Polycom 1500/1800/2000/4000 manual System Flags, Capacity Reduction During Traffic Shaping

Appendix L - Media Traffic Shaping

●Delays due to traffic shaping, if any, are limited to 10ms.

●This feature is not applied on audio, since the encoder output audio rate is constant.

●When LPR is enabled, traffic shaping is applied following packets repair and prior to packets sending.

System Flags

Traffic shaping usage is controlled by Collaboration Server configuration system flags (for the entire bridge):

●ENABLE_RTP_TRAFFIC_SHAPING - Controls traffic shaping. When set to YES, traffic shaping is applied to all ports, resulting in some port capacity reduction in MCUs with MPMx/MPMRx cards (see Capacity Reduction in MPMx and MPMRx MCUs). When set to NO (default), traffic shaping is disabled.

●VIDEO_BIT_RATE_REDUCTION_PERCENT - Indicates the percentage of actual reduction in bit rate sent from the MCU to the endpoint (negotiated bit rate is not reduced). This flag is applicable only when traffic shaping is enabled (ENABLE_RTP_TRAFFIC_SHAPING set to YES).

Range: 0-60; Default value: 15

●TRAFFIC_SHAPING_MTU_FACTOR - Used for the MTU (Maximum transmitting Unit - the size of transmitted packets) dynamic calculation:

New MTU = video bit rate / TRAFFIC_SHAPING_MTU_FACTOR

where the new MTU value is guaranteed to be a minimum of 410, and a maximum of 1460

(MAX_MTU). The purpose of this calculation is to match video rate in outgoing video to call rate, yet force lower encoder bit rates to avoid overflow.

This flag is applicable only when traffic shaping is enabled.

Range: 0-5000, where 0 signifies no change in MTU; Default value: 800

To modify any of these flags, manually add them into the MCMS user parameters section of the system configuration flags, and then modify their value (see Manually Adding and Deleting System Flags).

Capacity Reduction During Traffic Shaping

The table below describes the maximum capacity left after reduction due to traffic shaping in Collaboration Servers 1500/2000/4000. There is no capacity reduction in Collaboration Server 1800.

Capacity Reduction in MPMx and MPMRx MCUs

		MPMx		MPMRx
Resolution	Non-mixed Mode	Mixed Mode	Non-mixed Mode	Mixed Mode
CIF	70	40	150 *	100 *
SD	50	40	150 *	100 *
HD720p	30	20	100	66
HD1080p	15	10	50	40
Audio Only	70/360	40/360	300	150

* Assuming conference bit rate ≤ 1024 Kbps

Polycom, Inc. 1068