Comment 3 for bug 1688054

Or, perhaps NSX was a typo from before? Anyway, here's how I'd re-write this:

"Optional property that stands for receive / transmit (rxtx) factor. Can only be set on ports if the network backend supports the Quality of Service (QOS) extension, which includes Xen with nova-network. The rxtx factor is multiplied by the rxtx_base property of the network. Default value is 1.0, meaning, the receive / transmit value has the same value as attached network."