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IntroductionIn the last few years the number of notebook users has been increased tremendously, due

to the great improvement in this technology with respect to size, speed, and weight. In

addition, most organizations depend on sophisticated networks that link their employees

with their PCs and workstations. Besides, telecommuters, mobile salespersons, and

other highly mobile individuals, are becoming part of a mobile workforce. The previousreasons motivate the need for mobile computers to communicate with other computers,

fixed or mobile.

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The requirements which drove the design of Mobile IP

1. A mobile node must be able to communicate with other nodes after changing its

Link-layer point of attachment to the Internet.

2. A mobile node must be able to communicate using only its home (permanent) IP

address, regardless of its current Link-layer point of attachment to the Internet.

3. A mobile node must be able to communicate with other computers that do not

implement the Mobile IP mobility functions.

4. A mobile node must not be exposed to any new security threats over and above those

to which any fixed node on the Internet is exposed.

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Design goals for Mobile IP

1. In order to make Mobile IP suitable for use over a wide range of wireless links, the size

and frequency of network routing updates should be small. To reach this goal all of the

protocol messages defined by Mobile IP consists of a small, fixed-length portion

followed by one or more extensions.2. Mobile IP protocol should be as simple as possible to be implemented. This increases

the number of nodes which can potentially make use of Mobile IP, especially memory

and processing-constrained devices such as pagers, smart cellular telephones, and

personal organizers, in addition to fully functional notebook computers.

3. Avoid solutions which require mobile node to use multiple addresses, or which require

large pools of addresses to be made available for use by mobile nodes, unless

absolutely necessary. This assumption makes mobile IP suitable to be implemented

over IPv4which has a limited set of available addresses. To make the Mobile IP

suitable for wide range of communication technology the size, number and frequencyof network routing updates should be small.

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Assumptions made by Mobile IP

1. Unicast packets destined to a single recipient should be routed based only upon the

IP Destination Address and typically only the network prefix portion of that address.

2. The Internet should be capable of delivering packets between any pair of nodes in thenetwork.

3. All Mobile IP requires an infrastructure of routers and links that is capable of routing

packets to any node which is connected to its home link.

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Mobile IP Terminology1. Agent Advertisement - an ICMP advertisement message with one or more extensions.

2. Care of Address - a care of address is an IP address associated with a mobile node whilevisiting a particular foreign link.

3. Correspondent Node - A peer with which a mobile node is communicating. A

correspondent node may be either mobile or stationary.4. Foreign Network - Any network other than the mobile nodes Home Network.

5. Home Address - An IP address that is assigned for an extended period of time to amobile node.

6. Link - A facility or medium over which nodes can communicate at the Link layer.

7. Link layer Address - The address used to identify an endpoint of somecommunication over a physical link.

8. Mobility Agent - Either a home agent or a foreign agent.

9. Mobility Binding- The association of a home address with a care of address, alongwith the remaining lifetime of that association.

10. Tunnel - The path followed by a datagram while it is encapsulated.

11. Visited Network - A network other than a mobile nodes Home Network, to which themobile node is currently connected.

12. Visitor List - the list of mobile nodes visiting a foreign agent.

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New Architectural EntitiesMobile IP introduces the following new functional entities:

1. Mobile Node - a node which can change its point of attachment to the Internet fromone link to another while maintaining any ongoing communications and using onlyits (permanent) IP home address.

2. Home Agent - a router with an interface on the mobile nodes home link which:

a. the mobile keeps informed of its current location, as represented by its care ofaddress, as the mobile node moves from link to link.

b. advertises reachability to the network-prefix of the mobile nodes home address,thereby attracting IP packets that are destined to the mobile nodes home address.

c. intercepts packets destined to the mobile nodes home address and tunnels them tothe mobile nodes current location.

3. Foreign Agent - a router on a mobile nodes foreign link which:

a. Assists the mobile node in informing its home agent of its current care of address.

b. In some cases provides a care of address and de-tunnels packets for the mobilenode that have been tunneled by its home agent.

c. Serve as a default router for packets generated by the mobile node while its isconnected to this foreign link.

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X

X

Arbitrary Topology

of Routers andLinks

X

Mobile node

visiting a foreignLink

Foreign LinkHome

Agent

Home Link

Mobile node

at home

Mobile IP entities and relationships

Foreign Link

Foreign Agent

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Summary of How Mobile IP works

The purpose of this section is to illustrate Mobile IP at a very high level.

A. Mobile agents advertise their presence on any attached link by periodically

multicasting or broadcasting special Mobile IP messages called Agent

Advertisement. Home agents and foreign agents periodically broadcast AgentAdvertisements which are received by all nodes on the link.

