Product Documentation

Configuring NICs

Mar 12, 2013

XenServer automatically manages NICs as needed based on the related network, virtual network interface, server network, and bond configuration. You can view the available NICs, configure NIC bonds, and dedicate NICs to a specific function from the NICs tab.

NIC bonding can improve server resiliency by using two or more physical NICs as if they were one. Two or more NICs may be bonded to create a single, high-performing channel that provides connectivity between VMs and your external network. Three bond modes are supported:

This mode provides load balancing of virtual machine traffic across the physical NICs in the bond. If one NIC within the bond fails, all of the host's network traffic automatically routes over the second NIC.
Active-passive (active-backup)
This mode provides failover capability. Only one NIC in the bond is active; the inactive NIC becomes active if and only if the active NIC fails.
Link Aggregation Control Protocol (LACP) Bonding
This mode provides active-active bonding, where traffic is balanced between the bonded NICs. Unlike the active-active bond in a Linux bridge environment, LACP can load balance all traffic types.
Note: You must configure vSwitch as the network stack to be able to view the LACP bonding options in XenCenter and to create a new LACP bond. Also, your switches must support the IEEE 802.3ad standard. The switch must contain a separate LAG group configured for each LACP bond on the host. For more details about creating LAG groups, see XenServer Administrator's Guide.

When you bond separate NICs using XenCenter, a new NIC is created: this is the bond master , and the bonded NICs are known as the NIC slaves . The NIC bond can then be connected to a XenServer network to allow virtual machine traffic and server management functions to take place. You can create NIC bonds in XenCenter from the NICs tab or from the server's Networking tab (network type = Bonded Network).

Viewing available NICs

For each available NIC on a server, the following device properties are shown on the NICs tab:

NIC Identifies the physical network interface card or internal virtual network.
MAC The MAC (Media Access Control) address of the NIC.
Link Status The connection status of the NIC: Connected or Disconnected.
Speed The data transfer rate of the NIC.
Duplex The duplexing mode of the NIC: full or half.
Vendor, Device The NIC vendor and device names.
PCI Bus Path The PCI bus path for pass-through devices.

When you add a new physical interface on a XenServer host, for example, a new Ethernet controller, it may not appear in the list on the NICs tab. If this happens, click Rescan on the NICs tab to force XenServer to scan for new cards.

To create a new NIC bond

  1. Ensure that the NICs you want to bind together (the bond slaves) are not in use: you must shut down any VMs with virtual network interfaces using the bond slaves prior to creating the bond. After you have created the bond, you will need to reconnect the virtual network interfaces to an appropriate network.
  2. Select the server in the Resources pane then click on the NICs tab and click Create Bond.
  3. Select the NICs you want to bond together. To select a NIC, select its check box in the list. Up to four NICs may be selected in this list. Clear the check box to deselect a NIC. To maintain a flexible and secure network, You can bond either two, three, or four NICs when vSwitch is the network stack, whereas you can only bond two NICs when Linux bridge is the network stack.
  4. Under Bond mode, choose the type of bond:
    • Select Active-active to configure an active-active bond, where traffic is balanced between the bonded NICs and if one NIC within the bond fails, the host server's network traffic automatically routes over the second NIC.
    • Select Active-passive to configure an active-passive bond, where traffic passes over only one of the bonded NICs. In this mode, the second NIC will only become active if the active NIC fails, for example, if it loses network connectivity.

    • Select LACP with load balancing based on source MAC address to configure a LACP bond, where the outgoing NIC is selected based on MAC address of the VM from which the traffic originated. Use this option to balance traffic in an environment where you have several VMs on the same host. This option is not suitable if there are fewer virtual interfaces (VIFs) than NICs: as load balancing is not optimal because the traffic cannot be split across NICs.

    • Select LACP with load balancing based on IP and port of source and destination to configure a LACP bond, where the source IP address, source port number, destination IP address, and destination port number are used to allocate the traffic across the NICs. Use this option to balance traffic from VMs in an environment where the number of NICs exceeds the number of VIFs.

      Note: LACP bonding is only available for the vSwitch, whereas active-active and active-passive bonding modes are available for both the vSwitch and Linux bridge.

      For more information about the support for NIC bonds in XenServer, see the XenServer Administrator's Guide.

  5. To use jumbo frames, set the Maximum Transmission Unit (MTU) to a value between 1500 to 9216.
  6. To have the new bonded network automatically added to any new VMs created using the New VM wizard, select the check box.
  7. Click Create to create the NIC bond and close the dialog box.

XenCenter will automatically move management and secondary interfaces from bond slaves to the bond master when the new bond is created.

Note that a server with its management interface on a bond will not be permitted to join a pool. You will need to reconfigure the server's management interface and move it back on to a physical NIC before it can join a pool.

Deleting a NIC bond

If reverting a server to a non-bonded configuration, be aware of the following requirements:

  • As when creating a bond, all virtual machines with virtual network interfaces that use the bond must be shut down prior to destroying the bond. After reverting to a non-bonded configuration, reconnect the virtual network interfaces to an appropriate network.
  • Move the management interface to another NIC using the Management interfaces dialog box before you delete the bond, otherwise connections to the server (including XenCenter) will be dropped.

To delete a bond

  1. Select the server in the Resources pane then click on the NICs tab.
  2. Click Delete Bond.

Dedicating a NIC to a specific function

You can assign IP addresses to NICs to dedicate a NIC to a specific function, such as storage or other types of network traffic. For more information, see Configuring IP Addresses.