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1、CS 80240333,CUI Yong,1,Mobile Ad hoc network : MANET,CS 80240333 Instructor: CUI Yong,CS 80240333,CUI Yong,2,Outline,Routing in MANET MANET Routing Protocol Design Reactive protocols DSR and Optimization AODV Proactive protocols OLSR DSDV Hybrid protocols ZRP, LANMAR Conclusion,CS 80240333,CUI Yong,
2、3,Unicast Routing in MANET,Host mobility link failure/repair due to mobility may have different characteristics than those due to other causes Instability Rate of link failure/repair may be high when nodes move fast New performance criteria needed route stability despite mobility energy consumption
3、Proposed protocols Some have been invented specifically for MANET Others are adapted from older protocols for wired networks No single protocol works well some attempts made to develop adaptive protocols,CS 80240333,CUI Yong,4,Types of Protocols,On-demand/reactive the routes are determined when they
4、 are required by the source using a route discovery process; Global/proactive determine routes to all the destinations at the start up maintain by using periodic route update process; Hybrid combine the basic properties of the first two classes of protocols into one.,Advantage & Disadvantage? Intern
5、et router? BGP/OSPF/ISIS/RIP?,CS 80240333,CUI Yong,5,Trade-off,Latency of route discovery Proactive protocols may have lower latency since routes are maintained at all times Reactive protocols may have higher latency because a route from X to Y will be found only when X attempts to send to Y Overhea
6、d of route discovery/maintenance Reactive protocols may have lower overhead since routes are determined only if needed Proactive protocols can (but not necessarily) result in higher overhead due to continuous route updating Depend on the traffic and mobility patterns,CS 80240333,CUI Yong,6,How to se
7、nd messages to destination,Routing Reactive Proactive No routing in advance? Any simple solutions?,CS 80240333,CUI Yong,7,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Represents that connected nodes are within each others transmission range,Z,Y,Represents a node that has received packet P,M,N,
8、L,Sending a packet from S to D,CS 80240333,CUI Yong,8,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Represents transmission of packet P,Represents a node that receives packet P for the first time,Z,Y,Broadcast transmission,M,N,L,CS 80240333,CUI Yong,9,Flooding for Data Delivery,B,A,S,E,F,H,J,D,
9、C,G,I,K,Node H receives packet P from two neighbors: potential for collision,Z,Y,M,N,L,CS 80240333,CUI Yong,10,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Node C receives packet P from G and H, but does not forward it again, because node C has already forwarded packet P once,Z,Y,M,N,L,CS 8024
10、0333,CUI Yong,11,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Z,Y,M,Nodes J and K both broadcast packet P to node D Since nodes J and K are hidden from each other, their transmissions may collide = Packet P may not be delivered to node D at all, despite the use of flooding,N,L,CS 80240333,CUI
11、Yong,12,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Z,Y,Node D does not forward packet P, because node D is the intended destination of packet P,M,N,L,CS 80240333,CUI Yong,13,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Flooding completed Nodes unreachable from S do not receive packet P
12、 (e.g., node Z) Nodes for which all paths from S go through the destination D also do not receive packet P (example: node N),Z,Y,M,N,L,CS 80240333,CUI Yong,14,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,Flooding may deliver packets to too many nodes (in the worst case, all nodes reachable fro
13、m sender may receive the packet),Z,Y,M,N,L,CS 80240333,CUI Yong,15,Flooding for Data Delivery: Advantages,Simplicity Being efficient when Rate of information transmission is low enough the overhead of explicit route discovery/maintenance is relatively higher Example nodes transmit small data packets
14、 infrequently topology changes frequently Higher reliability of data delivery Because packets may be delivered to the destination on multiple paths,CS 80240333,CUI Yong,16,Flooding for Data Delivery: Disadvantages,High overhead Data packets may be delivered to too many nodes who do not need to recei
15、ve them Potentially lower reliability of data delivery Reliable broadcast? Flooding uses broadcasting - hard to implement reliable broadcast delivery without significantly increasing overhead,CS 80240333,CUI Yong,17,Outline,Routing in MANET MANET Routing Protocol Design Reactive protocols DSR and Optimization AODV Proactive protocols OLSR DSDV Hybrid protocols ZRP, LANMAR Conclusion,CS 80240333,CUI Yong,18,Flooding for Data Delivery,B,A,S,E,F,H,J,D,C,G,I,K,What if we have continuous data to send? How to extend flooding to routing?,Z,Y,M,N,L,Who should store the path? Find a path and store the