X

Mobile Agent

Host Host

Mobile

Node

Agent

Advertisement

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B. Mobile nodes listen to these Agent Advertisements and from the contents of thismessage it determines whether they are connected to their home link or a foreign

link. If it discovers that it is connected to the home link, then it acts as any

stationary node in this link, therefore, it does not use any mobile IP functionality.

Mobile nodes examine Agent Advertisements and determine whether they are

connected to this home or a foreign link.

IP Header

IPsrc = Agents Address

IPdst = Broadcast

IP protocol = ICMP

Agent Advertisement

FA Care of Address

Agent Advertisement

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C. A Mobile node connected to a foreign link acquires a care of address. A foreignagent care of address can be read from one of the fields within the foreign agents

Agent Advertisement. A collocated care of address must be acquired by some

assignment procedure, such as the Dynamic Host configuration Protocol (DHCP),

the Point to Point Protocols IP Control Protocol (IPCP), or manual configuration.

Mobile nodes connected to a foreign link obtain a care of address from the AgentAdvertisement.

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D. The mobile node registers the care of address acquired in step 3 with its homeagent using Registration Request. If the registration is granted by the Home

Agent it will send and Acceptance reply message to the Mobile Node, otherwise a

denial Reply message will be received by the Mobile Node from the Home Agent.

Mobile node registers its care of address with its Home Agent.

Home Link

Registration Reply

Arbitrary Topology of

Routers and LinksForeign Link

Foreign Agent Home Agent

Registration Request1

2

3

4

X X

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E. The home agent or some other router on the home link advertisers reachability tothe network prefix of the mobile nodes home address. The Home Agent will

send an ARP reply on behalf of the mobile node if it is attached to a Foreign Link

and it is receiving an ARP request from other nodes to identify its Data Link layer

Address. This type of ARP reply is called a proxy ARP. The Home Agent sends

a number of gratuitous ARPs to update the ARP caches for the other nodes whichstill have the original Data Link layer Address for the Mobile Node in their

caches. This Data Link layer Address will be substituted with the Data Link layer

Address of the Home Agent. When the Mobile node returns back to its Home link

it will send a number of gratuitous ARPs to update the ARP caches for other

nodes with its Data Link layer Address as opposed to the Data Link layer of HomeAgent. Home agent or other router advertisers reachability to mobile nodes Home

Address.

Router

Router

Home Agent

Routing Update

I can reach all destinationswith network - prefix equal

to mobile nodes home

address.X

X

X

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F. The Home Agent will intercept any packets sent to the mobile node.

Home Agent

Home LinkX

X

Host

Router

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G. The Home Agent tunnels the intercepted packets and send them to the Mobile

node care of address.

Foreign Agent removes original packets from the tunnel and delivers the original

packet to the mobile node over the foreign link.

XX

Mobile

Node Foreign Agent Home Agent

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H. If the mobile node wants to send packets, they will be sent directly to theirdestination without the need for tunneling. The foreign Agent serves as a router

for all packets generated by a visiting mobile node.

XX

Mobile

Node Foreign Agent Home Agent

Correspondent

Node

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What is agent discovery?

1. Determine Mobile Node if it is connected to foreign or home link.

2. Determine Mobile Node if it is moved from one link to another link.

3. Obtain a care of address if it is connected to foreign link.

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What Messages Comprise Agent Discovery?

Agent Advertisement

It is a message sent periodically as a multicast or broadcast message to each link

the Mobile Agent Node is configured to perform as Home Agent, Foreign Agent

or both. It is identical to ICMP router advertisement with IP time to live equal 1.

Agent Solicitation

When a Home Agent or Foreign Agent receives one, it should immediately

respond by transmitting an Agent Advertisement. Agent Solicitations are

identical to ICMP Router Solicitations, with IP time to live equal 1.

The IP header of an agent advertisement is used by the mobile node to

determine whether it is connected to its home link or a foreign link.

