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Ethernet (Medium Access Control Protocol)

A single shared comm. Line Used by all (each check if “free” or “busy”) Message is broadcasted to all

Message has “destination address” and “message-body”

A B C D

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Ethernet Protocol (how it works)

Node A wants to send something to node D Message’s “destination address” = D Message is broadcasted to all…

Every Machine checks If not mine, then discard; else process message;

A B C D

My message!! Process it…

Not mine. Discard it…

D message

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Ethernet Protocol (Collision)

What if shared line is busy when node B wants to send? Eg: If node A is currently sending…. Node B waits… and send after node A is done.

What if many nodes are waiting… And simultaneously send when node A is done!

A B C D

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LAN

Length of collision delay is randomly generated.

So, different delays for different waiting nodes….

How to Resolve Collisions !!

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LAN (MACP – details from text)

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LAN (MACP – details from text)

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LAN (MACP)

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WAN Network….

Paths from B to F?

What if node C is faulty?

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WAN

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WAN