Mobile IP

Prepared by: Purvik Rana Mihir Patel Nidhi Patel

Yagnesh Shinde Nirali Rana

Outline

Mobility and IP

Mobile IP

Foreign Agent Discovery

Home Agent Registration

Tunneling and Encapsulation

Route Optimization

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Mobility

With invention of the wireless technology the mobile

user live in the environment which provide services

Anytime

Anywhere

Two Kinds of Mobility

Seamless Mobility

Mobility is totally transparent to application

Portability Mobility

Mobility is not transparent to applications when we move, but we can still access

the network at a new place

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Problems

We have seen that mobile users can change point of attachment In a cellular network, a mobile changes base station.

A mobile user can work at office and at home at different in a day

We want our applications not to be disturbed from mobility We want to continue to talk with our cell-phone when we

change base-stations

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What is Mobile IP?

Mobile IP is an Internet Engineering Task Force(IETF) standard

protocols

Designed to allow mobile device users to move from one network

to another while maintaining a permanent IP address

Mobile IP is a layer-3 (network layer) mobility solution

Support mobile users (laptops,PC etc) in the Internet in a seamless

manner.

Higher protocol layers (TCP, UDP, RTP, etc) and applications are not

aware of mobility

Mobile stations change physical point of attachments at the Physical layer

Mobile IP is a solution that is independent of the physical and data-link

layers

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Mobile IP

Ethernet Token Ring PPP WLAN

802.11b Bluetooth

TCP UDP

Network Applications

and Protocols

Telnet, FTP, HTTP, etc. Mobility is seamless

to these.

....

The link layer can be anything.

TCP/IP

Protocol

STACK

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Why We Need Mobile IP?

It is recognized that Mobile IP lacks flexibility with respect

to the transparent and mandatory mobility support to

various applications

When multiple interfaces are available to one user device

to access heterogeneous networks flow level traffic

control is needed in addition to device level methods

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Mobile IP Approach

Mobile IP Uses two Types of address

A fixed Home Address

Used for Identification

A Care- of Address

Used for Routing

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Mobile IP Architecture

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Mobile IP Functions

Foreign Agent Discovery A Mobile node uses a discovery procedure to identify prospective home and foreign

agents

Home Agent Registration A Mobile node uses a registration procedure to inform its home agent of its care-of

address

Tunneling Tunneling procedure is used to forward IP datagrams from a home address to a care-

of address

There are various form of tunneling: Ip-Ip Encapsulation

Minimum Encapsulation

GRE

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Foreign Agent Discovery And

Home Agent Registration

Home Agent And Foreign Agent

Home Agent

is a router on a mobile node's home network that maintains

information

the device's current location, as identified in its care-of address.

Foreign Agent

is a router serving as a mobility agent for a mobile node

it works in conjunction with a home agent to support Internet

traffic forwarding - from any location other than its home

network of Mobile Node

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Mobile Agent Discovery

How a mobile node discovers the home and foreign

agents when it travels?

Agents periodically broadcast their presence (advertisement) on a link

Agent advertisement messages.

A mobile node receiving the advertisement understand

from the IP addresses included in the advertisement:

Whether it is in the home network or not?

Whether it has moved to new location or not.

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Agent Advertisement Message

Mobile nodes use agent advertisements to determine

their current point of attachment to the Internet

Its an Internet Control Message Protocol (ICMP) router

advertisement

Extended to also carry a mobility agent advertisement extension

A foreign agent can be too busy to serve additional mobile

nodes

Must continue to send agent advertisements

Already registered mobile nodes will know that they have not

moved out of range of the foreign agent and that the foreign

agent has not failed.

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Registration

Through agent advertisements, mobile nodes detect when

they have moved from one network to another

Getting Agent Advertisement Message, Registration begin which include,

The mobile node registers through the foreign agent

Even when the mobile node might be able to acquire its own co-located care-of address

Registration procedure consists of two type messages

Registration Request

Registration Reply

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Registration Process for Mobile node

If a mobile node is registering a foreign agent care-of address, the mobile node registers using that foreign agent

If a mobile node is using a co-located care-of address, and receives an agent advertisement from a foreign agent on the link on which it is using this care-of address, the mobile node registers using that foreign agent

If a mobile node uses a co-located care-of address, the mobile node registers directly with its home agent

If a mobile node returns to its home network, the mobile node deregisters with its home agent

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Registration Request

A mobile node registers with its home agent using a registration

request message so that its home agent can create or modify

a mobility binding for that mobile node (for example, with a new

lifetime). The foreign agent can relay the registration request to the

home agent. However, if the mobile node is registering a co-located

care-of address, then the mobile node can send the registration

request directly to the home agent.

HA FA

M

REQ

REQ

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Registration Reply

A mobility agent returns a registration reply message to a

mobile node that has sent a registration request message. If the

mobile node is requesting service from a foreign agent, that

foreign agent receives the reply from the home agent and

subsequently relays it to the mobile node. The reply message

contains the necessary codes to inform the mobile node about

the status of its request, along with the lifetime granted by the

home agent.

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Care-of-Address types

Normal Care-of-address

Care-of-address that mobile obtains at a new location is the IP address of a foreign agent serving at that new location

Registration and communication has to go through foreign agent

Co-located care-of-address

There is no separate foreign agent present at the new location

Mobile obtains an IP at the new location through some standard mechanisms like DHCP

Registration and communication is done directly between mobile and home agent

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Security

Security Problem

Fraud Registration should be detected.

