White Paper

Introducing Mobile IPv6 in 2G and 3G mobile networks

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ContentsExecutive summary 4

Mobile IP 5Mobile IPv4 6Mobile IPv6 6

Link layer mobility 9Link layer mobility in 2G and 3G mobile networks 10

Mobile IPv6 as a service in GPRS and WCDMA mobile networks 11Mobile IPv6 for Inter-PLMN mobility 11Roaming between different access technologies 12Mobile IPv6 providing static IPv6 addresses for mobile terminals 12Implementation of Mobile IPv6 in 2G and 3G mobile networks 13Application layer Mobile IPv6 main benefi ts 13

Conclusions 13

Abbreviations and Defi nitions 14

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Executive summaryThe goal of cellular mobility

standards in GPRS (General Packet

Radio Service) and WCDMA

(Wideband Code Division Multiple

Access) networks has been to

provide global connectivity, where

the IP (Internet Protocol) layer is

not involved in the mobility

management. This makes it

possible to continue using existing

IP enabled access devices when

moving in the network, e.g. laptop

computers connected to GPRS

terminals. This is called link layer

or layer 2 mobility.

In link layer mobility, access to

IP networks is through one specifi c

IP router (home GGSN). If the

terminal is roaming in a visited

network that is located far away

from the home network and local

services are used, the routing can

be ineffi cient. Another case is when

a multi-mode mobile terminal is

roaming between different access

networks. If a multi-mode terminal

moves from WCDMA coverage to

a Bluetooth or WLAN (Wireless

Local Area Network) coverage

area, it is given a new IP address.

When the IP address changes,

existing application connections are

lost, and need to be restarted.

A natural solution is to use IP layer

mobility. IP mobility allows

packets sent to the home address to

be delivered to the mobile node.

In addition, mobile IP can hide

any address changes from the

transport and application layers,

enabling the mobile terminal to

roam seamlessly between different

access networks.

IP mobility is a standardised part of

Internet Protocol version 6 (IPv6).

In Mobile IPv6, each mobile node

is identifi ed with a static home

address, independent of its current

point of attachment to the Internet.

The home address is stored by the

Home Agent (HA) router in the

home network. When the mobile

node is attached to a foreign link,

it is addressable by a ‘care-of

address’, in addition to its home

address. There may be several care-of

addresses defi ned for the mobile node,

but only one, the primary care-of

address, is bound to a specifi c home

address at any one time. The care-of

address provides information about

the mobile node’s current location.

The mapping or association between

the current care-of address and the

home address is called ‘binding’.

IP mobility is also specifi ed for IPv4,

but IPv6 provides more enhanced

support for it. Mobile IPv4 is not

deployed widely enough to satisfy

current mobility needs – a shortage

of globally routable IPv4 addresses

and the use of private IPv4

addresses with Network Address

Translators (NATs) hampers Mobile

IPv4 deployment in many cases.

The benefi ts of Mobile IPv6

compared to Mobile IPv4 include:

• The huge address space of IPv6

makes Mobile IPv6 deployment

more straightforward.

• IPv6 address autoconfi guration

simplifi es the care-of address

assignment for the mobile node.

It also eases the address

management in a large network

infrastructure.

• Optimised routing: Mobile IPv6

avoids so-called triangular routing

of packets from a correspondent

node to the mobile node via the

Home Agent. This reduces transport

delay and saves network capacity.

• No need for Foreign Agents in

Mobile IPv6.

• Using IP Security for all security

requirements.

Mobile IPv6 is a highly feasible

mechanism for implementing static

IPv6 addressing for mobile terminals.

In this case, the Mobile IPv6 home

address is the static address. The

mobile node can always be reached

using the same globally unique IPv6

address, independent of its current

location. Many applications and

services, such as push services

(for example WAP push), need static

IP addresses / static user identity.

Implementing application layer

Mobile IPv6 in 2G and 3G mobile

networks primarily requires

application layer IPv6 support from

the network, the installation of a

Home Agent (HA) router in the home

network, the use of mobile terminals

supporting Mobile IPv6 and the

implementation of IP Security (IPsec).

