自分のＰＣのＭＴＵとかＲＷＩＮの設定がどうなっているか調べることのできるサイトがある。
SpeedGuide TCP-IP Analyzer　ここで、WidowsXPとWindows98との違いを調べて見た。
Windows98と言ってもDrTCPで既に変更を加えてあるのでDefaltとは異なっている。

結果の詳細は以下の通りだが、大きな違いはRWINの値だ。
しかし、ＹＢＢ導入当時にすでにこのRWINの値は実験済みで大きな差はなかった。
この値が大きすぎると、行くサイトによっては再送回数が増加してかえってブラウジング
の速さが遅くなる場合があると言われている。今回のスピード測定では、1.3Mbps程度
の値が出ているので当面この値に設定しておくことにした。

以下は、SpeedGuide TCP-IP Analyzer　での測定結果。

（1）Windows98
SpeedGuide TCP/IP AnalyzerMainCable ModemsDiscussionWindows
9xReviewsEditorialsInformation">">">">">">">">">">">">">">">">">">">">
Wed Nov 14 21:20:36 2001.


SpeedGuide.net TCP/IP Analyzer
TCP properties for IP = 43.228.40.66 ()
Note: Read the FAQ if the above is not your IP address.
Browser/OS = Mozilla/4.0 (compatible; MSIE 5.5; Windows 98)
TCP options string = 02040586010303000101080a000000000000000001010402
MTU = 1454
MTU is not fully optimized for broadband. Consider increasing your MTU to
1500 for better throughput.
MSS = 1414
Maximum useful data in each packet = 1402, which is less than MSS because
of Timestamps, or other TCP/IP options used.
MSS is not fully optimized for broadband (although it might work well for
slower connections). Consider increasing your MTU value.
Default Receive Window (RWIN) = 16968
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 16968
RWIN is a multiple of MSS
Other values for RWIN that might work well with your current MTU/MSS:
520352 (MSS x 46 * scale factor of 8)
260176 (MSS x 46 * scale factor of 4)
130088 (MSS x 46 * scale factor of 2)
65044 (MSS x 46)
bandwidth * delay product:
Your RcvWindow limits you to: 678.72 kbps (84.84 KBytes/s) @ 200ms
Your RcvWindow limits you to: 271.488 kbps (33.936 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.
MTU Discovery (RFC1191) = ON
Time to live left = 44 hops
TTL value is ok.
Timestamps (RFC1323) = ON
Note: Timestamps add 12 bytes to the TCP header of each packet, reducing
the space available for useful data.
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000

46329 connections tested since 03.10.2001.
Analyzer version: Beta 0.99

（2）WidowsXP
SpeedGuide TCP/IP AnalyzerMainCable ModemsDiscussionWindows
9xReviewsEditorialsInformation">">">">">">">">">">">">">">">">">">">">
Wed Nov 14 21:12:45 2001.


SpeedGuide.net TCP/IP Analyzer
TCP properties for IP = 43.228.40.66 ()
Note: Read the FAQ if the above is not your IP address.
Browser/OS = Mozilla/4.0 (compatible; MSIE 6.0; Windows NT 5.1)
TCP options string = 020405b401010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which is equal to MSS.
Default Receive Window (RWIN) = 64240
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 64240
RWIN is a multiple of MSS
Other values for RWIN that might work well with your current MTU/MSS:
513920 (MSS x 44 * scale factor of 8)
256960 (MSS x 44 * scale factor of 4)
128480 (MSS x 44 * scale factor of 2)
bandwidth * delay product:
Your RcvWindow limits you to: 2569.6 kbps (321.2 KBytes/s) @ 200ms
Your RcvWindow limits you to: 1027.84 kbps (128.48 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 108 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000

46202 connections tested since 03.10.2001.
Analyzer version: Beta 0.99

（3）Windows98でMTUとRWINをWinXPに合わせた。
SpeedGuide TCP/IP AnalyzerMainCable ModemsDiscussionWindows
9xReviewsEditorialsInformation">">">">">">">">">">">">">">">">">">">">
Wed Nov 14 21:44:48 2001.


SpeedGuide.net TCP/IP Analyzer
TCP properties for IP = 43.228.40.66 ()
Note: Read the FAQ if the above is not your IP address.
Browser/OS = Mozilla/4.0 (compatible; MSIE 5.5; Windows 98)
TCP options string = 020405b40103030001010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which is equal to MSS.
Default Receive Window (RWIN) = 64240
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 64240
RWIN is a multiple of MSS
Other values for RWIN that might work well with your current MTU/MSS:
513920 (MSS x 44 * scale factor of 8)
256960 (MSS x 44 * scale factor of 4)
128480 (MSS x 44 * scale factor of 2)
bandwidth * delay product:
Your RcvWindow limits you to: 2569.6 kbps (321.2 KBytes/s) @ 200ms
Your RcvWindow limits you to: 1027.84 kbps (128.48 KBytes/s) @ 500ms
MTU Discovery (RFC1191) = ON
Time to live left = 44 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000

46769 connections tested since 03.10.2001.
Analyzer version: Beta 0.99

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