Routing in Manet

Agenda Ad-Hoc Introduction What MANET it is Proactive protocol DSDV Reactive protocol AODV DSR Hybrid Protocol ZRP Conclusion

Ad-Hoc Introduction Broadband Wireless Access Infrastructure Network – Base Station/ Access Point Ad-Hoc Network – Mobile device(ex: MANET ) Infrastr-ucture Ad-Hoc Infrastructure Ad-Hoc Need connect to Ethernet Not need Base station single -hop multi -hop Central Control Distributed routing Cost high Cost low Construct slow Construct fast Time synchronization easy Time synchronization tough

MANET(Mobile Ad-Hoc Network) Features

MANET Routing Protocol(2/2) Table-driven/Proactive more similar to conventional routing Update table information with a period On-demand-driven/Reactive only obtain route information when needed Hybrid both proactive and reactive in nature

Destination-Sequenced Distance Vector Protocol(DSDV) Highly Dynamic Destination-Sequenced Distance Vector Routing for Mobile Computer Charles E. Perkins, IBM, T.J. Waston Research Center Hawthrone, NY 10562 Pravin Bhagwat, Computer Science Department University of Maryland College Park, MD 20742 Speaker ：許景涵

Destination-Sequenced Distance Vector Protocol By using routing tables stored at each station of the network. Each node maintains routing information for all known destinations Advertise to each neighbor own routing information To maintain the consistency of routing tables in a dynamically varying topology Periodically transmits updates Immediately transmits updates as needed

Distance-Vector MH3 MH2 MH4 MH6 MH5 MH8 MH7 MH1

The Forwarding Routing Table All available destinations Next hop for each destination Number of hops to each available destination A sequence number for each route table entry, originated by the destination station Example ： MH4 Destination Next Hop Metric Seq. No Install Time Stable Data MH1 MH2 2 S406_MH1 T001MH4 Ptr1_MH1 MH2 MH2 1 S128_MH2 T001MH4 Ptr1_MH2 MH3 MH2 2 S564_MH3 T001MH4 Ptr1_MH3 MH4 MH4 0 S710_MH4 T001MH4 Ptr1_MH4 Etc.

Route Selection Update information is compared to own routing table Select route with higher destination sequence number – to ensure using newest information from destination Select the route with better metric when sequence numbers are equal. The Receiver adds an increment to the metric.

Rules to set sequence number Information On each advertisement increase own destination sequence number use only even numbers If a node is no more reachable (timeout) increase sequence number of this node by 1 set metric =  . Destination Next Hop Metric Seq. No Install Time Stable Data MH1 MH1 1 S406_MH1 T001MH2 Ptr1_MH1 MH2 MH2 0 S128_MH2 T001MH2 Ptr1_MH2 MH3 MH3  S561_MH3 T001MH2 Ptr1_MH3 MH4 MH4 1 S710_MH4 T001MH2 Ptr1_MH4 Etc.

Example of DSDV in operation MH 3 MH 6 MH 2 MH 1 MH 7 MH 4 MH 8 MH 5

Example of DSDV in operation MH 3 MH 6 MH 2 MH 1 MH 7 MH 4 MH 8 MH 5 MH 4 Forwarding table: Destination Next Hop Metric Seq. No MH 1 MH 2 2 S406_MH 4 MH 2 MH 2 1 S128_MH 1 MH 3 MH 2 2 S564_MH 2 MH 4 MH 4 0 S710_MH 3 MH 5 MH 6 2 S392_MH 5 MH 6 MH 6 1 S076_MH 6 MH 7 MH 6 2 S128_MH 7 MH 8 MH 6 3 S050_MH 8

Example of DSDV in operation MH 3 MH 6 MH 2 MH 1 MH 7 MH 4 MH 8 MH 5 MH 1 Update triggered by MH 1 , broadcasted to MH 7 and MH 8 On detection of broken link: Immediate incremental update triggered by MH 2 with odd sequence number and infinite metric Updates are propagated through the network

Example of DSDV in operation MH 3 MH 6 MH 2 MH 7 MH 4 MH 8 MH 5 MH 1 MH 4 advertised table (updated): Destination Next Hop Metric Seq. No MH 1 MH 6 3 S516_MH 4 MH 2 MH 2 1 S238_MH 1 MH 3 MH 2 2 S674_MH 2 MH 4 MH 4 0 S820_MH 3 MH 5 MH 6 2 S502_MH 5 MH 6 MH 6 1 S186_MH 6 MH 7 MH 6 2 S238_MH 7 MH 8 MH 6 3 S160_MH 8

Adjustment in carried information Reduce the amount of information carried in these packets Full dump will carry all the available routing information. Incremental packets: all information that has changed since the last full dump Full dump if incremental dump exceeds one NPDU (network protocol data unit) Full dumps can be transmitted relatively infrequently , when no movement of Mobile Hosts is occurring.

