2006 AODV Group Presentation

7/21/2019 2006 AODV Group Presentation

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Ad hoc On-demand Ad hoc On-demand

Distance Vector (AODV)Distance Vector (AODV)Routing ProtocolRouting Protocol

ECE 695ECE 695

Spring 2006Spring 2006



AODV Overview AODV Overview

AODV is a packet routing protocol designed forAODV is a packet routing protocol designed foruse in mobile ad oc net!orks "#A$E%&use in mobile ad oc net!orks "#A$E%& 'ntended for net!orks tat ma( contain'ntended for net!orks tat ma( contain

tousands of nodestousands of nodes One of a class ofOne of a class of demand-drivendemand-driven protocolsprotocols

) %e%e route discovery route discovery mecanism is in*oked onl( if amecanism is in*oked onl( if aroute to a destination is not kno!nroute to a destination is not kno!n

UDP UDP is te transport la(er protocolis te transport la(er protocol Source, destinationSource, destination andand next hopnext hop are addressedare addressed

usingusing IP addressingIP addressing Eac node maintains aEac node maintains a routing tablerouting table tat containstat contains

information about reacing destination nodes+information about reacing destination nodes+) Eac entr( is ke(ed to a destination node+Eac entr( is ke(ed to a destination node+



Routing Table FieldsRouting Table Fields

Destination ', addressDestination ', address Destination Se-uence $umberDestination Se-uence $umber Valid Destination Se-uence $umber .lagValid Destination Se-uence $umber .lag Oter state and routing flagsOter state and routing flags $et!ork 'nterface$et!ork 'nterface /op Count "needed to reac destination&/op Count "needed to reac destination&

$et /op$et /op ,recursor 1ist,recursor 1ist 1ifetime "route epiration or deletion time&1ifetime "route epiration or deletion time&



Overview (continued)Overview (continued)

outing table si3e is minimi3ed b( onl( includingouting table si3e is minimi3ed b( onl( includingnet op information4 not te entire route to anet op information4 not te entire route to adestination node+destination node+

Se-uence numbers for bot destination andSe-uence numbers for bot destination and

source are used+source are used+ #anaging te se-uence number is te ke( to#anaging te se-uence number is te ke( to

efficient routing and route maintenanceefficient routing and route maintenance) Se-uence numbers are used to indicate te relati*eSe-uence numbers are used to indicate te relati*e

freshnessfreshness of routing informationof routing information

) pdated b( an originating node4 e+g+4 at initiation ofpdated b( an originating node4 e+g+4 at initiation ofroute disco*er( or a route repl(+route disco*er( or a route repl(+

) Obser*ed b( oter nodes to determine fresness+Obser*ed b( oter nodes to determine fresness+



Overview (continued)Overview (continued)

%e basic message set consists of%e basic message set consists of

) E7 8 oute re-uestE7 8 oute re-uest) E, 8 oute repl(E, 8 oute repl(

) E 8 oute errorE 8 oute error

) /E11O 8 .or link status monitoring/E11O 8 .or link status monitoring



AODV Operation !essage T"pes AODV Operation !essage T"pes

E7 #essagesE7 #essages) ile communication routes bet!een nodes areile communication routes bet!een nodes are

*alid4 AODV does not pla( an( role+*alid4 AODV does not pla( an( role+) A E7 message is broadcasted !en a nodeA E7 message is broadcasted !en a node

needs to disco*er a route to a destination+needs to disco*er a route to a destination+) As a E7 propagates troug te net!ork4As a E7 propagates troug te net!ork4

intermediate nodes use it to update teir routingintermediate nodes use it to update teir routingtables "in te direction of te source node&+tables "in te direction of te source node&+

) %e E7 also contains te most recent%e E7 also contains te most recent

se-uence number for te destination+se-uence number for te destination+) A *alid destination route must a*e a se-uenceA *alid destination route must a*e a se-uence

number at least as great as tat contained innumber at least as great as tat contained inte E7+te E7+



RR#$ !essageRR#$ !essage

BB

??

BB

??BB

??

BB

??

BB??

BB

??BB

??