Mobile IPv6 is a promising technology

that complements the link layer

(layer 2) mobility in GPRS and

WCDMA mobile networks. Mobile

IPv6 can handle the mobility

management in multi-access networks

(e.g. a network with WCDMA and

WLAN coverage using multi-mode

mobile terminals supporting both

technologies). Additionally, Mobile

IPv6 is a feasible method of

providing static IPv6 addresses for

the mobile terminals. Nokia sees

Mobile IPv6 as the enabling platform

for creating IP layer mobility in

the evolution path towards next

generation service offerings.

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Visitednetwork

IPv4Internet

HA

Correspondent Node

178.24.9.36

Homenetwork

FA

Home Agent

Foreign Agent

Figure 1. General scenario of Mobile IPv4

Mobile IPMobile IP is the IETF proposed

standard solution for handling

terminal mobility among IP subnets

and was designed to allow a host to

change its point of attachment

transparently to an IP network.

Mobile IP works at the network

layer (layer 3), infl uencing the routing

of datagrams, and can easily

handle mobility among different

media (LAN, WLAN, dial-up links,

wireless channels, etc.).

The generic problem with IP

mobility is that when an IP node

moves to a new subnet, it either has

to change its IP address to refl ect

the new point of attachment,

or the routers must have host

specifi c routes for the mobile node.

Both these alternatives have their

drawbacks. Host-specifi c routes in

general cannot be scaled up for

Internet-wide use. Changing the

IP address seen by the transport

and the application layers every

time a MN (Mobile Node) moves

to a new network may be a solution

to infrequent roaming, but not to

mobility in general. This is because

the transport layer (e.g. TCP) uses

the IP address as an identifi er,

correlating IP packets to transport

sessions. If this IP address is changed,

then the correlation is lost and the

sessions need to be restarted.

Mobile IP solves the mobility

problem by managing the

correlation between a changing

IP address (care-of address) and the

static home address. The transport

and application layers keep using

the home address, allowing them to

remain ignorant of any mobility

taking place.

The home address is naturally

routed to the Home Agent (HA),

which maintains the mapping

(“binding”) from the home address

to the current (primary) care-of

address (CoA). The HA will tunnel

packets to the MN at its current

point of attachment via the CoA.

In Mobile IPv4 the care-of address

can be either hosted by a Foreign

Agent (FA in Figure 1) or co-located

with the mobile node itself.

The CoA is always assigned by the

visited network, so that the routing

of the packets to the mobile node

will remain transparent to the

routers in transit. The packets from

the MN to the correspondent

node (CN) will be routed naturally

without going through the home

agent. As the MN moves from one

subnet to another, and its CoA

changes, it will inform the HA of

the new binding.

Mobile IP was originally defi ned

for IPv4 (IETF RFC 2002).

This defi nition has suffered from

the fact that mobility support for

IPv4 is an add-on, and the vast

majority of IPv4 nodes do not

support Mobile IP. For IPv6,

the mobility support has been on

the list of required features from

the beginning. The Mobile IPv6

specifi cation is on its way to

becoming a standard, so it is

expected that virtually all IPv6

deployments will include at least the

minimal mobile IP support (i.e. the

correspondent node functions).

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Visitednetwork

IPv6Internet

HA

Correspondent Nodethat is communicatingwith the mobile node

Homenetwork

Home Agentin the home network

(the mobile node’s homeaddress is associatedwith the home agent)

Mobile Node(mobile terminal)

with acare-of address

Figure 2. General scenario of Mobile IPv6

Mobile IPv4Mobile IP was originally defi ned for

IP version 4, before IPv6 existed.

The base protocol is defi ned in RFC

2002. Many enhancements have

been proposed to Mobile IPv4 to

counter some of the identifi ed

problems, which include:

• Triangular routing as shown in

Figure 1. All packets sent to the

mobile node are routed through

its home agent, causing increased

load on the home network and

higher latency. This problem could

be solved with route optimisation

extension, but the required

update may not be practical.

