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Tip: Increase Internet speed by manipulating MTU size

Tip: Increase Internet speed by manipulating MTU size

Network throughput is affected by myriad variables, one of them being the MTU (maximum transmission unit) packet size setting.

As the name implies, MTU refers to the largest data packet that can be carried over your network pipe. MTU is measured in bytes, so a setting of "1600" would equal roughly 1.5 KB per packet.

For various reasons, setting the MTU at different levels can have a dramatic effect on your Internet access speed, so it's worth experimenting in order to determine what works best for your particular set-up.

If you have an Ethernet-based connection, setting the MTU is straightforward. Simply open the Network pane of System Preferences, and choose "Built-in Ethernet" from the "Show" pop-up tab (you may already be at this screen when you access the Network pane). Next, click the "Ethernet" tab and choose "Manually" from the "Configure" menu. Now click the button next to "Custom," and enter your desired MTU. After entering the MTU, click "Apply Now" then test your network setting.

If you have a wireless (AirPort or other) network, first log in as administrator, then open the Terminal (located in Applications/Utilities) and enter the following command:

  • sudo ifconfig en1 mtu SIZE

where SIZE is the MTU setting you desire, e.g. 750. You will be prompted for an administrator password.

Here are some good MTU numbers to test right away:

  • 500
  • 600
  • 625
  • 650
  • 750
  • 1000
  • 1500

Big variances in speed can occur with changes as small as 25 bytes, so keep testing your network speed after modifying the setting even slightly.

Have you had success manipulating your MTU size for increased network throughput? Please let us know.

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