Nortel Networks Remote Gateway 50 - Manual (Page 72)

Page 72 of 258 Bandwidth Management
553-3001-207 Standard 2.00 January 2006
When a Call Server receives a QoS alarm, the two zones that originated the
alarm are determined. Using this information, the Call Server reduces the
bandwidth limit between the two zones. This zone-to-zone bandwidth limit
(in effect at any particular time) is known as the Sliding Maximum
Bandwidth Limit and is a percentage of the Configured Interzone bandwidth
limit. The Sliding Maximum value is displayed using the prt interzone
command. The QoS Factor % is also displayed and is the percentage of the
Sliding Maximum versus the configured allowable bandwidth. The Call
Server checks the Network Bandwidth zone management tables for the
originating and terminating zones of the new call to determine the available
bandwidth for the call.
For more information about alarms, refer to Software Input/Output: System
Messages (553-3001-411).
When feedback indicates a significant QoS change in a zone, the Call Server
reduces the available bandwidth (Sliding Maximum Bandwidth Limit) in the
zone until the QoS reaches a satisfactory level. Once satisfactory QoS is
reached, the bandwidth is slowly raised until either the full bandwidth is
available or until QoS degrades again. Bandwidth changes can be configured
to be gradual (to reduce rapid swings and variations) or rapid.
Multiple Appearance Directory Numbers (MADN) can exist on different
zones. Calls to an MADN are handled the same as other IP Phone calls, and
are subject to the same bandwidth limitations.
New SNMP alarms are provided to monitor the system. When the bandwidth
limit between zones is reduced below configured levels, an alarm is raised. A
Warning alarm and an Unacceptable alarm, each corresponding to a drop
below a configured threshold, are used. When the bandwidth returns to
normal, the alarm is cleared. If the bandwidth limit reaches zero, an additional
Unacceptable alarm is raised. These alarms allow the system administrator to
monitor the system and take corrective action when required.
Adaptive Network Bandwidth Management configuration
parameters
Packet Loss (pl), Jitter (j) and Delay (d) measurements, along with the R
factor (r) in IP Phone 200x Phase II telephones, are used to calculate the QoS
level for the zones. The coefficients for these QoS measurements — packet