• Deployment problem: Mobile IPv4

typically requires each potential

foreign network to have foreign

agent(s). If foreign agents were

not used, every mobile node would

need a globally routable IPv4

address from the foreign network.

• Ingress fi ltering: In an ISP (Internet

Service Provider), any border router

may discard packets that contain

a source IP address that is not

topologically correct. In Mobile

IPv4, the Mobile nodes that are

away from home, i.e., in a foreign

ISP, use their home address as the

source IP address, resulting in the

likelihood of dropping of packets

by ingress fi ltering.

• Authentication and Authorisation:

Mechanisms specifi c to Mobile

IPv4 are used for authentication

of Mobile IPv4 registrations.

Mobile IPv4 has only a small

percentage (a few million nodes) of

the overall IPv4 deployment.

A shortage of globally routable

IPv4 addresses and use of private

IPv4 addresses with Network

Address Translators hampers its

deployment in many cases.

Mobile IPv6Mobile IPv4 and Mobile IPv6

protocols share similar ideas,

but their implementations are

somewhat different. Figure 2 shows

the basic elements of Mobile IPv6.

Mobility signalling and security

features (IPsec) are integrated in the

IPv6 protocol as header extensions,

whereas Mobile IPv4 uses a separate

UDP (User Datagram Protocol)

based protocol for registrations.

These registrations apply special

mobility security associations.

In IPv6 stateless address

autoconfi guration, addresses can

be generated easily by combining

the network prefi x of a visited

network and an interface identifi er

of the MN. In addition, address

exhaustion is not a problem.

Therefore, an IPv6 Care-of Address

(CoA) is always co-located at the

MN, and the concept of the foreign

agent has been eliminated. Also,

route optimisation is built into

Mobile IPv6. If route optimisation

is used, user privacy may be

violated, because it will reveal the

true location of the mobile node.

If the MN needs to discover its HA

dynamically, it can make the

enquiry using IPv6 anycast. This is

more effi cient and reliable than

IPv4 directed multicast, which may

return several replies.

Several ICMPv6 (Internet Control

Message Protocol for IPv6)

mechanisms provide support for

mobility management. These include:

• Router Advertisement

• Router Solicitation

• Address Auto-confi guration

(stateful and stateless)

• Neighbour Discovery

Some of these have been extended

in Mobile IPv6 to better support

its needs. These changes include a

new home agent bit to the router

advertisement, a new bit to the

prefi x information option format,

allowing the router to effi ciently

advertise its global IPv6 address

instead of the link local address.

Also, the timing rules for router

advertisements and solicitations

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Figure 3a. Mobile Node at a foreign link informing the Home Agent

Figure 3b. Mobile Node at its home link informing the Home Agent

Figure 3c. Mobile Node at a foreign link informing a correspondent node

Binding Update

Binding Acknowledgement

IPv6network

HA

Home link

Foreign link

Mobile Node

Home Agent

Binding Update

Binding Acknowledgement

IPv6network Home link

Mobile Node

HAHome Agent

Binding Update

Binding Acknowledgement

IPv6network

HA

Home linkForeign link

Mobile Node

Correspondent Node

Home Agent

have been refi ned and a new

Advertisement Interval Option

has been defi ned for Router

Advertisements.

The following subsections detail

the major functional elements of

Mobile IPv6 that make use of these

IPv6 features.

Movement detectionA mobile node can determine its

current location by listening to the

Router Advertisements and storing

the included network prefi x

information (as do the normal,

stationary IPv6 nodes). If one of

the network prefi xes equals the

network prefi x of the home address

of the MN, then the MN is on its

home link. Otherwise the MN is

on a foreign link.

The MN selects one of the

advertised routers as its default

router. Movement from one link to

another is initiated when the

currently selected default router

becomes unreachable.

If the MN does not want to wait for

a periodic Router Advertisement,

it can send a Router Solicitation

asking all the routers on the link to

send Router Advertisements.

