InternationalJournal of ComputerScienceTrendsand
Technology(IJCST) Volume3 Issue 4,Jul-Aug 2015 ISSN:
2347-8578www.ijcstjournal.org Page 159 ComparativeAnalysis of Link
State Routing ProtocolsOPSF and IS-IS Amanpreet Kaur [1], Er.Dinesh
Kumar [2] Department of Computer Science and Engineering GZS PTU
Campus, Bathinda Punjab - India ABSTRACT
IPRoutingisusedtofindthebestpathforanIPpacketfromsource to
destination. Major routing protocols used for interior gateway
routing are link state routing protocols, as they are more scalable
than their counterparts Distance Vector RoutingProtocols. Link
State routing protocols has two protocols listed in its category
and both of them uses the same
Dijkstra'sShortestPathFirstAlgorithm,andbothcametoexistenceataboutsametime.Butwhichprotocolisbest
between the two always creates confusion in the network engineers
minds all around the world. This paper explains the
twolinkstaterouting protocols used for internal routing purposes in
enterprise or service provider networks. Link state routing
protocols use the same algorithm but have so many differences. This
paper compares both the link state routing protocols on the basis
of performance, security and scalability.Keywords:-IP, OSPF,
IPv6,LSA,PDU,LSU,LSR,IS-IS I.INTRODUCTION
Whenadatagramissentbetweensource and destination
devicesthatareonthedifferentnetworks,theprocessis known as routing.
For IP routing, two types of methods can
beused,eitherwecanuseStaticRoutingorwecanuse
DynamicRouting.Instaticrouting,weaddtheroutes
towardsdestinationmanuallyandindynamicrouting,we
usedynamicroutingprotocolsthatfindthebestpath
towardsdestinationdynamically.Dynamicrouting
protocolsarefurtherdividedintotwocategoriesi.e.
InteriorGatewayProtocols(IGP)andExteriorGatewayProtocols(EGP).EGPsareusedwhenweneedtoconnect
withsome other routing domain, currently Border Gateway
Protocolisthe only EGP in the world. IGPs are used when
weneedtoperformroutingondifferentrouterswithina
singleroutingdomain.IGPsarefurtherdividedintotwo
types:DistanceVectorRoutingProtocols-Basedon
distanceanddirection.RoutingInformation
Protocol(RIP),EnhancedInteriorGatewayRouting
Protocol(EIGRP)andLinkState Routing Protocols. As our
mainemphasisisonLinkStateRoutingProtocols, therefore they are
described in the next section. A.Link State protocols
LinkStateprotocols,alsoknownasshortestpathfirstor
distributeddatabaseprotocols,arebuiltaroundawell-knownalgorithmofgraphtheory,E.W.Dijkstra's
shortest path first algorithm.LinkState protocols behave like a
road map.Eachroutersharesitslinkinformation in the form of
LinkStateAdvertisement(LSA),orLinkStatePDU(LSP).
Alinkstaterouteruseslinkstateinformationtocreatea topology map and
to select the best path to the destination in the topology. LSAs
propagates to every neighbor router
usingprotocolspecificmulticastaddress, each router that
receivestheLSA,updatesitsLink-State-Database(LSDB)
andforwardstheLSAtoitsneighborrouterswithinan area.SPFtree is then
applied to the LSDB to find the best path to reach the destination
and the best path is then added to the routing table.
