1. Mobile IP

2. References

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

• Mobile IP http://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

3. Motivation for the Mobile IP design

• 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

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

4. 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

5. Terminology

• Mobile Node (MN)

• • system (node) that can change the point of connection to the network 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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9. Mobility Binding

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

10. Mobility Binding

• The foreign agent maintains a visitor list

11. 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

12. Registration

• MN signals COA to the HA via the FA, HA acknowledges via FA to MN

• • these actions have to be secured by authentication

13. IP-in-IP Encapsulation

• Mandatory in RFC 2003

• Tunneling between HA and COA

14. IP-in-IP Encapsulation

15. Triangular Routing

• Sender sends all packets via HA to MN

• Higher latency and network load

16. 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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18. Data transfer from the mobile system

19. Reverse tunneling (RFC 2344)

20. 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 of 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.