CSE 581 Internet Technology Ad-hoc Routing Schemes Presented by Jason Liu

CSE 581 Internet TechnologyCSE 581 Internet Technology

Ad-hoc Routing SchemesAd-hoc Routing Schemes

Presented byPresented byJason LiuJason Liu

AgendaAgenda

A highly adaptive distributed routing A highly adaptive distributed routing algorithm for mobile wireless networks algorithm for mobile wireless networks by Vincent D. Park and M .Scott Corsonby Vincent D. Park and M .Scott Corson

Dynamic Source Routing in Ad Hoc Dynamic Source Routing in Ad Hoc Wireless Networks by David B. Johnson Wireless Networks by David B. Johnson and David A. Maltzand David A. Maltz

Performance Comparison of Two On-Performance Comparison of Two On-demand Routing Protocols for Ad Hoc demand Routing Protocols for Ad Hoc Networks by Das, Perkins and RoyerNetworks by Das, Perkins and Royer

A Performance Comparison of Multi-Hop A Performance Comparison of Multi-Hop Wireless Ad Hoc Network Routing Wireless Ad Hoc Network Routing Protocols by Broch, Maltz, Johnson, Hu, Protocols by Broch, Maltz, Johnson, Hu, and Jetchevaand Jetcheva

DefinitionDefinition

An ad hoc network -- a collection of An ad hoc network -- a collection of wireless mobile nodes dynamically wireless mobile nodes dynamically forming a temporary network forming a temporary network without the use of any existing without the use of any existing network infrastructure or network infrastructure or centralized administrationcentralized administration

A Highly Adaptive Distributed Routing A Highly Adaptive Distributed Routing Algorithm for Mobile Wireless NetworksAlgorithm for Mobile Wireless NetworksIntroductionIntroduction

Problems of routing in a mobile Problems of routing in a mobile wirelesswireless Nodes move about arbitrarilyNodes move about arbitrarily Potentially rapid and unpredictable Potentially rapid and unpredictable

changing topology changing topology Wireless links inherently have Wireless links inherently have

significantly lower capacity than significantly lower capacity than hardwired linkshardwired links

More prone to congestionMore prone to congestion

TORA -- TORA -- OverviewOverview

Minimizes reaction to topological Minimizes reaction to topological changeschanges

Decouples the generation of control Decouples the generation of control message propagation from the rate message propagation from the rate of topological changesof topological changes

Source initiatedSource initiated

TORATORA

The protocol can be separated into The protocol can be separated into three functions:three functions: Creating routesCreating routes

establishment of a sequence of establishment of a sequence of directed links leading from node to directed links leading from node to dest.dest.

Maintaining routesMaintaining routesre-establish routesre-establish routes

Erasing routesErasing routesupon detection of network partition, all upon detection of network partition, all links must be undirected to erase links must be undirected to erase invalid routesinvalid routes

TORATORA

It accomplishes three functions It accomplishes three functions through use of control packets: through use of control packets: Query (QRY) – used for creating Query (QRY) – used for creating

routesroutes Update (UPD) – for both creating and Update (UPD) – for both creating and

maintaining routesmaintaining routes Clear (CLR) – for erasing routesClear (CLR) – for erasing routes

TORATORABasic OperationsBasic Operations Creating RoutesCreating Routes

Requires use of the QRY and UPD Requires use of the QRY and UPD packetspackets

QRY packet – dest-ID (did)QRY packet – dest-ID (did) UPD – did and height of node I UPD – did and height of node I

broadcasting the packetbroadcasting the packet Each node maintains a route-required Each node maintains a route-required

(RR) flag, initially un-set(RR) flag, initially un-set Node with no directed links and an un-Node with no directed links and an un-

set RR flag requires route to dest, it set RR flag requires route to dest, it broadcasts a QRY packet, set RR flagbroadcasts a QRY packet, set RR flag