DijkstraAlgorithmis given: Dijkstra() {//Initialization Path={s}//s
means self for ( i = 1 to N ) { If (I is a neighbor of s andI s )
Di = Csi If (I is a not aneighbor of s )Di = } Ds= 0
RESEARCHARTICLEOPENACCESS InternationalJournal of
ComputerScienceTrendsand Technology(IJCST) Volume3 Issue 4,Jul-Aug
2015 ISSN: 2347-8578www.ijcstjournal.org Page 160 }// Dijkstra
//Iteration Repeat { // Findingthe next nodetobe added
Path=PathiifDiisminimumamongallremaning nodes // Updatethe shortest
distanceforthe rest For(j=1to M)//M numberof remainingnodes { Dj =
minimum(Dj,Dj+ cij) } until (allnodes include in the path , M = 0)
LinkState Routing Protocol includes - B.Open Shortest Path
First(OSPF) OSPFisaroutingprotocol,whichisdeployedinboth
enterpriseandserviceprovidernetworks.Networkis
dividedintoareas.Area0isknown as backbone area, for everyother
area0 connect with any other area except area
0,theyhavetoreachviaarea0astransitarea.OSPF
behaveslikeadistancevectorroutingprotocolwhen sharing routes from
one area to other area. OSPF uses Link
StateAdvertisements(LSAs)toshareinformation
regardingroutesinthenetwork.Figures howingbasic
OSPFimplementationis shown below: Figure 1:Basic OSPFImplementation
C.I ntermediate-System-to-I ntermediate-System(I S-I S)
ItisalinkstateprotocolsimilartoOSPF,usedin core of
SPnetworks.Itwasoriginallynot an IP protocol, and is a
partofCLNSstack,IntegratedIS-ISisanIPextension of
IS-IS.Itishighlyscalableandhaveasimpleflatnetwork design. It
supports both IPv4 and IPv6. IS-IS use Dijkstra's
SPFalgorithmtofindthebestpath.IS-ISalsousesa
differentaddressingformatthanofOSPF.ItusesISO
NSAPAddressingformat,whosemaximumsizeis20 bytesand minimum size of
8 bytes. It uses two "levels" of adjacency - Level2(L2)and Level
1(L1). Figure2:Basic Integrated IS-IS implementation.
II.LITERATURESURVEY OSPFVersion2[1]byJ.MoyinInternetEngineering
TaskForce(IETF)RFC-2328documentsversion2ofthe
OSPFprotocol.Thisdocumentrepresentsinternational standard document
used for OSPF. It is designed to be run internal to a single
Autonomous System. Each OSPF router maintains an identical database
describing the Autonomous
System'stopology.Fromthisdatabase,aroutingtableis
calculatedbyconstructingashortestpath tree. IETF RFC
2328isthestandardinuseforIPv4OSPFdesignand implementation.
TheOSPFNot-So-StubbyArea(NSSA)Option[2]byP.
MurphyofUSGeologicalSurveyinIETFRFC3101
documentsanoptionaltypeofOpenShortestPath First(OSPF) area that is
referredto as "not-so-stubby" area
(orNSSA).NSSAsaresimilartotheexistingOPSFstub area configuration
option but have the additional capability
ofimportingASexternalroutesin a limited fashion. OSPF
NSSAoptionwasoriginallydefinedinIETFRFC1587.
RFC3101isthecurrentdocumentusedinNSSA implementation.
GracefulOSPFRestart[3]byJ.MoyofSycamore
Networks,P.Pillay-EsnaultofJuniperNetworksandA.
LindemofRedbackNetworksinIETFRFC3623 InternationalJournal of
ComputerScienceTrendsand Technology(IJCST) Volume3 Issue 4,Jul-Aug
2015 ISSN: 2347-8578www.ijcstjournal.org Page 161
documentsanenhancementto the OSPF routing protocol,
wherebyanOSPFroutercanstayonthe forwarding path
evenasitsOPSFsoftwareisrestarted.Thisis
called"gracefulrestart"or"non-stopforwarding".A
restartingroutermaynotbecapableofadjustingits
forwardinginatimelymanner when the network topology
changes.Inordertoavoidthepossibleresultingrouting
loops,theprocedurein this memo automatically reverts to
anormalOSPFrestartwhensuchatopologychangeis
detected,orwhenoneormoreoftherestartingrouter's neighborsdo not
support the enhancements in this
memo.Propernetworkoperationduringagracefulrestartmakes
assumptionsupontheoperatingenvironmentofthe restarting router;
these assumptions are also documented.
