03 Performance
Network Criteria¶
- Fault Tolerance
- Scalability
- QoS (Quality of Service)
- High Throughput
- High Bandwidth
- Low Latency
- Security
Performance Criteria¶
| Bandwidth | Max number of bits transferrable per unit time (In analog world, it is the range of accepted frequencies) |
| Throughput | Actual number of bits transferred per unit time |
| Latency/ Delay | Duration to send info & its earliest possible reception |
| End-to-End Delay | Duration to transmit packet along its entire path - Created by application - Handed over to OS - Passed to NIC - Encoded, transmitted over a physical medium - Received by intermediate device (switch, router) - Analyzed, retransmitted over another medium, etc. |
| Round-Trip-Time | Duration to send and receive acknowledge |
Types of Delays¶
| Delay | Duration of | Formula |
|---|---|---|
| Transmission | Placing bits onto transmission mediaum | \(\frac{\text{Size}}{\text{Bandwidth}}\) |
| Propagation | Travel for a bit from one end of medium to other | \(\frac{\text{Distance}}{\text{Speed}}\) |
| Processing | Error verification Routing decision, ie - analyze packet header - decide where to send packet | No of entries inrouting table Implementatio of data structures Hardware specs |
| Buffer/ Queuing | Packet to wait until it is transmitted | Traffic intensity Type of traffic |
Latency = \(\sum\) all the above delays
Mediums¶
| Medium | Speed (m/s) |
|---|---|
| Vacuum | \(3 \times 10^8\) |
| Cable | \(2.3 \times 10^8\) |
| Fiber | \(2 \times 10^8\) |