TORA – TORA – Creating RoutingCreating Routing

Route-required flag set

TORA – TORA – Maintaining routesMaintaining routes Maintaining Routes performed only for nodes Maintaining Routes performed only for nodes

height > 0height > 0

TORA – TORA – Erasing RoutingErasing Routing

Following detection of a partition, Following detection of a partition, node I sets its height and the height node I sets its height and the height of neighbor to NULL of neighbor to NULL

Update all entries in link-state arrayUpdate all entries in link-state array Broadcast a CLR packetBroadcast a CLR packet

TORA – TORA – Erasing RoutingErasing Routing

Link (D,H) marked as failing

PerformancePerformance

TORA is able to localize its reaction TORA is able to localize its reaction to topological changes to topological changes

Best suited for relatively dense Best suited for relatively dense networks, only several nearby networks, only several nearby nodes involved in a reactionnodes involved in a reaction

Effect of localization – increased of Effect of localization – increased of scalabilityscalability

ConclusionsConclusions

Proposed a highly adaptive distributed Proposed a highly adaptive distributed routing algorithm that well-suited in routing algorithm that well-suited in mobile wireless networksmobile wireless networks

Decouple the generation of far-reaching Decouple the generation of far-reaching control message propagation from the control message propagation from the dynamics of the network topologydynamics of the network topology

Possible enhancement would be to Possible enhancement would be to periodically propagate refresh packets periodically propagate refresh packets outwards from the dest. outwards from the dest.

The refresh process permits intro of far-The refresh process permits intro of far-reaching control message propagation reaching control message propagation into the protocol independent of the into the protocol independent of the network topologynetwork topology

Dynamic Source RoutingDynamic Source RoutingIntroductionIntroduction Oftentimes, mobile users want to Oftentimes, mobile users want to

communicatecommunicate No fixed infrastructure availableNo fixed infrastructure available Not econo practical or physically Not econo practical or physically

possiblepossible Expediency of the situation not permit Expediency of the situation not permit

installationinstallation

Introduction – contIntroduction – cont

This paper describes the design and This paper describes the design and performance of DSR for ad hoc networks performance of DSR for ad hoc networks between hosts that want to communicatebetween hosts that want to communicate

Source Routing – the sender of a packet Source Routing – the sender of a packet determines the complete sequence of determines the complete sequence of nodes to forward the packetnodes to forward the packet Designed for use in wireless ad hoc Designed for use in wireless ad hoc

networksnetworks No periodic router admnts No periodic router admnts Dynamically determines route based on Dynamically determines route based on

cached info and on the results of a route cached info and on the results of a route discoverydiscovery

Benefits of DSR over conven Benefits of DSR over conven routing protocolrouting protocol No periodic routing adtsment msg, No periodic routing adtsment msg,

reducing network bandwidth reducing network bandwidth overheadoverhead

Conserve mobile host battery Conserve mobile host battery powerpower Not sending the ad and not receiving Not sending the ad and not receiving

themthem Not require transmissions between Not require transmissions between

hosts to work bidiectionallyhosts to work bidiectionally Able to adapt quickly to dynamic Able to adapt quickly to dynamic

topology changes, no protocol topology changes, no protocol overheadoverhead

Assumptions (1)Assumptions (1)

All hosts within ad hoc network are All hosts within ad hoc network are willing to participate fullywilling to participate fully Each host participating be willing to Each host participating be willing to

forward packets for other hostsforward packets for other hosts Diameter of ad hoc network be Diameter of ad hoc network be

small but often greater than onesmall but often greater than one Hosts do not continuously move so Hosts do not continuously move so

rapidly rapidly Hosts enable a promiscuous Hosts enable a promiscuous

receive modereceive mode

Assumptions (2)Assumptions (2)

A B C

Diameter of the ad hoc depicted in Figure 1 is two

DSR OperationDSR OperationOverviewOverview

To send a packet to another host, the sender To send a packet to another host, the sender constructs a source route in the packets constructs a source route in the packets headerheader

Each mobile host participating in the ad hoc Each mobile host participating in the ad hoc network maintains a route cache in which it network maintains a route cache in which it caches source routescaches source routes

If no route found, the sender may attempt to If no route found, the sender may attempt to discover one using the route discovery discover one using the route discovery protocol.protocol.

