Ad Hoc

Use Of Routing Protocols In Use Of Routing Protocols In Mobile Ad Hoc NetworkMobile Ad Hoc Network

Presented by :Presented by :

IQxplorerIQxplorer

Types Of Wireless NetworksTypes Of Wireless Networks

► Infrastructure based(Cellular Network).Infrastructure based(Cellular Network).

► InfrastructurelessInfrastructureless NetworkNetwork((Mobile Ad Mobile Ad hochoc

NETwork) (MANET).NETwork) (MANET).

Characteristics Of An Ad-hoc Characteristics Of An Ad-hoc NetworkNetwork

►Collection of mobile nodes forming a Collection of mobile nodes forming a temporary networktemporary network

►Network topology changes frequently and Network topology changes frequently and

unpredictablyunpredictably►No centralized administration or standard No centralized administration or standard

support servicessupport services►Host is also function as router.Host is also function as router.

Why Is Routing Different In Ad Why Is Routing Different In Ad Hoc ???Hoc ???

►Host mobilityHost mobility Dynamic topologyDynamic topology link failure/repair due to mobility link failure/repair due to mobility

►Distributed EnvironmentDistributed Environment►Bandwidth constrainedBandwidth constrained►Energy constrainedEnergy constrained

Categorization Of Ad-Hoc Categorization Of Ad-Hoc Routing ProtocolsRouting Protocols

Table Driven Routing ProtocolTable Driven Routing Protocol

► Proactive.Proactive.► Each node maintains one or more tables Each node maintains one or more tables

containing routing information to every other containing routing information to every other

node in the network.node in the network.► Tables need to be consistent Tables need to be consistent and up-to-date and up-to-date

view of the networkview of the network..► Updates propagate through the networkUpdates propagate through the network

Source Initiated On demand Source Initiated On demand Routing ProtocolRouting Protocol

► Reactive.Reactive.► on-demand style: create routes only when it on-demand style: create routes only when it

is desired by the source nodeis desired by the source node►When a node requires a route to a When a node requires a route to a

destination, it initiates a route discovery destination, it initiates a route discovery process process

► Route is maintained until destination Route is maintained until destination becomes unreachable, or source no longer is becomes unreachable, or source no longer is interested in destination.interested in destination.

Destination-Sequenced Distance Destination-Sequenced Distance Vector ProtocolVector Protocol

(DSDV) (DSDV)

► Basic Routing Protocol Basic Routing Protocol ► Each node maintains a list of all Each node maintains a list of all

destinations and number of hops destinations and number of hops to each destination.to each destination.

► Each entry is marked with a Each entry is marked with a sequence number.sequence number.

► Periodically send table to all Periodically send table to all neighbors to maintain topologyneighbors to maintain topology

Example Of DSDVExample Of DSDV DestinaDestina

tion tion Next Next

HoHopp

DistaDistancncee

Sequence Sequence NumberNumber

AA AA 00 S205_AS205_A

BB BB 11 S334_BS334_B

CC CC 11 S198_CS198_C

DD DD 11 S567_DS567_D

EE DD 22 S767_ES767_E

FF DD 22 S45_FS45_F

Destination Destination Next HopNext Hop DistanceDistance Sequence Sequence NumberNumber

AA AA 00 S304_AS304_A

BB DD 33 S424_BS424_B

CC CC 11 S297_CS297_C

DD DD 11 S687_DS687_D

EE DD 22 S868_ES868_E

FF DD 22 S164_FS164_F

A’s Routing Table Before Change

A’s Routing Table After Change

Clusterhead Gateway Switch Clusterhead Gateway Switch RoutingRouting (CGSR) (CGSR)

►Similar to DSDVSimilar to DSDV►Based on concept of clusters and cluster Based on concept of clusters and cluster

headsheads►Routing is done via the cluster heads and Routing is done via the cluster heads and

gatewaysgateways►A routing table among cluster heads are A routing table among cluster heads are

maintainedmaintained

Example Of CGSRExample Of CGSR

Data forwarding steps:•from cluster head to cluster head–in a hierarchical manner•then from cluster head to cluster members•between two cluster heads, gateways are used to forward the packets

Source Initiated On Source Initiated On Demand Demand

Routing ProtocolRouting Protocol

Ad Hoc On-Demand Distance Ad Hoc On-Demand Distance Vector RoutingVector Routing

(AODV)(AODV)► Pure on-demand protocolPure on-demand protocol► Node does not need to maintain knowledge of Node does not need to maintain knowledge of

another node unless it communicates with itanother node unless it communicates with it► AODV includes route discovery and route AODV includes route discovery and route

maintenance.maintenance.► AODV minimizes the number of broadcasts by AODV minimizes the number of broadcasts by

creating routes on-demand creating routes on-demand ► AODV uses only symmetric links because the AODV uses only symmetric links because the

route reply packet follows the reverse path of route reply packet follows the reverse path of route request packetroute request packet

PATH DISCOVERYPATH DISCOVERY

► In the path discovery (RREQ) In the path discovery (RREQ) phase, source broadcasts RREQ phase, source broadcasts RREQ message.message.

