routing - basics

Requires populaon of forwarding tables per desnaon

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Unformatted text preview: when end user wants to control the route. CS144, Stanford University 5 Forwarding Table Data B A Address B S2 Next- hop B S2 C S3 D S3 S1 S4 S3 C D •  An op/miza/on: Network handles hop- by- hop rou/ng. •  Requires popula/on of forwarding tables. •  Per- des/na/on state, not (necessarily) per- flow state. 6 Spanning Tree B A R1 C R2 R3 Spanning tree R4 R5 D R6 R7 R8 X -  Spanning: It reaches all leaves -  Tree: It has no loops 7 What is our metric? B A Choices -  -  -  -  -  -  -  -  -  Min distance Min hop- count Min delay Max throughput Least- loaded path Most reliable path Lowest cost path Most secure path … R1 C R2 R3 R4 R5 D R6 R7 R8 X 8 Example Annotated Graph B A 1 R1 2 1 R2 2 5 R3 C 4 4 R4 R6 3 3 R5 D 2 R7 3 2 R8 X 9 Example Annotated Graph B A 1 R1 2 1 R2 2 5 R3 C 4 4 R4 R6 3 2 R5 D 2 R7 3 2 R8 X Minimum cost spanning tree. In this case, simple. 10 How about this network...!? The Opte Project 11 The Basics Approaches -  -  -  -  Flooding Source rou/ng Forwarding table Spanning tree Metrics Shortest path spanning trees Other types of rou/ng -  Mul/path -  Mul/cast CS144, Stanford University 12 Mul/path B A R1 C R2 R3 R4 R5 D R6 R7 R8 X 13 Mul/cast B A R1 C R2 R3 R4 R5 D R6 R7 R8 X 14 Mul/cast B A R1 C R2 R3 R4 R5 D R6 R7 R8 X 15 Summary There are several ways to route packets across a network, star/ng with the simplest method, flooding. In prac/ce, we use rou/ng algorithms (aka rou/ng protocols) to calculate routes. Ojen, the algorithms calculate the minimum cost spanning tree to the des/na/on. Other types of rou/ng include: mul/path to spread load over links, and mul/cast to deliver to mul/ple end hosts. CS144, Stanford University 16 CS144, Stanford University 17...
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This note was uploaded on 11/03/2012 for the course CS 144 taught by Professor Levis,p;mazieres,d during the Fall '11 term at Stanford.

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