mobile ip 순천향대학교 정보기술공학부 이 상 정. 2003-1-voip 특론...

Mobile IP

순천향대학교 정보기술공학부이 상 정

순천향대학교 정보기술공학부 이 상 정 2

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References

Tutorial: Mobile IP http://www.computer.org/internet/v2n1/perkins.htm?SMSESSION=NO

Mobile IPhttp://www.acm.org/crossroads/xrds7-2/mobileip.html

How Mobile IP Works1.ppt http://www.mnlab.cs.depaul.edu/seminar/spr2002/MobileIP.pdf

mobile IP and TCP http://distcomp.ethz.ch/lectures/mobicomp/lecture/8/Chapter8MobileIPandTCP4Slides.pdf


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Motivation for the Mobile IP design

1. A mobile node has to change its IP address whenever it changes its point of attachment, so that packets destined to the node are routed correctly

2. To maintain existing TCP connections, the mobile node has to keep its IP address the same.


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Requirements to Mobile IP (RFC 2002)

Compatibility• support of the same layer 2 protocols as IP• no changes to current end-systems and routers

required• mobile end-systems can communicate with fixed

systems Transparency

• mobile end-systems keep their IP address• continuation of communication after interruption of

link possible• point of connection to the fixed network can be

changed Efficiency and scalability

• only little additional messages to the mobile system required (connection typically via a low bandwidth radio link)

• world-wide support of a large number of mobile systems

Security• authentication of all registration messages


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Terminology

Mobile Node (MN)• system (node) that can change the point of connection to the netwo

rk without changing its IP address Home Agent (HA)

• system in the home network of the MN, typically a router• registers the location of the MN, tunnels IP datagrams to the COA

Foreign Agent (FA)• system in the current foreign network of the MN, typically a router• typically the default router for the MN

Care-of Address (COA)• address of the current tunnel end-point for the MN (at FA or MN)• actual location of the MN from an IP point of view• can be chosen, e.g., via DHCP

Correspondent Node (CN)


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Mobility Binding

The home agent maintains the mobility binding in a mobility binding table

순천향대학교 정보기술공학부 이 상 정10

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Mobility Binding

The foreign agent maintains a visitor list


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Agent Discovery

HA and FA periodically send Advertisement messages into their

MN listens to these messages and detects, if it is in the home or a foreign network• If MN does not wish to wait for the

periodic advertisement, it can send out Agent Solicitation messages that will be responded by HA or FS

MN reads a COA from the FA advertisement messages


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Registration

MN signals COA to the HA via the FA, HA acknowledges via FA to MN• these actions have to be secured by authentication


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IP-in-IP Encapsulation

Mandatory in RFC 2003

Tunneling between HA and COA


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IP-in-IP Encapsulation


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Triangular Routing

Sender sends all packets via HA to MN

Higher latency and network load


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Change of FA

Packets on-the-fly during the change can be lost

New FA informs old FA to avoid packet loss, old FA now forwards

Remaining packets to new FA This information also enables the old FA to

release resources for the MN


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Data transfer from the mobile system


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Reverse tunneling (RFC 2344)


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Mobile IPv6

Mobility support in IPv6 solves many of the problems of basic Mobile IP

Some advantages of Mobile IPv6 over Mobile IPv4• Route Optimization is built as a fundamental part o

f Mobile IPv6• Foreign Agents are not needed in Mobile IPv6. The

enhanced features of IPv6 like Neighbour Discovery and Address Autoconfiguration enable mobile nodes to function in any location without the services of any special router in that location.

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