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DOA:DSR over AODV Routing for Mobile Ad Hoc Networks

DOA:DSR over AODV Routing for Mobile Ad Hoc Networks. Mobile Computing, IEEE Transactions Volume 5, Issue 10, Oct. 2006 Rendong Bai; Singhal, M.; 報告 : 柯竹蔚. Outline. 一、 Introduction 二、 W ay P oint R outing Hierarchy 三、 Performance Evaluation 四、 Conclusion. 一、 Introduction(1/5).

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DOA:DSR over AODV Routing for Mobile Ad Hoc Networks

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  1. DOA:DSR over AODV Routing for Mobile Ad Hoc Networks Mobile Computing, IEEE Transactions Volume 5, Issue 10, Oct. 2006Rendong Bai; Singhal, M.; 報告:柯竹蔚

  2. Outline • 一、Introduction • 二、Way Point Routing Hierarchy • 三、Performance Evaluation • 四、Conclusion

  3. 一、 Introduction(1/5) • Routing protocols can be grouped into proactive protocols and reactive protocols. • Proactive protocols propagate topology information periodically. Reactive protocols find routes on demand. • DSR and AODV belong to the category of flat routing protocols, all nodes are assigned the same functionalities. • Performance degrades rapidly as the network grow. Hierarchical routing protocols are developed to solve the scalability problem.

  4. 一、 Introduction(2/5) • Cluster head-Gateway Switch Routing (CGSR) is a typical hierarchical routing protocol. • Local routemaintenance activities will only affect a few neighboringclusters. Scalability is achieved. Q A C E G B D F

  5. 一、 Introduction(3/5) • In flat routing protocols , when a route breaks, typically discard the whole original route. • Actually, only a few hops are broken, but other hops are still intact. Wastes the knowledge of the original route. • AODV, Localrepair. Suitable forlink failuresnear thedestination. • Motivation: Maintaining active routes hierarchically, Routerepaired locally.

  6. 一、 Introduction(4/5) • Way Point Routing, a number of intermediate nodes on a route are selected as waypoints. • When a node on the route moves out or fails, instead of discarding the whole original route. • WPR is a lightweight scheme, CGSR and ZRP involves all nodes, hierarchy is easier to maintain.

  7. 一、 Introduction(5/5) • CGSR, ZRP built in two way dimensions. WPR hierarchy is built in one dimension

  8. 二、 WAY POINT ROUTING • Comparison of AODV and DSR • Packet header overhead: DSR is larger than AODV. • Learning capability: DSR learn more routing information. DSR contain complete route information. • Multiple routes: DSR is potentially to obtain multiple routes through multiple route replies. • Scalability: AODV is able to run on larger networks.

  9. Intrasegment Intersegment b c e f h J A D i G Segment AD Segment DG Segment GJ 二、 WAY POINT ROUTING • Way Point Routing Approach • Waypoint nodes divide a route into segments. • Forwarding nodes: Other nodes on the route.

  10. 二、 WAY POINT ROUTING • Advantages: • Broken route can be fixed at the level of a segment. • Length (hop count) of each segment on a route can be different. • Nodes move slowly, longer segments can be used • Nodes move faster, shorter segments can be used. • WPR only involves nodes on active routes.

  11. b c e f h J A D i G Segment AD Segment DG Segment GJ 二、 WAY POINT ROUTING • Combining AODV and DSR in WPR • Intrasegment routing: AODV • Intersegment routing: DSR AODV DSR

  12. 二、 WAY POINT ROUTING • DOA Route Discovery • When a source node requires a new route, it broadcasts an RREQinter • RREQ uniquely identified: <Source address , Broadcast ID number> • Intermediate node appends address in the RREQinter b D c … A A-b A A-b-c

  13. f h J i G … RREP_inter B-c-D-e-f-G-h-i-J 二、 WAY POINT ROUTING • DOA Route Discovery • Destination divides the path into segments, generates a RREPinter message. • Waypoint and forwarding nodes is placed into the RREPinter. • Source address is not listed because it appears as the destination.

  14. 二、 WAY POINT ROUTING • Two tables maintained by all nodes in the network: • Route cache (DSR) • Routing table (AODV) • Route cache • < destination : source route > • Source route only contains waypoint nodes. • Routing table • < end_node : next_hop > • next_hop to the end node of a segment • end_node of the current segment

  15. e f h J D i G … RREP_inter < G:G > < J:GJ > < J:J > 二、 WAY POINT ROUTING • When intermediate node receives RREPinter • Waypoint node, updates route cache and routing table. • Forwarding node, updates routing table. • To update route cache, node inserts source routes to the destination and to downstream intermediate waypoint.