To obtain a care-of address, the MN

can use either stateful or stateless

address auto-confi guration.

In the fi rst situation the MN

obtains a care-of address from

e.g. a DHCPv6 (Dynamic Host

Confi guration Protocol for IPv6)

server. In the latter situation,

the MN extracts the network prefi xes

from the Router Advertisements

and adds a unique interface

identifi er to form a care-of address.

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When the MN is not on its home

link, the home agent must intercept

packets destined for the MN

home address, causing them to be

delivered to the HA.

Binding management in Mobile IPv6Three destination options are

introduced in Mobile IPv6 for

binding management:

• Binding Update

• Binding Acknowledgement

• Binding Request

All these are implemented as IPv6

Destination Options, allowing

them to be either piggybacked with

any IPv6 packet being destined to

a desired destination, or sent

separately with no upper layer

payload.

IP Security is applied to Binding

Update and Binding

Acknowledgement: IPsec

Authentication Header (AH) is

required for authentication and

Encapsulating Security Payload

(ESP) can also be used together

with AH, if encryption is desired.

No authentication is required for

the Binding Request option.

A Binding Update is used to

inform the HA and any active

correspondent node (CN) of the

current (new) binding, consisting of

the new care-of address, the home

address and a binding lifetime

(Figures 3a and 3c). Each IPv6

node (either mobile or stationary)

is recommended to understand

the Binding Update message,

enabling the packets destined to

the MN to be effi ciently routed

without going through the HA.

Initially a new CN knows only the

Home address, but when the MN

receives packets routed via the HA,

it can send a Binding Update to the

new CN.

When the MN moves back to its home

link, it will notify the home agent

to delete the binding (Figure 3b).

The Binding Acknowledgement is

sent as a response to the Binding

Update, if so requested by the MN.

The Binding Acknowledgement is

also sent to reject the Binding

Update (e.g. for authentication

failure).

If a CN wants to know the care-of

address of a mobile node, it can

send a Binding Request to the MN,

which does not necessarily have to

respond to the request by sending

a Binding Update. The Binding

Request is mainly used to refresh

binding when nearing the end of

the current binding lifetime.

Mobile node moving in the networkWhenever the mobile node moves

from one subnet or network to

another it acquires a new care-of

address, which needs to be

registered with the HA serving the

mobile host. This process involves

the following events, each of which

takes some time:

1. Movement detection: The mobile

host determines that it has

moved and needs to acquire a

new care-of address. In IPv6 this

is facilitated in general by the

Router Advertisements being

sent periodically by the subnet

routers. In cellular networks,

the movement detection can be

co-ordinated with link layer

movement detection mechanisms.

2. Acquisition of a co-located

care-of address by some

mechanism (for example

stateless autoconfi guration).

3. Registration of the new care-of

address with the home agent.

Moving to a new subnet can cause

a short break in the IP layer

reachability of the mobile node,

causing packet loss during the

handoff. Such breaks are not

inevitable, depending upon layer 2

effects, range overlap and policy.

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Gi

PPP

IPv6

TCP

Laptopcomputer

PPP

Mobile terminal

PDCP PDCP

RNC

GTP

UDP

IPv4

L2

GTP

SGSN

GTP

UDP UDP

IPv4 IPv4

L2 L2

GTP

GGSN

IPv6

UDP

L2

IPv4

L2

GnIu-PSUuR

End user IPv6 connectivity

Back-bonelayers

Figure 4. Simplifi ed protocol architecture in a 3G network

Figure 5. Intra- and Inter-PLMN backbone networks

PLMN A

SGSN

Intra-PLMN Backbone

SGSN

GGSN BG

PLMN B

SGSN

Intra-PLMN Backbone

BG GGSN

Inter-PLMN Backbone

Packet Data Network

GpGi Gi

Link layer mobilityIn 2G and 3G mobile networks,

mobility is managed below the user

plane network layer i.e. on the layer

2 (the link layer). Layer 2 mobility

management is also used in other

systems, such as Wireless LANs,

for inter access point handovers.

