Comments on: Linux MTU Change Size

By: Anonymous

Anonymous — Wed, 12 May 2010 05:32:43 +0000

i think here is the driver limitation…
i have similar situation
root@bigboy:~# ifconfig eth0 mtu 1490
root@bigboy:~# ifconfig eth0 mtu 1501
SIOCSIFMTU: Invalid argument

By: davinder Singh

davinder Singh — Tue, 11 May 2010 16:03:35 +0000

I have givren the below.
DEVICE=eth0
#MTU=5000
BOOTPROTO=static
ONBOOT=yes
IPADDR=192.168.138.129
NETMASK=255.255.255.0
#MTU=5000

By: Anonymous

Anonymous — Mon, 10 May 2010 20:12:57 +0000

and what did you change?

By: davinder Singh

davinder Singh — Mon, 10 May 2010 16:06:59 +0000

I have tried the same but it is not working & giving the following error

[root@server home]# /etc/init.d/network restart
Shutting down interface eth0: [ OK ]
Shutting down loopback interface: [ OK ]
Bringing up loopback interface: [ OK ]
Bringing up interface eth0: SIOCSIFMTU: Invalid argument

By: Curiuos

Curiuos — Thu, 29 Oct 2009 15:02:31 +0000

Should this only be enable on interfaces that have local traffic only? What happens to the packets if they are routed to devices that do not support an MTU of that size?

By: Nate

Nate — Thu, 29 Oct 2009 03:40:06 +0000

I tied using MTU 9000 under using Debian under /etc/network/ interfaces with a DHCP applied address and the mtu seems to be taken from the DHCP settings which seems logical, but is a little frustrating.

By: Vivek Gite

Vivek Gite — Thu, 22 Oct 2009 16:57:37 +0000

@ Solaris/ Aaron,

The faq has been updated.

Appreciate your posts!

By: Aaron Toponce

Aaron Toponce — Thu, 22 Oct 2009 16:30:52 +0000

The /etc/rc.local file is severely deprecated, and shouldn’t be used at all. If you want to set MTU sizes on your NIC, then you should be editing the NIC’s config file, not init’s.

For RHEL/Fedora add “MTU=9000″ to /etc/sysconfig/network/ifcfg-eth0
For Debian/Ubuntu add “mtu 9000″ to /etc/network/interfaces

Take the interface down, then back up, and the setting should be applied. This gets a bit more troublesome on NICs that are bound together or for TAP/Bridge devices, but the concept is the same: edit the appropriate NIC config to make the setting.

By: Vivek Gite

Vivek Gite — Thu, 22 Oct 2009 16:22:19 +0000

Thanks for the heads up! I’ve fixed the problem. Earlier, today I patched up WP and something did went wrong with my functions file. Let me know if you’ve any more problem.

By: marc

marc — Thu, 22 Oct 2009 15:15:33 +0000

Hello, the “printable version” link adds an extra / slash to the url and then gives a 404. I think it happends on many other pages.

Great job on this site, i follow it by mail and i also use the forum, it’s one of my reference sites. nice job.

By: Solaris

Solaris — Thu, 22 Oct 2009 12:16:25 +0000

Or like this

/etc/network/interfaces

iface eth0 inet static
address 192.168.1.2
network 192.168.1.0
gateway 192.168.1.1
netmask 255.255.255.0
mtu 9000

By: Yevgen

Yevgen — Thu, 22 Oct 2009 09:51:18 +0000

You can use alse another command:
ip link set eth0 mtu 9000
ip link set eth0 up