Vista TCP Window Scaling Auto Tuning May Slow Down Network Performance Vista中的TCP window scaling自动调谐可能放缓的网络性能

TCP receive window size (RWIN) is the amount of received data (in bytes) that can be buffered during a connection. TCP接收窗口的大小（ rwin ）的金额收到的数据（字节） ，可以缓冲期间，一个连接。 According to据 Wikipedia维基百科 , the sending host can send only up to that amount of data before it must wait for an acknowledgment and window update from the receiving host. ，发送主机可以发送最多只能说，数据量之前，它必须等待一个承认和窗口更新从接收主机。 When a receiver advertises the window size of 0, the sender stops sending data and starts the persist timer.当一个接收器所宣传的窗口大小为0 ，发件人停止发送数据并启动坚持计时器。 The persist timer is used to protect TCP from the dead lock situation.该坚持的计时器是用来保护的TCP从死锁情况。 The dead lock situation could be when the new window size update from the receiver is lost and the receiver has no more data to send while the sender is waiting for the new window size update.死锁情况可当新的窗口大小更新从接收机是失去了和接收机已没有更多数据传送的同时，寄件人是等待新的窗口大小更新。 When the persist timer expires the TCP sender sends a small packet so that the receivers ACKs the packet with the new window size and TCP can recover from such situations.当坚持计时器到期的TCP发送者发出了一个小邮包，使接收acks包与新的窗口大小和TCP可以收回从这种情况。

The TCP window size field controls the flow of data and is limited to between 2 and 65,535 bytes, and cannot be expanded anymore.的TCP窗口大小领域的控制数据流和有限之间2和65535个字节，并不能扩大了。 Thus, a scaling factor is used to get a larger TCP receive window size to achieve more efficient use of high bandwidth networks.因此，结垢的因素是用来取得更大的TCP接收窗口的大小，以达到更有效地利用高带宽的网络。 The那个 TCP window scale option TCP窗口规模选项 is used to increase the maximum window size from 65,535 bytes to 1 Gigabyte.是用来增加最多的窗口大小从65535字节1 GB的。 Scaling up to larger TCP congestion window sizes is a part of what is necessary for TCP Tuning.规模较大的TCP拥塞窗口的大小是一个部分，什么是必要的TCP微调。 The window scale option is used only during the TCP 3-way handshake.窗口规模的选择是只用在了TCP 3向握手。 The window scale value represents the number of bits to left-shift the 16-bit window size field, and can be set from 0 (no shift) to 14.窗口规模的价值，代表了双边投资协定的数量，以左转向16位窗口大小领域，并可以设置从0 （无转移） 14 。

When dealing with slow network performance in Vista, the problem may be due to the above mentioned TCP Window Scaling option, where many older routers and and packet firewalls do not properly implement TCP Window Scaling, and rewrite the window scaling factor during a transmission, and causing sending and receiving sides to assume different TCP window sizes.在处理与网络性能变慢，在Vista中，问题可能是由于上述的TCP window scaling选项，许多老年人的路由器和防火墙和数据包不妥善落实的TCP window scaling ，和重写的窗口比例因子在传输，造成发送和接收双方承担不同的TCP窗口大小。 The situation causes malfunction Internet connection, non-stable traffic that is very slow, or network connection that is only available intermittently.情况的原因故障的网际网路连线，非稳定的交通，这是非常缓慢，或网路连线，就是只适用于间歇性。 In Vista, the connection may appear to start working again for no reason after a while.在Vista中，连接可能会出现开始工作，再次为没有理由后，虽然。 If “Diagnose Problem” is selected in Vista, an error message will display “Cannot communicate with primary DNS server.”如果“诊断问题”是选定在Vista中的错误讯息会显示“无法沟通的主DNS服务器” 。

