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Author: Tianle Yuan

Performance Indices⚓︎

Speed⚓︎

Networking speed?

The data (bit: 0 or 1) transmission speed.

e.g. bps or bit/sec -- bits per second

  • Mbps: 1,000,000 bit/s, is how many millions of bits a network can theoretically transfer each second.
  • mbps: 0.001 bit/s.
  • kbps: 1,000 bit/s.
  • Gbps: 1,000,000,000 bit/s.

Bandwidth⚓︎

Networking bandwidth?

Maximum amount of data your connection can handle at a moment (normally a second).

e.g. Ethernet bandwidth: 10 Mbit/s → the maximum amount of data can be transferred in a second is 10 Mbit.

Throughput⚓︎

Networking throughput?

The amount of data passing through a network (or channel, or interface) in a unit time.

e.g. We can understand it as real-time "traffic" on a "bandwidth lane". But the number of "cars" cannot be more than the number the "bandwidth lane" allows.

Delay⚓︎

Networking delay?

The time (s) required to travel from one end of a network to another end.

picture 1

There are 4 types of delays, corresponding to the concepts shown in the picture above:

Transmission delay

The transmission delay measures the speed of data.

It's the time from when the first bit of a file reaches a link to when the last bit reaches the link.

\[Transmission\:Delay = \dfrac{L(bis)}{R(bits/sec)}\]

\(L\) is the file size (bits). \(R\) is the transmission speed (bits/sec).

Propagation delay

The propagation delay measures the speed of the medium.

It's the amount of time a bit on the link needs to travel from the source to the destination, where the speed is dependent on the medium of communication.

\[Propagation\:Delay = \dfrac{D(m)}{S(m/s)}\]

\(D\) is the distance (meter). \(S\) is the propagation speed (meter/sec).

Queuing delay

The queuing delay measures the buffering rate.

If a packet arrives at its destination and the destination is busy, it will not handle that packet immediately. Instead, the packet has to wait in the input/output queues.

This delay depends on the following factors:

  • The number of packets arriving in a short time interval.
  • The transmission capacity.
  • The size of the queue.
Processing Delay

The processing delay measures the speed of the processor (router or host machine).

It is the time taken by a processor to process the data packet.

Round-Trip Time⚓︎

Networking Round-Trip time?

The duration in milliseconds (ms), taken by the network to go from a start-point sending a request to the start-point getting the response that the end-point has received the data.

Bandwidth-Delay Product⚓︎

Networking bandwidth-delay product?
\[Transmission\: delay\times Bandwidth\]

References⚓︎

What are the different kinds of computing network delays?

Picture resource

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