RoutingExtensionsforDiscoveryofMultiprotocol
(MPLS)LabelSwitchRouter(LSR)TrafficEngineering
(TE)MeshMembership[4]byS.YasukawaofNTT,S.
Previdi,P.PsenakofCiscoSystemsandP.Mabbeyof
ComcastinIETFRFC4972specifiesthesetupofafull
meshofMulti-ProtocolLabelSwitching(MPLS)Traffic
Engineering(TE)LabelSwitchedPaths(LSP)amongaset
ofLabelSwitchRouters(LSR),whichisacommon
deploymentscenarioofMPLSTrafficEngineeringeither
forbandwidthoptimization,bandwidthguaranteesorfast
reroutingwithMPLSFastReroute.Suchdeployment may
requiretheconfigurationofapotentiallylargenumberof TELSPs.
OSPFforIPv6[5]byR.ColtunofAcoustraProductions,
D.FergusonofJuniperNetworks,J.MoyofSycamore
NetworksandA.Lindem,EdofRedbackNetworksin
IETFRFC5340describesthemodificationstoOSPFto supportversion6 of the
Internet Protocol (IPv6). Changes
between(OSPFforIPv4,OPSFv2)and(OSPFforIPv6,
OSPFv3)aredescribedinthisdocument.Addressing
semanticshavebeenremovedfrom OSPF packets and the
basicLinkStateAdvertisements(LSAs).NewLSAshave
beencreatedtocarryIPv6addressesandprefixes.OSPF now runs on a
per-link basis rather than on a per-IP-subnet
basis.FloodingscopeforLSAshasbeengeneralized.
Authenticationhasbeenremoved from the OSPF protocol
andinsteadreliesonIPv6'sAuthenticationHeaderand Encapsulating
Security Payload.OSPFv3GracefulRestart[6]byP.Pillay-EsnaultofCisco
SystemsandA.LindemofRedbackNetworksinIETF
RFC5187describestheOSPFv3gracefulrestart.The
OSPFv3gracefulrestartisidenticaltothatofOSPFv2
exceptforthedifferencesdescribedinthisdocument.ThesedifferencesincludetheformatofthegraceLink
State Advertisements (LSAs) and other considerations.
TrafficEngineeringExtensionstoOSPFVersion3[7]by
K.Ishiguro,V.ManralofIPInfusion,A.DaveyofData
ConnectionLimitedandA.Lindem,Ed.ofRedback
NetworksinIETFRFC5329describesextensionsto
OSPFv3tosupportintra-areaTrafficEngineering(TE).ThisdocumentextendsOSPFv2TEtohandleIPv6
networks.AnewTLVandseveralnewsub-TLVsare defined to support IPv6
networks. OSPFExtensionsinSupportof Inter-Autonomous System
(AS)MPLSandGMPLSTrafficEngineering[8]byM.
Chen,R.ZhangofHuaweiTechnologies,X.Duanof
ChinaMobileinIETFRFC5392describesextensionsto
theOSPFversion2and3protocolstosupport
MultiprotocolLabelSwitching(MPLS)andGeneralized
MPLS(GMPLS)TrafficEngineering(TE)formultiple
AutonomousSystems(ASes).OSPF-TEv2andv3
extensionsaredefinedforthefloodingofTEinformation
aboutinter-ASlinksthatcanbeused to perform inter-AS TEpath
computation. OSIIS-ISIntra-domainRoutingProtocol [9] by D. Oran of
DigitalEquipmentCorporationinIETFRFC1142isa republicationofISO DP
10589 as a service to theInternet community.
