T., Nordmark, E., and W. Simpson, "Neighbor Discovery [24] 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.
[22] Kang, H., "Route Optimization for Mobile Network by Using Bi- [25] Kang, H., "Route Optimization for Mobile Network by Using Bi-
directional Between Home Agent and Top Level Mobile Router", directional Between Home Agent and Top Level Mobile Router",
draft-hkang-nemo-ro-tlmr-00 (work in progress), June 2003. draft-hkang-nemo-ro-tlmr-00 (work in progress), June 2003.
[23] Ohnishi, H., "HMIP based Route optimization method in a mobile [26] Ohnishi, H., "HMIP based Route optimization method in a mobile
network", draft-ohnishi-nemo-ro-hmip-00 (work in progress), network", draft-ohnishi-nemo-ro-hmip-00 (work in progress),
October 2003. October 2003.
[24] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6 [27] Lee, C., "SIP-based Network Mobility (SIP-NEMO) Route
Optimization", draft-ming-nemo-sipnemo-00 (work in progress),
October 2005.
[28] Conta, A. and S. Deering, "Generic Packet Tunneling in IPv6
Specification", RFC 2473, December 1998. Specification", RFC 2473, December 1998.
[25] Bormann, C., Burmeister, C., Degermark, M., Fukushima, H., [29] 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.
[26] Jonsson, L-E., "RObust Header Compression (ROHC): Terminology [30] Jonsson, L-E., "RObust Header Compression (ROHC): Terminology
and Channel Mapping Examples", RFC 3759, April 2004. and Channel Mapping Examples", RFC 3759, April 2004.
[27] Ng, C., "Extending Return Routability Procedure for Network [31] Ng, C., "Extending Return Routability Procedure for Network
Prefix (RRNP)", draft-ng-nemo-rrnp-00 (work in progress), Prefix (RRNP)", draft-ng-nemo-rrnp-00 (work in progress),
October 2004. October 2004.
[28] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure [32] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure
Neighbor Discovery (SEND)", RFC 3971, March 2005. Neighbor Discovery (SEND)", RFC 3971, March 2005.
[29] Aura, T., "Cryptographically Generated Addresses (CGA)", [33] Aura, T., "Cryptographically Generated Addresses (CGA)",
RFC 3972, March 2005. RFC 3972, March 2005.
[30] Arkko, J. and C. Vogt, "A Taxonomy and Analysis of Enhancements [34] Zhao, F., "Extensions to Return Routability Test in MIP6",
draft-zhao-mip6-rr-ext-01 (work in progress), February 2005.
[35] Arkko, J. and C. Vogt, "A Taxonomy and Analysis of Enhancements
to Mobile IPv6 Route Optimization", to Mobile IPv6 Route Optimization",
draft-irtf-mobopts-ro-enhancements-01 (work in progress), draft-irtf-mobopts-ro-enhancements-03 (work in progress),
July 2005. October 2005.
[31] Zhao, F., "Extensions to Return Routability Test in MIP6", [36] Bao, F., "Certificate-based Binding Update Protocol (CBU)",
draft-zhao-mip6-rr-ext-01 (work in progress), February 2005. draft-qiu-mip6-certificated-binding-update-03 (work in
progress), March 2005.
[32] Moskowitz, R., "Host Identity Protocol", draft-ietf-hip-base-03 [37] Moskowitz, R., "Host Identity Protocol", draft-ietf-hip-base-03
(work in progress), June 2005. (work in progress), June 2005.
[33] Nikander, P., "End-Host Mobility and Multihoming with the Host [38] Nikander, P., "End-Host Mobility and Multihoming with the Host
Identity Protocol", draft-ietf-hip-mm-02 (work in progress), Identity Protocol", draft-ietf-hip-mm-02 (work in progress),
July 2005. July 2005.
[39] Calderon, M., Bernardos, C., Bagnulo, M., and I. Soto,
"Securing Route Optimization in NEMO", Third International
Symposium on Modeling and Optimization in Mobile, Ad Hoc, and
Wireless Networks, WIOPT 2005, pages 248-254, April 2005.
Appendix A. Change Log
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 [Issue #5, #6,
#16]
* Added Section 4.9 [Issue #3]
* Added clarifying text to various parts of Sect 5 [Issue #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
skipping to change at page 35, line 16 skipping to change at page 39, line 29
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
Kamifukuoka, 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 Technology Center
Village d'Entreprises Green Side Village d'Entreprises Green Side
400, Avenue Roumanille 400, Avenue Roumanille
Biot - Sophia Antipolis 06410 Biot - Sophia Antipolis 06410
FRANCE FRANCE
Email: pthubert@cisco.com Email: pthubert@cisco.com
Appendix A. Change Log
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"
Intellectual Property Statement Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed to Intellectual Property Rights or other rights that might be claimed to
pertain to the implementation or use of the technology described in pertain to the implementation or use of the technology described in
this document or the extent to which any license under such rights this document or the extent to which any license under such rights
might or might not be available; nor does it represent that it has might or might not be available; nor does it represent that it has
made any independent effort to identify any such rights. Information made any independent effort to identify any such rights. Information
on the procedures with respect to rights in RFC documents can be on the procedures with respect to rights in RFC documents can be
found in BCP 78 and BCP 79. found in BCP 78 and BCP 79.
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