Host monitors the correct operation of a Host monitors the correct operation of a route in use, we call route maintenanceroute in use, we call route maintenance

DSR -- DSR -- Route DiscoveryRoute Discovery

Allows any host to dynamically Allows any host to dynamically discover a route to any other host discover a route to any other host in the ad hoc network.in the ad hoc network.

A host initiating a route discovery A host initiating a route discovery broadcasts a route request packetbroadcasts a route request packet

If successful, initiating host If successful, initiating host receives a route reply packetreceives a route reply packet

Each route request packet contains Each route request packet contains a route record, request id a route record, request id

DSR -- DSR -- Route MaintenanceRoute Maintenance

Conven routing protocol integrate Conven routing protocol integrate rd with rm by continuously sending rd with rm by continuously sending periodic routing updatesperiodic routing updates

Using rd, no periodic msg Using rd, no periodic msg Rm monitors the opr of the route Rm monitors the opr of the route

and informs the sender of any and informs the sender of any routing errorrouting error

Utilize a hop-by-hop ack to provide Utilize a hop-by-hop ack to provide early detection and retransmission early detection and retransmission of lost or corrupted packetsof lost or corrupted packets

DSR -- DSR -- Route OptimizationsRoute Optimizations

A number of optimizations areA number of optimizations are

possible to basic opr of routepossible to basic opr of route

discovery and route maintenancediscovery and route maintenance


Full use of the Route CacheFull use of the Route Cache

A B C D

F

E

Figure 2 An example of ad hoc network illustrating use of the route cache


Piggybacking on Route DiscoveriesPiggybacking on Route Discoveries Sender doesn’t have a route caches to Sender doesn’t have a route caches to

the dest host, initiate a separate route the dest host, initiate a separate route discoverdiscover

The delay for rd and total # of packets The delay for rd and total # of packets transmitted reduced by allowing data transmitted reduced by allowing data to be piggybacked on route req packto be piggybacked on route req pack

Use piggyback when sending route Use piggyback when sending route reply or route error packreply or route error pack


Reflecting Shorter RoutesReflecting Shorter Routes Two hosts comm using cached routesTwo hosts comm using cached routes Desirable to use shorter routes if Desirable to use shorter routes if

hosts move suffi closer togetherhosts move suffi closer together Basic route maint accomplish thisBasic route maint accomplish this Improvemnt – hosts opr in Improvemnt – hosts opr in

promiscuous receive modepromiscuous receive mode

B C D

Figure 3 Mobile host D notices that the route can be shortened

Performance EvaluationPerformance Evaluation

Optimal number of transmissions is the number of hops for the data packet needed to get from the sender to intended receiver

ConclusionConclusion

Presented a protocol for routing Presented a protocol for routing packets in an ad hoc networkpackets in an ad hoc network

Use dynamic source routingUse dynamic source routing Adapts to routing changes quicklyAdapts to routing changes quickly Requires little or no overhead during Requires little or no overhead during

hosts move less frequentlyhosts move less frequently Performs well over host density, and Performs well over host density, and

movement ratesmovement rates Overhead 1% of total packets Overhead 1% of total packets

transmitted of 24 mobile hoststransmitted of 24 mobile hosts Route length within a factor 1.02 of Route length within a factor 1.02 of

optimaloptimal

Performance comparison of two on-Performance comparison of two on-demand routing protocolsdemand routing protocols GoalGoal

Carry out a systematic performance Carry out a systematic performance study of two dynamic routing protocolstudy of two dynamic routing protocol

Common characteristicsCommon characteristics

DSR and AODV DSR and AODV Both initiate routing activities on an Both initiate routing activities on an

“on-demand” basis“on-demand” basis Both reactive vs traditional proactiveBoth reactive vs traditional proactive Reduce routing loadReduce routing load

DifferencesDifferences DSR DSR

Uses source routingUses source routing Doesn’t rely on timer-based activitiesDoesn’t rely on timer-based activities

