Nutanix: When Blunt Force Trauma Isn’t Enough on the vSwitch

My philosophy with most things is to keep it simple. The more bells and whistles turned and tooted usually lead to problems down the road. Each Nutanix node has over 20 Gb/s of available traffic which is a truck load in my mind. Living in the VDI land it’s common space to lots and lots of desktops running on one host. Multiple desktops, multiple vMotion streams during maintenance mode can take most of a 10 Gb link. If you want to ensure performance of your desktops you should look at using a virtual Distributed Switch(vDS). Lots of improvements have been made over the years with vDS and a great resource is the WhalNetwork.
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#VDI Tip 64: Follow the Network Checklist

Funny thing about Virtual Desktop Infrastructure, it usually relies heavily on the network. Most of my last two days has been spent troubling shooting dropped PCoIP packets, so I feel it’s timely to make sure you have your basis covered.

So here is the big tip of the day, Read and follow this check list – PCoIP Virtual Desktop Network Design Checklist

Networking isn’t my strongest skill but luckily I work with some really smart people. I think the biggest take away from the checklist is WRED.(Weighted Random Early Detection). It provides preferential traffic handling for packets with higher priority. It can selectively discard lower priority traffic when the interface begins to get congested. Try to get your PCoIP traffic prioritized just under VoIP traffic. The above document notes ” Do not configure WRED on the physical interface as it will override all other QoS policies”. Most traffic monitoring tools are not granularity enough to catch the spikes in traffic. In the land PCoIP, 1 minute intervals does not pass the test.

If you have access to your Cisco Router, you can check for drop packets by using the CEF (Cisco Express Forwarding) commands.
show cef drop
show ip cef switching statistics

You can also check for high CPU utilization. Sometimes high CPU utilization will cause buffering. Buffering = BAD

Run something different than Cisco? Please comment and leave commands for other vendors.