UMTS (Universal Mobile

Telecommunications System) is a

more general term for the 3G (third

generation) telecommunications

system based on the WCDMA high

capacity radio interface. The goal

of UMTS Packet Switched (PS)

Domain is to provide global layer 2

connectivity that can support any

layer 3 protocol. GPRS Tunneling

Protocol (GTP) handles the global

(macro) mobility. The MT (Mobile

Terminal) is attached to the same

GGSN AP all the time, and keeps

its layer 3 (e.g. IPv6) address.

In this case there is no vital need

for Mobile IP. Figure 4 shows a

simplifi ed transport protocol

structure in the UMTS PS Domain,

where user level IPv6 is tunnelled

across the internal GPRS elements.

In the fi gure, a laptop computer

is connected to the network using

a WCDMA terminal as a modem

(so-called dial-up emulation).

A GPRS attached MT can be

assigned either a static or dynamic

IP address. The static address is

assigned by the Home Public Land

Mobile Network (HPLMN)

operator at the time of subscription.

The dynamic IP address can be

allocated by the GGSN of either

HPLMN or the visited PLMN

(VPLMN) operator at the PDP

context activation time. In addition

to address allocation, a GGSN

implements the forwarding of IP

packets from the GTP tunnel to

a PDN over the Gi interface and

vice versa.

There are two kinds of PLMN

backbone networks: Intra-PLMN

backbone and Inter-PLMN

backbone (Figure 5). Every intra-

PLMN backbone network is a

private IP network intended for

packet domain data and signalling

within a PLMN only, and the

inter-PLMN backbone is used for

roaming from one PLMN to

another (via the Gp interface and

the Border Gateways). SGSN and

GGSN use the intra-PLMN

backbone to exchange PS Domain

data and signalling. When roaming,

both the intra-PLMN backbone

of the home and visited networks

are used, in addition to the inter-

PLMN backbone.

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IPv6Internet

IPv6Intranet

Home network

Edge RouterFW

Visited network

Edge RouterFW

GPRScore

OperatornetworkGGSN

SGSN

GPRScore

OperatornetworkGGSN

SGSN

BG

BG

GTP tunnelInter-PLMNbackbonenetwork

MT

Host

Figure 6. Link layer (layer 2) mobility in the 2G and 3G mobile network.

Link layer mobility in 2G and 3G mobile networksThe inter-PLMN backbone network

interconnects SGSNs and GGSNs

and intra-PLMN backbone

networks in different PLMNs.

When a subscriber is roaming to

another PLMN, known as the

visited PLMN (VPLMN), the user

needs to fi rst attach to the network.

In GPRS Attach, the MT informs

the SGSN of its intention to

connect to the network by giving

information about its identity,

capability and location. The SGSN

then checks the MT’s identity and

performs the authentication

procedure in order to secure the

transmission path. The attachment

is completed after the SGSN has

received the roaming subscriber data

from HLR of the subscriber’s Home

PLMN (HPLMN) and fi nished the

location update procedure.

After GPRS Attach, the MT sends

an ‘Activate PDP context’ Request,

in which the Access Point Name

(APN) is a reference to the GGSN

AP to be used in either the Home or

Visited PLMN backbone or in an

external network. The SGSN

selects the GGSN based on the PDP

context subscription record and

sends the context data to a selected

GGSN. The GGSN routes the

packets to the appropriate Packet

Data Networks (PDN).

When a subscriber is roaming in the

VPLMN, there are two possibilities

for GGSN selection:

1. Use the home network GGSN

via the inter-PLMN backbone,

BGs, and GTP tunnel over the Gp

interface (see Figures 5 and 6).

The home GGSN then routes the

packets to their destination.

2. Use a visited domain GGSN,

routing the packets from the

VPLMN to their destination

directly though a Packet Data

Network, such as the public

Internet using the Gi interface.

The fi rst case allows the mobile

terminal to have a network layer

identity from the home network.

