Nortel Networks NN43001-307 Call scenario

Adaptive Network Bandwidth Management 111

period. When the degradation is removed or the performance of the network

improves,the allowablebandwidth 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 newcalls. 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 zonein 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 Ser versare added to the network, it is not necessar y

to re-provision all the other Call Servers on the network to takeinto 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 Gateway50.

Call scenario

A call is requested from a telephone in VPNI1/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 Ser ver A sends a call setup message to Call Server B, identifying

the calling telephone’s VPNI and zone.

3. Call Ser verB deter mines if there is sufﬁcient bandwidth forthe call, and

sends back the VPNI and zone of the called telephone.

4. Call Ser ver A checks its bandwidth table to determine if there is sufﬁcient

bandwidth availablefor the call from Call Server A to Call Server B.

5. If Call Ser ver 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 forSRG 50

NN43001-307 02.02 Standard

Release 5.0 3 December 2007