Receiving Fluctuating Routes What might happen: MH 9 broadcasts update information to MH Collections I and II MH 2 transmits new routing information to MH 4 MH 4 : new sequence number  routing table update  broadcast update MH 6 transmits new routing information to MH 4 , same sequence number, better metric MH 4 : same seq.no., better metric  update routing table  broadcast update

Damping Fluctuation Causes for Fluctuation: Many hosts with irregular updates Different propagation speed Different transmission intervals Broadcasts are asynchronous events Solution: Keep a route settling time table in each node with a time to wait for a route with a better metric before advertising the update message.

Route Settling Time Table Decide how long to wait before advertising. Calculated by maintaining a running weighted average over the most recent updates of the routes for each destination. The settling time data is store in a table with following fields Destination address Last setting time Average settling time-use for this determination

DSDV Disadvantages and Improvement Disadvantages Periodically updates ： No sleeping nodes Bi-directional links required Overhead: most routing information never used Scalability is a major problem Many improved protocols based on DSDV have been developed Example: AODV: Ad-hoc On-Demand Distance Vector Routing

Unidirectional and Bi-directional links A B C D

Ad Hoc On-Demand Distance Vector Routing Protocol (AODV) Speaker ：方祥軒 Ad-hoc On-Demand Distance Vector Routing ECE697A Advanced Computer Networks Presented by Qifeng Lu Scalable AODV with Efficient Flooding based on On-Demand (Passive) Clustering Yunjung Yi and Mario Gerla University of California, Los Angeles

Outline Introduction AODV Features AODV Algorithm

Introduction An improved algorithm of DSDV A Source Initiated ( reactive ) routing protocol Main goals: Quick adaptation under dynamic link conditions Lower transmission latency Low network utilization ( less broadcast ) Loop-free property (How: using destination sequence #)

AODV Features V.S. DSDV Routes are created only when required Each node doesn’t maintain all routes to other nodes (only active routes) Use of sequence numbers at each destination to maintain freshness of routing information( solve loop problem ) Reduces periodic broadcast Paths generated are loop-free Uses symmetric links (if a link is not symmetric it is not up) Works both on wired media and wireless media

AODV Algorithm Path Discovery Reverse Path Setup Forward Path Setup Route Table Management Path Maintenance

Path Discovery Route Discovery Route Requests( RREQ) Route Replies (RREPs) Route Maintenance Route Errors (RERRs)

Route Discovery(1/2) Unique Unique RREQ freshness Reverse freshness RREQ RREQ source_addr source_sequence_# broadcast_id dest_addr dest_Sequence_# hop_cnt

Route Discovery(2/2) Route Reply (RREP) RREP RREP source_addr hop_cnt dest_addr source_sequence_# lifetime (expiration time for reverse path route entry)

Reverse Path Setup Initiated when no route to reach destination node S D RREP (Route Reply) RREQ (Route Request) Drop ClusterHead Gateway Ordinary Node

Forward Path Setup RREQ arrives at a node that has current route to the destination ( larger/same sequence number ) sequence number = 99 sequence number = 101 REEQ sequence number = 100 A C B D T^T Send RREQ =V= Send RREP Unicast

Route Table Management Route request expiration time: to purge reverse path routing entries from nodes are not on the path from source to destination Route caching timeout: when the route is considered to be invalid A B C D RERR

AODV with Efficient Flooding Clustering Scheme Cluster heads and gateways are dominant nodes Advantage Reduce AODV routing overhead Improves AODV scalability S D ClusterHead Gateway Ordinary Node

Dynamic Source Routing (DSR) Routing in Ad-Hoc Networks And the DSR Protocol Computer Network Dr. Jorge A. Cobb Upgrading Performance of DSR Routing Protocol in Mobile Ad Hoc Networks Mehdi Alilou , Mehdi Dehghan.t TPBDSR: A New DSR-based Energy Saving Routing in MANET XU Li WU Zi-wen & ZHENG Bao-yu Speaker ：呂璇

Dynamic Source Routing (DSR) On demand : No periodic router advertisements Source routing : to send a packet to another host, the sender constructs a source route in the packet’s header Caching : each mobile host participating in the ad hoc network maintains a route cache in which it caches source routes

Two Main Components Route Discovery the mechanism by which a sending node S obtains a route to destination D Route Maintenance the mechanism by which a sending node S detects that the network topology has changed and its route to D is no longer valid

Route Discovery(1/13) When two nodes which are not in wireless rang of each other, want to communicated with each other. process.

Route Discovery(2/13) Represents a node that has received RREQ for D from S B A S E F H J D C G I K Z Y M N L

Route Discovery(3/13) When two nodes which are not in wireless rang of each other, want to communicated with each other. If the source node has the related route to destination in its cache memory -> Insert the route in data packet headers and the packets will be sent from that specified route . If it doest have the related route to destination -> Begin the route discovery process.

