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Cisco CVA122/CVA122E Hardware Installation Guide
OL-0799-02 (05/2001)
Chapter 1
Product Overview
Features
•
If supported by the service provider, an Ethernet hub can be connected to the Ethernet connector,
and multiple PCs can be connected to the hub.
Note
The USB specification does not support networking multiple PCs using a USB
bridging hub.
The Cisco CVA122/CVA122E Cable Voice Adapter supports up to 254 PCs (and other CPE devices) in
bridging mode. No maximum limit exists in routing mode. However, the CMTS can impose its own
limitation on the maximum number of PCs and CPE devices.
Note
For network performance reasons Cisco recommends a maximum limit of 16 CPE devices.
The service provider may also set a different limit by changing the MAX CPE parameter
in the DOCSIS configuration file—the default MAX CPE value is one CPE device.
Voice Ports
The Cisco CVA122/CVA122E Cable Voice Adapter contains two analog (FXS) voice ports at the rear
of the unit. These ports can be connected directly to analog telephones, modems, or FAX devices in the
following ways:
•
A single-line telephone, modem, or FAX device can be connected to each voice port, using a
two-wire connection.
•
A two-line analog telephone, modem, or FAX device can be connected to the first voice port
(labeled “V1+V2”), using a four-wire cable. When a two-line telephone is plugged into this port,
the second line acts as if it were plugged into the V2 port. If a two-line telephone is used, a device
plugged into the V2 port acts as an extension to the second line of the two-line telephone.
•
Adapters can be used to connect multiple analog devices to a single voice port. When multiple
telephones connected to a voice port, they function as extensions.
The Cisco CVA122/CVA122E Cable Voice Adapter supports up to two simultaneous voice connections,
one on each voice port. Only one voice call—telephone, modem, or FAX —per VoIP line is active at a
time. The actual number of voice ports and voice devices supported depends on the services purchased
from the service provider.
Caution
Do not connect the voice ports to telephone wires that exit the building under any
circumstances—this is a safety hazard. The Cisco CVA122/CVA122E Cable Voice
Adapter is not designed to connect to the Public Telephone Switched Network (PTSN).
Multiple analog telephone devices can be connected to each of the VoIP telephone lines, provided the
total Ringer Equivalence Number (REN) for all telephones does not exceed the limits given in
Appendix A, “Technical Specifications.”
Note
A REN value is assigned to each terminal device to denote the percentage of the total load
to be connected to the telephone loop used by the device, to prevent overloading. When
the REN value is exceeded, the telephones might not ring properly or at all.
