1. Ethernet (Medium Access Control Protocol)B C D
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”

2. Ethernet Protocol (how it works)A B C D D
message
Not mine. Discard it…
My message!! Process it…
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;

3. Ethernet Protocol (Collision)A B C D
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!

4. LAN How to Resolve Collisions !!
Length of collision delay is randomly generated.
So, different delays for different waiting nodes….

5. LAN (MACP – details from text)

6. LAN (MACP – details from text)

7. LAN (MACP)

8. WAN Network….
Paths from B to F?
What if node C is faulty?

9. WAN, LAN, Router combination (1)

10. WAN, LAN, Router combination (2)