Routing Protocol

1. INTRODUCTION 1. 1 Whatis computing machine Ne iirk? The groupofcomputers and devices linked by communication channels bothowing rehearsers to fortune ascertaining, data, softw ar and hardw ar with further usancers is meant to be computer meshwork. Network communications communications communications protocols boundary hardwargon as well as package comp unrivalednessnts of entanglement. Two or morecomputers atomic number 18 saidto beina mesh topology if and only if they atomic number 18 committedmutuallyand beableto commune. Computers be affiliated to a cyberspace by the use of allthe ports i. e. , analogue ports, modem ports, Ethernet ports, serial ports, USB ports, fire wire ports and m some(prenominal) more in one and only(a) or more delegacy.But Ethernet port is the virtually broadly use portsfor cyberspaceing. Hosts, halt stations or workstations ar referred while talkingwell-nigh earningss. Anything tietothe intercommunicateincluding hubs, bridges, switches, routers,access points, firewalls, workstations, servers, mainframes, printers, s mountainners, copiers, fax machinesand more argon include under Host or end stations . Computers atomic number 18 connected in a meshwork for sharing of softw be and hardw be re germs, study and data as well as smooth the progress of communication. 1. 2 TCP/IP Layered architecture physical body TCP/IP Layeredarchitecture The next arethe layersofthe TCP/IParchitecture Application Layer In theapplication layer Simple get away Transfer Protocol (SMTP) and File Transfer Protocol (FTP) uses protocolfor network communication. Application layer protocolsare mostofttimeslinked with client-serverapplications. direct Layer End-to-end message transfer capability, flow tame, error control and fragmentation and so forthare providedby the transport layer. The transport layer ensures source to name and breed delivery of megabuckss safely and reliably.The service through which applications are co nnectedtogether viathe useof ports is provided by transport layer. Network Layer Packets are logically transmitted overthe entire network in the OSIs Network layer. Hosts addressing by assigningtheman IPaddressand piece of ground routing among binary networks are handled in this layer. This layer is concerned with routing data end to end message delivery etc. Interface Layer The data flip-flop betweenthe hostandthe network are monitored by theinterface layer. The protocols for visible transmissionof data is defined by Interface Layer . 1. 3Autonomous t accomplishkIP networksand routers collection underthe controlof one entity representing a common routing policy is called anAutonomous System. severallyAS begin a uniqueAS minutefor usein routing. Each network is uniquely identified onthe meshwork by ASN. IANA (Internet assign Numbersauthority) assign AS numbersand supplyto Regional profits Registries (RIRs)in blocks. Autonomous System foundation be dividedinto sightseerlet c ategories MultihomedAutonomous System Connectionsto more than oneAS is maintained by a MultihomedAS. Stubautonomous System Connectionto only one otherAS is Stubautonomous System.Transitautonomous SystemConnections through itselfto separate networks are provided by Transitautonomous System. 1. 4 Routing The methodof selecting elbow roomsina network via whichto send data is meant to be routing. The processof findinga racecourseway froma sendertoa desired name and address is also said to be routing. The telephone network,theinternetand transport networks, etc perform routing. Network Layerof either TCP/IP layered model orthe OSI (Open Systeminterconnect) Reference model in the main carry out routing. The logicallyaddressed software packages are passed fromtheir sourceto destination viaintermediary thickeners i. e. orwarding is directed by routing. Routing tasks are performed by routers. Routing and packet boat ship is performed by ordinarycomputers available with sextuple netw ork cards in a limited manner. Forwarding is directed by the routing process onthe basisof routing tables where routing record to different network destinations are maintained. In raise to vex efficient routing, construction of routing table heldinthe routers memory is most necessary thing. Only one network road are frequently utilize by routingalgorithmic programic programs ata time, butthe useof multiplealternative paths is made possible by multi-path routing techniques.Following are the fibersof routing delivery semantics Unicast A message is delivered toa single specified node by router. haoma of speech Unicasting Broadcast A message is deliveredtoall nodesinthe network by router. Fig Broadcasting Multicast A message is deliveredto assemblyof nodes that get down expressedinterestin acquiringthe message by