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Cisco VISM Installation and Configuration Guide
Release 3.0, Part Number OL-2521-01 Rev. D0, June 2004
Chapter4 Configuring VISM Features
Configuring VISM Features
Step 3 Type the cnfjtrinitdelay command, the jitter-buffer-size argument value, and press Enter to specify the
starting buffer size. Specify the jitter-buffer-size argument (defined in bytes) with a value from one of
the following ranges:
•For template numbers 1, 3, and 4, in the range from 0 to 100 in increments of 10.
•For template number 2, in the range from 0 to 100 in increments of 5.
You have completed configuring jitter. Proceed to the “Configuring the ATM Network Side” section on
page 4-31.

Configuring PNNI for AAL1/AAL2 SVCs

Use the cnfpncon command to configure Private Network-to-Network Interface (PNNI) priority routing
for AAL1/AAL2 switched virtual circuits (SVCs). Refer t o Chapter 5, “CLI Commands,” for more
information on using the cnfpncon command.
Configuring the ATM Network Side
Configuring the ATM network side consists of setting up ATM PVCs across the network and providing
the mechanism by which calls are routed over the correct PVC. The PVC configuration depends on the
VISM operating mode you require for your application.
•The Voice over IP switching operating mode requires you to set up an AAL5 PVC between the
VISM card and the PXM card, and then to an edge router. A single PVC is set up (a secondary PVC
may also be set up for redundancy). The PVC is used for bearer voice traffic and gateway protocol
communication between VISM and the call agent. The router extracts the IP frames from the ATM
cells and routes the frames accordingly.
•The AAL2 trunking operating mode requires you to set up as many as 64 AAL2 PVCs connected to
each remote location supported by the network. The PVCs carry voice traffic and optio na l CAS
signaling.
Each PVC is set up as three segments consisting of two local segments and one network segment.
The local segments are set up between the two VISM cards (one at the end of the PVC) and their
respective PXM cards. The network segment is set up between the two PXM cards across the
network. Refer to the Cisco MGX 8250 and MGX 8230 Release l installation and configuration
guides for more information.
In AAL2 trunking operating mode, you must bind endpoints to specific DS0s using the
addendpoint(s) commands. You must also create CIDs (connection identifiers) for each PVC that
binds the endpoints to the CID and a PVC. This ensures that calls arriving at a specific DS0 are
automatically routed to the preconfigured CID and PVC over nailed-down trunks. T here is no
switched or call agent involvement.