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Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
Link state routing protocol
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Link state routing protocol

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Introduction of Link-state routing protocol

Introduction of Link-state routing protocol

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  • 1. Link-state routingProtocolAung Thu Rha HeinChinnawat Noosrikong
  • 2. Outline• Overview• Features of Link-State routing protocols• link-state routing algorithm• Dijkstra’s algorithm• OSPF• IS-IS• Advantages and Disadvantages of LS routing protocols
  • 3. Overview• One of two main classes of interior gateway routing protocols • OSPF, IS-IS• Performed by every switching node in the networkBasic Concept• every node creates a map of the connectivity to the network • This graph shows which nodes are connected to which other nodes • Each node calculates the next best logical path to the destination • Collection of best paths form the routing table of the node
  • 4. Features of Link-state routingprotocolsLink-state advertisement (LSA) or Link-state Packet(LSP)• a small packet of routing information that is sent between routersTopological database or Link-state Database• a collection of information gathered from LSAsSPF algorithm• a calculation performed on the database that results in the SPF treeRouting table• a list of the known paths and interfaces
  • 5. link-state routing algorithm1. Each router is responsible for meeting its neighbors and learning their names. • Used a Hello Protocol, which send a data packet contains RID and address of the network on which the packet is being sent2. Each router constructs a LSP/LSA which consists of a list of names and cost for each of its neighbors.3. The LSP/LSA is transmitted to all other routers. Each router stores the most recently generated LSP/LSA from each other router. • Link-state flooding: Sequencing and Aging procedures • Each routers store the identical Link State Database4. Each router uses complete information on the network topology to compute the shortest path route to each destination node. • Use SPF or Dijkstra’s algorithm to calculate the shortest path
  • 6. Dijkstra’s algorithm Also known as the shortest path first (SPF) algorithmNodes 2 3 4 5(b) 61(a) 7 9 ∞ ∞ 14 2 7 9<7+10 7+15 ∞ 14 3 7 9 22<11+ ∞ 14<7+1 10+7 0+2 6 7 9 22 9+2+10 14 +7
  • 7. Dijkstra’s algorithm(Cont.)
  • 8. Open Shortest Path First (OSPF)• A routing protocol developed for Internet Protocol networks by the Interior Gateway Protocol (IGP)• Based on the Dijkstra’s Algorithm• Serving large, heterogeneous internetworks• OSPF Version 1 (1988)• OSPF Version 2 (1998) Supported IPv4• OSPF Version 3 (2008) Supported IPv6
  • 9. Open Shortest Path First(OSPF)OSPF can operate within a hierarchyCollection of networks under a common administration that share acommon routing strategy
  • 10. Additional OSPF Features• Equal-cost• Multipath routing• Routing based on upper-layer type-of-service (TOS) requests
  • 11. IS-IS• Intermediate System-to-Intermediate System (IS-IS)• That floods the network with link-state information to build a complete, consistent picture of network topology • Each IS-IS router independently builds a database of the networks topology• IS-IS uses Dijkstras algorithm for computing the best path through the network• IS-IS Metrics• A single required default metric with a maximum path value of 1024• Three optional metrics (costs): • Delay • Expense • Error
  • 12. Integrated IS-IS• Integrated IS-IS is a version of the OSI IS-IS• To support more network layer protocols than just CLNP• Dual IS-IS• Implementations send only one set of routing updates• Supporting multiple network layer protocols in a router
  • 13. Advantages and Disadvantages of LSrouting protocolsAdvantages• Smaller routing tables • Only a single optimal route for each network ID is stored in the routing table.• Low network overhead • do not exchange any routing information when the internetwork has converged.• Ability to scale. • scale well to large and very large internetworks.• Lower convergence time. • have a much lower convergence time and the internetwork is converged without routing loops.
  • 14. Advantages and Disadvantages of LSrouting protocols(cont.)Disadvantages• Complex • much more complex and difficult to understand than DV routing protocols.• More difficult to configure. • implementation requires additional planning and configuration.• Resource intensive. • For very large internetworks, the LS database and the calculation of routing table entries can be memory and processor intensive.

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