Three Authentication Extension defined for the Mobile IP

The mobile-home authentication extension.

The mobile-foreign authentication extension.

The foreign-home authentication extension

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Tunnelling with Encapsulation

Tunneling

The home agent will intercept datagram intended for the mobile

node

When a correspondent host sends an IP packet to a mobile (to its

home address)

packet is routed first to home agent of mobile through normal

routing

Home agent intercepts the packet and encapsulates it and tunnels

it to the care-of-address of the mobile.

The encapsulated packet is delivered to the care-of-address

using normal routing

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Encapsulation Methods

IP-IP Encapsulation

Minimal Encapsulation

GRE (Generic Routing Encapsulation)

HA FA

M

C

Encapsulated IP Packet

Tunnel

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IP – IP Encapsulation at HA

Dest Address = Addr of M

Src Address = Addr of C

TTL Protocol Header Checksum

Identification Fragm. Offset Flags

Total Length TOS Ver HL

0 8 16 31

IP PAYLOAD

Dest Address = Care-of-Address of M

Src Address = Home agent addres

TTL Protocol=4 Header Checksum

Identification Fragm. Offset Flags

Total Length TOS Ver HL

An IP packet is received at the

Home agent from a correspondent

host for a mobile host.

Home agent encapsulated the IP

Packet inside an other IP header and

Sends it to the care-of-address of

Mobile.

Inner

Header

Outer

Header

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IP – IP Decapsulation at FA

Dest Address = Addr of M

Src Address = Addr of C

TTL Protocol Header Checksum

Identification Fragm. Offset Flags

Total Length TOS Ver HL

0 8 16 31

IP PAYLOAD

Dest Address = Care-of-Address of M

Src Address = Home agent addres

TTL Protocol=4 Header Checksum

Identification Fragm. Offset Flags

Total Length TOS Ver HL

An encapsulated IP packet is received

at the foreign agent (or at the mobile

Itself for a collocated care-of-address).

Receiver understands that the packet

is IP-IP encapsulated by looking

to the protocol field (which is 4).

Inner

Header

Outer

Header

Receiver forwards (not routes)

the decapsulated IP packet to the

mobile node using

link-level mechanisms!

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Minimal Encapsulation at HA

Dest Address = Addr of M

Src Address = Addr of C

TTL Protocol Header Checksum

Identification Fragm. Offset Flags

Total Length TOS Ver HL

IP PAYLOAD

Dest Address = Addr of M

Src Address = Addr of C

Protocol Reserved Header Checksum

IP PAYLOAD

S

Dest Address = Care-of-addr of mobile

Src Address = Addr of home agent

TTL Proto=55 Header Checksum

Identification Fragm. Offset Flags

Total Length TOS Ver HL

Outer

header

Minimal

Inner

header

Packet comes from

Correspondent host

Encapsulated using

Minimal Encapsulation

Method

Tunneled to

care-of-address

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Sending Packets (Mobile FA)

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Sending Packets (Mobile FA)

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Sending Packets (FA Mobile)

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Decapsulation again

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Route Optimization

What it is?

Enable direct notification of the corresponding host

Direct tunneling from the corresponding host to the

mobile host

Binding cache maintained at corresponding host

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Three mobility scenarios addressed by

Route Optimization

MN traverses from its home domain to the foreign

domain with open communication sessions.

MN initiates new communication sessions when it is in

the foreign domain

MN moves from one foreign domain to another with

open communication sessions

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Route Optimization Messages

4 types of messages

Binding update

Binding request

Binding warning

Binding acknowledge

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Binding Update

When a home agent receives a packet to be tunneled

to a mobile host, it sends a binding update message to

the corresponding host

When a home agent receives a binding request

message, it replies with a binding update message

Also used in the smooth-handoffs optimization

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The current mobility management protocol Mobile IP

(MIP) specifies the use of a Home Agent (HA) in

forwarding datagram's to/from the Mobile Node (MN)

Either triangular routing

Reverse tunneling

Additional delay in data transmission.

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Route Optimization Techniques

FA to forward the datagrams destined for the MN to its

new care-of address for a short duration

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Route optimization scheme Operation:

Registration Process

Session Establishment:

Packet Delivery

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Advantages of Route Optimization

Allows the shortest communications path to be used

Eliminates congestion at the mobile node's home agent

and home link

The impact of any possible failure of the home agent or

networks on the path to or from it is reduced

Route optimization scheme attempts to reduce the

overhead and delay involved with traditional mobile

communication

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References

o http://www.ee.sunysb.edu/~xwang/public/readings/ieee-

mobileip98.pdf

o http://home.deib.polimi.it/capone/rmd/materiale_tarr/4-

mobile-ip/Perkins-book-chapter.pdf

o http://www.tcpipguide.com/free/t_MobileIPDataEncapsula

tionandTunneling.htm

o http://www.cs.colorado.edu/~rhan/CSCI_7143_001_Fall_

2002/Papers/Perkins_Tutorial_Mobile_IP.htm

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Cont…

Port Address Translation Based Route Optimization for

Mobile IP D Badami, N Thanthry, T Best, R Bhagavathula,

and R Pendse Department of Electrical and Computer

Engineering Wichita State University 1845 Fairmount,

Wichita KS 67260 USA (0-7803-8521-7/04/$20.00 ©

2004 IEEE)

Route Optimization in Network Mobility:Abu Zafar M.

Shahriar, Mohammed Atiquzzaman, Senior Member, IEEE,

and William Ivancic(1553-877X/10/$25.00 c 2010 IEEE)

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