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Contents Routing Protocol and Algorithm Classifications Link State Routing Algorithm Distance Vector Routing Algorithm LS Algorithm vs. DV Algorithm Hierarchical.

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Presentation on theme: "Contents Routing Protocol and Algorithm Classifications Link State Routing Algorithm Distance Vector Routing Algorithm LS Algorithm vs. DV Algorithm Hierarchical."— Presentation transcript:

1 Contents Routing Protocol and Algorithm Classifications Link State Routing Algorithm Distance Vector Routing Algorithm LS Algorithm vs. DV Algorithm Hierarchical Routing

2 Routing Protocol and Algorithm Determining the path(route) B A CE D F source host destination host first-hop router default router source router destination router least-cost path

3 Classifications Global vs. decentralized global(link state algorithm) : complete information about connectivity and link costs Static vs. dynamic static : routes change very slowly Load-sensitive vs. load-insensitive load-sensitive : link costs reflect congestion Typical used Dynamic link state routing algorithm Dynamic distance vector routing algorithm

4 Link State Routing Algorithm Each node broadcasts the identities and costs to its directly attached neighbors Dijkstra s algorithm

5 Link State Routing Algorithm Oscillation(page 307) DB C A e 11 2+e e e e e

6 Distance Vector Routing Algorithm Iterative, asynchronous, distributed Distance table D X (Y,Z) : cost of the direct link from X to Z + Z s currently known minmum-cost path to Y D X (Y,Z)=c(X,Z)+min w {D z (Y,w)}

7 Distance Vector Routing Algorithm Initialization: D X (*,v) = inifinite, D X (v,v)=c(x,v) Send min w D X (y,w) to each neighbor when they changes C(X,V) changes Neighbor node send its update

8 Distance Vector Routing Algorithm YXZ 7 21 DXDX YZ Y2 Z7 DYDY XZ X2 Z1 DzDz XY X7 Y1

9 Distance Vector Routing Algorithm YXZ 7 21 DXDX YZ Y28 Z37 DYDY XZ X28 Z91 DzDz XY X73 Y91

10 YXZ 7 21 DXDX YZ Y28 Z37 DYDY XZ X24 Z51 DzDz XY X73 Y91

11 YXZ DYDY XZ X46 DzDz XY X 5 1 Decrease

12 Distance Vector Routing Algorithm YXZ DYDY XZ X16 DzDz XY X 5 1 Decrease

13 Distance Vector Routing Algorithm YXZ DYDY XZ X16 DzDz XY X 2 1 Decrease

14 Distance Vector Routing Algorithm YXZ DYDY XZ X16 DzDz XY X 2 1 Decrease

15 Distance Vector Routing Algorithm Increase YXZ DYDY XZ X46 DzDz XY X 5 60

16 Distance Vector Routing Algorithm Increase YXZ DYDY XZ X606 DzDz XY X Routing loop

17 Distance Vector Routing Algorithm Increase YXZ DYDY XZ X606 DzDz XY X507 60

18 Distance Vector Routing Algorithm Increase YXZ DYDY XZ X608 DzDz XY X507 60

19 Distance Vector Routing Algorithm Increase YXZ DYDY XZ X608 DzDz XY X Too many iterations! (count-to-infinity problem)

20 Distance Vector Routing Algorithm Poisoned reverse YXZ DYDY XZ X4 DzDz XY X505 60

21 Distance Vector Routing Algorithm Poisoned reverse YXZ DYDY XZ X60 DzDz XY X505 60

22 Distance Vector Routing Algorithm Poisoned reverse YXZ DYDY XZ X60 DzDz XY X

23 Distance Vector Routing Algorithm Poisoned reverse YXZ DYDY XZ X6051 DzDz XY X

24 Distance Vector Routing Algorithm Poisoned reverse Cannot solve general count-to-infinity problem YXZ DYDY XZ X6051 DzDz XY X50 60

25 LS Algorithm vs. DV Algorithm LSDV Message complexity O(nE)Maybe small Speed of convergence O(n 2 ) algorithmSlow(count-to-infinity problem) RobustnessGoodBad

26 Hierarchical Routing View network as interconnected routers Scale Administrative autonomy Organize routers into autonomy systems(AS)

27 Hierarchical Routing B.a A.a A.b A.cA.d C.b C.c C.a Host H1 Host H2 Autonomy system(AS) Gateway router Intra-AS Inter-AS

28 Hierarchical Routing B.aA.aA.cC.a Topological view for inter-AS routing protocol

29 END


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