August 8, 2022
Judging from the names of 100M switches and 1000M switches, you can know that the exchange rates of the two are different. 100M is 100Mbps, 1000M is 1000Mbps, and the speed of 100M switches is 10 times that of 100M, and it is backward compatible with 100M products. .
The working mode of the switch is full-duplex mode, that is, it can upload and download at the same time without affecting the network performance, and the bandwidth utilization rate is theoretically close to 100%. It's just that the speed of gigabit is better than that of 100M. If you build a small network in application scenarios, high-quality 100M switches can meet the requirements.
In the field of security monitoring, it is common to encounter optional switches. Many novices have a hard time on how to choose. When to choose a 100M switch and when to choose a gigabit switch?
So let's start with the basics of monitoring. Surveillance cameras are currently using two protocol standards, one is H.264 and the other is H.265.
The meaning of the bit rate of a surveillance camera is simply how much data is transmitted per second. The default unit is Kbps, we can convert it into Mbps, that is, divide it by the feed rate 1024, and get how many Mb of data pass through per second. (Leave a question here, what is the difference between MB and Mb?)
Next, explain the bit rate calculation of the network camera, usually by adding the main stream value and the sub stream value. The main stream is a high-definition picture, which is used to support saving video and single-picture display; the sub-stream is a normal picture, which is used to support network transmission and multi-picture display.
Here, the common network camera bit rates are given directly, and the differences between different brands are not big.
The bit rate of 1 million pixels/1.3 million pixels is about 2.5Mb;
2 million pixel bit rate is about 4.5Mb;
The bit rate of 3 million pixels is about 6.5Mb;
The above is the code rate under the H.264 protocol standard. If we use a 100M switch, when we calculate the actual value of a 100M switch, in order to consider various factors, such as the brand of the switch, leave the necessary margin and other factors according to 50%-70% of the theoretical value to calculate. Then the 100M switch is calculated based on the actual bandwidth of 50M, and it can be calculated that it can connect 20 100/1.3 million pixel cameras, 11 2 million cameras, and 7 3 million cameras. Gigabit switches are also calculated in the same way, so I won't go into details here.
If the camera uses the H.265 technology standard, you must first know that the H.265 technology halves the code stream, so it is almost twice the number of cameras in the H.264 standard. H.265 technology can not only halve the bandwidth pressure, but also halve the storage capacity.
So when you choose a switch, you should first make an estimate based on the actual situation, and then decide which 100M or 1000M switch to choose.