router. Fig Multicasting Anycast A message is deliveredto either one outofa come downof nodes, typicallythe one undermentionedtothe source. Figanycasting 2. TYPESOF R OUTING Following are the typesof Routing mechanisms. Theyare Static Routing propellent Routing 2. Static Routing The processby which routes can be manually entered into the routing table with the help of a configuration file which scads automatically as soon as router starts is called static routing. Networkadministrator, who configures the routes, can enter these routes as an option. Thus static routes mean the routes that can non be counterchanged (excepta mortal changesthem) after their configuration. The simplesttypeof routing is static routing. In case of change of routing discipline often or configuration on a huge number of routing devices (router) it doesnt work fine as it is a manual process.The outages or down connections are non handled properly by static routing becausemanually configured route must be reconfigured physically in pastureto fix or renovateany lost connectivity. 2. 2 Dynamic Routing Network destinations are discovered dynamicallyby government agency of softwareapplications called Dynamic routing protocols. A routing table is created and managed by routerin Dynamic Routing. Firstly, a router will learn routestothe directly connected entire networks. It willthen learn routes from other routers using the same routing protocol.One or more better(p) routes are selected from the enumerate of routes for each and each network destination by router. Best route knowledge are distributedto other routers runningthe same routing protocol by Dynamic protocols, distributingthein stageion on what networks it subsistand can be reached. This provide dynamic routing protocolsthecapabilitytoget utilise to logical networktopology changes, equipment failures or network outages onthe fly. 2. 3 Typesof Dynamic Routing remoteness-Vector Routing Paths are calculated using Bellman Ford Algorithm bya blank space-transmitter routing protocol. bloodlinev1and 2and IGRP (Interior entrance Routing Protocol) are examplesof infinite-vector routing protoc ols. Earlier, distance vector protocols such as RIPv1 show classful behavior but newer distance vector protocols suchas RIPv2and Enhancedinterior Gateway Routing Protocol (EIGRP) show signs of classless(prenominal) behavior. outdistance-vector routing protocols boomingand competentin small networks Deprived convergence properties Facilitate inthe growthof more complex but more scalable link-state routing protocolsfor usein large networks. Periodic copiesofa routing table are passed from routerto router by distance vector routingalgorithms. Logical broadcast is the most commonly usedaddressing scheme. Periodic modifys are sent by routers runninga distance vector routing protocol even ifthereare no changesinthe network. Complete routing table is included underthe periodic routing update in a pure distance vector environment. All known routes can be verified and changes can be madeby gettinga dwells complete routing table base on simplifiedin data stageion also called as ro uting by rumor. Fig Distance Vector RoutingPeriodic routing updates are fitd from router A to router B inthe figure. Distance vector metric (suchas skip over count) are added by Router B to each route learned from router A,risingthe distance vector. Its own routing tablesare passed to its neighbor, router C. This process evanescesbetween directly connected neighbor routers inall directions. The chief purposeisto decidethe top routetocontaininthe table when the routing table is updated bya routing protocolalgorithm. Different routing metric is used to determinethe best route by each distance vector routing protocol.Metric valueis generated for each path through network by thealgorithm. Usually, the path is better if metric is smaller. private characteristicofa path helps in calculation of metrics and confederacy of several path characteristics helps in calculation of more complex metrics. The most commonly usedmetrics used by distance vector routing protocols are Hop Count Pack ets numberof passages passimthe product portof one router Bandwidth Links data energy Delay Time necessaryto shifta packet from beginning placeto destination.Load work load onrouter or link. dependability each network linkbit error rate maximum Transmission Unit (MTU)the utmost message extentin octets copasetictoall links onthe path. Link- advance Routing Packet-switched networks use link-state routing protocolfor computer communications. OSPFandIS-IS are its examples. Atopological database is built by the help of link-state routing that describes extrapreciseinter-network routes. lifesize networks use link state routing protocols and now used by most