https://wiki.bwt.com.de/index.php?action=history&feed=atom&title=Template%3AMTUTemplate:MTU - Revision history2026-04-04T01:41:45ZRevision history for this page on the wikiMediaWiki 1.43.0https://wiki.bwt.com.de/index.php?title=Template:MTU&diff=41&oldid=prevBrainwreckedTech: 1 revision2014-01-06T01:52:17Z<p>1 revision</p>
<p><b>New page</b></p><div><noinclude>{{Information/Template|additional=This template contains information that is common for any page discussing MTU settings. The subpages listed below contain solutions to getting the MTU settings to stick in various ways.}}<br />
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</noinclude>If you are using Gigabit Ethernet, you can change the MTU setting for better performance. Gigabit Ethernet accepts MTUs up to 9000, but a lot of Gigabit Ethernet chipsets do not go this high. '''This number cannot be any higher than any server you plan to communicate with.'''<br />
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Use the following command to determine which Ethernet device you are using. The one with an IP address is the one you are interested in.<br />
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ip addr<br />
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You'll get output like this:<br />
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1: lo: <LOOPBACK,UP,LOWER_UP> mtu 16436 qdisc noqueue state UNKNOWN <br />
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00<br />
inet 127.0.0.1/8 scope host lo<br />
inet6 ::1/128 scope host <br />
valid_lft forever preferred_lft forever<br />
2: eth0: <BROADCAST,MULTICAST,UP,LOWER_UP> mtu 1500 qdisc pfifo_fast state UP qlen 1000<br />
link/ether hh:hh:hh:hh:hh:hh brd ff:ff:ff:ff:ff:ff<br />
inet '''nnn.nnn.nnn.nnn/24''' brd 192.168.1.255 scope global eth0<br />
inet6 hhhh::hhhh:hhhh:hhhh:hhhh/64 scope link <br />
valid_lft forever preferred_lft forever<br />
3: eth1: <BROADCAST,MULTICAST> mtu 1500 qdisc noop state DOWN qlen 1000<br />
link/ether hh:hh:hh:hh:hh:hh brd ff:ff:ff:ff:ff:ff<br />
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Use the following command to determine the the max MTU setting.<br />
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sudo ip link set [device] mtu [1500-9000]<br />
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You'll basically be playing a game of guess-the-number. No feedback means the command was successful. You'll know you've gone too far when you see <tt>[DRIVER] answers: Invalid argument</tt>.<br />
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Once you've determined the largest valid number you can use, you need to to make sure that your network hub or router isn't a limiting factor and that the drivers aren't allowing you to set the MTU higher than the actual hardware can handle.<br />
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ping -s [size-minus-8] [ip-address]<br />
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If you do not receive a response with the MTU setting you got earlier (less 8 bytes for the ICMP header) then something is goofed and you will have to play the number guessing game again until you can make a successful ping.<br />
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Once you find your optimal MTU setting, it's time to get the setting to stick on every boot.</div>BrainwreckedTech