PowerPoint Presentation On Host Mobility

 PPT On Host Mobility

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Host Mobility Presentation Transcript:

1. Mobility : outline
What is the problem at the routing layer when Internet hosts move? Ongoing connections need to be maintained as the user moves. As users move, they have to be handed over from one coverage area to another (since the coverage areas of access points are finite). Can the problem be solved?

2. Problems?
The IP address associated with a mobile host is network dependent ! When user connects to another network, IP address needs to change. Packets belonging to ongoing connections somehow need to be delivered to the mobile host.

3. Problems (Contd.)?
What are the options? Make IP address host specific instead of network specific – obvious pitfalls? Change IP address of host and start using the new IP address in the subsequent packets belonging to the connections.

 4. Wireless Networking :
Approaches Mobile IP ( Network Layer ) IP substrates changes End-to-End approach ( Higher layer ) End application changes

5. Mobile IP Basics
Same as the post-office analogy Two other entities – home agent (old post-office), foreign agent (new post-office) Mobile host registers with home agent the new location Home agent captures packets meant for mobile host, and forwards it to the foreign agent, which then delivers it to the mobile host

6. Mobile IP Problems?
Triangular routing overhead ! Registration latency and associated problems ! Infrastructure required for mobile IP support ! Significant cost, complexity, performance degradation !

7. End-to-End Approach
Internet infrastructure does not change (like in mobile IP). Changes required at both the sender and receiver. Does connection migration when mobile-host moves.

8. E2E Approach (Contd.)
Hostname used as the invariant to identify mobile host instead of home agent in Mobile IP. Mobile host uses DNS updates to change hostname to IP address mapping No consistency problem as DNS entries can be made un-cacheable (TTL = 0) If client is mobile, DNS-support not used

9. E2E Approach (Contd.)
When a mobile-host undergoes a handoff, it re-issues a SYN (with a MIGRATE option identifying the previous connection). A unique token exchanged during initial connection set-up used to identify connection. The receiver of the SYN changes its state to represent the new address of the mobile-host. Connection proceeds as a regular TCP connection from thereon.

10. For more please refer our PPT. Thanks.