But it might not be the most

effective way especially in the case

local services (topologically near

the visited network) are used.

In the second case, the mobile

terminal is assigned an IPv6 address

from the address pool of the visited

GGSN. In that case it is impossible

for the mobile terminal to be

reachable via an address from the

home domain. A solution to that

based on Mobile IPv6 is described

in the following chapter.

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Mobile IPv6 as a service in GPRS and WCDMA mobile networksThis section describes the benefi ts

of the introduction of Mobile IPv6

as a service in GPRS and WCDMA

mobile networks. The use of

Mobile IPv6 as a complementing

mobility method and a method for

multi-access mobility is discussed.

The following section shows how

Mobile IPv6 can be used to provide

static IPv6 addresses for GPRS/

WCDMA terminals. Finally,

the benefi ts of Mobile IPv6 are

summarised.

Mobile IPv6 for Inter-PLMN mobilityConsider the situation that a GPRS

subscriber of an operator in

Finland is roaming in the U.S. and

accessing a local service there.

If the link layer mobility is used,

the user’s IP packets would fi rst be

tunnelled to Finland, and then

routed back to the U.S. In this

scenario a round trip time from the

mobile terminal to a server and

back could be unacceptable to

many services.

As a solution to this problem,

the roaming GPRS subscriber

should use the services of a local

GGSN in the visited network,

allowing IP packets to be routed as

soon as possible, without crossing

over to the home network. As the

IP address is now being assigned

from the visited network, the mobile

node would not be accessible via a

network layer identity of the home

network. For some applications this

may not be a problem, but in

general it would be desirable if the

mobile node could be reached with

an IP address being assigned from

the home network as well.

A natural solution to this problem

is to use Mobile IP to register

the visited network address with

the home network, allowing

packets sent to the home address to

be delivered to the mobile node.

The basic operation of Mobile IPv6 in GPRS/WCDMA networkWhen the mobile terminal is

roaming in a foreign network, it is

addressable by a care-of address,

in addition to its home address.

The IPv6 address prefi x in the

mobile terminal’s care-of address

is the prefi x of the foreign link.

The care-of address is acquired by

the addressing mechanism provided

by the visited network. While

roaming in the foreign network,

the mobile terminal registers one

of its care-of addresses with the

home agent and sends a “Binding

Update” to the home agent.

The home agent replies with

“Binding Acknowledgement.”

Any IPv6 packets containing

Binding Update or Binding

Acknowledgement destination

options must be authenticated using

IP Security AH (Authentication

Header). After the binding, this

care-of address becomes the mobile

terminal’s primary care-of address.

The home agent intercepts all IPv6

packets from a correspondent node

(for example a WWW server that is

communicating with the mobile

terminal) addressed to the mobile

terminal’s home address. The home

agent encapsulates each intercepted

packet using IPv6 encapsulation,

with the outer header addressed to

the mobile terminal’s primary

care-of address. After the mobile

terminal has received the fi rst

encapsulated packet from the

home agent, it sends a Binding

Update to the correspondent node

informing it of its care-of address:

the correspondent node then replies

with a Binding Acknowledgement.

After this, sending IP packets

between the correspondent node

and the mobile terminal is

straightforward and routing via a

home agent is not needed.

For packets sent by a mobile

terminal while away from home,

the mobile terminal’s care-of

address is typically used as the

source address in the packet’s

IPv6 header. The Home Address

option can be used to inform the

packet recipient of the mobile

node’s home address.

The correspondent node can then

substitute the mobile node’s home

address for this care-of address

making the use of the care-of

address transparent to the

correspondent node. The upper

protocol layers (e.g. TCP) thus only

see the home address. (Figure 7.)

