Allowing data to flow more quickly and efficiently over the network. This is the function of QoS that can prioritize a specific type of traffic.
QoS can be used in networks that have different types of services such as audio, video and data working together. It can also be used with IP CCTV.
Comparing QoS with car traffic
Special vehicles have priority
Have you ever been stuck in traffic in a big city like New York? That's a situation with a huge queue of cars and you're standing still for hours while you see priority cars like ambulances, firefighters, and police running right through.
These special vehicles are like packets that have priority on a computer network. Switches and routers verify that the packets are marked and give them priority to their destination.
Qos stands for Quality of Service and it is very important on a networks with different type of traffic or on networks with services that are super important.
In CCTV we should be careful with the use of QoS, we do not always have to enable it on the cameras, especially if they are all in a single network designed exclusively for monitoring, just like if all the cars in the traffic are normal cars or all of them are ambulances. If all are equal and have the same priority level there is no need to enable QoS because it will cause network devices like switches and routers to use more processing power.
It is necessary to use "end to end QoS"
The idea is simple: you enable QoS on the camera and it will mark the packets that go out to the network. The switches and routers that are in the way must understand this marking and check the priority of the packets to forward them properly.
If one of the switches or routers that are in the path between the camera and the recording or monitor system are not ready to work with QoS, all the effort is wasted.
We can buy switches and routers that have the QoS feature, and then make the proper configuration so that all network traffic flows in order to prioritize the most important services, so in practice it is necessary to configure the camera and each of the devices by where the camera packs will pass.
Types of QoS available on your network
You probably already have heard of the terms DiffServ and IntServ which are the different methods of using QoS.
The first means priority for different types of services, so the DiffServ would then be used for devices to mark the packets to make them "special" so they can travel through the network and the entire verification process by the swithes and routers proceeds as previously explained.
The second process is the resource reservation from start to end of the path, so imagine that a quantity of bandwidth is left available in the camera path to the recorder, no matter whether you are using it or not, this bandwidth is reserved for the camera .
Which method should you use?
Unfortunately there is no direct answer to this question, everything will depend on your type of application and available resources on the network.
However, in most cases DiffServ is used because in this way it is possible to use all available bandwidth for other applications and when the traffic with the QoS tag appears, the device gives priority in the network.
Since Interserv always has this buffer available for the type of service, even if it is not being used, then the other services never use the bandwidth reserved there, which is ultimately a waste of resources.
The bottom line is that you as a professional is the one who will choose the method to use and make the proper settings on your camera and network devices.
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