A Dynamical Redirection Approach to Enhancing Mobile IP with Fault Tolerance in Cellular Systems

1. A Dynamical Redirection Approach to Enhancing Mobile IP with Fault Tolerance in Cellular Systems Jenn-Wei Lin, Jichiang Tsai, and Chin-Yu Huang IEEE Global Telecommunication Conference 2002 Taipei, Taiwan, R.O.C., Nov. 17-21, 2002 Department of Computer Science & Information Engineering, Fun Jen Catholic University, Taipei, Taiwan jwlin@csie.fju.edu.tw 1

2. Outline • Introduction • Background • Proposed Approach • Evaluation • Conclusions 2

3. Introduction • Mobility IP in Cellular Systems • Ongoing data sessions without disruption due to mobility • IETF RFC 2002 • Two kinds of mobility agents • Foreign agent (FA) • Home agent (HA) • Failure Occurrence • Interrupting the data executable capability of mobile users 3

4. Application Server Internet Mobile Packet Backbone Mobile Node Home Agent Foreign Agent Radio Access Network Introduction • Mobile Packet Data Flow • Data request 4

5. Application Server Internet Mobile Packet Backbone Mobile Node Foreign Agent Home Agent Radio Access Network Introduction • Mobile Packet Data Flow • Data response 5

6. Application Server Internet Failure Mobile Packet Backbone Mobile Node Foreign Agent Radio Access Network Introduction • Failure Occurrence • Failures in FAs • Data requests unable to be delivered Home Agent 6

7. Application Server Internet Failure Mobile Packet Backbone Mobile Node Home Agent Foreign Agent Radio Access Network Introduction • Failure Occurrence • Failures in HAs • Data response unable to be sent back 7

8. Introduction • Goal • Not terminating the data services of mobile users when failures occur in mobility agents • Proposing a reliable Mobile IP protocol in cellular systems • Tolerating multiple failures of mobility agents • Not needing the hardware support 8

9. Outline • Introduction • Background • Proposed Approach • Evaluation • Conclusions 9

10. Background • Wireless Network Model 10

11. Background • Previous Approaches • R. Ghosh and G. Varghese [1998] • J. H Ahn and C. S. Hwang [2001] • Features • Mobility agent • Hardware replication • Mobility information • Potential long registration delay • Stable storage • Fault-tolerant range • Within a network segment 11

12. Outline • Introduction • Background • Proposed Approach • Evaluation • Conclusions 12

13. Proposed Approach • Basic Idea • Workload redirection • Network-initiated handoff • Redirecting the workload of the faulty FA to other failure-free FAs • Tunneling • Redirecting the workloads of the faulty HA to other failure-free HAs 13

14. Proposed Approach • Network-Initiated Handoff • Modifying the FA selection algorithm • Relationship between RANs and FAs before a FA failure 14

15. Proposed Approach • Network-Initiated Handoff • Resetting the FA selection algorithm (Cont.) • Relationship between RANs and FAs after a FA failure Virtually moving the locations of MNs under the coverage area of the faulty FA 15

16. Proposed Approach • Tunneling • Performing the tunneling on the neighbor routers 16

17. Proposed Approach • Tunneling • Intercepting the response packets by failure-free HAs 17

18. Proposed Approach • Reconstructing mobility information • Sending a mobility-reconstruction message to each FA • Filtering the visitor list to find the MNs originally managed by the faulty HA • Re-organizing each selected visitor entry as the form of a mobility binding entry 18

19. Outline • Introduction • Background • Proposed Approach • Evaluation • Conclusions 19

20. Evaluation • Performance Degradation on a Failure-Free Mobility Agent • Probability of blocking packet data in a failure-free mobility agent • Packet data to a mobility agent • Poisson distribution • Processing time of packet data in a mobility agent • Arbitrary distribution • M/G/c/c queuing model 20

21. Evaluation • Blocking Probability of a Failure-Free Mobility Agent • Erlang’s loss formula given from the M/G/c/c queuing model 21

22. Evaluation • Traffic Parameters 22

23. Evaluation • Blocking Probability of a failure-free FA 23

24. Evaluation • Blocking Probability of a failure-free HA 24

25. Evaluation • Blocking Probability • When is not too large (e.g. 10 in FA and 10, 25 in HA), the blocking probability nearly approaches 0 regardless of the variance of wk. • When is very large (e.g. 100), the blocking probability may be not large for the smaller wk. • Four used traffic intensities are larger than the general traffic intensity in a commercial wireless system 25

26. Outline • Introduction • Background • Proposed Approach • Evaluation • Conclusions 26

27. Conclusions • A New Approach to Tolerating Multiple Failures of Mobility Agents • Not incurring failure-free overhead • Not requiring hardware support • Dynamically generating the backups of faulty mobility agents • Overhead • Performance degradation on a failure-free mobility agent • M/G/c/c queuing model (Erlang’s loss formula) 27

28. Conclusions • Comparisons 28

29. Thank You for Your Attention Jenn-Wei Lin jwlin@csie.fju.edu.tw 29