Preface
This article combs the commonly used performance indicators in computer networks.
Speed-related indicators: rate, bandwidth, throughput
and time-related indicators: delay, delay bandwidth product, round trip delay RTT to
measure the overall: utilization rate
rate
The rate is the data rate or data transmission rate or bit rate.
The rate at which the host connected to the computer network transmits the number of bits of data on the digital channel.
The unit is b/s.
bandwidth
In computer networks, bandwidth is used to indicate the ability of the network's communication lines to transmit data. Usually refers to the highest data rate that can pass from one point to another in the network per unit time. The highest speed supported by the network device.
The unit is b/s.
The highest rate at which data can be sent at the sending entrance.
Throughput
Indicates the amount of data passing through a certain network (or channel, interface) in a unit time. The unit is b/s.
Throughput is limited by the bandwidth of the network or the rated rate of the network.
Time delay
The time required for a datagram (message/packet/bit stream) to be transmitted from one end of the network (or link) to the other end. Also called delay or delay.
The unit is s.
Including transmission delay, propagation delay, queuing delay and processing delay.
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Transmission delay (transmission delay): the time
from the first bit of the packet to the end of the last bit of the packet.
Transmission delay = data length/channel bandwidth (transmission rate). -
Propagation delay
The time it takes for electromagnetic waves to travel a certain distance on the channel. Depends on the electromagnetic wave propagation speed and link length.
Propagation delay = channel length / rate of electromagnetic wave propagation on the channel. -
Queuing delay The time required to
wait for the output link or input link to be available. The time that the buffer waits to be processed in the router. -
Processing delay Time
to detect errors and find the exit while the router is waiting for forwarding.
Delay bandwidth product
Delay bandwidth product = propagation delay * bandwidth. Describe the properties of the channel capacity. The unit is b/s.
The delay-bandwidth product is also called the link length in bits , that is , how many bits a certain link currently has.
Describe how many bits the channel has in 1s.
RTT
It refers to the total time delay from the sender sending the first data until the sender receives the receiver's confirmation.
It can be viewed through ping.
- RTT includes:
round-trip propagation delay (propagation delay * 2) + terminal processing time (receiver processing time)
Utilization
Utilization is divided into channel utilization and network utilization.
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Channel utilization = data passing time / (yes+no) data passing time
-
Network utilization = weighted average of channel utilization