Network Interface Card (NIC) Settings

  1. Select Network > Interfaces.
  2. Select the interface you want to configure. Click Edit.
  3. Click Advanced General Settings.

Interface Advanced settings for NIC, Link Speed, MTU, and MAC Address Override

  1. In the Link Speed drop-down list, select Auto Negotiate if you want the XTM device to select the best network speed. You can also select one of the half-duplex or full-duplex speeds that you know is compatible with your other network equipment.

Auto Negotiate is the default setting. We strongly recommend that you do not change this setting unless instructed to do so by Technical Support. If you set the link speed manually and other devices on your network do not support the speed you select, this can cause a conflict that does not allow your XTM device interface to reconnect after failover.

  1. In the MTU text box, specify the maximum packet size, in bytes, that can be sent through the interface. We recommend that you use the default, 1500 bytes, unless your network equipment requires a different packet size.
    You can set the MTU from a minimum of 68 to a maximum of 9000.

For XTM 5 Series models, interface 0 supports a maximum MTU of 1500.

  1. To change the MAC address of the external interface, select the Override MAC Address check box and type the new MAC address.

For more information about MAC addresses, see the subsequent section.

  1. Click Save.

About MAC Addresses

Some ISPs use a MAC address to identify the computers on their network. Each MAC address gets one static IP address. If your ISP uses this method to identify your computer, then you must change the MAC address of the XTM device external interface. Use the MAC address of the cable modem, DSL modem, or router that connected directly to the ISP in your original configuration.

The MAC address must have these properties:

If the Override MAC Address check box is not selected when the XTM device is restarted, the device uses the default MAC address for the external network.

To avoid problems with MAC addresses, the XTM device makes sure that the MAC address you assign to the external interface is unique on your network. If the XTM device finds a device that uses the same MAC address, the XTM device changes back to the standard MAC address for the external interface and starts again.

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