BB

A A




E, #essagesE, #essages) en a E7 reaces a destination node4 teen a E7 reaces a destination node4 te

destination route is made a*ailable b(destination route is made a*ailable b(unicasting a E, back to te source route+unicasting a E, back to te source route+

) A node generates a E, ifA node generates a E, if 't is itself te destination+'t is itself te destination+ 't as an acti*e route to te destination+ E an't as an acti*e route to te destination+ E an

intermediate node ma( also respond !it an E, if itintermediate node ma( also respond !it an E, if itas a :fres enoug; route to te destination+as a :fres enoug; route to te destination+

) As te E, propagates back to te sourceAs te E, propagates back to te sourcenode4 intermediate nodes update teir routingnode4 intermediate nodes update teir routingtables "in te direction of te destination node&+tables "in te direction of te destination node&+



RR#P !essageRR#P !essage

BB

A A

A A

A A

A A

A A

A A

A A




E #essagesE #essages

) %is message is broadcast for broken%is message is broadcast for broken

linkslinks

) <enerated directl( b( a node or passed<enerated directl( b( a node or passed

on !en recei*ed from anoter nodeon !en recei*ed from anoter node




/ello #essages/ello #essages

) /ello #essage = E, !it %%1 = >/ello #essage = E, !it %%1 = >

) %is message is used for broadcasting%is message is used for broadcasting

connecti*it( information+connecti*it( information+ E 'f a neigbor node does not recei*e an( packetsE 'f a neigbor node does not recei*e an( packets

"/ello messages or oter!ise& for more tan"/ello messages or oter!ise& for more tan

A11OED?/E11O?1OSS @ /E11O?'$%EVA1A11OED?/E11O?1OSS @ /E11O?'$%EVA1

mseconds4 te node !ill assume tat te link to tismseconds4 te node !ill assume tat te link to tis

neigbor is currentl( lost+neigbor is currentl( lost+) A node sould use /ello messages onl( if it isA node sould use /ello messages onl( if it is

part of an acti*e route+part of an acti*e route+



!essage routing!essage routing

A

% D

F&

'

#

RREQ

RREQ

RREQ

RREQ

RREQ

RREQ

RREQ

RREQ

RREQ

RREP

RREP

RREP

Source

Destination



&ongestion andling&ongestion andling

One metod tat AODV andle congestionOne metod tat AODV andle congestion

isis

) 'f te source node recei*es no E, from te'f te source node recei*es no E, from te

destination4 it ma( broadcast anoter E74destination4 it ma( broadcast anoter E74up to a maimum of E7?E%'ES+up to a maimum of E7?E%'ES+

) .or eac additional attempt tat a source node tried to.or eac additional attempt tat a source node tried to

broadcast E74 te !aiting time for te E, isbroadcast E74 te !aiting time for te E, is

multiplied b( 2+multiplied b( 2+

DS is not capable of andling congestion+DS is not capable of andling congestion+



&ongestion andling&ongestion andling

Oter possible metods to impro*e AODVOter possible metods to impro*e AODV

congestion andlingcongestion andling

) A route ma( predict !en congestion is aboutA route ma( predict !en congestion is about

to occur and tr( to a*oid it b( reduce teto occur and tr( to a*oid it b( reduce tetransmission rate+transmission rate+

) Scedule te re-uests so tat it !ill notScedule te re-uests so tat it !ill not

o*erload te net!ork+o*erload te net!ork+



AODV Routing AODV Routing

%ere are t!o pases%ere are t!o pases

) oute Disco*er(+oute Disco*er(+

) oute #aintenance+oute #aintenance+

Eac node maintains a routing table !it kno!ledge aboutEac node maintains a routing table !it kno!ledge about

te net!ork+te net!ork+ AODV deals !it route table management+AODV deals !it route table management+

oute information maintained e*en for sort li*ed routes 8oute information maintained e*en for sort li*ed routes 8

re*erse pointers+re*erse pointers+



#ntries in Routing Table#ntries in Routing Table

Destination ', AddressDestination ', Address Destination Se-uence $umberDestination Se-uence $umber Valid Destination Se-uence $umber flagValid Destination Se-uence $umber flag Oter state and routing flags "e+g+4 *alid4 in*alid4Oter state and routing flags "e+g+4 *alid4 in*alid4

repairable4 being repaired&repairable4 being repaired& $et!ork 'nterface$et!ork 'nterface /op Count "number of ops needed to reac destination&/op Count "number of ops needed to reac destination& $et /op$et /op 1ist of ,recursors1ist of ,recursors

