Tweaking MTU Settings

TWEAKING MTU SETTINGS

As you become more experienced with Linux you maybe want to fine tune your internet connection settings . . . . .

The default of 1460 bytes per packet can vary with the connection, distro or hardware you have.
On some systems you can have better results with low MTU settings and some with high MTU settings, you will just have to see and try what works best for you.

Here is how you can change the MTU settings for your network interface:

First have a look on how the settings are now:

CODE

# ifconfig eth0

And you will get something similar to this:

QUOTE = ifconfig

eth0 Link encap:Ethernet HWaddr 00:07:95:XX:XX:59
inet addr:10.0.0.152 Bcast:10.0.0.255 Mask:255.255.255.0
UP BROADCAST RUNNING MULTICAST MTU:1500 Metric:1
RX packets:29861 errors:0 dropped:0 overruns:0 frame:0
TX packets:26784 errors:0 dropped:0 overruns:0 carrier:0
collisions:0 txqueuelen:1000
RX bytes:6378900 (6.0 Mb) TX bytes:2889677 (2.7 Mb)
Interrupt:11 Base address:0xd400

Now we will test another setting ( MTU 1460 ):

CODE

# ifconfig eth0 mtu 1460

And see if you get better results . . . No ? Well, try again

CODE

# ifconfig eth0 mtu 1300

CODE

# ifconfig eth0 mtu 1200

Now imagine you found the value you want to make permanent: MTU 1250 , pull up the file "/etc/sysconfig/network-scripts/ifcfg-eth0" and make it read:

QUOTE = /etc/sysconfig/network-scripts/ifcfg-eth0

DEVICE=eth0
MTU=1250
BOOTPROTO=dhcp
NETMASK=255.255.255.0
ONBOOT=yes
METRIC=10

After the next boot the MTU settings will be on 1250

Have fun, but be careful not to break things !

Bruno

-- Mar 26 2005 ( Revised Dec 13 2005 ) --