Polycom 3725-76302-001LI manual MCU Availability and Reliability Tracking

DMA Operations Guide MCU Pool Orders

5If no MCUs are available in any of the MCU pools in the pool order:

—If fallback is enabled, select the best MCU available to the Polycom DMA system, based on the system’s capability algorithm.

—If fallback is not enabled, reject the call.

See also:

“MCU Pool Orders” on page 156

“MCU Availability and Reliability Tracking” on page 160 “MCU Pool Order Procedures” on page 162

MCU Availability and Reliability Tracking

In order to minimize the number of failed calls, the Polycom DMA system employs mechanisms for detecting and handling MCU availability and reliability issues:

•If it can’t reach an MCU’s management interface, the DMA system won’t route calls to that MCU.

•If an MCU reports zero capacity via its management interface, the DMA system won’t route calls to that MCU.

•When calls to a specific MCU fail, the DMA system reduces the MCU’s reliability score, causing it to be selected less frequently than other MCUs.

An MCU’s reliability depends on the number of consecutive failed calls. As that number increases, the DMA system treats a growing percentage of the MCU’s ports as if they were in use. Since the DMA system selects the least used of the capable MCUs in its pool, the likelihood that an MCU with failures will be chosen for the next call declines rapidly (depending on the number of consecutive failed calls and the remaining capacity in the MCU pool).

Table 6-15How failed calls reduce the apparent capacity of an MCU

Consecutive	Percentage of Ports
Failed Calls	Assumed To Be in Use
1	24%
2	43%
3	56%
4	67%
5	74%
6	80%

160 Polycom, Inc.