1. Network Delays, Statistical Multiplexing
EE 122 Discussion
9/12/11

2. Transmission and Propagation Delay
Host 1
Switch 1
Propagation delay
between Host 1
and Switch1
Speed of light
Physical distance
Transmission delay
Size of transfer
Bandwidth of link

3. Queuing Delay (Problem #3)C
Transmission delay doubles
Brown packet waits for half the trans. delay of blue packet

4. Statistical Multiplexing
Over-subscribe “peak” requirements of flows and hope that “average” requirements are under capacity
“Hope is a good thing, maybe the best of things…” 

5. Animation from class Data Rate 1 Time Data Rate 2 Capacity Time

6. Animation from class Data Rate 1 Time Data Rate 2 Capacity / 3

7. Animation from class Time Below capacity of link all the time! Time

8. Why and when will this work?
Zone #1
Zone #2
Zone #3
Probability of a flow transmitting in each time zone is 1/3
What is the expected value of the overall flow?
Time
Time
Time