1ifetime "epiration or deletion time of te route&1ifetime "epiration or deletion time of te route&

DS maintains additional table entries4 causing a largerDS maintains additional table entries4 causing a largermemor( o*ereadmemor( o*eread





Algorithm or Discover" Algorithm or Discover"

OriginatorOriginator 'f a route to te destination is a*ailable4 start sending data+'f a route to te destination is a*ailable4 start sending data+ Else generate a E7 packet+ 'ncrement te E7'D b(Else generate a E7 packet+ 'ncrement te E7'D b(

>+'ncrement te se-uence number b( >+Destination ',>+'ncrement te se-uence number b( >+Destination ',address 4currentl( a*ailable se-uence number included+address 4currentl( a*ailable se-uence number included+

'ntermediate $ode'ntermediate $ode <enerate route repl(4 if a fres enoug route is a *alid<enerate route repl(4 if a fres enoug route is a *alid

route entr( for te destination !ose associated se-uenceroute entr( for te destination !ose associated se-uencenumber is at least as great as tat contained in te E7+number is at least as great as tat contained in te E7+Cange te se-uence number of te destination node ifCange te se-uence number of te destination node if

stale4 increment te op count b( > and for!ard+stale4 increment te op count b( > and for!ard+

Destination >+'ncrement se-uence number of teDestination >+'ncrement se-uence number of tedestination+ 2+<enerate a E7 message and sent back todestination+ 2+<enerate a E7 message and sent back toOriginator+Originator+



Discover"Discover"



!aintenance!aintenance

/ello messages broadcast b(/ello messages broadcast b( activeactive nodes periodicall(nodes periodicall(

/E11O?'$%EVA1+/E11O?'$%EVA1+

$o ello message from a neigbor in DE1E%E?,E'OD4link$o ello message from a neigbor in DE1E%E?,E'OD4link

failure identified+failure identified+

A local route repair to tat net op initiated+A local route repair to tat net op initiated+ After a timeout 4error propagated bot to originator andAfter a timeout 4error propagated bot to originator and

destination+destination+

Entries based on te node in*alidated+Entries based on te node in*alidated+



*normation +Freshness,*normation +Freshness,

Assured Assured Eac originating node maintains a monotonicall(Eac originating node maintains a monotonicall(

increasing se-uence number+increasing se-uence number+

sed b( oter nodes to determine te fresness ofsed b( oter nodes to determine te fresness of

te information+te information+

E*er( nodes routing table contains te latestE*er( nodes routing table contains te latest

information a*ailable about te se-uence numberinformation a*ailable about te se-uence number

for te ', address of te destination node for !icfor te ', address of te destination node for !ic

te routing information is maintained+te routing information is maintained+

) pdated !ene*er a node recei*es ne! informationpdated !ene*er a node recei*es ne! informationabout te se-uence number from E74 E,4 orabout te se-uence number from E74 E,4 or

E messages recei*ed related to tat destination+E messages recei*ed related to tat destination+



*normation +Freshness,*normation +Freshness,

Assured Assured AODV depends on eac node in te net!ork to o!nAODV depends on eac node in te net!ork to o!nand maintain its destination se-uence number+and maintain its destination se-uence number+

A destination node increments its o!n se-uenceA destination node increments its o!n se-uencenumber immediatel( before it originates a routenumber immediatel( before it originates a routedisco*er(disco*er(

A destination node increments its o!n se-uenceA destination node increments its o!n se-uencenumber immediatel( before it originates a E, innumber immediatel( before it originates a E, inresponse to a E7response to a E7

%e node treats its se-uence number as an unsigned%e node treats its se-uence number as an unsignednumber !en incrementing accomplising se-uencenumber !en incrementing accomplising se-uence

number rollo*er+number rollo*er+ Destination information is assured b( comparing teDestination information is assured b( comparing te

se-uence number of te incoming AODV messagese-uence number of te incoming AODV message!it its se-uence number for tat destination+!it its se-uence number for tat destination+



