Media Flow Manager Overview : Admission Control

Admission Control
Admission Control works with Service Director. Media Flow Manager runs the Service Director mechanism to control the edge servers that serve client requests for content, based on the geographical location of the client. Service Director allows you to configure the closest Media Flow Controller for a given geographical location. Admission Control leverages the interface statistics from the Media Flow Controllers and controls the outgoing bandwidth for the content served by the Media Flow Controllers using the Service Director.
Media Flow Controllers are designed to track the interface stats (RX bytes and TX bytes) on every network interface. In a typical setup, the TX bytes would be the content delivered by the Media Flow Controller while the RX bytes would the data fetched from the origin server. The Media Flow Manager Admission Control feature fetches the interface stats from the Media Flow Controllers at regular intervals (5 minutes). These RX and TX stats from the various Media Flow Controllers are then collated to calculate the delivered bandwidth and the received bandwidth. These collated bandwidths are recorded and plotted on a graph for easy viewing in the Media Flow Manager. The Service Director uses the configuration of location-to-host mapping to return an XML with the host name of the edge Media Flow Controller based on the client’s location. To assist with Admission Control, configure a high watermark bandwidth and low watermark bandwidth used by the Service Director in the following way:
If the current bandwidth measured in the last 5 minutes goes above the set high bandwidth watermark, the Service Director only returns the default configured host (typically the CDN). This would mean that no new traffic comes to the Media Flow Controllers while they serve all the current requests.
If the current bandwidth drops below the set low bandwidth watermark, the Service Director goes back to normal operation returning hosts based on the set configuration.
This lets you throttle the aggregate bandwidth delivered by the Media Flow Controllers, ensuring that the publisher does not pay bandwidth overage charges.

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Media Flow Manager Administrator's Guide and CLI Command Reference
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