AODVAODV Uses table-driven routing framework Uses table-driven routing framework

and dest sequence numberand dest sequence number rely on timer-based activitiesrely on timer-based activities

DSRDSR

Uses source routingUses source routing Sender knows complete hop-by-hop Sender knows complete hop-by-hop

route to destroute to dest Routes stores in route cache, carried Routes stores in route cache, carried

in packet headerin packet header Uses route discoveryUses route discovery

Flooding network with route req Flooding network with route req pack(RREQ) and reply with (RREP)pack(RREQ) and reply with (RREP)

Link broken notified using route error Link broken notified using route error (RERR) packet(RERR) packet

Source removes link from cacheSource removes link from cache New route discovery initiatedNew route discovery initiated

AODVAODV

Uses routing table to propagate a Uses routing table to propagate a RREP back to sourceRREP back to source

Uses sequence number to Uses sequence number to determine freshness of routing info determine freshness of routing info and prevent routing loopand prevent routing loop

Timer-based states in each node Timer-based states in each node regarding routing table entriesregarding routing table entries

Nodes notified (RERR) when next Nodes notified (RERR) when next hop link brokenhop link broken

Critique of DSR and AODV (1)Critique of DSR and AODV (1)

1.1. DSR has access to a greater DSR has access to a greater amount of routing info than AODVamount of routing info than AODV DSR uses single req-reply cycleDSR uses single req-reply cycle Promiscuous listening give access toPromiscuous listening give access to

great amount of infogreat amount of info In absence of above two, AODV In absence of above two, AODV

gather only limited amount of routing gather only limited amount of routing infoinfo

AODV reply on route discovery flood AODV reply on route discovery flood more oftenmore often


2.2. DSR replies to all requests reaching DSR replies to all requests reaching dest from a single req cycle. dest from a single req cycle. Could save route discovery floodCould save route discovery flood

AODV – dest replies only once to AODV – dest replies only once to req arriving first and ignore the restreq arriving first and ignore the rest The routing table maintain at most The routing table maintain at most

one entry per destone entry per dest


3.3. Current spec of DSR not expire Current spec of DSR not expire stale routes in the cache faced stale routes in the cache faced multi choicesmulti choices Stale entries are deleted by route Stale entries are deleted by route

error packetserror packets

AODV more conservative AODV more conservative When faced with two choices, the When faced with two choices, the

fresher route is always chosen (dest fresher route is always chosen (dest sequence #)sequence #)

If routing table entry not used If routing table entry not used recently, this entry expiredrecently, this entry expired


4.4. Route deletion using RERR is Route deletion using RERR is conser in AODVconser in AODV

In DSR, route error backtracks the In DSR, route error backtracks the data pack meets a failed linkdata pack meets a failed link


50 nodes experiments with 10, 40 50 nodes experiments with 10, 40 traffic sourcestraffic sources Packet rate – 4 pack/sec for 10 Packet rate – 4 pack/sec for 10

sourcessources Packet rate – 3 pack/sec for 40 Packet rate – 3 pack/sec for 40

sourcessources DSR and AODV – similar pack frac DSR and AODV – similar pack frac

for 10 or 20 sourcefor 10 or 20 source

AODV outperform DSR with 30 and AODV outperform DSR with 30 and 40 sources40 sources



Performance EvaluationPerformance EvaluationPacket delivery fractions for 50 node model

Performance with increasing offered load with 100 nodes Performance with increasing offered load with 100 nodes and 10 sourcesand 10 sources

DSR

ConclusionsConclusions

DSR outperforms AODV in less DSR outperforms AODV in less “stressful” situations“stressful” situations Smaller # of nodes, lower Smaller # of nodes, lower

load/mobilityload/mobility AODV outperforms DSR in more AODV outperforms DSR in more

stressful situationsstressful situations DSR generates less routing load DSR generates less routing load

than AODVthan AODV

Performance comparison of Multi-hop Performance comparison of Multi-hop Wireless ad hoc network Routing protocolWireless ad hoc network Routing protocol