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Vers = 4 IHL Type of Service Total Lengthidentification Flags Fragment offset

Time to Live= 1 Protocol= ICMP Header check sum

Source Address = Foreign Agent IP Address

Destination = 255.255.255.255 (broadcast) or 224.0.0.1 (multi)

Type = 9 code check sum

Num addresses Address entry size Line time of this advert

Router Address (1)

Preference Level (1)

Router Address (2)

Preference Level (2)

Type = 16 Length Sequence #

Registration Lifetime R B H F M G V rsd

Care of address (1)

Care of address (2)

Type - 19 Length Prefix 1 Prefix 2

IP Header

(RFC791)

ICMP Router

Advertisement

(RFC1256)

Mobility Agent

Advertisement

Extension

(RFC2002)

Prefix-Length

Extension

(RFC2002)

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Vers = 4 IHL Type of Service Total Length

identification Flags Fragment offset

Time to Live= 1 Protocol= ICMP Header check sum

Source Address = mobile nodes home address

Destination = 255.255.255.255 (broadcast) or 224.0.0.1 (multi)

Type = 10 code=0 check sum

IP Header

(RFC791)

ICMP Router

Advertisement

(RFC1250)

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Agent Advertisement = receive Agent Advertisement ( )

srcIP address = receive SrcIP address (agent Advertisement)

Has Mobile Node

moved?

COA = get COA (agent Advertisement)

Register Home Agent (COA, Mobile Node Home

Address)

Mobile Node Deregister with Home Agent ( )

Home Agent sends gratuitous ARPs to update

nodes caches on the Home Link

Mobile Node location detection

NO NO

YES (Node in Home

Link)

NO (Node in

Foreign Link)

YESYES

Has Mobile Node

moved?

Network Prefix (SrcIP address = =

Network Prefix (Mobile Node Homeaddress)

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How Does a Mobile Node Determine That It Has Moved

Move Detection Using Lifetime

The first method uses the Lifetime field within the ICMP router advertisement portion

if an Agent Advertisement. This field effectively tells the mobile node how soon it

should expect to hear another advertisement from the same agent. If a mobile node is

registered with a foreign agent, and fails to hear an advertisement from that agent

within the specified lifetime, then the Mobile node assumes that it has moved to a

different link or that its foreign agent is broken.

Move Detection Using Network Prefix

In this method we assume that the mobile node is registered with a foreign agent on

some link and has recorded the Agent Advertisement by which it discovered that

foreign agent. To determine whether two advertisements were received on the same

link, the mobile node computes the network prefix(es) of the respective

advertisements, and the recorded advertisement. If those network prefix(es) are

equal, so the node doesnt move otherwise it is moved.

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Lifetime = get Lifetime (Agent Advertisement)

wait for lifetime period

We receive Agent

Advertisement and

Lifetime for the

current Agent

Advertisement

not equal to the

old Lifetime for

the old Agent

Advertisement

We did not

receive Agent

Advertisement

at Lifetime period

We receive Agent

Advertisement at

exactly Lifetime period

Moved

Send AgentSolicitation

get Agent

solicitation

moved Foreign Agent

is broken

yes no

error

Not Moved

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Recorded Net Prefix = get Sub-network Prefix (recorded Agent Advertisement

New Agent Advertisement = get Agent Advertisement ( )

Move Detection Using Network Prefixes

NO

YES

New Net Prefix = get Sub-network Prefix (new Agent Advertisement)

Length (recorded Net Prefix) = =

length (new Net Prefix)

i = 0

i < length (newNet Prefix)

YES

YES

i = i + 1

Recorded Net Prefix [ i ] = =

new Net Prefix [ I ]

YES

NOTMOVED

NO

MOVEDNO

MOVED

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Mobile Node Registration

Mobile node registers with its Home Agent in the following situation:

a. whenever it detects that its point of attachment to the network has changed fromone link to another.

b. when its registration time has expired.

The Registration process includes the following tasks

1. Get a care of address from the Foreign Agent.

2. Inform its home agent of its current care of address.3. Renew a registration when it is about to expire.

4. Deregister when it returns to its home link.

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Message Comprise Registration

The registration process consists of the exchange of two messages: a Registration

Request and a Registration Reply. Registration messages are carried in a Data

Portion of a UDP packet.

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IHL Type of Service Total Length identification Flags Fragment offset

Time to Live= 1 Protocol= UDP Header check sum

Source Address

Destination address

Source Port Destination Port = 434

Length Check sum

Type=1 S B D M G Y res Lifetime

Mobile Nodes Home Address

Home Agent Address

Care of Address

Optional Extension

Type = 32 Length Security Parameter

Index (SPI)

Authentication (Default equal keyed MD5)

IP Header

(RFC791)

Registration Request Message

UDP Header

(RFC768

Fixed length portion

of Registration

Required

(RFC2002)

Mobile Home

Authentication

Extension

(RFC2002)Mandatory

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Registration Reply

Type = 3 Code Lifetime


Home Agent Address

Identification

Fixed length

portion of

Registration

Reply (RFC2002)

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Registration Scenarios

The purpose of registration is for the mobile node to inform its Home Agent of its

current care of address(es), the address(es) to which the Home Agent will tunnel

packets forwarded to the mobile node. The Home Agent will construct a table of

binding entries, as a result of this registration process, each entry has a Mobile Node

Home address and care of address. There are three scenarios of registration process:

1. A mobile node registers on a foreign link using a Foreign Agent care of

address.2. A mobile node registers on a foreign link using a collocated care of address

(perhaps because no foreign agent is present on a Foreign Link).

