Nortel Networks SRG 50 NN43001-307 - Manual (Page 110)

110 Bandwidth Management
Command Description
• Type= PRIVATE/SHARED
• Strategy = BB/BQ
• ZoneIntent = MO/VTRK
Adaptive Network Bandwidth Management
CS 1000 Release 4.5 supports the Adaptive Network Bandwidth
Management feature.
Description
The Adaptive Network Bandwidth Management feature enhances the
performance of Voice over Internet Protocol (VoIP) networks based
on real-time interaction. It provides the means to automatically adjust
bandwidth limits and take corrective action in response to Quality of Service
(QoS) feedback. This dynamic bandwidth adjustment maintains a high level
of voice quality during network degradation.
The Adaptive Network Bandwidth Management feature dynamically adapts
to QoS in the network and reduces the bandwidth available for interzone
calls if QoS degrades. Typically, each Call Server in the network has a zone
assigned to it. The Call Server keeps track of the bandwidth being used
between its own zone and zones belonging to other Call Servers. If the QoS
degrades between the Call Server’s zone and a particular zone belonging
to another Call Server, the available bandwidth is reduced automatically
between those two zones. When the QoS between the two zones improves,
then the bandwidth limit is allowed to return to normal.
When an IP Phone encounters degradation of the network, it informs the
Call Server through various QoS alarms. These QoS alarms (packet loss,
jitter, delay, and, for phase 2 IP Phones, R value) get reported to the Call
Server. Depending upon the rate of the incoming alarms and the value of the
alarms, the Call Server reduces the available bandwidth available to make
new calls. The Call Server will lower/limit the number of new calls allowed,
based on the available bandwidth. This prevents excessive calls being
placed on a network with limited bandwidth (resulting in poor voice quality).
Once the adjusted (lowered) bandwidth reaches its full capacity, new calls
are either routed to an alternate route (if available) using Network Alternate
Routing Service (NARS) , or Alternative Routing for Network Bandwidth
Management feature, or new calls are blocked. For further information about
the Alternative Routing for Network Bandwidth Management feature, see
Branch Office Installation and Commissioning (NN43001-314). The Call
Server continues to monitor the network throughout the network degradation
Nortel Communication Server 1000
Main Office Configuration Guide for SRG 50
NN43001-307 02.02 Standard
Release 5.0 3 December 2007
Copyright © 2005-2007, Nortel Networks
.