A Study of Mobile IP Kunal Ganguly Wichita State University CS843 – Distributed Computing

Outline Introduction How Mobile IP works Protocols of Mobile IP Next Generation Mobility – Mobile IPv6 Conclusion OUTLINE 1/19

Introduction IP addresses are usually associated with a fixed point of access to the network/Internet. The IP protocol does not support mobility The Problem: –Current network models insist on assigning a new IP address every time a node changes its point of attachment. –For mobile nodes, receiving data in a reliable fashion would be impossible if its IP address changes from time to time. INTRODUCTION 2/19

Introduction Solving the Problem Mobile IP (RFC 3344) uses 2 IP addresses to help a mobile node receive uninterrupted service: –Home Address Static Makes the mobile node appear logically connected to the home network Allows the mobile node to remain addressable via the home address –Care-of Address Changes at every new point of attachment Identifies the mobile node’s point of attachment with respect to the network topology INTRODUCTION 3/19

How does Mobile IP manage 2 IP addresses? Agents of Mobile IP –Home Agent Gets packets intended for the mobile node and delivers them transparently to the mobile node’s current point of attachment –Foreign Agent Comes into play only if node is on a foreign network Receives encapsulated packets from the Home Agent, decapsulates them, and sends them to the intended mobile node INTRODUCTION 4/19

What does Mobile IP offer? INTRODUCTION 5/19

How does Mobile IP work? HOW DOES 6/19 Successful cooperation between 3 mechanisms: –Discovering the care-of address –Registering the care-of address –Tunneling to the care-of address

Discovering the Care-of Address The Home and Foreign Agents announce their presence using Agent advertisements at regular intervals Agent advertisements: –Same as Router Advertisements, except that some extra information is added about the care-of addresses –Informs of alternative encapsulation techniques –Lets mobile node know whether it is on a Home or Foreign network HOW DOES 7/19

Discovering the Care-of Address Contd. The mobile node listens for the Home Agent advertisement to get its address. Once on a foreign network, the mobile node listens for a Foreign Agent advertisement and registers itself, and informs the Foreign Agent of its Home Address. The Foreign Agent contacts the Home Agent and registers the care-of address. HOW DOES 8/19

Registering the Care-of Address When the Home Agent receives a registration request for the care-of address, its adds the necessary information to its routing table. It then sends a registration reply back to the Foreign Agent. Registration requests: –Contain a binding – Home address, care-of address and Registration Lifetime (how long may the agent use the binding). –Allow the Home Agent to associate the care-of address with the home address of the mobile node. –Define parameters and flags which characterize the tunnel to be used. HOW DOES 9/19

Tunneling to the Care-of Address The Home Agent and the Foreign Agent use a tunnel to communicate. –A tunnel defines the end-points of the route to be followed by a IP packet. –Start point is the Encapsulator (done by Home Agent) –End point is the Decapsulator (done by Foreign Agent) HOW DOES 10/19

Tunneling to the Care-of Address Contd. Encapsulation The default Encapsulation mechanism that must be supported by all mobility agents using Mobile IP is IP-within-IP. The original IP packet is made the payload of a new IP packet (encapsulated) whose destination field in the header shows the care-of address. HOW DOES 11/19

Tunneling to the Care-of Address Contd. Decapsulation At the end-point of the tunnel, the packet is Decapsulated, where the Foreign Agent extracts the payload and sends the packet to the mobile node identified by its hardware address. HOW DOES 12/19

Tunneling to the Care-of Address Contd. 2 kinds of Tunneling Triangular RoutingReverse Tunneling HOW DOES 13/19

Protocols of Mobile IP The Physical layer and Data-link layers support: –Signal Modulation –Encryption –Compression –Interference control –Channel Access/Selection –Modifications to allow Gratuitous or Proxy ARP PROTOCOLS 14/19

Protocols of Mobile IP Contd. At the Network layer, Mobile IP offers: –Addressing –Routing –Location Management –Authentication PROTOCOLS 15/19

Protocols of Mobile IP Contd. Since Mobile IP is implemented at the Network layer, no major changes are required on the layers above (transport, session, presentation, & application). However, services such as Congestion control, Flow control and Quality of Service are introduced at the Transport layer, and Resource discovery and Link adaptation layer are introduced at the application layer. PROTOCOLS 16/19

Mobile IPv6 Great deal of improvements over Mobile IPv4 Stateless Address Autoconfiguration, Neighbor Discovery mechanisms – no need for DHCP, Foreign Agents or ARP Mobile IPv6 can use IPsec (IP Security Protocol) for all actions which require security, such as authentication and data integrity protection Route optimization is greatly improved in Mobile IPv6. Mobile IPv6 does not have a problem with ingress filtering by routers, hence the wasteful technique of Reverse Tunneling is not required. Mobile IPv6 has a special routing header, doing away with the need for encapsulation. IPv6 17/19

Conclusion Increased user acceptance of mobile devices fuels the need for developers to provide wireless connectivity to network services from these devices. Mobile IP, already a reality with some implementations, commercial and in academic institutions, is definitely going to be a standard in the devices of tomorrow. CONCLUSION 18/19

QUESTIONS? QUESTIONS 19/19