3. A mobile node deregisters upon returning to its home link.

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IP

Header

UDP

Header

Link Layer

HeaderSource Address = mobile modes Link Layer Address

Destination Address = copied from Foreign Agent Advertisement

Source Address = Home Address IP

Destination Address = Foreign Agent IP

Source Port = anything

Destination Port = 434

Registration

Request

B = 1 if mobile mode want a copy of broadcast OM Home Link

D = o, tell the HA that the Foreign Agent is doing encapsulation

Mobile Nodes IP Home Address

Home Agent IP Address

Copied from a Foreign Agent Advertisement

Life Time

Registration Reply

Registration Request

Foreign LinkForeign Agent Home Agent

1 2

34

MobileNode Home Link

Fields of Registration Request as set by Mobile Node forForeign Agent care of Address


Routers and LinksX X

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Link Layer

Header

IP

Header

Source Address = mobile nodes Link Layer Address

Router Address = Select Router in Foreign Link without FA ( )

Destination Address = ARP (COA, Router Address)

Source Address = cane of Address

Dst Address = Home Agent IP Address

Registration

Request

Dst Port = 434

B = 1 if a mobile node want a copy of broadcast on Home Agent

D=1 Tell the Home Agt. that the mobile node is doing decapsulation

Mobile Nodes IP Home Address

Home Agent IP AddressCollocated care of address

Source Port = anything

Life Time

Foreign LinkHome Agent

Registration Request

Registration Reply

Home LinkArbitrary Topology of

Routers and Links

X

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Link Layer

HeaderSrc Address = mobile node Link Layer Address

Dst Address = ARP (Home Agent IP Address)

Src Address = Mobile Node IP AddressIP

Header Dst Address = Home Agent IP Address

Mobile Node Home IP AddressRegistration

Request Home Agent IP Address

mobile node Home Address

Life Time = 0

Fields in Deregistration Request as set by Mobile Node

Home LinkHome Agent

deregistration request

deregistration reply


Routers and Links

X

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How Does a Foreign Agent Process a Registration Request

We assume that we are registering through the Foreign Agent. When the foreign

agent receives the Registration Request it applies a sequence of validity checks. If

any of them fails it send a Registration Reply with the cause of the failure.

Otherwise, it consumes the IP and UDP header, constructs new IP and UDP headerscontaining the original Registration Request, and sends it to the home agent.

How Does a Home Agent Process a Registration Request

When a Home Agent receives a Registration request, it applies a set of validity

checks. If it is invalid, the Home Agent sends a Registration Reply to the MobileNode with error code defining the problem. If it is a valid Registration Request then

the Home Agent updates the binding entry according to the specified care of address,

Mobile node Home Address, Lifetime, and S field.

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reg Request = Read Registration Request From Mobile Node ( )

Authentication Field Registration Reply ( )

invalid

Lifetime > maximum

validyes

Sufficient Resourcesto handle

Mobile Node

no

Registration Reply ( )

no

Type of Tunnelingis supported Registration Reply ( )

yesno

Payload = get Pay Load (reg Request)

Src Address = Foreign Agent IP address

Dst Address = Home Agent Field of Registration Request

Construct Packet (Src Address,Dst Address, payload)

Send Packet

How Foreign Agent Process a Registration Request


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big problem

registration Req = get Registration Request ( )

AuthenticationInvalid


Sufficient Resources Registration Reply ( )

validNoCreate a Binding

for the specified

care-of Address

leaving any existingBinding unmodified

Care of Address= = home Address

LifeTime > 0S = = 0

No

Replace all the mobile

node existing bindingwith new binding

for the specified

care of address

YesS = = 1 Delete all the

mobile node

Binding

LifeTime = = 0

Delete the mobile node binding for the

specified care of address leaving the

rest untouched

Yes

No

Successful Registration Reply ( )Send Gratuitous ARPs

Yes

Yes

No

Yes

No

No

How Does a Home Agent Process A Registration Request

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registration Reply = get Registration Reply ( )

Src Addr = Data Link for Foreign Agent )

