Nortel Networks SRG 50 NN43001-307 - Manual (Page 111)

Adaptive Network Bandwidth Management 111
period. When the degradation is removed or the performance of the network
improves, the allowable bandwidth returns to provisioned levels and the Call
Server gradually starts allowing new calls.
Essentially, Adaptive Network Bandwidth Management provides a fallback to
PSTN on QoS degradation for new calls. As a result, bandwidth is managed
and quality measured between all the zones across the entire network, and
when necessary corrective action is taken. Due to the real-time interaction
with the network, less maintenance is required for the network since the
system reacts automatically to network conditions.
With Adaptive Network Bandwidth Management, it is not necessary to
provision bandwidth parameters between every zone in the network. Rather,
the Call Server automatically learns of new zones in the network and applies
Adaptive Network Bandwidth Management to these new zones as required.
Therefore, as new Call Servers are added to the network, it is not necessary
to re-provision all the other Call Servers on the network to take into account
this new Call Server. Conversely, when Call Servers are removed from the
network, the remaining Call Servers age out the old Call Server information
and therefore, provide only up to date bandwidth information.
This feature operates between all IP Peer CS 1000 systems, including the
Media Gateway 1000B and Survivable Remote Gateway 50.
Call scenario
A call is requested from a telephone in VPNI 1/Zone 2 on Call Server A to a
telephone in VPNI 3/Zone 3 on Call Server B. Both zones have Adaptive
Network Bandwidth Management enabled.
1. Call Server A contacts the Network Redirect Server to obtain the
address of Call Server B.
2. Call Server A sends a call setup message to Call Server B, identifying
the calling telephone’s VPNI and zone.
3. Call Server B determines if there is sufficient bandwidth for the call, and
sends back the VPNI and zone of the called telephone.
4. Call Server A checks its bandwidth table to determine if there is sufficient
bandwidth available for the call from Call Server A to Call Server B.
5. If Call Server A determines there is enough bandwidth available, the call
is established; otherwise, alternate treatment is provided in the form
of blocking or rerouting the call.
Both Call Server A and Call Server B must consult their own bandwidth
tables to determine if there is enough bandwidth for the call to proceed.
Figure 34 "Call Progress with Adaptive Network Bandwidth Management"
(page 112)
shows this scenario.
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
.