Mobile IP Seamless connectivity for mobile computers Problem

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 of the MN is address of FA. • Colocated COA – IP address belonging to the home sub-net. – A topologically correct IP

Mobile 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.