Windows的TCP協議參數

 　　登錄編輯程式：regedit

　　表項：HKEY_LOCAL_MACHINESYSTEMCurentControlSetServicesTcpipParameters

　　視窗擴大因子 & 時間戳記選項

　　Tcp1323Opts REG_DWORD 0x00000001 (1)

　　Tcp1323Opts的取值如下：

　　0 - disable RFC 1323 options.禁用視窗擴大因子和時間戳記選項，是預設值。

　　1 - window scaling enabled only.只啟用視窗擴大因子選項。

　　2 - timestamp enabled only.只啟用時間戳記選項。

　　3 - both options enabled.同時啟用視窗擴大因子和時間戳記選項。

　　SACK選項

　　SackOpts REG_DWORD 0x00000001 (1)

　　SackOpts取值範圍為0 | 1,預設值為1.

　　描述：

　　Enables and disables the Selective Acknowledgement (SACK) feature of Windows Server 2003 TCP/IP.

　　SACK is specified in RFC 2018.

　　TcpMaxDupAcks

　　TcpMaxDupAcks REG_DWORD 0x00000002 (2)

　　TcpMaxDupAcks的取值範圍為1-3,預設為2.而Linux的預設值為3.

　　描述：

　　Specifies how many duplicate ACks (ACKs for the same sequence numbers) constitute a signal to

　　retransmit a segment.

　　When data arrives with a sequence number that is greater than expected, the receiver assumes that data

　　with the expected number was dropped, and it immediately sends an ACK with the ACK number set to the

　　expected sequence number. The receiver sends ACKs set to the same missing number each time it receives

　　a TCP segment that has a sequence number greater than expected.

　　The sender recognizes the duplicate ACKs and sends the missing segment.

　　擁塞控制演算法

　　微軟最新的TCP擁塞控制演算法為Compound TCP (CTCP)，windows 7預設不啟用。

　　(1)windows Vista/2008/7

　　CTCP is enabled by default in computers running beta versions of Windows Server 2008 and disabled

　　by default in computers running Windows Vista and 7.

　　CTCP can be enabled with the command:

　　> netsh interface tcp set global congestionprovider=ctcp

　　or disabled with the command:

　　> netsh interface tcp set global congestionprovider=none

　　To display the current setting for CTCP use:

　　> netsh interface tcp show global

　　Parameter "Add-On Congestion Control Provider" will either have a value of "none" if CTCP is disabled

　　or "ctcp" if it is enabled.

　　(2)Windows 8

　　CTCP is now enabled using PowerShell as netsh is deprecated:

　　> set-nettcpsetting -Settingname Custom -CongestionProvider CTCP

　　(3)Windows 2003 & XP x64

　　A hotfix is available that adds CTCP support to 64 bit Windows XP and Windows Server 2003.

　　The following registry key can be set to 1 to enable, or 0 to disable:

　　> HKEY_LOCAL_MACHINESYSTEMCurrentControlSetServicesTcpipParametersTCPCongestionControl

　　最大接收視窗

　　TcpWindowSize REG_DWORD number of bytes

　　取值範圍：0-0x3FFFFFFF.

　　描述：

　　In practice the TCP/IP stack will round the number set to the nearest multiple of maximum segment size

　　(MSS)。 Values greater than 64KB can be achieved only when connecting to other systems that support

　　RFC 1323 Window Scaling.

　　初始值

　　the smaller of the following values:

　　0xFFFF (65536)

　　GlobalMaxTcpWindowSize

　　The larger of four times the MSS (5840)

　　16384 rounded up to an even multiple of the MSS

　　The stack also tunes itself based on the media speed:

　　Below 1 Mbps: 8KB

　　1 Mbps - 100 Mbps: 17KB

　　Greater than 10 Mbps: 64KB

　　This parameter determines the maximum TCP receive window size offered.

　　全域最大接收緩衝

　　GlobalMaxTcpWindowSize REG_DWORD number of bytes

　　取值範圍：0-0x3FFFFFFF.

　　Default: This parameter does not exist by default.

　　描述：

　　Determines the largest TCP receive window that the system offers.

　　The TcpWindowSize parameter can be used to set the receive window on a per-interface basis.

　　This parameter can be used to set a global limit for the TCP window size on a system-wide basis.