Overview… enabling, suppressing and capping streams
A stream needs to be enabled before it is included in the traffic generated for a port:
The sum of the rates defined for all enabled streams must not exceed the effective bandwidth of the port. The effective bandwidth of a port can itself be slightly reduced, in parts-per-million, by specifying a speed reduction parameter on the “PORT PROPERTIES” panel in the XenaManager.
When also counting non-enabled streams, the total rate is allowed to exceed the port rate, allowing you to maintain a collection of stream definitions that are enabled in various combinations. Even a single non-enabled stream rate can exceed 100%, which can be helpful while defining the streams and adjusting their rates.
But if an enabled stream would bring the total bandwidth consumption above 100% the rate needs to be capped. This can be done explicitly by pressing the “Cap” button in the XenaManager:
Capping will be automatically enforced when enabling a stream or when editing the rate of a stream that is already enabled.
Capping can also be applied to the packet length, if for example you try to increase the packet length of a stream whose rate is specified in packets-per-second (or by decreasing the packet length when the rate is specified in Mbps, because the relative inter packet overhead increases).
An enabled stream can be suppressed while traffic is generated for the port, stopping it from contributing outgoing packets. It can be re-enabled again, and these operations do not affect the packets contributed from any other streams for the port.
Streams can also be initially in the suppressed state when traffic generation for the port is started. Unlike disabled streams, suppressed streams use a part of the port’s bandwidth, and are subject to capping just like enabled streams.
When changing port-level parameters that affect the overall bandwidth, like minimum inter frame gap on the “PORT PROPERTIES” panel, all streams are disabled, and you must re-enable them in whichever combination you choose.