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Offline chrisyzfr6

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MTU again
« on: September 22, 2011, 10:31:12 AM »
I checked my packets and they were fragmented. I dropped the MTU ping from 1500 to 1472 and packets were good, so I changed the MTU setting in my router to 1472 then rechecked it and packets were fragmented again. What gives, how do i fix this?

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Offline Shane

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Re: MTU again
« Reply #1 on: September 22, 2011, 11:05:18 AM »
You may need to have your computer renew its IP info from the router.

Try my repair network tool at the bottom of this page
http://www.pcwintech.com/shanes-toolbox

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Offline chrisyzfr6

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Re: MTU again
« Reply #2 on: September 22, 2011, 11:39:24 AM »
Hi Shane, tried that, i get the same thing
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Offline Shane

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Re: MTU again
« Reply #3 on: September 22, 2011, 11:41:23 AM »
Perhaps it does need to be changed in Windows. Give this a try :wink:
http://support.microsoft.com/kb/826159

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Offline chrisyzfr6

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Re: MTU again
« Reply #4 on: September 22, 2011, 12:57:02 PM »
I'v tried what you sent me and i get the same thing everytime. This is quite puzzling. Every time i change my mtu packet to a number that tested good that number gets fragmented  ....uhm. Think about that and tell me what you think. Also just to through another monkey wrench in, the icons from three programs in system tray have poped up again after several reboots for this mtu thing.

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Re: MTU again
« Reply #5 on: September 22, 2011, 01:02:32 PM »
I am not sure at this point.
http://www.cisco.com/en/US/tech/tk827/tk369/technologies_white_paper09186a00800d6979.shtml

Try setting a lower MTU in the router - 1432 and see how it does for you.

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Offline chrisyzfr6

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Re: MTU again
« Reply #6 on: September 22, 2011, 01:50:06 PM »
Sorry Shane

    Looks like I'v been going about this the wrong way. Everytime I checked the mtu packets and set it to that number and then check it again it was off, then i noticed a pattern that it was of by 28 everytime. So it goes like this.

  Ping www.pcwintech.com -f -l 1500

it would be fragmented. So I would drop it slowly untill I got a good result which is 1472. I would set it to that number and then it would be off by 28 again. I would have to set to 1444 to get a good result and so on and on and on. I done some research and found this.

www.richard-slater.co.uk/archives/2009/10/23/change-your-mtu-under-vista-or-windows-7

Tell me what you think






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Offline Shane

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Re: MTU again
« Reply #7 on: September 22, 2011, 02:01:58 PM »
I wonder if it is the windows network auto tuning doing it?
Perhaps your fine leaving it. Have you had any problems with dropped connections or any kind on internet lag?

Shane
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When people ask "Why fix what isn't broken?" I reply "To make it better."
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Offline chrisyzfr6

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Re: MTU again
« Reply #8 on: September 22, 2011, 02:07:41 PM »
It might lag once in a blue moon. I have autotuning off
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Offline Shane

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Re: MTU again
« Reply #9 on: September 22, 2011, 02:10:29 PM »
The fragmentation is needed it looks like, I think your fine. here is what I get.

Ping www.pcwintech.com -f -l 1500

Pinging www.pcwintech.com [69.163.136.13] with 1500 bytes of data:
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.
Packet needs to be fragmented but DF set.

Ping statistics for 69.163.136.13:
    Packets: Sent = 4, Received = 0, Lost = 4 (100% loss),

Quote
Error Message:

Packet needs to be fragmented but DF set.

Explanation:

The packet length is to big to be processed by the ping command.

User Action:

Turn off the Do Not Fragment flag by removing the -f option from the command line and then try again. You may try decreasing the packet size by using the -l option prior to disabling the Do Not Fragment flag.

Shane
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(About Shane)
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When people ask "Why fix what isn't broken?" I reply "To make it better."
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Offline chrisyzfr6

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Re: MTU again
« Reply #10 on: September 22, 2011, 02:21:24 PM »
Perfect. I did it without the -f option and all is well with 1500 on both the router and computer, just like yours. Now if I fully understood what I was doing from the begining I wouldn't have spent so much time trying to figure out that there was never a problem to begin with lol. Thanks. On the flip side I'm still having the icons unhide on reboot. Your solution worked for a while, but after all the reboots today trying to figure the mtu thing, they started to unhide again (Cleanmem, Drive Speedometer and Simple Internet Meter Lite).


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Offline Shane

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Re: MTU again
« Reply #11 on: September 22, 2011, 02:22:42 PM »
Lets continue the icon thing in the other thread :-)

If your all set with the MTU thing I will lock this thread :wink:

Shane
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When people ask "Why fix what isn't broken?" I reply "To make it better."
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Offline chrisyzfr6

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Re: MTU again
« Reply #12 on: September 22, 2011, 02:28:26 PM »
Okay
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Offline Shane

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Re: MTU again
« Reply #13 on: September 22, 2011, 02:29:17 PM »
Locking thread :wink:

Shane
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When people ask "Why fix what isn't broken?" I reply "To make it better."
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Honor & Respect is all that matters.

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