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Cisco VISM Installation and Configuration Guide
Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004
Chapter3 VISM Functional Description
Signaling Function
Note You can configure the VISM card to support CCS signaling without VISM card involvement. In this
configuration, a CCS channel is connected directly to the call agent that handles all necessary
processing of signaling information.
Figure3-2 VISM Signaling Paths
CAS signaling can be configured, in the switched AAL2 PVC operating mode, to send th e sig nalin g t o
the call agent or over an AAL2 PVC as in the AAL2 application.
CAS Processing in VoIP Switching and Switched AAL2 PVC Operating Mode
In the VoIP switching and switched AAL2 operating modes, CAS signaling is processed by the call agent
using SGCP.
The call agent performs the following functions:
•Issues the SGCP Notification Request command to instruct VISM which CAS signals are to be
reported to the call agent.
•Instructs VISM which CAS signals to send out the DS0.
The VISM card performs the following functions:
•Responds by sending acknowledge messages in return to call agent commands.
•Sends received CAS signals back to the call agent by using the SGCP Notify command.
•Interfaces with the DSP drivers, which perform the detection and generation of CAS signals.
Mode?
Type?
Type?
Type?
CAS (AAL2 Type 3)
CAS (xGCP)
CAS (xGCP)
CAS (trunk)
CCS (AAL5 PVC)
CCS (Q.931 using RUDP/UDP/IP)
VoIP switching/trunking,
AAL1/AAL2 SVC
TDM Grooming
AAL2 Trunking
T1/E1
S
ignaling
To Call Agent
To ATM
Trunks
7
2674
Switched
AAL2
CCS (AAL5 PVC)