of the organization and ISP.Router performs the link-state protocol inthe network. A mapofthe connectivityofthe network is constructed by either node in the form of graph showing node connection to other node is the basic conceptof link-state routing. The best next hop is calculated by each nodeindependently for every possible destinationinthe network. The routing table for the node is formed bythe collectionof best next hops. Fig Link-State Routing To find outthe shortest path from itselfto every other nodeinthe network analgorithm is run by each nodeindependently overthe map.OSPF, EIGRP and Novells NLSP (NetWare Link State Protocol) are the examples of link state routing protocol. IPX is only supported by Novells NLSP. A partial mapofthe network is maintained by each router in this typeof routing protocol. Link stateadvertisement (LSA)is flooded throughoutthe network whena network link changes state (upto down, or vice versa). The changes are noted and routes are re-computed by allthe routersaccordingly. Greater flexibilityand sophistry are provided by Link State Routing protocols thanthe Distance Vector routing protocols. general broadcast traffic is reducedand better closes are made approximately routing by winning characteristics suchas bandwidth, delay, reliability,and loadinto consideration,ins teadof takingtheir decisions only on hop count. 3. ROUTINGALGORITHMS 3. 1 Bellman-FordAlgorithm Also called as Label Correctingalgorithm Used for negative molding weight equivalent as Dijkstrasalgorithm In order to maintain distance tables, this algorithm is used by router Exchanging entropy withthe neighboring nodes help to update information in the distance table All nodesin the network is represented by the numberof datainthe table The directlyattached neighbors are represented by the columnsof table and all destinationsinthe network are represented by the row. The numberof hops, latency,the numberof outgoing packets, etc. are measurements in this algorithm. 3. 2 DijkstrasAlgorithm Edsger Dijkstraconceived Dijkstrasalgorithm broadly used for routing Is a graph search algorithm The single-source shortest path troublefora graph is solved by this algorithm with non negative edge path costs The shortest path head is produced as a output Helps in finding shortest ro ute from one router to other A shortest-path spanning point having route to all possible destinationis built by this algorithm for router The router usingthealgorithmisthe sourceof its shortest-path spanning tree 4. ROUTING PROTOCOLS Routing protocol describe the way of communication between routers which helps in the selection of routes between any two nodes on a network. Usually, cognition of immediate neighbors is known by each router. Thisinformation is shared bya routing protocol to have routers the knowledgeofthe networktopology. Most commonly used Routing protocols are as follows 4. RIP (Routinginformation Protocol) dynamicinter-network routing protocol used in private network routes are automatically discovered routing tables are built a Distance-Vector routing protocol uses Bellman-Fordalgorithm 15 hops areallowed with RIP 180 entropy is the hold down time Full updates are transmitted every 30 sec by each RIP router Works at network layer Prevent routing loop s Hop limit incorrect routinginformation are forecloseed from being propagated easy configuration no parameter postulate Two indicationsof RIP are as follows RIPv1 classful routing is used subnet information is not carried by periodic routing updates no support for VLSM (variable length subnet masks) Same network class have different sized subnet by the use of RIPv1 No router enfranchisement Broadcast based and 15 is the maximum hop count A RIPv1 packetformatis shown below picFig RIP packetformat Commanddetermine whetherthe packetisa implore ora response. A router sendall or partof its routing table is asked bythe request. Replytoa request or regular routing update means the response. Routing table entries are contained in responses. Version number RIP version used is specified.Potentiallyincompatible versions can be signaled by this field. naught RFC 1058 RIP doesnt use this field it wasadded to have backward compatibility provided to pre-standard varietiesof RIP. direct family identifier (AFI) Theaddress family used is specified. Address-family identifier is contained ineach doorwaytospecifythe syndicateofaddress being dilate. TheAFIfor IPis 2. Address The IPaddress is particularizedforthe entry. MetricThe number of inter-network hops traversedinthe triptothe destination is indicated. 1and 15foran applicable route, or 16foran standoffish route. RIPv2 Developedin 1994 Classlessinter-Domain Routing (CIDR) is supported Subnetinformation can be carried Addition of MD5authentication and Rudimentary plain textauthentication for the security of routing updates. Routing updates are multicast to 224. 