Provide a realistic quantitative Provide a realistic quantitative analysis comparing the analysis comparing the performance of a variety of multi-performance of a variety of multi-hop wireless ad hoc network hop wireless ad hoc network routing protocolrouting protocol

Present results showing the relative Present results showing the relative performance of four ad hoc routing performance of four ad hoc routing protocols: DSDV [18], TORA [14,15], protocols: DSDV [18], TORA [14,15], DSR [9,10,2], and AODV [17]DSR [9,10,2], and AODV [17]

Ad hoc routing protocols review (1)Ad hoc routing protocols review (1)

Destination-Sequenced Distance Vector (DSDV)Destination-Sequenced Distance Vector (DSDV) A hop-by-hop distance vector routing A hop-by-hop distance vector routing

protocol protocol requires each node to periodically broadcast requires each node to periodically broadcast

routing updatesrouting updates Guarantees loop-freedom over traditional Guarantees loop-freedom over traditional

protocolsprotocols Each node maintains a routing table listing Each node maintains a routing table listing

the “next hop”the “next hop” DSDV tags each route with a sequence DSDV tags each route with a sequence

number number


Temporally-ordered routing algorithm (TORA)Temporally-ordered routing algorithm (TORA) A distributed protocol based on “link-reversal”A distributed protocol based on “link-reversal” Discover routes on-demand, provide multi-route to Discover routes on-demand, provide multi-route to

dest, minimize comm overhead by localizing reaction dest, minimize comm overhead by localizing reaction to topological changesto topological changes

Dynamic Source Routing (DSR)Dynamic Source Routing (DSR) Uses source routing rather than hop-by-hop routingUses source routing rather than hop-by-hop routing Packet header carries ordered list of nodes to passPacket header carries ordered list of nodes to pass Intermediate nodes don’t need to maintain up-to-date Intermediate nodes don’t need to maintain up-to-date

routing info routing info Eliminates need for periodic route advertisement and Eliminates need for periodic route advertisement and

neighbor detection packetsneighbor detection packets


Ad hoc on-demand distance vector (AODV)Ad hoc on-demand distance vector (AODV) A combination of both DSR and DSDVA combination of both DSR and DSDV Borrows on-demand mechanism of Route Discovery Borrows on-demand mechanism of Route Discovery

and Route Maintenance from DSRand Route Maintenance from DSR Plus use of hop-by-hop routing, sequence number, Plus use of hop-by-hop routing, sequence number,

and periodic beacons from DSDVand periodic beacons from DSDV

Performance Comparison Summary (1)Performance Comparison Summary (1)

Node mobilityNode mobility

Performance Comparison Summary (2)Performance Comparison Summary (2)

DSR has least overhead, TORA has mostDSR has least overhead, TORA has most

Performance Comparison Summary (3)Performance Comparison Summary (3)Packet Delivery Ratio

Performance Comparison Summary (4)Performance Comparison Summary (4)Routing OverheadRouting Overhead

ConclusionsConclusions These protocols, DSDV, TORA, DSR, and AODV These protocols, DSDV, TORA, DSR, and AODV

covers range of designcovers range of design including periodic advertisements vs. on demand including periodic advertisements vs. on demand

routing discoveryrouting discovery Hop-by-hop routing vs. source routingHop-by-hop routing vs. source routing

DSDV performs predictablyDSDV performs predictably Node mobility rate, movement speed are lowNode mobility rate, movement speed are low

TORA performs worst of routing overheadTORA performs worst of routing overhead DSR performs very good at all mobility rates DSR performs very good at all mobility rates

and movement speedsand movement speeds Use of source routing increase # of routing bytes reqUse of source routing increase # of routing bytes req

AODV performs almost as well as DSR atAODV performs almost as well as DSR at Mobility rates, and movement speedsMobility rates, and movement speeds Accomplishes goal of eliminating source routing Accomplishes goal of eliminating source routing

overheadoverhead

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CSE 581 Internet Technology Ad-hoc Routing Schemes Presented by Jason Liu