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Services Utility: QoS RSVP Service

Display Name (?): QoS RSVP
Short Name (?): RSVP
Executable (?): rsvp.exe
Library (?): None.
Depends On (?): TcpIp, Afd, Remote Procedure Call (RPC)
Supports (?): None.
Description (?): Provides network signaling and local traffic control setup functionality for QoS-aware programs and control applets.
OS (?): 2000 Professional, XP Home/Professional, Vista Home/Business, 2000 Server, Server 2003, Vista Server
Startup (?):

Explanation (?):

The QoS RSVP service (quality of service reservation protocol) is used in reserving bandwidth for time critical events. This is done by using priority queuing to schedule data communication, either by raising or lowering the priority of a data communication tunnel. This allows for congestion management so that critical events have more available bandwidth and less than critical events yield to the critical events when required.

In Windows terms this service provides programs with a window of bandwidth that will take priority over less critical data communications. This is done through the QoS Packet Scheduler. Under normal conditions no bandwidth is reserved, but if this service is active and the feature is enabled then programs that support QoS can reserve up to the maximum allowed amount. This amount can be set in group policies and by default this amount is set for 20%. This can be set in gpedit.msc under administrative templates, network, QoS packet scheduler and under the option of "limit reservable bandwidth". Most programs do not use this feature though, so it isn't really an issue. When no programs use this feature then no bandwidth is reserved, so changing this feature is not much of a tweak even though many tweak sites claim it as such.

The benefit of this service varies, but would be the most useful for servers. On a corporate or business network you may want to reserve bandwidth for an application that is mission critical, such as a hospital's patient monitor. Using this feature from this example would mean things such as copying files over the network to the server wouldn't congest the network so much that someone would die because the server was being flooded. This service could also be useful for people with voice over IP (VoIP) phones that use Internet bandwidth for their phone lines, but of course the phone modem would have to support this feature along with Windows.

Most programs in Windows do not use this feature. One program that does though is the Internet COnnection Sharing feature (in Windows XP and above). This allows you to use a computer as a home proxy (router) so that other computers on your network can connect to the Internet through that computer. Since the connection between the Internet to the proxy computer and the proxy computer to the proxying computers are different, the proxying computers have the potential to flood the connection between the proxy server and the Internet, especially if the Internet connection is dial-up. This service has the potential to detect such issues and limit bandwidth from the proxying computers that the proxy server realizes it can support for Internet connectivity.

For the vast majority of people this service is entirely useless. However, by default this service isn't active unless called upon. I would recommend leaving the service to manual unless you know you need it. Also, if you don't need it then I would recommend removing it from your Internet settings. By default most current Windows installs add the QoS Packet Scheduler as a protocol as the means for the service to limit your bandwidth. This can be accessed from the properties of your network settings on a particular network adapter. So if you don't need then you can uninstall this protocol. If you are running a server that uses QoS then you would want to set this to automatic.

Please visit /tools/services/ for the complete Services utility.