Reserved bandwidth in Windows: what it is and how to manage it

In all Microsoft Windows operating systems since the XP version, we have an option called ” reserved bandwidth “, this option determines the percentage of connection bandwidth that the system can reserve at a certain time. This value limits the bandwidth reservations combined by all the programs running on the system, in order to prevent one program from being able to “hog” all the bandwidth of the Internet connection. Today in RedesZone we are going to explain in detail what this functionality is and how to manage it properly.

What is reserved bandwidth?

This functionality is present in Windows operating systems from the Windows XP version, therefore, if you use the latest versions of Windows 10 we will also have it available. This function is very important because it depends on it that web browsing, downloads and other tasks that we carry out on the Internet are done correctly and without problems of slowness or saturation. This functionality that we can modify is used to determine what percentage of the bandwidth available in the system can be reserved by the different programs.

By default, the reservable bandwidth value is 80%, this means that the packet scheduler limits the system to 80% of a connection, although logically it can be changed without problems through the Windows 10 administrative tools. Yes We enable the option and define a specific parameter, this percentage will be the one that will be used, if we disable the functionality of ” limit reservable bandwidth ” by default Windows will use 80%. A very important detail is that through the Windows registry we can also establish a bandwidth limit for a specific network adapter (WiFi or wired network card), in this case, the option to “limit bandwidth reservable »will not be used, and the value defined in the Windows registry will be given priority.

This default value of 80% does not mean that QoS is continuously activated, taking 20% ​​of our bandwidth, only in certain cases when a program or application requires it. When there is no program running, by default we will be using 100% of the available bandwidth. This means that, if we disable QoS, it does not mean that you are recovering 20% ​​of the bandwidth that has “disappeared”, but that you will be eliminating the 20% reserved when QoS is not being used.

In principle, it is not advisable to modify this parameter unless you know very well what you are doing, because having 100% bandwidth does not mean that you browse faster or download through BitTorrent at maximum speed, you are already doing that without modifying this parameter. What you will do is, if a program requires the QoS packet scheduler, it will not be available. Microsoft itself has already stated that the Windows operating system does not reserve at any time 20% of the available bandwidth for QoS.

Reservation Bandwidth Limiter Settings

In RedesZone we only recommend modifying the default value of the reservable bandwidth if you know what you are doing, and if you are really going to use it, because QoS is not running continuously. It is possible that if you change this value and a program uses it, you will have problems with that program, therefore, you must be careful when choosing the correct value based on your needs.

The first thing we have to do is click on the «Windows» key on your keyboard, and put the following command:


You will see something like this:

Once you have put this, click on “Enter” and the “Local Group Policy Editor” will open, once you are here, you must go to the following path:

  • Computer Configuration / Administrative Templates / Network / QoS Packet Scheduler

Once inside here, you should go to the section ” Limit reservable bandwidth “, by default it will be in “Not configured”, as we have explained previously, so the default value is 80%. To enable this functionality, click on “Enabled” and define the percentage that we want.

Once we have done it, click on “OK” and proceed to restart our computer to apply the changes correctly. From this moment on, the QoS will have a certain percentage reserved.

Other options that we can configure

In this same section of “Computer Configuration / Administrative Templates / Network / QoS Package Scheduler” we will have the possibility to configure other advanced options at the network level in the Windows operating system. For example, we will have the possibility to configure a DSCP value of packets that meet the specifications, and other DSCP values ​​of packages that do not meet the specifications. Within this configuration, we will be able to configure the type of best effort service, controlled load service, guaranteed service, network control service and qualitative service. We must remember that the DSCP (Differentiated Services Code Point) protocol is a fundamental protocol in QoS, and is responsible for differentiating the quality of communication that the data that is transported has, in order to prioritize these packages. Any QoS has both the DSCP functionality as well as the CoS function to prioritize the different packets. Finally, other available options are to change the layer 2 priority values, in this case we will also have the same options as before in the DSCP values.

In principle, with all the default values ​​of the Windows 10 operating system, Internet browsing and downloads should work as well as possible, being able to squeeze the maximum bandwidth from our Internet connection, so modifying these parameters will surely not solve your problem. Here are some tips to detect and solve possible problems:

  • Connect by cable directly to the router instead of WiFi, and check if you still have problems.
  • Check if you have problems with other computers as well, or if all devices work fine except a Windows computer.
  • Verify the drivers of the network card, go to the manufacturer’s website and download the latest version that usually corrects errors.
  • Check that the router is working properly, without any red lights, and that the Internet connection is working properly.

We hope that, with these basic tips without going too deep, you can detect possible bandwidth or speed problems on your computer.

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