0. 0. 9 15 is the maximum hop count A RIPv2 packetformat is shown below pic Fig RIPv2 packetformat Commanddetermine whetherthe packetisa request ora response. A router sendall or partof its routing table is asked bythe request. Replytoa request or regular routing update means the response. Routing table entries are contained in responses.Version number RIP version used is specified. Unused set is the value set. Address-family identifier (AFI)Theaddress family used is specified. assay-markinformation is contained in the death of the entry iftheAFIforthe initial entryis 0xFFFF inthe message. At present,simple word of honor is the onlyauthentication type. Route tag The methodology is providedfor distinguishing between intimate routes (learned by RIP)and external routes (learned from other protocols). IPaddress IPaddress is particularizedforthe entry. Subnet maskThe subnet mask is containedforthe entry.No subnet mask has been particularizedforthe entry if this fieldis zero. Next hop The IPaddressofthe next hop is indicatedto which packetsforthe entry should beforwarded. MetricThe number of inter-network hops traversedinthe triptothe destination is indicated. 1and 15foran applicable route, or 16foran unapproachable route. 4. 2 OSPF (Open Shortest Path First) A Link-State protocol usedfor routing between routers betoa sing leautonomous system link-state technology is used information close tothe direct connectionsand links is communicated between the routers Identical database is maintained by each OSPF router for the description of theautonomous Systemstopology deliberateness of a routing table by the construction of a shortest- path tree from this database. Routes are quickly recalculated in the face of topological changes equal-cost multi-path are supported corroboration of all OSPF routing protocol exchanges Designed for TCP/IP environment routing updates authentication IP multicast are utilized in sending/receivingthe updates routes IP packets based exclusively onthe target IPaddress originateinthe IP packet header Grouping of sets of networks IP subnets are flexibly configured Destinationand mask is available to the route distributed by OSPF The sideline figure showsthe packetformat used by OSPF picFig OSPF packetformat Version numberthe OSPF version used is specified. Typethe OSP F packet type is identifiedas oneofthe following Hello neighbor relationships are established and maintained. Database descriptionthe contentsofthetopological database are described. Link-state request piecesofthetopological database are pass on from neighbor routers.Link-state updatea link-state request packet is responded. Link-stateacknowledgment link-state update packets are acknowledged. Packet lengththe packet length,the OSPF header is specified. Router ID the sourceofthe packet is identified. Area ID Thearea of packet is identified. All OSPF packetsarelinked witha singlearea. Checksumthe complete packet contents are checkedforany harm sufferedin travel. credential typetheauthentication type is contained. Authentication ofall OSPF protocol exchanges. Configuration of theauthentication type on per-area basis.Authentication authenticationinformation is contained. Data encapsulated upper-layerinformation is contained. 5. WORKING 5. 1 Distance Vector Routing The following method s showthe overall working(a)ofthe Distance-Vector Routing . There is no predefined route i. e. entire route for a particular destination is not known to any router. The port to send out a unicast packet is known by each router on the basis of destination address. progressively the route is made and there is the formation of the route by the region of each router when it receives the packet.The optimal tree is not predefined in DVRP actually. No routers have knowledge for making an optimal tree. Slowly and gradually the tree is made. The tree is formed as soon as a router receives a packet it is forwarded by router through some of the ports, on the basis of source address. different down-stream routers make the rest of the tree. The formation of the loops must be proceeded by this protocol. Duplications are also prevented in order to make the entire network receive only one copy. In addition to this, the shortest path from source to the destination is the path travelled by a cop y.Inconsistencies occurring with Distance-Vector Routing Incorrect routing entries are caused by slowinter-network convergence which may bring inconsistencies maintaining routing information. .The following example describes howinconsistencies occurin Distance-Vector routing The entire figure describes the inconsistencies occurring with Distance-Vector Routing. Defininga maximumto prevent counttoinfinity . With thisapproach,the routing table update loop is permitted by routing protocol untilthe metric exceeds its maximumallowed value. Fig Defininga maximumto prevent counttoinfinity 6 hops are defined as the maximumallowed value. Whenthe metric value exceeds 16 hops, we cannot reach network 10. 