  16. 二、 WAY POINT ROUTING • To update routing table, node inserts or updates an entry in the table < end_node : next_hop > • A-b-c-D-e-f-G-h-i-J, when h receives the RREPinter, it searches the route to end node J. For the new route, next hop is i, the hop count is 2. • When the RREPinter reaches the source node that initiated the intersegment route discovery, the source updates both route cache and routing table.

  17. b c e A D … 二、 WAY POINT ROUTING • Data Forwarding • Source node inserts the source route into the header • source route only contains waypoint nodes. • Source node processes intrasegment routing for the first segment.

  18. 二、 WAY POINT ROUTING • Route Maintenance • Node can confirm if a packet is correctly received by the downstream node through: • Link-level • Passive • Network-layer • A broken route can be repaired locally in DOA at the level of the broken segment or at the level of a few segments.

  19. 二、 WAY POINT ROUTING • Two levels of route repairs: • Intrasegment route repair (first) • Intersegment route repair • If Intrasegment route repair succeeds, waypoint are not changed. Source node does not need to be notified. • Intersegment route repair will be tried and it works over multiple segments, including broken and downstream segments.

  20. 二、 WAY POINT ROUTING • Intrasegment Route Repair • When node finds the next hop node is unreachable, it sends a RERRintra its precursor nodes. • RERRintra contains: broken link and end node of the broken segments. • Precursor node sets the state of the broken segments to invalidated.

  21. 二、 WAY POINT ROUTING • Start node of a broken segment knows the route error, it becomes the initiator of the route repair. • Initiator broadcasts RREQintra TTL: SEGMENT_LEN+1 • During the route repair period, initiator buffers data packets. b c e D f h J i A G u v buffer

  22. b c e D f h J i A G w u v 二、 WAY POINT ROUTING • Intrasegment route repair may also establish a new path for the previous segment, • Intrasegment route repair at the segment DG also builds a new path for the previous segment AD. Broadcast RREQ

  23. 二、 WAY POINT ROUTING • Intersegment Route Repair • Three types of RERRinter message: • REPAIR: intersegment route repair succeeded. • BROKEN: route repair failed. • LOOP: removes a loop on the route. • Intersegment route repair discovers a path to the end node of the segment after the broken segment (2 * SEGMENT_LEN). • When the target receives the RREQinter, it divides the path recorded into segments.

  24. e f h J k D i L G 二、 WAY POINT ROUTING • Initiator updates its route cache, sends a RERRrepair to the source through upstream waypoint nodes. • A-b-c-D-e-f-G-h-i-J-k-L, denoted as A-D-G-J-L Suppose segment DG is broken, A-D×G-J-L • D is the initiator of the intrasegment route repair. • If failed, D tries the intersegment route repair to discover a path to the end node J. initiator target

  25. 二、 WAY POINT ROUTING • Suppose the route discovery succeeds, New path from D to J, D-u-v-W-x-y-J • Node D updates its route cache, sends RERRrepair • Initiator use timer Inter_CheckReplied when route repair. If failed, initiator then sends a RERRbroken e f h J k D i L G … … u W v initiator target x y

  26. 二、 WAY POINT ROUTING • Routing Loops Detection • Upon receiving a data packet, intermediate node checks its routing table < end_node : next_hop > • If it has next_hop to the end node of the current segment as well as to the end node of another downstream segment. Loop exist.

  27. 三、 Performance Evaluation • Simulation Environment • Radio bandwidth: 2Mb/s • Radio range: 250m • Traffic: constant bit rate (CBR) • Source transmitted data packets four 512-byte per second • Mobility model: Speed from 0 m/s ~ 10 m/s • Scalability: 100 ~ 1,400 nodes

  28. 三、 Performance Evaluation • Scalability - Control Overhead • Using hierarchy in MANET is to reduce the routing overhead, DOA has less control overhead because use waypoint

  29. 三、 Performance Evaluation • Scalability - Route Repair Success Ratio • More than 80 percent of intrasegment and intersegment route repairs succeed for all network sizes.

  30. 三、 Performance Evaluation • Varying CBR Flows – Packet Delivery Ratio • Simulations aim: Performance of DOA when the number of CBR flows increases. • CBR flows increased from 20 to 60 66% 34%

  31. 三、 Performance Evaluation • Varying CBR Flows - End-to-End Delay • DOA incurs the lowest end-to-end delay among three protocols.

  32. 五、Conclusions • Way Point Routing(WPR),maintains active routes hierarchically. Divides an active route into segments. • An instantiation of WPR termed DSR over AODV. • Simulation results show that DOA scales well for more than 1,000 nodes, routing overhead significantly reduced. • Future work: • heuristic methods toselect waypoint nodes

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