Route Discovery(4/13) Step 1 ： Source( S ) broadcasts RREQ message for specified destination( D ). R oute Req uest packet (RREQ) Destination Address Source Address Request ID Route Record

Route Discovery(5/13) Represents transmission of RREQ Broadcast [S] [X,Y] Represents route record stored in RREQ B A S E F H J D C G I K Z Y M N L

Route Discovery(6/13) Step 2 ： When intermediate node receive RREQ message. Adds itself to path in message Forwards (broadcasts) message toward D until…… A node that has a route to D is found -> Early Route-Replies.

Route Discovery(7/13) [S,E] [S,C] [S,B] B A S E F H J D C G I K Z Y M N L

Route Discovery(8/13) Step 2 ： When intermediate node receive RREQ message. Adds itself to path in message Forwards (broadcasts) message toward D until…… A node that has a route to D is found -> Early Route-Replies. A node has already received the same RREQ message -> Discard the packet. Source Address Request ID

Route Discovery(9/13) C receives RREQ from G and H , but does not forward it again, because C has already forwarded RREQ once [S,C,G] [S,E,F] [S,B,A] [S,B,H] B A S E F H J D C G I K Z Y M N L

Route Discovery(10/13) J and K both broadcast RREQ to D [S,C,G,K] [S,E,F,J] [S,B,H,I] [S,E,F,J,D] [S,C,G,K,D] B A S E F H J D C G I K Z Y M N L

Route Discovery(11/13) D does not forward RREQ, because D is the intended target [S,E,F,J,M] B A S E F H J D C G I K Z Y M N L

Route Discovery(12/13) Step 3 ： When D receive RREQ message, it copies route into a RREP packet and sends it back to S. R oute Rep ly packet (RREP) If MAC protocol is bidirectiona l , use reverse path as data. With unidirectional links , Destination may need to discover route to source to deliver Route Reply If a route exists in its cache, use it O.W. piggyback Route Reply onto new Route Request

Route Discovery(13/13) RREP [S,E,F,J,D] Represents RREP control message B A S E F H J D C G I K Z Y M N L

Route Maintenance(1/6) Used when link breakage occurs. Step 1 ： Intermediate nodes using Acknowledge to detect link status/breakage. link-layer ACKs (MACAW) passive ACKs DSR ACK request

Route Maintenance(2/6) B A S E F H J D C G I K Z Y M N L

Route Maintenance(3/6) Step 2 ： The intermediate node sent RERR message to S when break detected. R oute Err or (RERR) Bidirectional -> Reverse path Unidirectional -> Cache or Piggyback

Route Maintenance(4/6) Represents RERR message [S,E,F] B A S E F H J D C G I K Z Y M N L

Route Maintenance(5/6) Step 3 ： Source deletes rout e . Step 4 ： Source try another path if one cached, or issues new RREQ (new route discovery).

Route Maintenance(6/6) [S,E,F,J,D] [S,C,G,K,D] B A S E F H J D C G I K Z Y M N L

DSR vs. AODV AODV DSR Path Information Limited information More detail Times of Route Discovery Many Few Traffic when RREP Low High Live time of route path New We don’t know Delete invalid path when RRER Delete all Only delete some node

Hybrid Protocol Zone Routing Protocol (ZRP) combines Proactive protocol/ Table-Driven : Intra-Zone Routing Reactive protocol/ On-Demand : Inter-Zone Routing Routing Zone Inter-Zone Routing Intra-Zone Routing On-Demand Table-Driven

Conclusion(1/2) Routing class Proactive Reactive Hybrid Routing structure Both Mostly flat Mostly hierarchical Availability of route Always available Determined when needed Depend on the location of the destination Control traffic volume High medium low Periodic updates Yes No Usually used inside each zone , or between gateways Handling effects of mobility Usually updates occur at fixed intervals. AODV,DSR uses local route discovery Usually more than one path maybe available. Single point of failures are reduced by working as a group

Conclusion(2/2) Routing class Proactive Reactive Hybrid Storage requirements High Depends on the number of routes kept or required. Usually lower than proactive protocols Usually depends on the size of each cluster or zone may become as large as proactive protocols if clusters are big Delay level Small routes are predetermined Higher than proactive For local destinations small. Inter-zone maybe as large as reactive protocols Scalability level Usually up to 100 nodes. Source routing protocols up to few hundred nodes. Designed for up to 1000 or more nodes

References A review of routing protocols for mobile ad hoc networks Mehran Abolhasan , Tadeusz Wysocki , Eryk Dutkiewicz 以路徑為基礎的 MANET 網路群播路由協定之研究研究生：蘇平嘉　指導教授：陳彥文無線 Ad Hoc 行動隨意網路架構之技術發展評析　惠汝生

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Routing in Manet

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Routing in Manet