UseofOSIIS-ISforRoutinginTCP/IPandDual
Environments[10]byR.CallonofDigitalEquipment
CorporationinIETFRFC1195specifiesanintegrated
routingprotocol,basedontheOSIIntra-DomainIS-IS
RoutingProtocol,whichmaybeusedasaninterior
gatewayprotocol(IGP)tosupportTCP/IPaswell as OSI. This allows a
single routing protocol to be used to support
pureIPenvironments,pureOSIenvironments,anddual environments. This
specification was developed by the IS-IS workinggroup of the
Internet Engineering Task Force.
RestartSignalingforIS-IS[12]byM.Shandand
L.GinsbergofCiscoSystemsinIETFRFC5306describes
amechanismforarestartingroutertosignaltoits neighborsthatit is
restarting, allowing them to reestablish
theiradjacencieswithoutcyclingthroughthedown state,
whilestillcorrectlyinitiatingdatabasesynchronization.
Thisdocumentadditionallydescribesamechanismfora
restartingroutertodeterminewhenithasachievedLink
StateProtocolDataUnit(LSP)databasesynchronization
withitsneighborsandamechanismtooptimizeLSP
databasesynchronization,whileminimizingtransient routing disruption
when a router starts. InternationalJournal of
ComputerScienceTrendsand Technology(IJCST) Volume3 Issue 4,Jul-Aug
2015 ISSN: 2347-8578www.ijcstjournal.org Page 162
IS-ISExtensionsforTrafficEngineering[13]byT.Liof
RedbackNetworksinIETF RFC 5305 describes extensions
totheIntermediateSystemtoIntermediateSystem(IS-IS)
protocoltosupportTrafficEngineering(TE).This
documentextendstheIS-ISprotocolbyspecifyingnew
informationthatanIntermediateSystem (router) can place
inLinkStateProtocolDataUnits(LSP). This information
describesadditionaldetailsregardingthestateofthe
networkthatareusefulfortrafficengineering computations. Routing
IPv6 with IS-IS[14] by C. Hopps of Cisco Systems
inIETFRFC5308specifiesamethodfor exchanging IPv6
routinginformationusingtheIS-ISroutingprotocol.The
describedmethodutilizestwonewTLVs:areachability
TLVandaninterfaceaddressTLVtodistributethe
necessaryIPv6informationthroughoutaroutingdomain.Using this method,
one can route IPv6 along with IPv4 and OSIusing a single
intra-domainrouting protocol.
IPv6TrafficEngineeringinIS-IS[15]byJ.Harrison,J.
BergerandM.BarlettofMetaswitchNetworksinIETF
RFC6119specifiesamethodforexchangingIPv6traffic
engineeringinformationusingtheIS-ISroutingprotocol.
ThisinformationenablesroutersinanIS-ISnetworkto calculate
traffic-engineeredroutes using IPv6 addresses.
OSPFandIS-IS:AComparativeAnatomy[16]byDave
Katz,ofJuniperNetworksdoesacomparativeanalysis of OSPFand
IS-ISprotocol. III. PROBLEM DEFINITION Asstatedinthe Introduction
part of thisdocument, when
IETFwastochoosebetweenOSPFandIS-ISrouting
protocoltomakethemasthestandardInteriorGateway
RoutingProtocoloftheinternet,theyleftthatto Internet Service
Providers and Enterprise Networks by making both protocols as
standards and let the ISP and Enterprise select which routing
protocol they want to
use.Therearenoperfectdocumentationonwhichisthe better routing
protocol of the two. ISO engineers say that ISIS is best, while
according to IETFengineers, OSPFis the best.Both protocols use the
same algorithm, yet they are so different. IV.OBJECTIVE To find the
best link-state routing protocol on the basis of
performance,security, scalability,and usage of CPUresources. To
find the best link-state routing protocol for service provider
networks for their core network. V.RESULTS
A.PerformanceAnalysisofOSPFandI SI S protocol using default
parameters OSPFandIS-ISbothdefinetheirnetworkwithinareas.
