Mobile IP Seamless connectivity for mobile computers

Problem definition IP combines routing information with host identification in a globally unique IP address. On mobility it needs to get a new IP address to indicate the new point of attachment to router.

Problem definition TCP uses IP internally to maintain connection state for connections being operated by mobile computer. On IP change connection status cannot be maintained. Reason : IP used for both routing & host identification.

Issues of mobile IP Compatibility co-work with wired infrastructure. Scalability Support large number of users. Transparency No difference in wired or wireless domain.

Terminologies MN – Mobile Node,requiring mobility support. CN - Correspondent Node, a node to which MN communicates. FA - Foreign agent, currently connected router. HA – Router corresponding to MN IP’s Subnet.

Essence of Mobile IP Usage of old IP address but with a few additional mechanisms, to provide mobility support MN assigned another Care of Address (COA)

Mobile IP Two types of COA Foreign Agent Based COA COA of the MN is address of FA. Colocated COA –IP address belonging to the home sub-net. –A topologically correct IP

Mobile IP

Both methods use IP Tunneling Packet encapsulated at HA. The place of de- capsulation is difference in two methods. High degree of in-efficiency.

Asymmetric Routing

Registration with HA Initiated when MN moves to a new location. MN sends agent advertisement packet. Involves authentication & authorization of MN by HA.

Advertising packet

Practical Constraints Ingress filtering Firewalls TTL Packets get blocked or dropped. Reduce TTL by only one till home. Follow triangular routing.

Simultaneous Binding More than one COA. HA needs to send duplicated packets to all COA. Improves reliability of data transmission.

Route Optimization Make CN Mobility aware Ability to de - capsulate packets from MN Ability to send packets directly to MN by passing HA.

Route Optimization Binding cache Associating mobile node’s IP address with COA & lifetime is called binding. This binding is done during registration. Send this to CN.

Binding Cache Maintenance Four new UDP messages defined. Binding warning. Binding request. Binding update. Binding Acknowledgement.