CSCI 465Data Communications and Networks

Lecture 17

Martin van Bommel

CSCI 465Data Communications & Networks

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ARPANET Routing Strategies1st Generation

CSCI 465Data Communications & Networks

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ARPANET Routing Strategies2nd Generation

CSCI 465Data Communications & Networks

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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 465Data Communications & Networks

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ARPANET Routing Strategies3rd Generation

CSCI 465Data Communications & Networks

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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 465Data Communications & Networks

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