MTU parameters usually appear in association with a communications interface (NIC, serial port, etc.). Standards (Ethernet, for example) can fix the size of an MTU; or systems (such as point-to-point serial links) may decide MTU at connect time. A higher MTU brings greater efficiency because:
- each packet carries more user-data
- protocol overheads, such as headers or underlying per-packet delays, remain fixed,
- higher efficiency means a slight improvement in bulk protocol throughput
For sending bulk data, the Internet generally works better when using larger packets. Each packet implies a routing decision, when sending a 1 megabyte file, this can either mean around 700 packets when using packets that are as large as possible, or 4000 if using the smallest default.
However, not all parts of the Internet support full 1460 bytes of payload per packet. It is therefore necessary to try and find the largest packet that will 'fit', in order to optimize a connection.
This process is called 'Path MTU Discovery', where MTU stands for 'Maximum Transfer Unit.'
Setting MTU value in OpenSuSe Linux:
Go to Yast → Network Device → Network Settings
In Network Setting dialog dialog box, select "Overview" tab and click on "Edit" button, this will open up your Network card setting dialog box, click on "General" tab to set the MTU for this card as shown in the figure below
To view the updated MTU, type command: ip link list you should see the output similar to ...
mtu 16436 qdisc noqueue state UNKNOWN
link/loopback 00:00:00:00:00:00 brd 00:00:00:00:00:00
mtu 1500 qdisc pfifo_fast state UNKNOWN qlen 1000
link/ether 00:19:d1:18:ba:a6 brd ff:ff:ff:ff:ff:ff