NetScaler SDX: Does it Matter What Interface You Use?

One thing it seems I’m constantly educating my customers about when I install a NetScaler SDX is the difference between the ports. Large corporations so often use NetScaler SDX 0/1 and 0/2 interfaces, or as I like to refer to them- 0/X interfaces-  for data traffic and it only leads to stability problems down the road. I can’t emphasize enough how important it is that the 0/X interfaces are used only for management traffic. The reason behind requires a little further explanation about XenServer, the Hypervisor that runs the NetScaler SDX.

XenServer normally connects network interfaces to an Openvswitch running in the DOM0 partition. These network switches then have ports connected to the various virtual machines running on the XenServer. XenServer also has the ability to use SR-IOV (Single Root I/O Virtualization) when the network card supports it. The 0/1 and 0/2 interfaces of a NetScaler SDX which reside on the motherboard of the NetScaler SDX device do not support SR-IOV so they are connected to the standard XenServer Openvswitch. 1/1-1/n and 10/1-10/n are all SR-IOV capable. The 1/X interfaces support up to 7 VMs each and the 10/X interfaces support up to 40 VMs each.  With SR-IOV, each VM is able to connect directly to the hardware of the Network Interface.  The diagram below illustrates how the different interfaces connect.

Diagram

So if you’re reading this and have been using the Management interface on you NetScaler SDX for data traffic, I highly recommend getting some help in migrating to a more reliable configuration. In the end, it will help you avoid a bottle neck and an extra layer of virtualization that you don’t need.

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