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