I had a recent discussion with some of my colleagues on the value of Virtual Connect FlexNICs when use with VMware NetIOC virtual Distributed Switch(vDS). NetIOC was first introduced with ESX 4.1. One key feature it added was the ability to manage network bandwidth using shares like other VMware performance attributes (i.e. CPU and memory). When this capability first became available we wondered if FlexNICs would have any value in this environment.
As we became familiar with NetIOC, and got experience in customer implementations, it became apparent that FlexNICs still had a place in ESX deployments. One use case is for the management network.
I’ve seen cases where the network has been misconfigured using NetIOC or 3rd party vDS. It can be very difficult to regain management connectivity when the management interface is part of the network being managed. By using a separate pair of FlexNICs and a tradition vSwitch, the management interface is protected from such misconfiguration.
There are other use cases as well. Some designers want separate interfaces for different application tiers. Some designers prefer to segregate IP based storage traffic. I’m sure there are other use cases as well. Whatever your use case is, Virtual Connect and FlexNICs can add value to any VMware implementation.