Bandwidth Considerations

Preparing an Avaya Communication Manager Environment › Bandwidth Considerations

Bandwidth Considerations

Call volume is the key metric to consider when determining the scale of any UC Monitor deployment. In Avaya environments, call volume affects not only database size and growth and collector load, but also bandwidth usage, as many endpoints send quality data to the collector. However, our testing indicates that the amount of additional bandwidth used is negligible.

The following breakdown is based on our testing and provides a range that includes the approximate usage in your environment.

In an Avaya system, the average RTCP packet size is 250 bytes, which includes Ethernet and UDP headers. By default, the Avaya phones and voice gateways send RTCP call-quality reports at 5-second intervals, which amounts to 12 packets sent per call minute, per endpoint.
With two different devices sending reports, you can see 2 x 12 = 24 packets sent per call minute. With 24 packets per minute at 250 bytes each, network traffic from Avaya endpoints to the collector reaches approximately 6000 bytes per minute, or .0977 Kbps. Or equally, 100 bytes per second, per call minute, which is .0000954 MBps per call minute.
When endpoints encounter congestion, they increase the 5-second interval to throttle the number of report packets sent. To prevent congestion on WAN links, increase the interval to 10 seconds and use the class-default queue for the RTCP traffic.

The following table illustrates bandwidth usage that is based on the number of simultaneous calls and the average duration of each call:


	Average Call Duration (in minutes)
Busy-Hour Calls	2	3	4	5
1000	0.19 MBps	0.29 MBps	0.38 MBps	0.48 MBps
5000	0.95 MBps	1.43 MBps	1.91 MBps	2.38 MBps
10000	1.91 MBps	2.86 MBps	3.81 MBps	4.77 MBps
20000	3.81 MBps	5.72 MBps	7.63 MBps	9.54 MBps
50000	9.54 MBps	14.3 MBps	19.1 MBps	23.8 MBps
100000	19.1 MBps	28.6 MBps	38.1 MBps	47.7 MBps

The call detail records (CDRs) that the Avaya Communication Manager sends to the collector are 155 bytes per call. Only one CDR is sent for each call, containing information for both directions of call data flow. CDR-related traffic is further reduced when you install the UC Monitor collector near the Communication Manager.