► Intermediate nodes record in Intermediate nodes record in their route tables the address their route tables the address of neighbor from which RREQ is of neighbor from which RREQ is received to establish a reverse received to establish a reverse path.path.

► When RREQ reaches destination When RREQ reaches destination or an intermediate node or an intermediate node responds by unicasting a route responds by unicasting a route reply (RREP) back to neighborreply (RREP) back to neighbor

► If source node moves, If source node moves, reestablish the path.reestablish the path.

► If destination or intermediate If destination or intermediate node moves, send link failure node moves, send link failure notification message to each of notification message to each of its active upstream.its active upstream.

► Then reinitiate path discovery .Then reinitiate path discovery .

Dynamic Source Routing Dynamic Source Routing Protocol Protocol

(DSR)(DSR)► on-demandon-demand► A node maintains route cache containing the A node maintains route cache containing the

routes it knowsroutes it knows► Two main phasesTwo main phases

Route discoveryRoute discovery Route maintenanceRoute maintenance

► Basic Operation is similar to AODV.Basic Operation is similar to AODV.

Example Of DSRExample Of DSR

DISADVANTAGE OF DISADVANTAGE OF PROACTIVE AND PROACTIVE AND

REACTIVE APPROACHREACTIVE APPROACH

Hybrid Routing Hybrid Routing ProtocolsProtocols

Zone Routing ProtocolZone Routing Protocol

► Hybrid of table-driven and on-demand!!Hybrid of table-driven and on-demand!!► From each node, there is a concept of From each node, there is a concept of ““zonezone””..

Within each zone, the routing is performed in Within each zone, the routing is performed in a a

table-driven manner (proactive).table-driven manner (proactive). However, a node does not try to keep global However, a node does not try to keep global

routing information.routing information.► For inter-zone routing, on-demand routing is For inter-zone routing, on-demand routing is

used.used.

Example Of ZRPExample Of ZRP

► Three types of Three types of nodes:nodes: Border NodesBorder Nodes Peripherals NodesPeripherals Nodes Interior NodesInterior Nodes

ComparisonComparison

ParametersParameters On DemandOn Demand Table DrivenTable Driven

Availability of routingAvailability of routing

informationinformationAvailable Available when when

neededneeded

Always available Always available regardless of needregardless of need

Routing philosophyRouting philosophy FlatFlat Mostly flat, except Mostly flat, except for CGSRfor CGSR

Periodic route updatesPeriodic route updates Not requiredNot required RequiredRequired

Coping with mobilityCoping with mobility Use localized Use localized route route discoverydiscovery

Inform other nodes Inform other nodes to achieve to achieve consistent routing consistent routing tabletable

Signaling traffic Signaling traffic generatedgenerated

Grows with Grows with

increasing increasing mobilitymobility

Greater than that of Greater than that of on demand routingon demand routing

ReferencesReferences

► Elizabeth M. Royer, Chai-Keong Toh, Elizabeth M. Royer, Chai-Keong Toh, A Review of Current A Review of Current Routing Protocols for Ad Hoc Mobile Wireless Networks,Routing Protocols for Ad Hoc Mobile Wireless Networks,Proc. Proc. IEEE,1999.IEEE,1999.

► David B. Johnson, " David B. Johnson, " Routing in Ad hoc Networks of Mobile Routing in Ad hoc Networks of Mobile HostsHosts", Proc", Proc

IEEE Workshop on Mobile Computing Systems and IEEE Workshop on Mobile Computing Systems and Applications.Applications.

► Nicklas Beijar “Nicklas Beijar “Zone Routing ProtocolZone Routing Protocol “. “.► www.cse.wustl.edu/~jain/cis788-99/adhoc_routing/ www.cse.wustl.edu/~jain/cis788-99/adhoc_routing/ ► http://www.comp.brad.ac.uk/~sburuha1/index.htmhttp://www.comp.brad.ac.uk/~sburuha1/index.htm► www.computingunplugged.com/ www.computingunplugged.com/

issues/issue200407/00001326001.html issues/issue200407/00001326001.html ► http://www.ietf.org/rfc/rfc3561.txthttp://www.ietf.org/rfc/rfc3561.txt

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