Dst Addr = stored Data Link Address for Mobile Node

Src Addr = IP address for Foreign Agent

Dst Addr = stored IP address for Mobile Node

Src Port # = Any

Dst Port # = stored Port #

Valid Reply

How Does a Foreign Agent Process a Registration Reply

NO YES

update Reply code with the error

transmit Reply to Mobile Node

Payload = get Payload (registration Reply)

Update list of Visiting Mobile Node

transmit Reply to Mobile Node

Link Layer

Header

IP

Header

Registration

Reply

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How Does a Foreign Agent Process a Registration ReplyWhen the foreign agent receives the reply, it applies a validity check for the reply. If

the reply is invalid because it contains an unrecognized extension, or fails home-

agent-to foreign-agent authentication then the foreign agent forms another reply with

the proper error code and relays the new reply to the Mobile Node. If it is valid then

it relays the reply to the Mobile Node using some of the fields which has recordedduring registration Request.

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IPsrc = Original SenderIPdst = Ultimate Destination

original IP packet Header payload

Header payloadOuter Header

IPsrc = Tunnel Entry-Point (Home Agent)

IPdst= Tunnel Exit-Point (care of address)

Encapsulating IP Packet

IP Tunneling

A tunnel from a

home agent to aforeign agent

Home Agent

XX

Mobile

Node Foreign Agent

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X X

Foreign Link


Routers and Links

Foreign Agent

Mobile Node

Home Agent

Home Link

Correspondent Node

How Packets are Routed when a Mobile Node is at Home

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X X

Mobile Node

Correspondent Node

Foreign Link Home Link


Arbitrary Topology 01

Router and Links

How Packets are Routed when a Mobile Node is at Foreign Link and Correspondent

Node is sending Packets to Mobile Node

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X X

Mobile Node

Foreign Agent

Foreign Link Home Agent

Home Agent

Correspondent Node


Routers and Links

How Packets are Routed when a Mobile Node is at Foreign Link and Mobile

Node is sending Packets to Correspondent Node

bil

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X X

Mobile Node

Foreign Link Home Link


Correspondent Node


Routers and Links

How Packets are Routed when a Mobile Node is at Foreign Link and Correspondent Node is

sending Packets to Mobile Node in case of collocated Care of Address

Using Routing Header

M bil IP

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Src Addr 255.225.285.255 Data

network prefix.111.

Home Agent COA

IP

Receiving a Broadcast Message with a Foreign Agent Care of Address

The Mobile node should instruct the Home Agent to deliver a copy of all broadcast

messages by setting the B=1. Also, it instructs the Home Agent that the foreign Agent

will do the de-capsulation process. The Home Agent will use nested encapsulation to

deliver broadcast packets to mobile node. The encapsulated packet forwarded to theForeign Agent is formed as follows:

When the Foreign Agent receives this packet it will remove, decapsulate a unicase packetwhose destination address is the Mobile Node Home address. The resulting Unicast

message will be decapsulated again and the Routing Algorithm will send the resulting

broadcast packet to the Mobile Node.

Home

Agent

Mobile

Node IP

M bil IP

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Src Addr 255.255.255.255. Data

Home Agent COA

IP IP

Mobile Nodes Receiving Broadcast messagesThe destination address for the broadcast message is in the form of network-prefix

.11.11 (prefix-specific broadcast or 255.255.255.255) (link specific broadcast).

The delivery mechanism depends upon whether the mobile node is using Foreign Agent

care of address or collocated care of address.

Receiving a Broadcast Message with a Collocated care of address

The Mobile Node should instruct the Home Agent to deliver a copy of all broadcast

messages by setting the B-1. Also, it should instruct the Home Agent that it will do thedecapsulation by setting the process D bit. The encapsulated packet sent by the Home

Agent is formed as follows:

M bil IP

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Src Addr 255.255.255.255 Data

Mobile Node Home Agent

Home Address address

The resulting packet will be routed to the Home Agent.

Sending Broadcast Message by Mobile Node

There are three types of broadcast message which are sent by the Mobile Node

a. If the destination broadcast address is a link-specific broadcast (255.255.255.255)

intended for the Foreign Link, then Mobile node will use the data link broadcast

Address to deliver this packet to all nodes in the Foreign Link.

b. if the destination broadcast address is a link-specific broadcast (255.255.255.255)

intended for the Home Link, then the Mobile Node should encapsulate this broadcast

message as follows:

Mobile IP

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Internet

Normal Registration Scenario - 1 (IPv4)

GTE.comNortel.com

RAS

EmadRuss

Firewall Firewall Wireless

PPP

Not explicitly specified in MIP (RFC2002)

MN DS MNHA FA1Agent Advertisement

4 User profile lookup3Reg Req.

5

2 Reg Req

Reg ReplyReg Reply

8

76

Startses

sion

Mobile IP

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DS MNHA FA1Age

ntAdv

2Agent

Solicitatio

n

AgentAdv

Wait for agent

Adv.

