View Full Version : How do I change MTU Settings for 56 K
I recently have been having Intermitent problem loading web pages and sending and recieving E Mail. I am using XP with a 56 K Dialup connection. After numerous e mails with tech support of my ISP and numerous attemps at solutions from tweaking setting to blaming my Norton AV program, the latest tech said my MTU settings might be set too high and sent me here to analyze and adjust.I have run the analyzer and it shows my MTU at 1500 which tech support says is too high. They say it should be set at 576. I have downloaded both the "TCPIP optimizer and the cablenut adjuster and cant seem to change the setting of the MTU . I run the program then go back to the analyzer and the MTU settings are still 1500. What am I doing wrong?:rolleyes:
12-22-03, 10:14 AM
Your ISP is wrong. A MTU of 1500 works better than 576 with 56K. Unless they are limiting your MTU. Try the tweaks I posted HERE (http://forums.speedguide.net/showthread.php?s=&threadid=68127) and see if it fixes the problem. If not we can lower your MTU but in my experience it only lowers your overall throughput.
I was not completely convinced that the ISP knew what they were talking about, as my problem is intermitent and coincidently happens at peak internet use times and I have been E mailing back and forth for a week before anyone suggested this. The following is my analyzer results after applying changes, i will wait and see wht happens for a few days. If you see anything that should be changed please post back--Thank YOU
TCP options string = 020405b401010402
MTU = 1500
MTU is fully optimized for broadband.
MSS = 1460
Maximum useful data in each packet = 1460, which equals MSS.
Default Receive Window (RWIN) = 3216
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 3216
For optimum performance, consider changing RWIN to 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)
64240 (MSS x 44)
bandwidth * delay product:
Your RcvWindow limits you to: 128.64 kbps (16.08 KBytes/s) @ 200ms
Your RcvWindow limits you to: 51.456 kbps (6.432 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.
MTU Discovery (RFC1191) = ON
Time to live left = 35 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349) = 00000000
12-22-03, 10:30 AM
Follow the link I provided above and use the settings I suggested.
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