OSPFhasabackboneareai.e.Area0.0.0.0orArea0.In OSPF,thereis a
prerequisite for every non-backbone area,
thatinorderforanon-backbonearea to connect or share routes with any
other non-backbone area, there has to be a backbone area as a
transit point in between them. Without
Area0inbetweentwonon-backboneareas by default do not share their
routes. OSPF topology can be either
single-areaormultiple-area.AsingleareaOSPFdesignisshow below.
Figure 3-OSPFand ISIS design IntheaboveOSPFsingle area network
design, six routers areusedandallareinthesameareai.e.Area0,andthe
cloud C1 is our Laptop's loopback address used to connect
PRTGTrafficAnalyzerandMonitoringToolwithour
topology.HerewewillmonitorR6'sloopbackaddress
6.6.6.6withPRTG,whichwillsendasimplepingto
6.6.6.6everysecondtomonitoritsperformanceand availability.We have
two paths towards destination and the
bestpathisviaR1-R2-R3-R6-6.6.6.6,Followinggraphin Figure 1.2 will
show the amount of timethat the link takes
toconvergeifthebestlinkto6.6.6.6isfailed.Graph shown below is taken
without tuning any OSPF timers and
LSApacingmechanism,alsonootherfaster convergence
mechanismlikeBi-directionalForwardingDetection
(BFD)orSPFThrottlingis used : InternationalJournal of
ComputerScienceTrendsand Technology(IJCST) Volume3 Issue 4,Jul-Aug
2015 ISSN: 2347-8578www.ijcstjournal.org Page 163 Figure4-PRTG
Graph shows the amount of time it takes to converge the link
fromprimaryto secondary link Intheabovegraphcreatedfrom PRTG
Traffic Monitoring Tool,amountoftime(minimumormaximum)inmsecis
shownforapacket to reach destination is also shown. Its
clearfromtheabovePRTGgeneratedgraphthatOSPF
takesaround5secondstoconvergefromprimaryto
backuplink,iftheprimarylinkgoesdown.Intheabove topology we have not
used any faster convergence protocol
likeBidirectionalForwardingDetectionorFastRouting
ConvergencemethodlikeThrottlingShortestPath First(SPF)timers.
IS-ISontheotherhandisalsousedinserviceprovider
networksfortheirinternalnetworks.Thereisalwaysa debate regarding
the best interior gateway routing protocol in service provider
networks. OSPF and ISIS have so many similarities as both are
link-state routing protocols and uses
thesameShortestPathFirst(SPF)algorithm,yettheyare
sodifferentasoneofthemis used is IP based, and other one is created
for ISO CLNS environments and then it was adoptedbyIETFandnamed it
Integrated IS-IS. Topology that we used is show below : Figure 5 -
Integrated IS-ISSingle Area Topology
IS-ISisconceptuallysimilartoOSPFinsomanyways,
originallydevelopedbyISO,ISISreferredarouterasan
IS(IntermediateSystem)andahostorendsystemasan ES(EndSystem).
IntheaboveIS-ISnetworkdesign,alltherouterscome
underthesameIS-ISarea,withR1-R2-R3-R4-4.4.4.4as
theprimarylinkandR1-R6-R5-R4-4.4.4.4assecondary
linkwith4.4.4.4isconnectedwithR4.Theconvergence time in IS-IS with
default setting without tuning any timers
orchanginganyotherparametersisshow below with the help of a graph
created in PRTGtrafficmonitoring tool : Figure 6-IS-ISConvergence
timegraph in PRTG Now as shown above, IS-IS gives much lesser
downtime as compared to OSPF.
IS-IS,whenusesameareaforitsentirenetworkhasa
muchlesserconvergencetimebydefault,i.e.3seconds.
IS-ISprotocolsupportsatwolevelhierarchytoscale
routinginlargenetworks.Tablebelowdisplaysdefault convergence
difference between ISISand OSPF.
