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Old 05-28-2016, 11:05 PM   #1
Registered: Aug 2012
Posts: 30

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I can not change MTU size

Dear friends,

I've installed (the same) RHEL6 on 2 computers :
1. PC
2. Sony VAIO Lptop

I changed MTU value on the PC to 5000 bytes easily.
But after changing MTU size on the laptop, it remains
intact. The settings section of NIC says MTU is 5000, but after ifdown and ifup, ifconfig shows me that it is still 1500.
Actually I can not increase its value to greater than 1500. I mean, if I set MTU to values less than 1500
it will be activated. The strange point is that the OSs on the computers are the same.

Can anyone help me?
Old 05-29-2016, 03:01 AM   #2
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Location: Horgau, Germany
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Why do you want to change the MTU size?
Old 05-29-2016, 03:48 AM   #3
Registered: Aug 2012
Posts: 30

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I should, That's why. Thank you for your help.
Old 05-29-2016, 10:19 AM   #4
LQ Sage
Registered: Nov 2004
Location: Saint Amant, Acadiana
Distribution: Gentoo ~amd64
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All hardware involved must support jumbo frames for it to work. You do not expect it to work on wireless?
Old 05-29-2016, 10:44 AM   #5
Registered: Aug 2012
Posts: 30

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Dear Emerson,

I have to use wired Ethernet.
I don't know why RHEL on laptop does not accept mentioned MTU for NIC.
I used a live version of Ubuntun to boot up the laptop. Then I could surprisingly set MTU to 5000 !
But I need to run my computer and my program under RHEL6
So the problem is still to be solved.

Last edited by NetProgrammer; 05-29-2016 at 10:49 AM.


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