Specifications

Chapter 6 Multisite WAN with Distributed Call Processing
Call Admission Control
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Cisco IP Telephony Network Design Guide
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have registered with it. Also, by way of Cisco IOS configuration, the gatekeeper
knows which Cisco CallManager belongs to what zone, and the amount of
bandwidth associated with each zone.
To verify that a particular Cisco CallManager has registered with the gatekeeper,
use the following Cisco IOS
show command:
show gatekeeper endpoint
Following is an example of the output from this command:
MS-2621-3A#show gatekeeper endpoint
GATEKEEPER ENDPOINT REGISTRATION
================================
CallSignalAddr Port RASSignalAddr Port Zone Name Type F
--------------- ----- --------------- - ---- --------- ---- --
10.122.1.17 1720 10.122.1.17 1710 zone1 VOIP-GW
H323-ID: 10.122.1.17
10.122.1.19 1720 10.122.1.19 1710 zone2 VOIP-GW
H323-ID: 10.122.1.19
10.122.1.20 1720 10.122.1.20 1710 zone3 VOIP-GW
H323-ID: 10.122.1.20
Total number of active registrations = 3
Once Cisco CallManager has registered, it always checks with the gatekeeper
before making an outbound call or accepting an inbound call. Cisco CallManager
performs this check by issuing an Admission Request (ARQ) to the gatekeeper,
as shown in Figure 6-7. As part of the ARQ, Cisco CallManager also requests a
specific amount of bandwidth, depending upon the type of codec used for the call.
It requests 128 kbps if the call uses a G.711 codec or 20 kbps if the call uses a
G.729 codec.