TABLE1-DefaultconvergencedifferencebetweenISIS and OSPF
ProtocolConvergenceTime OSPF5 seconds Integrated IS-IS3 seconds As
we can see in the above table, 5 seconds and 3 seconds
arethedefaultconvergencetimethatOSPF and IS-IS can
take,incaseiftheprimarylinkgoesdownand
convergenceneedstohappentowardsBackupLink.
Defaultconvergencetimeiswaytoomuchfortoday's networks, but we can
shorten the times by using techniques
likedecreasingthehelloandSPFcalculationtimersof
protocolsorwecanalsouseBidirectionalForwarding
DetectionfeaturewithOSPFandISIS,whichcanprovide
sub-secondconvergencefromprimarytobackuplinkin case of
primarylinkfailure. AsbothOSPFandIS-ISroutingprotocolsusethesame
Dijkstra's Shortest Path First(SPF) algorithm, i have tries to
fastentheSPFcalculationsinordertocheckwhateffect does it make to
the convergence time.What i have done is,
ichangedthe"DelaybetweenreceivingachangetoSPF InternationalJournal
of ComputerScienceTrendsand Technology(IJCST) Volume3 Issue
4,Jul-Aug 2015 ISSN: 2347-8578www.ijcstjournal.org Page 164
calculationto100msec","Delaybetweenfirstand second
SPFcalculationto100msec"and"Maximumwaittimefor
SPFcalculationsto120msec".The result after configuring SPFtimers is
shown below in a graph : Figure 7-Convergence Time after fasten the
process of SPF
calculationAswecanseefromtheabovegraph,aftertuningSPF
timers,convergencetimehasdecreasedtosub-second, which is much
betterthan the default timers. Both ISIS and
OSPFcangivesub-secondconvergenceaftertuningSPF timers.
TABLE2-SPFfast convergence between ISIS and OSPF:
ProtocolConvergence Time(Default Parameters) Convergence
Time(WithSPF timers tuned) OSPF5Sub-Second ISIS3Sub-Second
B.Performance Analysis of Link State Routing Protocols using I Pv6
OSPFandISIS,bothcanruninIPv4andIPv6
environments,OSPFwhenusedwithIPv6isknownas
OSPFv3andisquitedifferentthanOSPFv2.Ihavealso used OSPFv3 for
performance analysis. Topology used for OSPFv3performance analysis
is shown below: Figure 8-OSPFv3topology used for Performance
AnalysisAbove topology is used for OSPFv3 performance analysis,
cloudshowninabovediagramisactingasaPChaving PRTGinstalled and is
testing the reachability towards R4's loopbackaddress2010::1
address. In the topology, R1 has two paths to reach R4, one via R2
and R3 and the other one viaR5andR6,Bydefaultthe best path is
decided on the basis of cost from source to destination, path with
the least costbecomesthebestpathtowardsdestination,iftwo paths have
same cost from source to destination, then both
entersintoroutingtable.Inourcase,trafficisgoing
throughR2andR3whichis the better link with the better
cost,butwhenthelinkbetweenR2andR3goesdown, how fast does the
network converge is shown in the graph below:
Figure9-Graphshowingthemaximum,minimumand convergence time in
OSPFv3implementationusing PRTG
Ontheotherhand,wheniuseISISwithIPv6,itismuch
easiertoimplement,asithasthesameversionforboth
IPv4andIPv6.TopologyusedforISISwithIPv6is same
asintheOSPFv3withjustroutingprotocolischanged
fromOSPFv3toISIS.IPv6addressingisusedisstillthe
same.ResultstakenfromtheISISwithIPv6topologyin case of
primarylinkfailureis shown below:
Figure10-Graphshowingthemaximum,minimumand
convergencetimeinISISwithIPv6implementationusing PRTG
InternationalJournal of ComputerScienceTrendsand Technology(IJCST)
Volume3 Issue 4,Jul-Aug 2015 ISSN: 2347-8578www.ijcstjournal.org
Page 165 Astheabove graph shows, the maximum time to complete
asimplepingpacketis183msec,minimumtimeis49msec
andtheconvergencetimebetweenthe primary link failure
andtrafficshiftfromprimarylink towards backup link is 5
seconds.Therefore with default parameters, ISIS with IPv6
isagainbetterthanOSPFv3.Tablebelowshowsthe
comparisonofconvergencetimes of both OSPFv3 and IS-IS with IPv6.