RegReq. 4RegR

eq

3

5

7

6

8 9

10

RegReq. RegReq.

Registration Scenario - 2 (IPv4) MNdoes not rcv advertisement

x

Mobile IP

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Registration Scenario - 3 (IPv4)

MN does not rcv advertisementMN does not rcv response for solicitation

MNDS FADCHPHA

RegReq. 8RegReq

10

12

11

13

14

RegReq. RegReq.

Wait for agent adv

Wait for agent advWait for rtrn adv.

No response from

agent

xAgentAd

v

5

4

3

21

7

6

x

x

AgentSolic

AgentSoli

c

QueryDHCP

ReqIPaddrfromD

HCP

DHCPresponses

ReplyfromDHCPwithIP(COA)

9

Mobile IP

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Registration Scenario - 4 (IPv4)

HOME AGENT DISCOVERYMN does not rcv adv.

MN does not rcv response for solicitationMNFADCHPHA-1

5

4

3

21

7

6

x

x

AgentSo

licAgen

tSolic

QueryDHCP

ReqIPaddrfromD

HCP

DHCPresponses

ReplyfromDHCPwithIP(COA)

RegRep.8Reg

Req10

12

1113

14

RegRep. RegReq.

AgentAdv

HA-2HA-3

RegReq(BCAST,MCA

ST)

RegReqrejectingregRCPrej

9

Mobile IP

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ISPISP

FA

InternetInternet

InternetInternet

InternetISP

HA

Data Routing Scenarios

ISP

FA

MNCN

CN

Internet

HAMN

MN

HA by -passed for optimization

CN

ISPs

ISP FA

HA, FA are by-passed

Normal routing with FA, HA involvement

ISP HA

MNCN

IPv6

Mobile IP

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Russ, Emad, Al and Leo must have a video conference.

Russ mobile registers in France.

- How does the VLR fetch Russ profile?

- How does GGSN interface to the Internet?

- What address should Russ use to conference others?

Emad has the same issues in Mexico.

Leo is Calgary in his hotel room and would have similar issues as Russ and Emad.

Al dials up using ISDN from home.

How would Russ, Emad, Al and Leo have a real-time video conference?

Mobile IP

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SGSN

MPNMPN

GSN/UMTS

France

GGSN

Russ

Internet

Nortel.com

AOL ISP MIP

Slip

Dialup

NAC

MexicoIWF

IP

Wireless

PPP

3G 2GWireless

PPP

Emad

Calgary

Ottawa

ISDN

Dialup

HA

Leo

Mobile IP

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Interface Option-1

- 2G system is similar; however, IWF replaces SGSN & GGSN

- Calgarys interface is already MIP compatible.

SGSN HLRIVLR GGSN MPN HA/HAD DS

France IP Network Nortel

MN

MN 1 2

3

4

6

7

10 9

5

8

Current 3G Loc

up Response3G Reg. Resp.

3G Reg. Req.

3G Loc up Resp

3G Loc update IP Hdr 3G Loc update

IPResolve user profile

Create content

Tunnel

Tunnel

Convert to MIP

Mobile IP

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- 3G & 2.5G

Place MIP elements such as FA, HA at SGSN, GGSN & IWF

Adv.

- Eliminate the MPN passthrough function- Eliminate the protocol conversion at the HA/HAD

- Unify network mobility across different platforms

Dis.

- All infrastructures have to incorporate MIP components.

- MIP is not mature for real time commercial systems.

Mobile IP

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MIP Signaling Issues

IP Network

HA FA

In MIP Registration

procedure is repeated

during handoff to inform

HA of new location

MN

1

3

2Dropped in the network due to

congestion

X

XDropped due to congestion

RegReq

RegReq

- Today IP network does not provide any preference for MIP/signaling messages?

- congestion can cause latency

- normal conditions also may cause latency

- Therefore, unpredicted impact on handoff latency.