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Figure 7. IPv6 mobility in the 2G and 3G mobile network

IPv6Internet

IPv6 Intranet

Home network

EdgeRouter

FW

Visited network

FW

GPRScore

OperatornetworkGGSNSGSN

GPRScore

OperatornetworkGGSNSGSN

BG

BG

Inter-PLMNbackbonenetwork

MT

HA

CorrespondentNode

EdgeRouter

Roaming between different access technologiesThe need for multi-access mobility

raises, when a multi-mode mobile

terminal roams between different

access networks. For example,

when a multi-mode terminal moves

from WCDMA coverage to

Bluetooth or WLAN (Wireless

Local Area Network) coverage

area, it is given a new IP address.

When the IP address changes,

existing application connections are

lost, and need to be restarted.

A solution to this problem also is to

use IP layer mobility (Mobile IPv6).

This allows packets sent to the

home address to be delivered to the

mobile node’s current care-of

address. In addition, mobile IP can

hide any address changes from the

transport and application layers,

enabling the mobile terminal to

roam seamlessly between different

access networks.

Mobile IPv6 providing static IPv6 addresses for mobile terminals

The basic addressing method in

GPRS and WCDMA mobile

networks is dynamic addressing

(stateless address autoconfi guration).

This means that GGSN allocates

IPv6 addresses dynamically to

mobile terminals. These addresses

do not typically have registered

DNS (Domain Name System)

names, making it diffi cult to use,

for example, peer-to-peer services

without explicit support from a

network server that could keep

track of the dynamic addresses.

There are services that benefi t from

static IPv6 addressing. For example,

push services (e.g. WAP push) need

static customer identities. It can be

noted that the use of static IPv6

addresses and using Mobile IPv6 to

provide those is a generic solution

for the static identity requirements.

Two-player games implemented in

mobile terminals are an example of

peer-to-peer services. If there is no

static addressing (at the user layer),

the users who want to play a game

together would need to meet via a

network resident server. This could

mean that new games could not

be introduced into new mobile

terminals, before making sure that

the deployed servers (if any) meet

the specifi c requirements of the

game in question.

Mobile IPv6 can be used as a solution

to this problem. The dynamic

address being assigned by the

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GGSN is used as the Mobile IPv6

co-located care-of address.

By registering this address with a

home agent, a mapping of the

dynamic address to a more static

home address is created. This allows

the mobile node to be reached with

the home address, and also via a

DNS name, since the home address

can be registered with the DNS.

Implementation of Mobile IPv6 in 2G and 3G mobile networks

Implementation of Mobile IPv6 in

2G and 3G mobile networks

primarily requires user plane

(application layer) IPv6 support

from the network, installing a home

agent (HA) router in the home

network, using mobile terminals

supporting Mobile IPv6 and

implementing IP Security

infrastructure, because Mobile

IPv6 uses IPsec for all its security

requirements.

The home agent can be located in

the network operator’s network or

some other network (e.g. company

intranet, home network, etc.).

In both cases, the GGSN elements

do not necessarily need to be

involved with the Mobile IPv6

protocol. A feasible place to install

the home agent could be near the

operator’s network edge router.

Application layer Mobile IPv6 main benefi tsThe main benefi ts of Mobile IPv6

in the application layer include:

• effi cient roaming from the visited

network to local network services

• seamless roaming between

different access technologies,

i.e. reachability via the same

address also from other types of

access networks (WLAN,

Bluetooth, etc.)

• providing a feasible static IPv6

addressing method for mobile

terminals

• reachability via the home address

also when using services of a

visited GGSN

• peer-to-peer services to be

used by the mobile node;

allowing services to be run on

the terminals with no explicit

support by the operator’s

network.

ConclusionsThe two mobility mechanisms in

GPRS and WCDMA mobile

networks are link layer (layer 2)

and IP layer mobility. GPRS and

WCDMA networks provide link

layer mobility using GTP tunnels

to connect to the home network

GGSN. Mobile IPv6 is the

technology to support the IP layer

mobility – it is a very suitable

technology for complementing the

link layer mobility.

