Summary
Networked Quality of Service (QoS) refers to the various communication or program types that are applied throughout the network connection.
Technology
, these technologies
are not just dependent on The best effort "connect. QoS mechanisms are built into Microsoft Windows 2000 and Windows XP. This article describes the QoS enhancements provided by Windows XP. This article also provides a reference to the QoS features first introduced in Windows 2000.
QoS for Internet Connection Sharing (ICS)
When a network is connected to another network through a slow link or connection (such as a dial-up line), communication through slow links The delay may increase. The reason for this delay is that the speed recognized by the communication terminal station does not match the speed of the slow link, resulting in a bottleneck of the network path. This only applies to connection-oriented communication (using TCP).
On a relatively fast network (such as 100 Mb/s Ethernet), if the receiving client is running behind a computer running Windows XP's ICS service, and the server that is communicating with this receiving client is located After remote access on a fast network, there is a mismatch. In this case, the receiving client's receiving window is set to a larger value based on the speed at which the receiving client connects to the link. The sender starts sending at a low rate, but if the packet is not lost, the speed will continue to increase and eventually packets of almost full window size will be sent.
This affects other properties of the same network through the TCP connection, so that their packet data awaiting transmission over the slow network may be a long row of the queue. If packet loss occurs, the data must be retransmitted (up to full window size), making the link more clogged.
appropriate solution is to have a computer in the network edge running ICS automatically set the receive window to a smaller size suitable for slow links, specifications covering the receiving clients. This setting does not adversely affect communication because the window size is set accordingly if the receiving client is directly connected to the slow link. This window adjustment is made by the QoS Packet Scheduler component running on the ICS computer.
QoS
modems and remote access As of January 2002, many users are still connected over a slow link to the Internet, such as connection speeds of 56 kilobytes per second. Although the link speed is limited, many users still have to run multiple programs that access the network at the same time. This may include browsing, downloading, emailing, chatting, and even audio or video streaming. Most of these programs use TCP as the basic transport protocol, and each program uses its own connection. A first link
program initially exclusive use, is connected so that it reaches a steady state, so as to achieve full TCP window of data transmission. When the next program starts transmitting data, the connection it uses is constrained by the slow start algorithm, which limits the amount of unacknowledged data that can be transferred. Since the established program is transferring a certain amount of data, the second program takes much longer to reach a steady state, and the same size of data transfer is much slower.
Windows XP running on a slow link, to achieve a reasonable solution called a "deficiency loop (DRR)" is. Windows 2000 also uses this scheme, but in Windows XP, this scheme is turned on by default when slow links are detected. This scenario allocates several data streams and assigns new application data streams to those flows. These flows are automatically serviced in a round-robin fashion, resulting in better network communication response and performance without requiring the user to do any manual configuration.
Clarification of QoS in Terminal Computers Running Windows XP
Like Windows 2000, in Windows XP, programs can also utilize QoS through the QoS Application Programming Interface (API). All programs can share 100% of the network bandwidth, with the exception of programs that require bandwidth priority. Other programs can also use this "reserved" bandwidth, except for the requestor that is sending data. By default, the program reserves a bandwidth that is up to 20 percent of the basic link speed of each interface on the terminal computer. If the amount of data sent by a program that reserves bandwidth does not completely run out of bandwidth, the unused portion of the reserved bandwidth can be used for other data streams on the same host. For more information about the QoS Packet Scheduler is
, please refer to Windows XP help. The Windows 2000 Technology
library provides additional information about Windows 2000 QoS.
Some errors in correcting Windows XP QoS support
Many published technical
articles and newsgroup articles have repeatedly mentioned that Windows XP usually retains QoS for QoS Twenty available bandwidth. From the above article we can conclude that "QoS reserves 20% of the available bandwidth" is wrong.