Mobile IP

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ICMPv6 Router Discovery

ICMPv6Router Discovery consists of two Messages:

a. Router Advertisement Message:

Routers Transmit router Advertisement Message on a periodic basis - or in responseto a hosts Router Solicitation on message. The source address is the address of thesenders interface and the destination is the source address of an invoking RouterSolicitation, or the all-nodes multicast address.

b. Router Solicitation Message:

The Router Solicitation Message is transmitted by a host to prompt routers to generateRouters Advertisement massage quickly. The source address defines the sendinginterface address and the destination is all-routes multicast address.

Mobile IP

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Home Agent List

Binding Update List (maintained by each mobile node)

Binding Cache (maintained by each IPv6node)

Lifetime

Lifetime

Home Agent IP Address

Care of Address

Care of Address Lifetime Value

IP address for node

Mobile Node Home Address Max sequence #

Mobile IP

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Vers = 6 prio=ls Flow Label

payload length next header=58 Hop limits

Source address-router or home agents address

Destination address=mobile nodes address or All-Nodes Multicast Address

Type=134 code=0 check sum

current Hop Limit M O reserve Router lifetime

Reachable Time

Retransmission Times

Type=3 Length=4 Prefix Length Reserved

valid lifetime

preferred lifetime

Reserves 2

Network Prefix

IPMv6Header

(RFC 1883)

IPv6Router

Advertisement

(Fixed Portion)

RFC 1970

Prefix

information

option

RFC1970

Mobile IP

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Vers = 6 prio=l5 Flow Label

payload length=8 (_______) next header=58 Hop limits

Source address= the Mobile Nodes unicast address

Destination address=the All-router Multicast Address

Type=133 code=0 check sum

reserved

IPv6Header

(RFC 1883)

ICMPv6Router

solicitation (RFC

1970)

ICMPv6Router Solicitation

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Location Detection

The mobile node examines the network prefix contained in the received advertisementagainst its home address network prefix. If there is a match then the mobile node isconnected to its Home Link, otherwise it is connected to a foreign link.

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Router Advertisement=get Router Advertisement ( )

Network Prefix = get Network Prefixes (router Advertisement)

i = o

Location Detection Algorithm

Moved

Moved

i< length

(network

Prefixes)

Network Prefixes [i]= = network

Prefix [mobile Node Home

Address]

i = i+1

Deregister ( )

Coa=get Care Of Address ( )

Register with Home Agent ( )YES

YES

YES

YES

NO

NO

NO

NO

(connected to

foreign Link)

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Motion Detection Algorithm

Old Network Prefixes=get Network Prefixes (old Router Advertisement

New Router Advertisement=get Router Advertisement ( )

Moved

Moved

New Network Prefixes=get Network Prefixes (new Router Advertisement

size of (new Network Prefixes) = =

size of (old Network Prefixes)

i=0

i < size of (new

Network Prefix)

i=i+1Not

MovedNew Network Prefixes [i]= =

old Network Prefixes [i]NO

NO

NO

YES

YES

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Movement Detection:

The mobile node checks the most recent set of network Prefixes with those set of networkprefixes belongs to previous Router Advertisements.

How Does a Mobile Node Obtain A Care of Address

One the Mobile node detected that it has moved, it will acquire a new care of address by oneof two methods. The M=1 in the Router Advertisement message informs the Mobile Nodethat it will use Stateful Address Auto configuration method otherwise it will use StatelessAddress Auto. An example for stateful address assignment is the dynamic Hostconfiguration Protocol (DHCP) for IPv6which is similar to Dynamic Host Configuration

Protocol in IPv4.

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The stateless Address Auto configuration is a method to acquire care of addressautomatically or without server. There is no functionality similar to this functionality in IPv4.

This method works as follows:

1. Acquire the interface token which is similar to data link layer address for the networkinterface. For example the network interface address for Ethernet is 98 bits.

2. Get the Network Prefix for the current link from the prefix Information Optioncontained in the Router Advertisement.

3. Concatenate the interface token with the network prefix to form a care of address. Inorder to proof the uniquenin of a generated address a Neighbor Solicitation message istransmitted with the generated address as the target address. If another node is usingthis address a Neighbor Advertisement Message will be returned. In this event, autoconfiguration stops and some manual intervention is required.