Mobile IPv6 can handle the mobility

management in multi-access

networks (e.g. a network with

WCDMA and WLAN coverage

using multi-mode mobile

terminals). Additionally, Mobile

IPv6 is a feasible method of

providing static IPv6 addresses for

the mobile terminals. The home

address is the static IP address and

care-of addresses are taken in use

dynamically when roaming in

foreign networks. The association

between the current care-of address

and the home address is called

‘binding.’ With Mobile IPv6,

routing between the correspondent

node (for example a WWW server

communicating with the mobile

node) and the mobile node’s care-of

address is optimised. Providing

static IPv6 addresses to customers is

a business case for operators –

Mobile IPv6 is an effi cient way to

implement that.

Implementation of application

layer Mobile IPv6 in 2G and 3G

mobile networks basically requires

user plane IPv6 support from

the network, installing a home

agent (HA), using mobile terminals

supporting Mobile IPv6 and

implementing IP Security.

Nokia sees that the Mobile IPv6

protocol will have an essential

role in future mobile networks.

The time is ripe to consider

implementing Mobile IPv6 support

in the network.

14

White Paper

Abbreviations and Defi nitions2G Second Generation Mobile

Telecommunications,

including GSM and GPRS technologies

3G Third Generation Mobile

Telecommunications,

including WCDMA/UMTS technology

AH IPsec Authentication Header

AP Access Point

BG Border Gateway

CN Correspondent Node

CoA Care-of Address

DHCPv6 Dynamic Host Confi guration Protocol

for IPv6

DNS Domain Name System

ESP IPsec Encapsulating Security Payload

FA Foreign Agent

FW Firewall

GGSN Gateway GPRS Support Node

GPRS General Packet Radio Service

GTP GPRS Tunneling Protocol

HA Home Agent

HLR Home Location Register

ICMP(v6) Internet Control Message Protocol

IETF Internet Engineering Task Force

IP Internet Protocol

IPsec IP security

IPv4 Internet Protocol, version 4

IPv6 Internet Protocol, version 6

ISP Internet Service Provider

LAN Local Area Network

MN Mobile Node

MT Mobile Terminal

PDCP Packet Data Convergence Protocol

PDN Packet Data Network

PDP Packet Data Protocol

PLMN Public Land Mobile Network

RFC Request For Comments

(a specifi cation by IETF)

SGSN Serving GPRS Support Node

TCP Transmission Control Protocol

TE Terminal Equipment

UDP User Datagram Protocol

UMTS Universal Mobile Telecommunications

System

VoIP Voice over IP

WAP Wireless Application Protocol

WCDMA Wideband Code Division Multiple Access

WLAN Wireless LAN

WWW World Wide Web

BindingThe association/mapping between the mobile node’s

home address and a care-of address

Care-of AddressA temporary IP address associated with a mobile node

while visiting a foreign link

Correspondent NodeA node that is communicating with the mobile node

(for example a WWW server)

Home AddressA static IP address assigned to the mobile node in

the home network

Home AgentA router on the mobile node’s home network with

which the mobile node has registered its current

care-of address. The mobile node’s home address is

associated with the home agent

Mobile NodeA node that can change its point of attachment in

the IP network. A mobile node can be reached via its

static home address

Primary Care-of AddressThe care-of address of a mobile node most recently

registered with its home agent

15

White Paper

Copyright © Nokia Networks Oy 2001. All rights reserved.

No part of this publication may be copied, distributed, transmitted, transcribed, stored in a retrieval system, or translated into any human or computer language without the prior written permission of Nokia Networks Oy.

The manufacturer has made every effort to ensure that the instructions contained in the documents are adequate and free of errors and omissions. The manufacturer will, if necessary, explain issues which may not be covered by the documents. The manufacturer’s liability for any errors in the documents is limited to the correction of errors and the aforementioned advisory services.

The documents have been prepared to be used by professional and properly trained personnel, and the customer assumes full responsibility when using them. The manufacturer welcomes customer comments as part of the process of continual development and improvement of the documentation in the best way possible from the user’s viewpoint. Please submit your comments to the nearest Nokia sales representative.

NOKIA is a registered trademark of Nokia Corporation. Any other trademarks mentioned in this document are the properties of their respective owners.

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