事实(请说明任何虚假陈述)：
>我在两个相隔80毫秒的站点之间有100 Mbps的连接
>这是一个长胖连接,可以从大的TCP窗口大小中受益,可能高达100 Mbps * 0.08秒= 1,000,000字节
>两台计算机都运行Windows Server 2012.“接收窗口自动调整级别”在两者上均正常.两者都禁用“窗口缩放启发式”.
>我一边是“iperf -s”,另一边是“iperf -c”.转移发生在5 Mbps.我从另一个方向得到了相同的结果.
>双方都宣称在其SYN中支持TCP滑动窗口.
>接收方请求TCP窗口大小为64,512字节(0xFC00)
在整个运行过程中,TCP窗口缩放值为“无移位”
(0x000的).
>网络能够处理更大的窗口大小(参见序列
图表)
>接收器使窗口小于网络支持
>此连接发生在IPSEC VPN中.隧道接口的MTU在两个方向上减少到1400字节.
题
>为什么接收器保持窗口小？
无答案
>网络坏了
在同一网络上运行的Linux机器将TCP窗口打开到1.5兆字节,并以6倍的带宽传输数据
>启用窗口缩放启发式扫描
窗口缩放启发式被禁用(参见下面的“netsh interface tcp show heuristics”的输出)
>接收窗口自动调整级别不正常
接收窗口自动调整级别正常(参见下面的“netsh interface tcp show global”的输出)
>这在ESXi中的虚拟机上运行不正常
在同一主机上运行的虚拟Linux机器上,性能提高了6倍.
2015年6月12日下午4:30更新
我通过将linux放在连接的一端来修改测试.果然,当linux向Windows Server 2012发送数据时,Windows提供了一个太小的TCP接收窗口(64,512字节).
当我将数据从Windows发送到linux时,linux提供了足够大的TCP接收窗口(1,365,120字节).但是,Windows限制发送到飞行中最多约60,000个字节.
更新于2015年6月13日下午3点(太平洋时间)
更接近根本原因的一步.在我的设置中,SO_SNDBUF和SO_RCVBUF都没有设置(通过iperf).这些是有效绑定接收窗口的发送和接收缓冲区.未指定这些值时,Windows Server 2012提供的默认值为64 kB.所以现在的问题是：
题
>如果未指定一个,为什么Windows Server 2012不会动态增加SO_SNDBUF / SO_RCVBUF以适应MSDN所述的长胖管道？
无答案
>“netsh winsock show autotuning”已禁用
它已启用.
更新于2015年8月24日下午4点(太平洋时间)
netsh显然已被Set-NetTcpsetting和family取代. Get-NetTcpsetting结合Get-NetTCPConnection显示我在“互联网”制度下运行,它为我提供了以下设置：
SettingName : Internet MinRto(ms) : 300 InitialCongestionWindow(MSS) : 4 CongestionProvider : CTCP CwndRestart : False DelayedAckTimeout(ms) : 50 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384
发件人TCP设置
PS C:\Users\acs> netsh interface tcp show global Querying active state... TCP Global Parameters ---------------------------------------------- Receive-Side Scaling State : enabled Chimney Offload State : disabled NetDMA State : disabled Direct Cache Access (DCA) : disabled Receive Window Auto-Tuning Level : normal Add-On Congestion Control Provider : none ECN Capability : enabled RFC 1323 Timestamps : disabled Initial RTO : 3000 Receive Segment Coalescing State : enabled PS C:\Users\acs> netsh interface tcp show heuristics TCP Window Scaling heuristics Parameters ---------------------------------------------- Window Scaling heuristics : disabled Qualifying Destination Threshold : 3 Profile type unkNown : normal Profile type public : normal Profile type private : normal Profile type domain : normal PS C:\Users\acs> Get-NetTcpsetting SettingName : Automatic MinRto(ms) : InitialCongestionWindow(MSS) : CongestionProvider : CwndRestart : DelayedAckTimeout(ms) : MemoryPressureProtection : AutoTuningLevelLocal : AutoTuningLevelGroupPolicy : AutoTuningLevelEffective : EcnCapability : Timestamps : InitialRto(ms) : ScalingHeuristics : DynamicPortRangeStartPort : DynamicPortRangeNumberOfPorts : SettingName : Custom MinRto(ms) : 20 InitialCongestionWindow(MSS) : 4 CongestionProvider : DCTCP CwndRestart : True DelayedAckTimeout(ms) : 10 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384 SettingName : Compat MinRto(ms) : 300 InitialCongestionWindow(MSS) : 2 CongestionProvider : Default CwndRestart : False DelayedAckTimeout(ms) : 200 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384 SettingName : Datacenter MinRto(ms) : 20 InitialCongestionWindow(MSS) : 4 CongestionProvider : DCTCP CwndRestart : True DelayedAckTimeout(ms) : 10 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384 SettingName : Internet MinRto(ms) : 300 InitialCongestionWindow(MSS) : 4 CongestionProvider : CTCP CwndRestart : False DelayedAckTimeout(ms) : 50 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384
发件人SYN
No. Time Source Destination Protocol Length Delta Sequence number AckNowledgment number Bytes in flight Calculated window size Info
814 5.036577000 10.10.0.21 10.11.0.1 TCP 66 0.000000000 0 0 64512 49758→5001 [SYN,ECN,CWR] Seq=0 Win=64512 Len=0 MSS=1460 WS=1 SACK_PERM=1
Frame 814: 66 bytes on wire (528 bits),66 bytes captured (528 bits) on interface 0
Ethernet II,Src: 00:11:22:33:44:55,Dst: aa:bb:cc:dd:ee:ff
Internet Protocol Version 4,Src: 10.10.0.21 (10.10.0.21),Dst: 10.11.0.1 (10.11.0.1)
Transmission Control Protocol,Src Port: 49758 (49758),Dst Port: 5001 (5001),Seq: 0,Len: 0
Source Port: 49758 (49758)
Destination Port: 5001 (5001)
[Stream index: 73]
[TCP Segment Len: 0]
Sequence number: 0 (relative sequence number)
AckNowledgment number: 0
Header Length: 32 bytes
.... 0000 1100 0010 = Flags: 0x0c2 (SYN,CWR)
Window size value: 64512
[Calculated window size: 64512]
Checksum: 0x1451 [validation disabled]
Urgent pointer: 0
Options: (12 bytes),Maximum segment size,No-Operation (nop),Window scale,SACK permitted
Maximum segment size: 1460 bytes
No-Operation (nop)
Window scale: 0 (multiply by 1)
Kind: Window Scale (3)
Length: 3
Shift count: 0
[Multiplier: 1]
No-Operation (nop)
No-Operation (nop)
TCP SACK Permitted Option: True
序列图的发送者视角
接收器TCP设置
PS C:\Users\acs> netsh interface tcp show global Querying active state... TCP Global Parameters ---------------------------------------------- Receive-Side Scaling State : enabled Chimney Offload State : disabled NetDMA State : disabled Direct Cache Access (DCA) : disabled Receive Window Auto-Tuning Level : normal Add-On Congestion Control Provider : none ECN Capability : enabled RFC 1323 Timestamps : disabled Initial RTO : 3000 Receive Segment Coalescing State : enabled PS C:\Users\acs> netsh interface tcp show heuristics TCP Window Scaling heuristics Parameters ---------------------------------------------- Window Scaling heuristics : disabled Qualifying Destination Threshold : 3 Profile type unkNown : normal Profile type public : normal Profile type private : normal Profile type domain : normal PS C:\Users\acs> Get-NetTcpsetting SettingName : Automatic MinRto(ms) : InitialCongestionWindow(MSS) : CongestionProvider : CwndRestart : DelayedAckTimeout(ms) : MemoryPressureProtection : AutoTuningLevelLocal : AutoTuningLevelGroupPolicy : AutoTuningLevelEffective : EcnCapability : Timestamps : InitialRto(ms) : ScalingHeuristics : DynamicPortRangeStartPort : DynamicPortRangeNumberOfPorts : SettingName : Custom MinRto(ms) : 20 InitialCongestionWindow(MSS) : 4 CongestionProvider : DCTCP CwndRestart : True DelayedAckTimeout(ms) : 10 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384 SettingName : Compat MinRto(ms) : 300 InitialCongestionWindow(MSS) : 2 CongestionProvider : Default CwndRestart : False DelayedAckTimeout(ms) : 200 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384 SettingName : Datacenter MinRto(ms) : 20 InitialCongestionWindow(MSS) : 4 CongestionProvider : DCTCP CwndRestart : True DelayedAckTimeout(ms) : 10 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384 SettingName : Internet MinRto(ms) : 300 InitialCongestionWindow(MSS) : 4 CongestionProvider : CTCP CwndRestart : False DelayedAckTimeout(ms) : 50 MemoryPressureProtection : Enabled AutoTuningLevelLocal : normal AutoTuningLevelGroupPolicy : NotConfigured AutoTuningLevelEffective : Local EcnCapability : Enabled Timestamps : disabled InitialRto(ms) : 3000 ScalingHeuristics : disabled DynamicPortRangeStartPort : 49152 DynamicPortRangeNumberOfPorts : 16384
接收器SYN
No. Time Source Destination Protocol Length Delta Sequence number AckNowledgment number Bytes in flight Calculated window size Info
817 5.110501000 10.11.0.1 10.10.0.21 TCP 70 0.073924000 0 1 64512 5001→49758 [SYN,ACK,ECN] Seq=0 Ack=1 Win=64512 Len=0 MSS=1460 WS=1 SACK_PERM=1 [ETHERNET FRAME CHECK SEQUENCE INCORRECT]
Frame 817: 70 bytes on wire (560 bits),70 bytes captured (560 bits) on interface 0
Ethernet II,Src: aa:bb:cc:dd:ee:ff,Dst: 00:11:22:33:44:55
Internet Protocol Version 4,Src: 10.11.0.1 (10.11.0.1),Dst: 10.10.0.21 (10.10.0.21)
Transmission Control Protocol,Src Port: 5001 (5001),Dst Port: 49758 (49758),Ack: 1,Len: 0
Source Port: 5001 (5001)
Destination Port: 49758 (49758)
[Stream index: 73]
[TCP Segment Len: 0]
Sequence number: 0 (relative sequence number)
AckNowledgment number: 1 (relative ack number)
Header Length: 32 bytes
.... 0000 0101 0010 = Flags: 0x052 (SYN,ECN)
Window size value: 64512
[Calculated window size: 64512]
Checksum: 0xb5bb [validation disabled]
Urgent pointer: 0
Options: (12 bytes),SACK permitted
Maximum segment size: 1460 bytes
No-Operation (nop)
Window scale: 0 (multiply by 1)
Kind: Window Scale (3)
Length: 3
Shift count: 0
[Multiplier: 1]
No-Operation (nop)
No-Operation (nop)
TCP SACK Permitted Option: True
[SEQ/ACK analysis]
序列图的接收器透视图
TCP窗口
我已将此视为特定于驱动程序的问题;在我的情况下,QLogic网络控制器试图使用TCPChimney.此链接描述了Windows 2008中添加的TCPChimney功能 – 但我很确定它仍然适用：
https://support.microsoft.com/en-us/kb/951037
我建议按顺序测试以下内容;每次测试后,重新启动并查看接收器是否按预期开始增加TCP RWIN.
1)在接收计算机上加载网络适配器的最新版本的驱动程序.
1)在接收计算机上禁用TCPChimney
2)禁用所有“TCP接收”卸载.这可以在网络适配器属性的高级设置中找到(与Speed& Duplex设置的区域相同)
3)禁用所有“TCP发送”卸载(也在网络适配器的高级属性中)
(与评论相反“超过65k的大TCP窗口大小对服务器不利,因为那时连接的内存需求增加.单独65k也可能不会让你足够开心.– user303507 2015年8月6日11:30”,大TCP接收Windows本身对服务器不利.在高带宽,高延迟链路(如卫星中继)的情况下,需要大的RWIN值,以便我们在“管道”中有更多的TCP数据.想象一下600 Mbps的连接,延迟为3000毫秒;高带宽链路将限制在大约20 KBps;因为一次只有65 KB的未确认TCP数据可能“在管道中”.)