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CMSC 628 - Presentation

CMSC 628 - Presentation. An End-to-End Approach to Host Mobility Alex C. Snoeren and Hari Balakrishnan. Overview. Introduction Mobile IP Other IP layer approaches to mobility Transport layer approaches Proposed architecture Issues Conclusions. Introduction.

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CMSC 628 - Presentation

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  1. CMSC 628 - Presentation An End-to-End Approach to Host Mobility Alex C. Snoeren and Hari Balakrishnan

  2. Overview • Introduction • Mobile IP • Other IP layer approaches to mobility • Transport layer approaches • Proposed architecture • Issues • Conclusions

  3. Introduction • Routing issue with legacy TCP/IP stack • Host location and hand-off support • End-End Vs other approaches • Keeping mobility transparent from the transport layer

  4. Mobile IP • Essentially, mobility handled by ‘third party’ • Triangle routing and tunneling • Pure routing solution • Only IP substrate changed

  5. Other network layer approaches • For the most part, enhancements of Mobile IP • Cache care-of address of mobile host • IPv6 mobility support

  6. Transport layer approaches • Migration NOT transparent to TCP • Proxy approaches: transparent to sender • Current approach

  7. The End-to-End architecture • Addressing • Host location • TCP connection migration • Security

  8. Host Location • In case of fixed servers, no special service required • In case of mobile servers, use dynamic DNS updates • Set TTL of DNS cache entries to zero • Problems with fast mobility

  9. TCP connection migration • Use secure tokens to identify TCP connections • Token negotiated during handshake • Migrate-permitted option to negotiate token • Migrate option to migrate a connection

  10. TCP connection migration

  11. TCP connection migration • Migrate Permitted option

  12. TCP connection migration • SYN from client contains client’s public key • Likewise for SYN from the server • Shared secret key computed from the above • Token computed as a hash of the shared key and initial sequence numbers

  13. TCP connection migration • Migrate option

  14. TCP connection migration • Migrate option used in the SYN after migration • ReqNo used to order migrate requests • Token identifies the connection • Request is an authentication mechanism • Essentially, hash of the initial sequence numbers, shared key, request number, and the migrate SYN segment

  15. TCP connection migration • At the other end, compare token • Check if ReqNo is one greater than prev • Compute request hash and compare • Update destination address and port • The Migrate-Wait state

  16. Security • Denial of Service • Connection Hijacking • Key security

  17. Performance

  18. Limitations • Slow start begins after migration • Both hosts cannot move simultaneously • Address caching

  19. Conclusions • End-to-End architecture • Transport layer aware of mobility • Hosts have choice over approach used, hence more flexible • Pretty secure • Some limitations

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