Beside, Windows Vista enhances further TCP window scaling with auto tuning feature, where TCP stack in Vista system will auto tune and adjust the RWIN size to increase the percentage of full-sized TCP segments that are used during bulk data transmission based on the network scenario it encountered.旁边， Windows Vista的增强，进一步的TCP window scaling自动调整功能，其中的TCP协议栈在Vista系统会自动调重弹，并调整rwin大小的比例提高全尺寸的TCP段期间使用的批量数据传输的基础上，网络的情况它遇到的。 And thus it’s no longer possible to specify a custom size for the TCP/IP Receive Window (RWIN) size with the inclusion of new auto tuning feature, unless the application it self uses SO_RCVBUF.因此，它的已不再可能指定一个自定义大小的TCP / IP接收窗口（ rwin ）的大小与列入新的自动调整功能，除非应用它的自我用途so_rcvbuf 。 However, Vista TCP auto tuning feature may get things wrong sometimes.不过， Vista中的TCP自动调整功能可能得到的东西，有时是错误的。 Instead of optimal true receive window size, incompatible and out of range RWIN size may be used.而不是最优的真实接收窗口大小，兼容，超出范围rwin大小可使用。

By default, Vista in normal auto tuning level will use RWIN size of 256 bytes with a scale factor of 8.默认情况下， Vista的在正常的自动调谐水平将使用rwin的大小256字节，与规模因素， 8 。 This value is not suitable for all routers and servers which does not support TCP scale factor, and continue to communicate with 65536 bytes.这个值是并不适合所有路由器和服务器，其中不支持的TCP规模的因素，并继续沟通与65536个字节。 For Windows Vista, users can change the behavior and the way Vista automatically tune the RWIN, by using “netsh” command to set the value for “autotuninglevel” parameter.适用于Windows Vista ，用户可以改变行为方式和Vista的自动调rwin ，用“的netsh ”命令，以将该值设置为“ autotuninglevel ”参数。

To change the value for Receive Window Auto-Tuning Level parameter in Vista,改变值为接收窗口自动调谐水平的参数在Vista中， run elevated command prompt运行提升的命令提示符 , and then type in one of the following commands, depending on your preference how you want Vista to use the RWIN size. ，然后键入下列命令之一，这取决于您的喜好，您要如何Vista中使用rwin大小。

netsh interface tcp set global autotuninglevel=disabled 在netsh界面的TCP设置全球autotuninglevel =禁用
Disable the autotunning feature in Vista completely, and fit and lock the RWIN receive window to default value 65536 bytes.禁用autotunning功能在Vista中完全，并适当人选锁定rwin接收窗口为预设值65536字节。

netsh interface tcp set global autotuninglevel=highlyrestricted 在netsh界面的TCP设置全球autotuninglevel = highlyrestricted
Allow for the receive window to grow beyond the default value, but do so very conservatively.允许接收窗口的增长超出了预设值，但这样做非常保守。 In this mode, Vista will by default use RWIN of 16,384 bytes with a scale factor of 2.在此模式下， Vista将默认情况下使用rwin的16384个字节，与规模因素2 。

netsh interface tcp set global autotuninglevel=restricted 在netsh界面的TCP设置全球autotuninglevel =限制
Allow for the receive window to grow beyond the default value, but limit such growth in some scenarios.允许接收窗口的增长超出了预设值，但限制这种增长在某些情况下。

netsh interface tcp set global autotuninglevel=normal在netsh界面的TCP设置全球autotuninglevel =正常
Allow for the receive window to grow to accommodate almost all scenarios.允许接收窗口成长，以容纳几乎所有的情况。 The default setting in Vista.默认设置在Vista中。 Specifying this command mean you want to turn back on AutoTuning feature.指定这个命令意味着你要回头就自动调谐功能。

netsh interface tcp set global autotuninglevel=experimental 在netsh界面的TCP设置全球autotuninglevel =实验
Allow for the receive window to grow to accommodate extreme scenarios.允许接收窗口成长，以容纳极端的情况。 Note The experimental value can decrease performance in common scenarios.注意实验值可以减少表现在常见的情况。 This value should be used only for research purposes.此值应只用于研究用途。

Users should try out the various possible configurations for the Vista TCP RWIN Auto Tuning Level in order to get the best value that improve network performance and increase download speed.用户应尝试各种可能的配置为Vista中的TCP rwin自动调校水平，以获得最佳的价值，提高网络性能和提高下载速度。

IMPORTANT : This is a machine translated page which is provided "as is" without warranty. 重要说明 ：这是一个机器翻译网页是“按原样”提供的担保。 Machine translation may be difficult to understand.机器翻译可能很难理解。 Please refer to请参阅 original English article英文原版的文章 whenever possible.只要有可能。

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