請教版上前輩
假 FTTX 20M/5M TCP WINDOWS RWIN 值正常嗎？有做優化*註 但數值不變？
Recommended RWINs: 64400, 128800, 257600, 515200, 1030400
要如何正確修改與鍵入適當的數值？

SpeedGuide.net TCP Analyzer Results
Tested on: 2016.05.27 22:49
IP address: 112.104.xx.xx
Client OS/browser: Linux (Firefox 44.0)

TCP options string: 020405780402080a000075400000000001030307
MSS: 1400
MTU: 1440
TCP Window: 29312 (NOT multiple of MSS)
RWIN Scaling: 7 bits (2^7=128)
Unscaled RWIN : 229
Recommended RWINs: 64400, 128800, 257600, 515200, 1030400
BDP limit (200ms): 1172kbps (147KBytes/s)
BDP limit (500ms): 469kbps (59KBytes/s)
MTU Discovery: ON
TTL: 43
Timestamps: ON
SACKs: ON
IP ToS: 00000000 (0)

註
echo 256960 > /proc/sys/net/core/rmem_default
echo 256960 > /proc/sys/net/core/rmem_max
echo 256960 > /proc/sys/net/core/wmem_default
echo 256960 > /proc/sys/net/core/wmem_max
echo 0 > /proc/sys/net/ipv4/tcp_timestamps
echo 0 > /proc/sys/net/ipv4/tcp_sack
echo 1 > /proc/sys/net/ipv4/tcp_window_scaling

SG FAQ 寫到：
8. The Analyzer reads my RWIN value incorrectly ?
Tags: TCP Window, RWIN
The TCP Analyzer reads the TCP Window (RWIN) value from actual TCP/IP packet headers during the TCP handshake between you and our server. It does not read Registry values. With that in mind, what the Analyzer displays is what your client advertises to other web servers.

Some modern Operating systems (Linux, Windows 7, Vista) have auto-tuning algorithms for the TCP Receive Window (RWIN) value. Under those OSes, a small RWIN value is advertised by the client first, but then it changes with each packet until it settles to a larger value to accomodate broadband transfers. Those OSes can still be tweaked as described in our tweaking articles, and are still supported by our free tweaking software, the TCP Optimizer. However, under Windows 7/Vista, you may not be able to set a fixed RWIN value directly.

Google Chrome is the only known browser that can also modify the TCP Window for sockets it creates under some OSes, and therefore servers may not get your corret RWIN value. We've confirmed that Chrome changes the advertised RWIN under some versions of Windows XP and Windows 2003. If the RWIN value seems wrong under Chrome, you may want to test with a different browser. (See: issue ID 6356)

1.ubuntu16.04 pppoe連網，SG TCP/IP Analyzer的結果RWIN是 29056

2.目前新一代的作業系統這個RWIN值已經是動態調整(自適應)了，只有XP之類比較早期的OS才有人手動修改

（其實不改也沒差到那去，然後一堆啥優化的很多時候根本是系統問題的亂源）

：）