Specifications

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Cisco IP Telephony Network Design Guide
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Chapter 6 Multisite WAN with Distributed Call Processing
Call Admission Control
Figure 6-7 Request to Admit a Call
The gatekeeper then checks its configuration to determine the amount of
bandwidth available in the zone to which this particular Cisco CallManager is
assigned. It also checks the number of calls already in progress to or from that
zone. If bandwidth is available, the gateway issues an Admission Confirm (ACF)
that allows Cisco CallManager to complete the call. If bandwidth is not available,
the gatekeeper issues an Admission Reject (ARJ), which prevents call completion
and causes the caller to receive a busy tone.
As illustrated in Figure 6-8, the local Cisco CallManager performs the following
actions when it receives an incoming call from a remote Cisco CallManager
through the gatekeeper:
• It uses the E.164 address from the incoming H.225 setup information to
search its route patterns for a match. A matching route pattern enables the
local Cisco CallManager to determine whether the incoming call is from a
valid device and the amount of bandwidth (type of codec) needed for the
incoming call.
• It sends an ARQ to the gatekeeper to request the required bandwidth before
accepting the incoming call.
Site 1
IP
V
Cisco
3600
x1111
Zone 1
ARQ
ACF
PSTN
IP WAN
Cisco CallManager sends its E.164
address in ARQ.
Cisco CallManager uses returned IP
address in ACF to target remote
Cisco CallManager.
1)
2)
Cisco CallManager requests proper
bandwidth in ARQ.
3)
49083
Cisco IOS
Gatekeeper