R#RR !essagesR#RR !essages

) #essage is broadcasted !en#essage is broadcasted !en

i+i+ A node detects tat a link !it adacentA node detects tat a link !it adacent

neigbor is broken "destination no longerneigbor is broken "destination no longerreacable&+reacable&+

ii+ii+ 'f it gets a data packet destined to a node'f it gets a data packet destined to a node

for !ic it does not a*e an acti*e routefor !ic it does not a*e an acti*e route

and is not repairing+and is not repairing+iii+iii+ 'f it recei*es a E from a neigbor for'f it recei*es a E from a neigbor for

one or more acti*e routes+one or more acti*e routes+



R#RR Processing (or aboveR#RR Processing (or above

broadcasts)broadcasts)

) uild Affected Destination 1istinguild Affected Destination 1istingi+i+ 1ist unreacable destinations containing1ist unreacable destinations containing

unreacable neigbor F destination usingunreacable neigbor F destination using

unreacable as net opunreacable as net opii+ii+ Onl( one unreacable destination4 !ic nodeOnl( one unreacable destination4 !ic node

alread( as+alread( as+

iii+iii+ 1ist of nodes !ere E is net op1ist of nodes !ere E is net op

) pdate informationpdate information

) %ransmit E for eac item listed%ransmit E for eac item listed



R#RR inormation updateR#RR inormation update

) Destination Se-uence GDestination Se-uence GB pdate se-uence G for case i and iipdate se-uence G for case i and iiB Cop( se-uence G for case iiiCop( se-uence G for case iii

) 'n*alidate route entr('n*alidate route entr(

) pdate 1ifetime field as "currtime Hpdate 1ifetime field as "currtime H

DE1E%E?,E'OD&DE1E%E?,E'OD&

) Onl( no! ma( route entr( be deletedOnl( no! ma( route entr( be deleted



R#RR message transmissionR#RR message transmission

) nicastnicastB Send E to single recipientSend E to single recipient

) nicast iteriti*enicast iteriti*eB Send E to a number of recipientsSend E to a number of recipients

indi*iduall(indi*iduall(

) roadcastroadcastB $otif( multiple recipients simultaniousl($otif( multiple recipients simultaniousl(B roadcast *ia 255+255+255+255 %%1 = >roadcast *ia 255+255+255+255 %%1 = >



R#RR message transmissionR#RR message transmission

) nicastnicast AA node detectsnode detects tat a link !it adacenttat a link !it adacent

neigbor is broken "destination no longerneigbor is broken "destination no longerreacable&+reacable&+

'f it gets a data packet destined to a node'f it gets a data packet destined to a nodefor !ic it does not a*e an acti*e routefor !ic it does not a*e an acti*e routeand is not repairing+and is not repairing+

'f it recei*es a E from a neigbor for one'f it recei*es a E from a neigbor for one

or more acti*e routes+or more acti*e routes+) nicast iteriti*enicast iteriti*e

) roadcastroadcast



ow %roen .ins are andledow %roen .ins are andled

All nodes directl( using te brokenAll nodes directl( using te broken

link get a E packet+link get a E packet+

%en tose nodes sends te E%en tose nodes sends te E

packet to teir predecessor nodes+packet to teir predecessor nodes+

%is is continued all te !a( to te%is is continued all te !a( to te

source nodes+source nodes+




(&ont)(&ont) pon completion of sending tepon completion of sending te

E packet troug te sourceE packet troug te source

node !ill no longer use te link+node !ill no longer use te link+

) AODV uses loop freeBroutes+AODV uses loop freeBroutes+

) %ere are onl( a finite number of nodes%ere are onl( a finite number of nodes

in a adBoc net!ork+in a adBoc net!ork+




(&ont)(&ont) DS does not remo*e te pat asDS does not remo*e te pat as

!ell+!ell+

) 'n DS nodes in te net!ork can still'n DS nodes in te net!ork can still

tink te broken link is still *alid+tink te broken link is still *alid+

) %is can lead to a*ing to searc for%is can lead to a*ing to searc for

ne! pats multiple times+ne! pats multiple times+



Reestablishing a .inReestablishing a .in

%e source node can restart te%e source node can restart te

disco*er( process if a pat is stilldisco*er( process if a pat is still

needed+needed+

%e source node or an( node on te%e source node or an( node on te

pat can rebuild te route b(pat can rebuild te route b(

sending out a E7+sending out a E7+

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2006 AODV Group Presentation

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