TABLE3-ConvergencebetweenOSPFv3andISISwith IPv6.
ProtocolConvergenceTime OpenShortestPath First-Version3 (OSPFv3) 7
seconds Intermediate-Systemto Intermediate-System withIpv6(ISISwith
IPv6) 5 seconds C.Security Analysis of Link State Routing
Protocols: SecurityisalwaysoneofthemajorconcernsofNetwork
Industry.Bydefaultroutingprotocolssharerouting
informationwiththeirneighborroutersinaveryinsecure manner.We can
use passwords for neighbor authentication,
sothatroutingprotocolscansharetheirrouting
informationonlyiftheirpasswordsmatch.Ihaveused
neighborauthenticationwithboththelinkstaterouting
protocolandcapturedtheOSPFandISISpacketsin
WiresharkPacketSniffertogathersomemore information
regardingtheauthenticationinordertocompareboth authentication
mechanisms. 1)I S-I S Neighbor
AuthenticationISISsupportsbothclear-textandMD5based
authentication.InISIS,wecanapplyauthenticationon
threelevels:betweenrouters,area-wide(Level1),and
Domain-wide(Level2).Authenticationis always configured separately
for L1 and L2 adjacencies.If no level is defined
duringauthenticationprocess,thenauthenticationis
appliedtobothL1andL2levels.AuthenticationinISIS
authenticatestheHelloProtocolDataUnits(PDUs).ISIS
useskey-chainmechanismforpasswordauthentication
whichisusedmainlytoconfiguremultiplepasswords according to time.
Figure11-WiresharkCaptureofaHelloProtocolData Unit with
authentication applied. AbovecaptureinWiresharkshows the Hello PDU
in ISIS protocol,Italsodisplaystheneighborauthenticationis used
with MD5 hashing algorithm is in use. 2)OSPF Neighbor
Authentication InOSPF,authenticationcanbeconfiguredintwoways;
eitheritcan be for area or for specific neighbor connected with
some interface. If area based authentication is applied,
thenitmustbeconfiguredfortheentirearea,while interface passwords
need not to be matched on entire area.
OSPFsupportsthreeauthenticationtypes:Null Authentication,ClearText
Passwords, MD5 cryptographic checksums.Authentication keys are
locally significant to an interfacein case of interface based
passwords, and can be different on a per interface basis.
Figure12-WiresharkcaptureofOSPFHellopacket showing Authentication
Applied. 3)Link State Routing Protocols with I PSec Applied
IPSECisaprotocolsuiteoracollectionofprotocols and
algorithmstoprotectIPpacketsatLayer3,whichisthe
reason,itsalsoknownasIPSecurityorIPSec.IPSec InternationalJournal
of ComputerScienceTrendsand Technology(IJCST) Volume3 Issue
4,Jul-Aug 2015 ISSN: 2347-8578www.ijcstjournal.org Page 166
provides the benefits of confidentiality through encryption,
dataintegritythroughhashingandhmac,and authentication using
pre-shared keys and digital signatures. Apartfromthese,IPSec also
provides anti-replay support.
AgraphbelowshowstheIPtrafficfromsourceto
destinationsandpacketswhichareencryptedand
decrypted.BelowgraphistakenfromCiscoConfiguration Professional.
Figure13-GraphsshowingEncryptedandDecryptedIP traffic.
