 JohkalCool CatPremium,MVM
join:2002-11-13
Happy Valley
kudos:5
 ·Comcast
 ·Comcast Digital ..
| reply to DrummerBoy52
Re: [Speed] Does Comcast limit MTU? Lets try CableNut.
Download CableNut v4.08: »cablenut.com/
Set as shown
Save to registry
Exit
Reboot PC
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Write me up a 125.......I Can't Drive 55 »redrocker.com/ »cabowabo.com/ |
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| said by Johkal:Lets try CableNut. Download CableNut v4.08: » cablenut.com/Set as shown Save to registry Exit Reboot PC Cablenut detects I'm running W2K, but I'm running XP. Is this a problem? |
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JohkalCool CatPremium,MVM
join:2002-11-13
Happy Valley
kudos:5 | Not an issue. |
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| OK. I'll post results in about 5 minutes after reboot... |
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| reply to Johkal
said by Johkal:Lets try CableNut. Download CableNut v4.08: » cablenut.com/Set as shown Save to registry Exit Reboot PC applied settings & rebooted.
Speedguide still shows 1415:
« SpeedGuide.net TCP Analyzer Results »
Tested on: 04.07.2008 16:34
IP address: 98.240.xx.xx
TCP options string: 0204055f0103030101010402
MSS: 1375
MTU: 1415
TCP Window: 128480 (NOT multiple of MSS)
RWIN Scaling: 1
Unscaled RWIN : 64240
Reccomended RWINs: 63250, 126500, 253000, 506000
BDP limit (200ms): 5139kbps (642KBytes/s)
BDP limit (500ms): 2056kbps (257KBytes/s)
MTU Discovery: ON
TTL: 47
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0) |
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JohkalCool CatPremium,MVM
join:2002-11-13
Happy Valley
kudos:5 | Try a direct connection from PC to modem & apply settings again. |
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| said by Johkal:Try a direct connection from PC to modem & apply settings again. OK, will do. |
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JohkalCool CatPremium,MVM
join:2002-11-13
Happy Valley
kudos:5 Reviews:
·Comcast
·Comcast Digital ..
| If that doesn't do it, then I would focus on the the VPN software as tshirt  noted. Even though you aren't using the VPN now, it will dictate what global MTU is used.
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Write me up a 125.......I Can't Drive 55 »redrocker.com/ »cabowabo.com/ |
|
| Still 1415..
« SpeedGuide.net TCP Analyzer Results »
Tested on: 04.07.2008 16:47
IP address: 98.240.xx.xx
TCP options string: 0204055f0103030101010402
MSS: 1375
MTU: 1415
TCP Window: 128480 (NOT multiple of MSS)
RWIN Scaling: 1
Unscaled RWIN : 64240
Reccomended RWINs: 63250, 126500, 253000, 506000
BDP limit (200ms): 5139kbps (642KBytes/s)
BDP limit (500ms): 2056kbps (257KBytes/s)
MTU Discovery: ON
TTL: 48
Timestamps: OFF
SACKs: ON
IP ToS: 00000000 (0) |
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| reply to Johkal
said by Johkal:If that doesn't do it, then I would focus on the the VPN software as tshirt noted. Even though you aren't using the VPN now, it will dictate what global MTU is used. So - how do I find out if the VPN software is doing an over-ride?? |
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JohkalCool CatPremium,MVM
join:2002-11-13
Happy Valley
kudos:5 Reviews:
·Comcast
·Comcast Digital ..
1 edit | I've never used VPN, but look for settings.
If possible, you can uninstall it, apply TCP settings, test and reinstall after if you want.
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Write me up a 125.......I Can't Drive 55 »redrocker.com/ »cabowabo.com/ |
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 tshirtPremium,MVM
join:2004-07-11
Snohomish, WA
kudos:3
·Comcast
| reply to Johkal
I believe Cisco VPN software hard sets the reduced MTU to allow for VPN header encryption.
This is set at 1415 to insure no fragmention even in the "worse case" (possible backdoor risk with fragmented VPN packets- was in a Cisco whitepaper a while back)
It will/may continue as long as the software is installed, even if it is never used. |
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| awesome.. said by tshirt: I believe Cisco VPN software hard sets the reduced MTU to allow for VPN header encryption. This is set at 1415 to insure no fragmention even in the "worse case" (possible backdoor risk with fragmented VPN packets- was in a Cisco whitepaper a while back) It will/may continue as long as the software is installed, even if it is never used. Awesome, thanks. I tried setting the VPN MTU to 1500 but no luck there either. I'll uninstall just to see what the deal is. Thanks for the help - both of you!!! |
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tshirtPremium,MVM
join:2004-07-11
Snohomish, WA
kudos:3 | reply to tshirt
Re: [Speed] Does Comcast limit MTU? »en.wikipedia.org/wiki/IPv6
IPv6 also adds header overhead (part of what Cisco software/hardware is allowing space for) |
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