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Fast switch or gigabit switch?
- Apr 19, 2018 -

Actual bandwidth?

 

The actual bandwidth of our commonly used switches is 50%-70% of the theoretical value, so the actual bandwidth of a 100Mbit is 50M-70M.

 

How much bandwidth does each camera need? Let us introduce a concept - code rate first.

 

The code rate is a parameter that describes the size of the video data. The unit is usually Kbps, which means how many Kb data per second. If you set this parameter to 1024, the unit can be converted to Mbps, which is how many Mb data per second.

 

 

Common code rate -H.264

 

For Hikvision H.264 network cameras, when calculating the code rate, it is usually necessary to add the size of the main stream and the size of the substream.

 

(*The main stream is generally a high-definition picture for recording and single-screen display; the sub-stream is usually a standard definition picture for network transmission or multi-picture display, usually 0.5M)

 

The common code rates for cameras with different pixels are as follows:

 

100W/130W = 2.5M

200W=4.5M

300W=6.5M

 

If you use a 100M switch, the actual bandwidth is calculated as 50M:

 

50÷2.5=20 It can connect 20 100W/130W cameras

50÷4.5=11 You can connect 11 200W cameras

50÷6.5=7 that can connect 7 300W cameras

 

 

Common code rate -H.265

The H.265 technology halved the code stream, and the common code rate of cameras with different pixels is as follows:

 

200W=2.5M

300W=3.5M

400W=4.5M

 

It is also a 100 megabit switch and is calculated at a 50% utilization rate.

 

50÷2.5=20 It can connect 20 200W cameras

50÷3.5=14 It is possible to connect 14 300W cameras

50÷4.5=11 You can connect 11 400W cameras

 

Gigabit switch or Gigabit port?

 

Usually, the access layer (mainly connected to the camera) switches only need 1 or 2 ports to be Gigabit ports. Because for the network port connected to the camera, it only needs to meet the code stream transmission of the corresponding single camera, usually not more than 10M.

 

The network port that is under pressure is the network port that collects data connected to a video recorder or other aggregation device. The data volume of this network port is the sum of the bit rates that we calculated before. If the sum of code rates exceeds 50M, only one or two switches with Gigabit Ethernet ports can be purchased.