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Acquiring Care of Address

M=1YES NO

Done

Done

Coa=get COA from DHCP ( )

Address is unique

Interface Address=get Interface Address ( )

Network prefix=get link Network Prefix ( )

Transmit Neighbor Solicitation (COA)

Coa=merge (interface Address, Network Prefix)

Wait for Neighbor Advertisement

Address is not unique, Manual

Intervention is required

Not Received

Received

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Registration

In IPv4the mobile node informs its Home Agent about its care of address throughRegistration Request and Registration Reply message. These Registration Request andReply are carried in the payload of UDP/IP packet. In IPv6 the Mobile Node informs the

Home Agents and various other nodes about its care of address using the DestinationOptions. When the Mobile node obtains its care of address it informs it Home Agent aboutthis care of address. The Home Agent will use this care of address as an exit point of thetunnel to get back to the mobile agent. The mobile node also informs a set of correspondentnodes of its current care of address, which will be used by the correspondent nodes to route

packets directly to mobile nodes. Messages which are involved in Registration are:

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1. Binding Update - this message is sent to the Home Agent or the correspondent nodes toinform them about its care of address. The A bit is set by the mobile node to inform thereceiver of the option should send Binding Acknowledgement. The H bit is set by themobile node to inform the recipient that the mobile node wishes it to serve as a Home

Agent. The L bit is set by the mobile node to receive packets destined not only to itsglobally routable home address but also to its link local Home Address.

2. Binding Acknowledgement - a binding acknowledgement message is sent by the HomeAgent or correspondent node to indicate that it has successfully received the MobileNode Binding Update.

3. Binding Request - a binding request is sent to a mobile node by a correspondent node torequest that the mobile node sent Binding Updates. This is useful when Lifetime in anoriginal Binding Update is near expiration and the correspondent node has reason tobelieve that it will continue to send packets to the mobile node.

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Ver=6 prio Flow label

payload length next header=51 Hop Limit

Source Address=mobile nodes globally routable home address

Destination Address=Home Agent or correspondent node

next header=60 length=9 RESERVEDSecurity Parameters Index (SPI)

Authentication Data

next header Hdr Ext len option type=16 option length

A H L Reserved Lifetime

Identification


care of Address

Mobile Nodes Link Local Home Address

(only present if L bit equal 1)

IPv6Payload (if this Binding Update is being piggy backed)

Binding Update

IPv6Header

(RFC 1883)

Authentication

Header for IVv4 and

IPv6(RFC 1820)

Destination option

header RFC 1883

containing IPv6

Binding UpdateOption

Mobile IP

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Binding Acknowledgement

Ver=6 prio Flow label


Source Address=home Agent or Correspondent node

Destination Address=mobile nodes home address (or care of address)

next header=60 length=9 RESERVEDSecurity Parameters Index (SPI)

Authentication Data

next header Hdr Ext len option type=193 option length

Status Refresh Lifetime

Identification


IPv6 Payload (if this Binding Acknowledgement is being piggy backed)

IVv6 Header

(RFC 1883)

Authentication Headerfor IPv4 and IPv6 (RFC

1826)

Destination option header

RFC 1883 containing the

Mobile IPv6 Binding

Acknowledgement Option

Mobile IP

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Vers=6 Prio Flow label


Source Address=home agent or correspondent node

Destination Address=mobile node home address (or care of address)

next header Hdr Ext Len Option Type=199 Option length=0

IPv6 Payload (if this Binding Request is being piggy backed

Binding Request

IPv6 Header

(RFC 1883)

Destination Option Header

(RFC 1883) containing the

Mobile IPv6 Binding

Request Option

Mobile IP

Binding Update

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Binding Update

1. A mobile node connects to the Foreign Link and informs its home agent of its new care of address

2. A mobile node connects to a Foreign link and informs a correspondent node of its new care of address

Foreign LinkHome Agent

X

Home Link

Mobile Node


X

Home Link

Home AgentForeign Link


Binding Update

Mobile IP

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Binding Update

X

Home LinkHome Agent


3. A mobile node returns to its home link and informs its home agent that it is no longer attached to a foreign

link

Correspondent

Node

X

Home Agent

Home Link

Foreign Link

Mobile Node

4. The correspondent node requesting an update for the Mobile Node care of address when the Lifetime is an

original Binding Update near expiration.

Binding Request

Binding Update

Mobile IP

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Visiting list kept by Foreign Agent

Binding list kept by Home Agent

Mobile IP address

Mobile IP address

Care of Address

Care of Address

Lifetime

LifetimeData Link layer address Port #

Mobile IP

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Vers=6 prui Flow label

payload length next header=43 Hop limit

Source Address=correspondent Node Address

Destination Address=mobile nodes care of address

next header=6 Hdr Ext Len=2 Routing type=0 segments left=1

Reserved strict/loose bit map=all 0s

Address [i] = mobile nodes home address

tcp header and user date

Source-Routed Packet from Correspondent Node to Mobile Node

IPv6Header

(RFC 1883)

IPv6Type 0

Routing Header

(RFC 1883)

Documents

mobile ip