DMA OperationsGuide MCU Pool Orders
160 Polycom, Inc.
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 page156
“MCU Availability and Reliability Tracking” on page 160
“MCU Pool Order Procedures” on page162
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 6-15 How failed calls reduce the apparent capacity of an MCU
Consecutive
Failed Calls Percentage of Ports
Assumed To Be in Use
124%
243%
356%
467%
574%
680%