Categories: XenServer, Hyper-V, Alike v3, Alike v4

Introduction

The following article is for Alike users with XenServer environments. The below information was based on user/community feedback, and may not be appropriate for your particular environment. For more troubleshooting guides, or articles on Hyper-V, please visit our KB home.

XenServer v6.1 has announced native support for LACP. It is recommended to upgrade to v6.1 or above in order to gain proper and supported use of LACP NIC bonding.

Bonding Modes

The default bonding mode for Citrix XenServer 5.5/5.6 is “1,” or active-backup (slb). This mode only provides fault tolerance, since only one NIC in the bond is active at a time. For more heavily utilized production systems, an active-active configuration is preferable.

The two bonding modes that provide full send/receive balancing across all NICs are 4 (802.3ad) and 6 (alb). Mode 4 provides link aggregation according to the 802.3ad specification, and requires an etherchannel to be configured on the switch.

How to Configure Your Switchports for an LACP Etherchannel

The following is an example of how to configure an LACP/802.3ad bond with XenServer 5.5 and a Cisco 3750 switch running IOS:

Note: In this case, we are making the etherchannel/Bond a trunk port which will only allow VLANs 2 – 11. We have two NICs from our XenServer that make up the bond0 interface, plugged int Gi1/0/1 and Gi2/0/1.

1. // Configure the EtherChannel first
• interface Port-channel1
  description Etherchannel Team for XenServer1
  switchport trunk encapsulation dot1q
  switchport trunk native vlan 2
  switchport trunk allowed vlan 2-11
  switchport mode trunk
  spanning-tree portfast
  spanning-tree bpduguard enable
  !
2. // now configure the individual switchports
• nterface GigabitEthernet1/0/1
  description XenServer1 – eth0
  switchport trunk encapsulation dot1q
  switchport trunk native vlan 2
  switchport trunk allowed vlan 2-11
  switchport mode trunk
  speed 1000
  duplex full
  channel-protocol lacp
  channel-group 2 mode active
  !
• nterface GigabitEthernet2/0/1
  description XenServer1 – eth1
  switchport trunk encapsulation dot1q
  switchport trunk native vlan 2
  switchport trunk allowed vlan 2-11
  switchport mode trunk
  speed 1000
  duplex full
  channel-protocol lacp
  channel-group 2 mode active
  !
3. // now make sure things are configured properly:
   show etherchannel 2 summary
4. // this should output something like the following:
   …
   Number of channel-groups in use: 4
   Number of aggregators: 4

Group Port-channel Protocol Ports
——+————-+———–+———————————————–
2 Po2(SU) LACP Gi1/0/1(P) Gi2/0/1(P)

// Note: You may see the two nics in (I) instead of (P) until you configure and reboot your XenServer

Now, make the following changes to your XenServer host:

1. Create a Bonded interface from XenCenter. Select your server, then the NICs tab and choose ‘Create Bond.’ Add the PIFs you want.
2. The Citrix recommended option. Run the following command on the XenServer host console. Make sure to use the UUID of the Bonded interface.
   xe pif-param-set uuid= other-config:bond-mode=802.3ad
   (note: to find your PIF’s uuid: xe pif-list host-uuid= )
   (note: to find your Host’s uuid: xe host-list )
3. Some of our users have reported problems getting the official recommendation working, and suggested an alternate method:

   On the XenServer host, edit the following file:
   /opt/xensource/libexec/interface-reconfigure

   find the following line:
   “mode”: “balance-slb”,
   and replace it with
   “mode”: “802.3ad”

   Then save and restart the XenServer. This will change the default bonding method for all Xen bonds to “802.3ad.”

4. To make sure things are working as expected, run (replace X with your bond number):
   cat /proc/net/bonding/bondX

   You should see something similar to this:
   Ethernet Channel Bonding Driver: v3.1.2 (January 20, 2007)

   Bonding Mode: IEEE 802.3ad Dynamic link aggregation
   Transmit Hash Policy: layer2 (0)
   MII Status: up
   MII Polling Interval (ms): 100
   Up Delay (ms): 31000
   Down Delay (ms): 200

   802.3ad info
   LACP rate: slow
   Active Aggregator Info:
   Aggregator ID: 1
   Number of ports: 2
   Actor Key: 17
   Partner Key: 2
   Partner Mac Address:

   Slave Interface: eth0
   MII Status: up
   Link Failure Count: 0
   Permanent HW addr:
   Aggregator ID: 1

   Slave Interface: eth1
   MII Status: up
   Link Failure Count: 0
   Permanent HW addr:
   Aggregator ID: 1

5. Test and verify. At this point, your new team should be up and functional.

Final Notes

If you are having trouble with any of the above steps, please open a support ticket. See the KB article, “How to Use Quadric Support,” for instructions on how to open a ticket.