Vista TCP Window Scaling Auto Tuning May Slow Down Network Performance Vista中的TCP window scaling自動調諧可能放緩的網絡性能

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 ）的金額收到的數據（字節） ，可以緩衝期間，一個連接。 According to據 Wikipedia維基百科 , 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. ，發送主機可以發送最多只能說，數據量之前，它必須等待一個承認和窗口更新從接收主機。 When a receiver advertises the window size of 0, the sender stops sending data and starts the persist timer.當一個接收器所宣傳的窗口大小為0 ，發件人停止發送數據並啟動堅持計時器。 The persist timer is used to protect TCP from the dead lock situation.該堅持的計時器是用來保護的TCP從死鎖情況。 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.死鎖情況可當新的窗口大小更新從接收機是失去了和接收機已沒有更多數據傳送的同時，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.當堅持計時器到期的TCP發送者發出了一個小郵包，使接收acks包與新的窗口大小和TCP可以收回從這種情況。

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窗口大小領域的控制數據流和有限之間2和65535個字節，並不能擴大了。 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，結垢的因素是用來取得更大的TCP接收窗口的大小，以達到更有效地利用高帶寬的網絡。 The那個 TCP window scale option TCP窗口規模選項 is used to increase the maximum window size from 65,535 bytes to 1 Gigabyte.是用來增加最多的窗口大小從65535字節1 GB的。 Scaling up to larger TCP congestion window sizes is a part of what is necessary for TCP Tuning.規模較大的TCP擁塞窗口的大小是一個部分，什麼是必要的TCP微調。 The window scale option is used only during the TCP 3-way handshake.窗口規模的選擇是只用在了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.窗口規模的價值，代表了雙邊投資協定的數量，以左轉向16位窗口大小領域，並可以設置從0 （無轉移） 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.在處理與網絡性能變慢，在Vista中，問題可能是由於上述的TCP window scaling選項，許多老年人的路由器和防火牆和數據包不妥善落實的TCP window scaling ，和重寫的窗口比例因子在傳輸，造成發送和接收雙方承擔不同的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.情況的原因故障的網際網路連線，非穩定的交通，這是非常緩慢，或網路連線，就是只適用於間歇性。 In Vista, the connection may appear to start working again for no reason after a while.在Vista中，連接可能會出現開始工作，再次為沒有理由後，雖然。 If “Diagnose Problem” is selected in Vista, an error message will display “Cannot communicate with primary DNS server.”如果“診斷問題”是選定在Vista中的錯誤訊息會顯示“無法溝通的主DNS服務器” 。

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.旁邊， Windows Vista的增強，進一步的TCP window scaling自動調整功能，其中的TCP協議棧在Vista系統會自動調重彈，並調整rwin大小的比例提高全尺寸的TCP段期間使用的批量數據傳輸的基礎上，網絡的情況它遇到的。 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個自定義大小的TCP / IP接收窗口（ rwin ）的大小與列入新的自動調整功能，除非應用它的自我用途so_rcvbuf 。 However, Vista TCP auto tuning feature may get things wrong sometimes.不過， Vista中的TCP自動調整功能可能得到的東西，有時是錯誤的。 Instead of optimal true receive window size, incompatible and out of range RWIN size may be used.而不是最優的真實接收窗口大小，兼容，超出範圍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.默認情況下， Vista的在正常的自動調諧水平將使用rwin的大小256字節，與規模因素， 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.這個值是並不適合所有路由器和服務器，其中不支持的TCP規模的因素，並繼續溝通與65536個字節。 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.適用於Windows Vista ，用戶可以改變行為方式和Vista的自動調rwin ，用“的netsh ”命令，以將該值設置為“ autotuninglevel ”參數。

To change the value for Receive Window Auto-Tuning Level parameter in Vista,改變值為接收窗口自動調諧水平的參數在Vista中， run elevated command prompt運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. ，然後鍵入下列命令之一，這取決於您的喜好，您要如何Vista中使用rwin大小。

netsh interface tcp set global autotuninglevel=disabled 在netsh界面的TCP設置全球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，並適當人選鎖定rwin接收窗口為預設值65536字節。

netsh interface tcp set global autotuninglevel=highlyrestricted 在netsh界面的TCP設置全球autotuninglevel = highlyrestricted
Allow for the receive window to grow beyond the default value, but do so very conservatively.允許接收窗口的增長超出了預設值，但這樣做非常保守。 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將默認情況下使用rwin的16384個字節，與規模因素2 。

netsh interface tcp set global autotuninglevel=restricted 在netsh界面的TCP設置全球autotuninglevel =限制
Allow for the receive window to grow beyond the default value, but limit such growth in some scenarios.允許接收窗口的增長超出了預設值，但限制這種增長在某些情況下。

netsh interface tcp set global autotuninglevel=normal在netsh界面的TCP設置全球autotuninglevel =正常
Allow for the receive window to grow to accommodate almost all scenarios.允許接收窗口成長，以容納幾乎所有的情況。 The default setting in Vista.默認設置在Vista中。 Specifying this command mean you want to turn back on AutoTuning feature.指定這個命令意味著你要回頭就自動調諧功能。

netsh interface tcp set global autotuninglevel=experimental 在netsh界面的TCP設置全球autotuninglevel =實驗
Allow for the receive window to grow to accommodate extreme scenarios.允許接收窗口成長，以容納極端的情況。 Note The experimental value can decrease performance in common scenarios.注意實驗值可以減少表現在常見的情況。 This value should be used only for research purposes.此值應只用於研究用途。

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.用戶應嘗試各種可能的配置為Vista中的TCP rwin自動調校水平，以獲得最佳的價值，提高網絡性能和提高下載速度。

IMPORTANT : This is a machine translated page which is provided "as is" without warranty. 重要說明 ：這是一個機器翻譯網頁是“按原樣”提供的擔保。 Machine translation may be difficult to understand.機器翻譯可能很難理解。 Please refer to請參閱 original English article原來的英語文章 whenever possible.只要有可能。

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