XCP NIC Bonding
NIC bonding can improve server resiliency by using two physical NICs as if they were one. Two NICs may be bonded to create a single, high-performing channel that provides connectivity between VMs and your external network. [1]
You can create a NIC bond in XenCenter by using "Add Network" in the Networking tab and choosing Bonded network.
Active/Active
This is the default mode with traffic balanced between NICs using Source Level Balancing (SLB). This mode will only work properly on a single logical switch (e.g. a single physical switch, or multiple switches that are stacked with proprietary backplanes such that they appear as a single switch). The advantage of this mode is it will use both interfaces for increased capacity, and also will fail-over between ports if one fails.
Active/Backup
If you're trying to setup simple fail-over redundancy with 2 separate switches, you probably want active/backup, which you can only configure from the CLI.
The recommended method is setup the bond first in XenCenter, then change the type to active/backup as below:
xe bond-list
Pick out the bond's master UUID like master ( RO): 4b9c2fa4-daa0-f9e8-4313-90cfa57019f3
xe pif-param-set uuid=4b9c2fa4-daa0-f9e8-4313-90cfa57019f3 other-config:bond-mode=active-backup
