1.4 Performance

Processing Delay: Time for packet forwarding and integrity checks; typically microseconds or less.
Queuing Delay: Waiting time for packet transmission based on congestion.
Transmission Delay: Time to push all bits of a packet onto the link; calculated as $\frac{l}{r}$ where $l$ is packet length and $r$ is transmission rate.
Propagation Delay: Time for a bit to travel through the medium; affected by distance and medium speed, e.g., 270 ms to a geosynchronous satellite.

Transmission vs. Propagation Delay: Transmission delay is related to processing (e.g., toll booth analogy), while propagation delay is about distance traveled (e.g., time taken for the last car to reach the next toll booth).

Traffic Intensity: Ratio of bits arriving to system capacity; defined as $\frac{l \cdot a}{r}$ (where $a$ = average packet arrival rate).
- Low traffic intensity leads to minimal queue, while intensity >1 leads to infinite delays (overflow).
Delays increase rapidly as traffic intensity approaches 1.

Functionality: Measures packet delay across hops; provides RTT measurements for each step toward destination.

Example RTT values for hops from gaia.cs.umass.edu to uracom.fr, varying due to propagation delays across distances.
Occasional '*' indicates unresponsive routers.

Concept: Packet loss occurs when buffers fill, leading to backlog and potential high losses (>10-20% in congestion scenarios).

Definition: Rate of successful message delivery over time; can be instantaneous or averaged over intervals.
Analogy: Water flow through pipes representing transmission capacity; limited by the thinnest pipe (bottleneck).
Calculations: Throughput determined by the minimum rate among series of connections (e.g., $\min(r<em>s, r</em>c, \frac{r}{10})$ for shared capacity among connections).

Explored characteristics of network performance focusing on delay, tools for measurement, effects of congestion, and throughput limitations.