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System Administration Guide: Network Interfaces and Network Virtualization

ProcedureHow to Enable Support for Jumbo Frames

Enabling support for Jumbo frames in a network setup is a common task for most network scenarios. Support for Jumbo frames requires increasing the size of a data link's maximum transmission unit (MTU). The following procedure includes the use of customized names to identify data links. For an overview of customized names and their use in network configuration, see Overview of the Networking Stack.

  1. On the system that has the link whose MTU you want to modify, assume the System Administrator role.

    The System Administrator role includes the Network Management profile. To create the role and assign the role to a user, see Chapter 9, Using Role-Based Access Control (Tasks), in System Administration Guide: Security Services.

  2. To identify the specific Ethernet device whose MTU size you need to reset, display the links in the system.


    # dladm show-phys

    Perform this step especially if your network configuration uses customized names for data links. With customized names, data links are no longer necessarily identified by their hardware-based names. For example, the Ethernet device is bge0. However, the data link over the device is renamed net0. Therefore, you would need to configure the MTU size of net0. Refer to Data Link and IP Interface Configuration (Tasks) for examples of configuration tasks on data links that use customized names.

  3. (Optional) Display the data link's current MTU size and other properties.

    • To display a specific property of a data link, use the following syntax:


      dladm show-linkprop -p property data-link

      This command displays the settings of the property that you specify.

    • To display several selected properties of the data link, use the following syntax:


      # dladm show-link data-link

      This command displays data-link information, including MTU size.

    Note –

    See Link Administration and Monitoring for additional examples of the use of the dladm show-link syntax to display data-link information.

  4. Unplumb the interface that is configured over the data link.


    # ifconfig interface unplumb

  5. Change the value of the link's MTU size to 9000, the value for Jumbo frames.


    # dladm set-linkprop -p mtu=9000 data-link

  6. Plumb the IP interface over the link.


    # ifconfig interface plumb IP-address up

    For additional options that you can use with the ifconfig command, see the ifconfig(1M) man page.

  7. (Optional) Verify that the interface uses the new MTU size by using one of the command syntaxes in Step 3.


    # dladm show-linkprop -p mtu data-link

  8. (Optional) Display the link's current Ethernet settings.


    # dladm show-ether data-link
Example 1–1 Enabling Support for Jumbo Frames

The following example that enables support for Jumbo frames builds on the following scenario:


# dladm show-phys
LINK       MEDIA        STATE     SPEED     DUPLEX     DEVICE
net0       ether        up        100Mb     full       bge0
itops1     ether        up        100Mb     full       qfe3
web1       ether        up        100Mb     full       bge1

# dladm show-linkprop -p mtu web1
LINK     PROPERTY     VALUE     DEFAULT     POSSIBLE
web1     mtu          1500      1500        --

# ifconfig web1 unplumb
# dladm set-linkprop -p mtu=9000 web1
# ifconfig web1 plumb 10.10.1.2/24 up

# dladm show-link web1
LINK     CLASS     MTU      STATE     OVER
web1     phys      9000     up        --

Notice that the MTU value is now 9000. In this example, the dladm command enabled you to change web1's MTU size directly. The previous method would have required you to unplumb net0 as well, which would have unnecessarily disrupted the primary interface's operations.