Chapter 10. Configuring a persistent qeth device on IBM Z


Channel-based network interfaces on the IBM Z platform are virtualized and not automatically visible to RHEL when attached to your logical partition (LPAR) or z/VM guest. Before you can use the device in a network configuration, you must manually group subchannels into a single logical qeth device and activate it.

Prerequisites

  • You defined the I/O subchannels and attached them to your LPAR or z/VM guest.
  • You installed the s390utils-base package.

Procedure

  1. Unmask the device IDs of the qeth device:

    • If you know the device IDs, unmask these IDs. For example:

      # cio_ignore --remove 0.0.0600,0.0.0601,0.0.0602
      Copy to Clipboard Toggle word wrap

      Specify the device IDs comma-separated as shown or as a range, for example 0.0.0600-0.0.0602.

    • If you do not know the device IDs, you can unmask all IDs:

      # cio_ignore --remove-all
      Copy to Clipboard Toggle word wrap
  2. Display the available qeth devices:

    # lszdev qeth
    Copy to Clipboard Toggle word wrap
    TYPE  ID                         ON  PERS  NAMES
    qeth  0.0.0600:0.0.0601:0.0.0602 no  no
    Copy to Clipboard Toggle word wrap

    The output contains the following columns:

    • TYPE: Displays the device type. If you ran lszdev qeth, the command returns only qeth devices.
    • ID: Displays the subchannel addresses of the hardware. This is a triplet of three hexadecimal addresses used for read, write, and data transfers.
    • ON: Indicates the current operational state of the device where no means that the driver has not yet grouped the channels and created a functional network device.
    • PERS: Indicates the persistence status of the configuration where no confirms that no udev device manager rule exists and, therefore, the device is not automatically be enabled after a reboot.
    • NAMES: Displays the network interface name you can use in NetworkManager. If the field is empty, the channels have not been grouped or set online yet.
  3. Create a udev rule and activate the qeth device:

    # chzdev qeth 0.0.0600 -e
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    You can specify only the first address of a triplet, and the chzdev utility automatically detects the associated write and data channels.

Verification

  • Verify the hardware state, and display the assigned interface name:

    # lszdev qeth
    TYPE  ID                         ON  PERS  NAMES
    qeth  0.0.0600:0.0.0601:0.0.0602 yes yes   enc600
    Copy to Clipboard Toggle word wrap

    Ensure that both the ON and PERS column return yes for your device. Note the interface name displayed in the NAMES column. You require the name when you create a network configuration that uses this device.

Next steps

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