4. 0. 0 Routing Loopsin Distance-Vector Routing A routing loop is said to be occurred if two or more routers havefalse routinginformationrepresenting thata applicable pathtoan unapproachable destination exists via other routers. Fig Routing Loop Solutionsto eliminate routing loops class horiz onThe information is not sent in the direction from where passe-partout information comes. The split horizon function is illustrated by the following figureFig Split Horizon Route intoxicationRouting loops are eliminated. The following figure providesan exampleof Route Poisoning Fig Route Poisoning Inadditionto split horizon, route poisoningand holddown timers, poison reverse, holddown timersand triggered updatesare other methodsto eliminate routing loops. 5. 2 Link-State Routing The following methods showthe overall workingof Link-State Routing. Gathering of the neighborinformation continuously. Router answering to this protocol are broadcasted the list of neighborinformation, process knownas flooding.Soon, thisinformation is distributed to all routers onthe network. Flooding of the neighborinformation in caseofa (routing- noteworthy) changeinthe network. The best path can be calculated to any host on any destination network as everything closethe network is known by every router . 6. ADVANTAGESAND DISADVANTAGES Distance-Vector Routing Advantagesof Distance-Vector Routing simpleand flat network No special hierarchical design is undeniable. Implementation of hub-and-spoke networks No concern for worst-case convergence timesina network less memoryand processing power usageDisadvantagesof Distance-Vector Routing Incorrect routing entries create inconsistencies in maintainingthe routinginformation Rise of a condition counttoinfinity accompaniment of a routing loop Variable Length Subnet Masking (VLSM) or top-notch netting is not supported multi-vendor routing environment is not supported Link-State Routing Advantagesof Link-State Routing Paths are chosen via network by the use of cost metrics changesinthe networktopology are reported toall routersinthe network quickly fast convergence times No occurrence of routing loops routing decisions are based on the most recent setofinformation Link-State protocols use cost metricsto choose paths thoughth e network. The cost metric reflectsthe energyofthe links on those paths. Disadvantagesof Link-State Routing Topology database,anadjacency database,andaforwarding database is required. a significantamountof memoryis required in large or complex networks significantamountof CPU power usage strike of a strict hierarchical network design to reduce significantamountof CPU power usage network capability or performance is low to transport data . APPLICATIONAREAS Distance-Vector Routing used in mobile, wireless and hoc networks (MANETs) used for mobilead hoc routing (Ad hoc On-Demand Distance Vector Routing) . Link-State Routing usedin larger, more complicated networks Optimized Link State Routing Protocol (OLSR) intentional for mobile, wireless and hoc networks 8. COMPARING DISTANCE-VECTORAND LINK-STATE ROUTING STRATEGIES Mostly, best path is determined by Distance Vector protocols, while bandwidth, delay, reliabilityand load are considered to make routing decision by Link-Sta te protocols Distance Vector protocols are simple and efficient where as Link-State protocols are flexible and sophisticated Routinginformation Protocol (RIP v1and v2)andinterior Gateway Routing Protocol (IGRP developed by Cisco) are Distance Vector protocols where as OSPF, EIGRP, Novells NLSP (NetWare Link State Protocol) are Link-State protocols Notion of a distance is not required in Distance Vector routing where as Link-State routing is based on minimizing some notion of distance Uniform policies are not required at all routers in Distance Vector routing but supply policy is required in Link-State routing Router have little knowledge about network topology in Distance Vector routing where as routing sector has excessive knowledge about topology information in Link-State routing 9. deduction Introduction, working, use, advantages and disadvantages of Distance-Vectorand Link-State routingare explainedin this project. Bellmanfordand Dijkstrasalgorithm are also discussed. This project describes the popularity of Distance-Vectorand Link-State routingbecause of their complex, sophisticated, flexible features in recent computer networking field..