QoS is a term describing the network and telephony system performance. In this blog, we’ll focus more on the network aspect of the QoS.
The term QoS refers to 2 things, one of which is the quality of the network service and how it is measured (Read here to find out).
Before we move on, here’s a video to help with understand what a network really is:
QoS as a Resource Control Mechanism
The other thing that QoS refers to is the prioritizing of certain applications so that their network access and performance is guaranteed. It is a resource control mechanism. This means that QoS (resource control) actually gives more network performance to certain applications while sacrificing others, hence the term prioritizing.
For example, you enable QoS resource control for your online game. At the same time, you are downloading a video. QoS resource control will ensure that your online game will not lag, but your video downloading speed will also noticeably slow down.
In more technical terms, this means that the packets from certain applications are prioritized in being sent and received, and network resources are reserved for these applications. In reservation terms, QoS resource control reserves network resources for packets from these applications
Some Terms to Know
- Packets:Data from applications which are cut into smaller chunks to be sent over the network.
- Throughput: Rate of successful packet/data delivery. (further explanation in different article)
- Packet Drop: Packets that fail to arrive at the destination.
- Destination: The intended receiving device (PC or server etc.) for the packet
- Source : The origin of the packet, also known as packet sender.
- Latency (Ping): The time needed for data to arrive to the destination (one-way).
- One-Way: Refers to the traveling of data from the sender to the receiver only.
- Two-Way: Refers to the traveling of data from the sender to the receiver and then back to the sender.
Network - Quality of Service 
I’m confused about paragraph 4.
Is the technical term and the reservation term different ?
OR is this what it is meant ?
The technical term, packets are prioritize and network resource are reserved FOR the applications while the reservation term just reserves network resource FROM the applications.
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I’m sorry about the confusion. To clarify, paragraph 4 refers to the resource control mechanism.
QoS can either refer to the quality of the internet itself, or the resource control mechanism, but not both at the same time.
Thank you for your feedback. Changes will be made to clarify the confusion.
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Say, let say if I’m watching a movie online and downloading games at the same time. Priority goes from most to least: Game downloads > Online movies. Obviously, the game download has better network performance. But sometimes, what if the priorities are switched?
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If the priorities were switched, online movies will stream much better with less stutter and loading pauses. However, don’t suddenly expect your 1Mbps to stream HD videos smoothly.
Note that setting online movies as 1st priority will “kill” your download, so expect failed downloads or much slower speeds, unless your connection is fast enough (fiber optics comes to mind).
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Is it the Qos can control or adjust the bandwidth for downloading the video and online game?
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Yes, QOS resource control can control the allocation of bandwidth for downloading video or playing online games by means of prioritizing. You can adjust the QOS mechanism yourself to either prioritize online gaming more or video downloading. However, QoS adjustments are router/modem specific. Some computer network interfaces (MSI laptops) also provide their own QoS management system, which is similar to the router/modem version.
Note that when adjusting QoS priority order, take into account the tendency of applications to use bandwidth. In particular, video and file download bandwidth needs override online gaming bandwidth requirements.
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hmmm, which means QOS also can be used on those torrent downloader or any downloader to priotize the internet speed for the user based on which application required more internet speed?
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Well if you put it that way, yeah. QoS enables you to prioritise which applications require more priority over the other. Examples can also include online games, streaming videos and such. By the way, certain torrent downloader basically has somewhat of QoS enabled provided the settings are optimised properly.
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Latency is the time needed for a package to reach the destination. That term is also widely known as ping in the world of online games… Ping fluctuating in online games is also popular. Why is that? In short, why would ping fluctuate in an online game if QoS is only prioritizing that game (only program running) ??
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Consider a very busy router is located between you and the server, and your data needs to pass through the router to reach the server. The router will route your data at times (ping drops), while it would route data to other places at times and place your packet on queue (ping increases)(Congestion). This can happen with every router your data passes through on the way to the server. Same thing happens on the server itself, whereby it processes data from other players and put yours on queue and vice versa.
Consider that this happens to all users data, it is no surprise that ping fluctuates. Furthermore, the reply packets from the server are also subjected to this as well.
An extra note, QoS prioritizing for games on your PC/modem/router does not help this, as the cause of ping fluctuation is on the path to the server, not due to your (client) side.
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