D.Scalability Analysis of OSPF and I S-I S ProtocolLarge Internet
Service Provider networks can be created by
buildingalargeLevel-1(L1)areawithoutaddingany
hierarchiesinIS-ISanditcanstillworkinbettermanner
thanifOSPFhasalargenumberofrouterspresentina single area.
Inter-Area traffic engineering has lots of issues and is not easy
to manage, therefore most service providers prefer to use single
area design which can be much easy to
manage.WithISIS,bignetworkscanbemadewithout
havinghierarchicaldesign as all IP prefixes are considered
asleafnodesin the Shortest Path First for IS-IS. The best
thingwithSPFinISISisthatfullSPFcalculationisnot triggered for an
interface or a route flapping instance, while OSPFdoesfull SPF
calculation every time any information
changes.GraphbelowshowsrisingCPUutilizationwith ISISand OSPF:
Figure 14- ISISScalabilitygraph withrising traffic. Figure
15-OSPFscalability graph with rising traffic
TABLE4-PerformanceTableofLinkStateRouting Protocols Protocol
Convergence Time ConvergenceTime withSPF Timers Open Shortest Path
First v2 5 secondsSub-Second Intermediate-Systemto
Intermediate-System 3 secondsSub-Second Open Shortest Path
First-Version 3 (OSPFv3) 7 seconds1.5-2seconds
Intermediate-Systemto Intermediate-Systemwith Ipv6(ISIS with IPv6)
5 secondsSub-Second VI.CONCLUSIONAND FUTURE SCOPE
OSPFandISIS,bothusethesamealgorithmtofindthe
bestpath.ISISbehavesmuchbetterwithdefault parameters,and converges
the network in 3 seconds while
OSPFtakesaround5seconds.WhenSPFtimersare
decreasedtomillisecondsthentheconvergencetime also
decreasedtosub-secondforbothprotocols.Forsecurity
analysis,neighborauthenticationpasswordsforsecure
sharingofIPpacketsbetweenboththerouting
protocolshaveused.OSPFandISISbothusesMD5hashing technique but ISIS
has the ability to use the key-chain, with InternationalJournal of
ComputerScienceTrendsand Technology(IJCST) Volume3 Issue 4,Jul-Aug
2015 ISSN: 2347-8578www.ijcstjournal.org Page 167 which we can
create multiple passwords according to time,
whileOSPFusesinterfaceorareabasedpasswords.To
secureIProutingprocessofOSPF and ISIS, IPSec is also
used,whichprovidesencryption,hashing,authentication features to
both the protocols providing them security over
Publicnetworkslikeinternet.Inscalabilityperspective,
ISISbehavesbetterthanOSPFinlargerServiceProvider
Networks,asitcanhavea large single area and it does n't run full
SPF calculation when some route flaps, therefore it
straightwayresultsinlesserconsumptionofCPU
resources.AlsoISISusesTLVformat,withwhichifwe wanttoadd some new
feature, it can be easily added with new TLV,which is not the case
with OSPF. OSPFandISISarethepioneerIGPsusedinService
ProviderIndustryfortheirCoreNetworks.LinkState routingprotocolsare
improving with the time. With all the
IPtrafficincreasingatratehigherthan ever, there needed tobe some
improvements needed in terms of scalability as
theserviceproviderandenterpriserouterswillgetmore
routingtrafficthanbeforeanditcanonlyincreasewith
timethereforethereisneedofmoreefficiencyinLink State Routing
Protocols. ACKNOWLEDGMENT
Thispaperhasbeenmadepossiblethroughtheconstant efforts and help
from my parents and guide. I would like to
thankAssosiateProf.Er.DineshKumar, for his guidance, help and
valuable suggestions. REFERENCES
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InternationalJournal of ComputerScienceTrendsand Technology(IJCST)
Volume3 Issue 4,Jul-Aug 2015 ISSN: 2347-8578www.ijcstjournal.org
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