1. LAN Performance From Stallings text on LANs

2. CSMA/CD What is the maximum utilization possible for n nodes?

3. Probability of ONE node transmitting Probability each node transmitting Maximize A with respect to P

4. So… the maximum value of A is

5. Probability of ONE node transmitting Estimate the length of the contention interval!

6. Therefore: Maximum utilization is

7. Token Ring

8. a<1 and n nodes a is the fraction of the frame which can exist on the link OR the “time” it will take for the head to propagate back to the sender a/n is the time required to propagate from one node to the next node (time to pass the token) IF the token is released immediately after xmit:

9. a>1 and n nodes More than one frame fits. Head does not return to sender before xmit completes If sender needs the leading edge before forwarding the token: If sender needs the trailing edge before forwarding the token:

10. Asymptotic Token Ring Behavior as

11. See graphs