Comcast.net Settings
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ExtremistAS
- Member
- Posts: 26
- Joined: Thu Jun 14, 2001 1:44 pm
Comcast.net Settings
Okay, I want to tweak my settings for Comcast.net. Here is my TCP/IP Analyzer results. I am running Windows XP Professional. What should I use to change my settings?
SpeedGuide.net TCP/IP Analyzer
TCP properties for IP = XXX.XXX.XXX.XXX ()
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; Q312461)
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) = 17520
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 17520
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)
64240 (MSS x 44)
bandwidth * delay product:
Your RcvWindow limits you to: 700.8 kbps (87.6 KBytes/s) @ 200ms
Your RcvWindow limits you to: 280.32 kbps (35.04 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.
MTU Discovery (RFC1191) = ON
Time to live left = 111 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000
44267 connections tested since 03.10.2001.
Analyzer version: Beta 0.99
SpeedGuide.net TCP/IP Analyzer
TCP properties for IP = XXX.XXX.XXX.XXX ()
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; Q312461)
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) = 17520
RWIN Scaling (RFC1323) = 0 bits
Unscaled Receive Window = 17520
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)
64240 (MSS x 44)
bandwidth * delay product:
Your RcvWindow limits you to: 700.8 kbps (87.6 KBytes/s) @ 200ms
Your RcvWindow limits you to: 280.32 kbps (35.04 KBytes/s) @ 500ms
Consider increasing your RWIN value to optimize TCP/IP for broadband.
MTU Discovery (RFC1191) = ON
Time to live left = 111 hops
TTL value is ok.
Timestamps (RFC1323) = OFF
Selective Acknowledgements (RFC2018) = ON
IP type of service field (RFC1349)= 00000000
44267 connections tested since 03.10.2001.
Analyzer version: Beta 0.99
your RWIN is low, you should change it
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jpalminteri
- Member
- Posts: 59
- Joined: Mon Feb 19, 2001 12:00 am
- Location: Mechanicsburg, PA
RWIN Change Due!!!
Change RWIN to 64240 and speed test and you should see a dramatic improvement. Other settings are OK.

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jpalminteri
- Member
- Posts: 59
- Joined: Mon Feb 19, 2001 12:00 am
- Location: Mechanicsburg, PA
Speed Test Site!!!
Try several of the servers that are nearest your POP. Use this URL:
http://www.speakeasy.net/main.php?page=sup_pops

http://www.speakeasy.net/main.php?page=sup_pops
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DaveG
Are there simple directions for changing the RWIN value?
I mean even simpler than the ones on the Speedguide
Registry Tweaks page. I'll admit I've never edited my
Registry and I'm a bit reluctant. But I'm getting terrible
performance from my new SB4100 cable modem and I'm
guessing it may be because my RWIN is set at 2144.
Thanks
I mean even simpler than the ones on the Speedguide
Registry Tweaks page. I'll admit I've never edited my
Registry and I'm a bit reluctant. But I'm getting terrible
performance from my new SB4100 cable modem and I'm
guessing it may be because my RWIN is set at 2144.
Thanks
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jpalminteri
- Member
- Posts: 59
- Joined: Mon Feb 19, 2001 12:00 am
- Location: Mechanicsburg, PA
RWIN Guess is correct!!!
Go to this URL and download Dr.TCP it will make life easier.
http://www.dslreports.com/forum/news,61
Look for the reference to it and other tools in the middle of the page and then download it to the Desktop. Use it to change all common parameters. Use an RWIN of 64240 to start. Leave TS OFF, WS OFF, Sel Acks ON, MTU 1500, MAXDUPACKS 2. That should give you a good start. If you desire a larger RWIN, try the 100K, 250K and the 500K ranges. Use an even multiple of MSS as it makes for one less operation for the OS.
BTW, Path MTU ON and Black Hole Detect OFF are additional settings.

http://www.dslreports.com/forum/news,61
Look for the reference to it and other tools in the middle of the page and then download it to the Desktop. Use it to change all common parameters. Use an RWIN of 64240 to start. Leave TS OFF, WS OFF, Sel Acks ON, MTU 1500, MAXDUPACKS 2. That should give you a good start. If you desire a larger RWIN, try the 100K, 250K and the 500K ranges. Use an even multiple of MSS as it makes for one less operation for the OS.
BTW, Path MTU ON and Black Hole Detect OFF are additional settings.
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ExtremistAS
- Member
- Posts: 26
- Joined: Thu Jun 14, 2001 1:44 pm
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jpalminteri
- Member
- Posts: 59
- Joined: Mon Feb 19, 2001 12:00 am
- Location: Mechanicsburg, PA
Cablenut ?
This is one of the reasons I do not use that program. There are ways to restore to defaults. You must make another post to ask for detailed help on that subject. Cablenut can restore to defaults.
