EtherChannel configuration considerations

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Consult this list of recommendations before configuring EtherChannel.

  • You can have up to eight primary Ethernet adapters and up to eight backup Ethernet adapters per EtherChannel.
  • You can configure multiple EtherChannels on a single system, but each EtherChannel constitutes an additional Ethernet interface. The ifsize option of the no command might need to be increased to include not only the Ethernet interfaces for each adapter, but also any EtherChannels that are configured. In AIX 5.2 and earlier, the default ifsize is eight. The default size is 256.
  • You can use any supported Ethernet adapter in an EtherChannel (see Supported adapters). However, the Ethernet adapters must be connected to a switch that supports EtherChannel. See the documentation that came with your switch to determine if it supports EtherChannel (your switch documentation may refer to this capability also as link aggregation or trunking).
  • All adapters in the EtherChannel should be configured for the same speed (100 Mbps, for example) and should be full duplex.
  • The adapters used in the EtherChannel cannot be accessed by the system after the EtherChannel is configured. To modify any of their attributes, such as media speed, transmit or receive queue sizes, and so forth, you must do so before including them in the EtherChannel.
  • The adapters that you plan to use for your EtherChannel must not have an IP address configured on them before you start this procedure. When configuring an EtherChannel with adapters that were previously configured with an IP address, make sure that their interfaces are in the detach state. The adapters to be added to the EtherChannel cannot have interfaces configured in the up state in the Object Data Manager (ODM), which will happen if their IP addresses were configured using SMIT. This may cause problems bringing up the EtherChannel when the machine is rebooted because the underlying interface is configured before the EtherChannel with the information found in ODM. Therefore, when the EtherChannel is configured, it finds that one of its adapters is already being used. To change this, before creating the EtherChannel, type smitty chinet, select each of the interfaces of the adapters to be included in the EtherChannel, and change its state value to detach. This will ensure that when the machine is rebooted the EtherChannel can be configured without errors.

    For more information about ODM, see Object Data Manager (ODM) in General Programming Concepts: Writing and Debugging Programs.

  • If you will be using 10/100 Ethernet adapters in the EtherChannel for AIX versions prior to AIX 5L Version 5.2 with the 5200-03 Recommended Maintenance package, you may need to enable link polling on those adapters before you add them to the EtherChannel. Type smitty chgenet at the command line. Change the Enable Link Polling value to yes, and press Enter.
    Note: In AIX 5L Version 5.2 with the 5200-03 Recommended Maintenance package and later, enabling the link polling mechanism is not necessary. The link poller will be started automatically.
  • If you plan to use jumbo frames, you may need to enable this feature in every adapter before creating the EtherChannel and in the EtherChannel itself. Type smitty chgenet at the command line. Change the Enable Jumbo Frames value to yes and press Enter. Do this for every adapter for which you want to enable Jumbo Frames. You will enable jumbo frames in the EtherChannel itself later.
    Note: Enabling jumbo frames in every underlying adapter is not necessary once it is enabled in the EtherChannel itself. The feature will be enabled automatically if you set the Enable Jumbo Frames attribute to yes.
  • AIX 5.3 and AIX 6.1 levels support the following configurations for Host Ethernet Adapters (HEA).
    • Link aggregation between dedicated HEA port and PCI/PCI-E adapter is supported for both manual aggregation and LACP aggregation.
    • EtherChannel configuration that includes non-dedicated HEA port support, EtherChannel with backup adapter configured as PCI/PCI-E, or virtual Ethernet.
      Note: For non-dedicated HEA port in EtherChannel configuration, limitations about Link aggregation apply.
  • AIX Version 6.1 with the 6100-06 Technology Level and later supports EtherChannel on stacked switches.
  • Network boot or network installation over EtherChannel on Network Installation Management (NIM) client is not supported.