17 comment

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

2. 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

3. 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.

   1. 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.

4. 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.

5. @ Solaris/ Aaron,

   The faq has been updated.

   Appreciate your posts!

6. 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.

7. 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?

8. 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

   1. and what did you change?

      1. 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

         1. 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

   2. It happened to me (in our company cluster) that the issue was with the mode that interface was in. It was in the datagram instead in the connected. With “# echo connected >> echo connected > /sys/class/net/ethX/mode” you can change the mode, and that enables you to also change the MTU.

      Hope it helps. -R

9. “SIOCSIFMTU: Invalid argument” is the drivers way to tell you that the hardware doesn’t support that framesize. Try increment iteratively til reaching the roof.

   Does your switch support this MTU?

   Remember that both sides needs to support this MTU or else fragmentation will occur!

   Try your setting out by pinging with a specific MTU:

   ping -s [MTU-28] -M do [ip-address]

   Remember to substract 28 from the set MTU giving space for headers. If packets are dropped or messages about fragmentation is recieved, lower MTU size further.

   Have a look at these pages too:
   Linux Configure Jumbo Frames to Boost Network Performance / Throughput

10. my linux does’nt haveinternet accses in dual-boot system

11. need any help plsssssssssssssssssss

12. hi….
    please help me any one how to change MTU size in Linux pc .we able to set MTU as 9000 but it is not reflecting ……

    /sbin/ifconfig eth0 mtu 9000 up …. i trying use this command , i able to see the “invalid argument” error

    /sbin/ifconfig eth0 mtu 4000 up ….till 4000 i able to change the value and ifconfig also getting changed …..

    what could be the issue please any help for this issue ….?

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