CSCI 465 D ata Communications and Networks Lecture 17 Martin van Bommel CSCI 465 Data Communications & Networks 1

ARPANET Routing Strategies 1st Generation CSCI 465 Data Communications & Networks 2

ARPANET Routing Strategies 2nd Generation CSCI 465 Data Communications & Networks 3

Link State Routing Oscillation Bi-partite network – must pass through A or B Routes all use A – high delay – flood changes All will switch to B – new high delay CSCI 465 Data Communications & Networks 4

ARPANET Routing Strategies 3rd Generation CSCI 465 Data Communications & Networks 5

ARPANET Delay Metrics Delay normalized to idle line Queue delay rises exponentially Cost estimate kept at normalized minimum value until threshold Reduces routing overhead Cost level capped at 3x minimum – Can avoid high delay line by no more than two additional hops Minimum higher for satellite – Higher propagation delay CSCI 465 Data Communications & Networks 6