The eight indicators are as follows:
1. Speed
Manufacturer data and data data conversion:
Example: There is a data block to be sent, the size is 100 MB, and the transmission rate of the network card is 100 Mbps, how long does it take the network card to send the data block?
Solution: Note that one byte is eight Bit, rate and bit rate conversion
2. Bandwidth
Significance in analog signals:
Bandwidth Significance in computer networks:
3. Throughput
As shown in the figure:
4. Delay
The components of network latency are as follows:
- It takes time for the source host to send the packet to the transmission line, which is called the sending delay.
- The electrical signal of the packet is transmitted at the end of the link, which also takes a certain amount of time. We call this period of time the propagation delay.
- After the router receives the signal, it also takes time to store and forward, and this period of time is called the processing delay.
There are multiple routers between the source host and the target host, so there are multiple propagation delays and processing delays
.
Example: (channel width is 1Mb/s)
For example:
V. Summary
6. Delay-bandwidth product
The following is equivalent to calculating a volume:
7. Round-trip time
In many cases, information on the Internet is not only transmitted in one direction, but is exchanged in two directions, and RTT is the round-trip time.
As shown in the figure:
The satellite link has a lot of time, and the propagation delay is relatively large.
8. Utilization
As shown below:
The higher the channel utilization, the better, and the delay will also increase as the utilization increases, as follows:
9. Packet Loss Rate
The packet loss rate is the packet loss rate, which refers to the ratio of the number of packets lost during transmission to the total number of packets within a certain time range .
The packet loss rate can be divided into interface packet loss rate, node packet loss rate, link packet loss rate, path packet loss rate, network packet loss rate, etc.
The packet loss rate is a network performance indicator that network operation and maintenance personnel are very concerned about, but for ordinary users they often do not care about this indicator because they are usually unaware of network packet loss.
There are two cases of packet loss:
- The packet has a bit error during transmission and is discarded by the node;
- Packets are dropped when they arrive at a packet switch with a full queue; network congestion can occur when traffic is high.
Therefore, the packet loss rate reflects the congestion of the network:
a high packet loss rate can make a website inoperable.
10. Summary
Summarized as follows:
11. Reference
Gao Jun, MOOC Computer Network