An Efficient Quorum-based Fault- Tolerant Approach for Mobility Agents in Wireless Mobile Networks Yeong-Sheng Chen Chien-Hsun Chen Hua-Yin Fang Department of Computer Science, National Taipei University of Education

Outline Introduction Related Work Cyclic Quorum-based Replication Mechanism Performance Evaluation Conclusion

Introduction Mobile IP Protocol is a protocol to support Hosts mobility. The architecture of mobile IP Mobile Host (Mobile Node) Mobility Agent Home Agent Foreign Agent

Introduction HA MN RAN Router Radio Access Network Home Agent

Introduction HA MN FA RAN Router Internet

Introduction HA MN FA FA 1 FA RAN Router Register HA allocates an address and maintains the MN A Router Internet Send data to A through HA and FA 1

MN Introduction HA FA RAN Router Request Care-of Address Allocate CoA or DHCP Tell HA stores MN ’ s CoA

MN Introduction HA FA RAN Router A A wants to send data to MN

Introduction In multiple mobility agents environment, data will be distributed stored in the different agent. Distributed data processing will cause some problem Fault tolerance Registration delay Load balance

Introduction HA MN FA HA crashed

Introduction To offer solutions to these problems, many fault-tolerant approaches have been proposed.

R. Ghosh and G. Varghese, “ Fault-Tolerant Mobile IP, ” Technical Report WUCS , Washington Univ., Apr Related Work- FTMIPP HA A FA RAN Router Registration request Acquire Home Address under HA Update HA ’ s bindings

Related Work- FTMIPP The drawback of FTMIPP Long registration time Low resource utilization Conclusion Use fully redundant mobile agent to solve fault tolerant problem

Related Work J. W. Lin and J. Arul, “ An Efficient Fault-Tolerant Approach for Mobile IP in Wireless Systems, ” IEEE Transactions on Mobile Computing, VOL. 2, NO. 3, Jul.-Sep HA A FA Search MNs Response Request to store the bindings OA&M (Operation Administration and Maintenance ) Detect failed Manage the region belong to HA

Related Work HA A FA Request to Restore OA&M HA recovered

Related Work The drawback of the scheme Spend extra time on Searching MNs Delivering bindings Extra hardware cost

Goal The backup mechanism should maintain and backup bindings efficiently should not bring heavy system load should balance Many researches use quorum-based mechanisms to backup data in distributed systems.

Cyclic Quorum-based Replication Mechanism Assumption Not all HAs of a quorum in a home network will fail at the same time. Whenever a HA crashes, any data in the volatile media of the HA will be gone The failure occurs in the network only by reason of the faulty HA The home network will divide into several network segments and each HA will take charge of one of the segments.

Cyclic Quorum-based Replication Mechanism To balance the backup load, the author uses quorum to achieve the goal Per-allocate the storage place with location by using quorum

Cyclic Quorum-based Replication Mechanism Cyclic Quorum-based could balance the load 1 N N-1 …

Cyclic Quorum-based Replication Mechanism Quorum typeQuorum proposed Quorum Size VotingWeighted Majority Hierarchical Quorum Consensus GridRectangular Grid N=R*CN=R*C Square Grid Triangular Grid Tree CycleCircle M. J. Yang, Y. M. Yeh, and Y. M. Chang, “ Legion Structure for Quorum-Based Location Management in Mobile Computing, ” Journal of Information Science and Engineering, Vol. 20, pp , 2004.

Cyclic Quorum-based Replication Mechanism 1 N N-1 … There are N HAs in the networks and N distinct quorum According to Cyclic Quorum, each HAs need backup bindings of other HAs

Cyclic Quorum-based Replication Mechanism Example: There are 8 MAs in the network The Quorum sets ={Q 1,Q 2,Q 3 ….,Q 8 } Ex. Q 1 ={HA 1,HA 2,HA 3 }, Q 2 ={HA 2,HA 3,HA 4 }, Q 3 ={HA 3,HA 4,HA 5 }, …… Q 8 ={HA 8,HA 1,HA 2 } HA 1 selects Q 1, HA 2 selects Q 2 …………,HA N selects Q N

Cyclic Quorum-based Replication Mechanism Q1Q1 Q2Q2 Q3Q3 Q4Q4 Q5Q5 Q6Q6 Q7Q7 Q8Q8

HA 1 stores in 3 quorums EX. HA 1 stores in {Q 1,Q 7,Q 8 } for backup Q7Q7 Q8Q Q1Q1

Cyclic Quorum-based Replication Mechanism HA 1 MN RAN Router HA 7 HA 8 HA 1 will sends the bindings to HA 7 and HA 8 periodly

Cyclic Quorum-based Replication Mechanism If HA 1 failed, HA 7 and HA 8 will takeover the member of HA Q1Q1 Q7Q7 Q8Q8

Cyclic Quorum-based Replication Mechanism If HA 1 recovers, HA 7 and HA 8 will sends the bindings to HA Q1Q1 Q7Q7 Q8Q8

Performance Evaluation Simulator :QualNet Compare with FTMIPP

Performance Evaluation Number of MNs Bindings per backup HA FTMIPP CQFTP

Performance Evaluation Number of MNs Extra Backup Message FTMIPP CQFTP

Performance Evaluation Number of Multiple HAs Number of registered MN per Backup HA FTMIPP CQFTP

Performance Evaluation Number of Multiple HAs Average Registration Delay (Sec) FTMIPP CQFTP

Performance Evaluation Average Registration Delay (Sec) Mobility Rate FTMIPP CQFTP

Conclusion The authors proposed a mechanism Don ’ t need any extra hardware cost Reduce backup bindings by using the small quorum size Balance the load of take over process Low registration overhead