Distance Limitations for Interface Cables
When planning your installation, consider distance limitations and potential electromagnetic interference
(EMI) as defined by the Electronic Industries Association (EIA). Distance-limitation information is included
for the following Voice Gateway ports:
•
Gigabit Ethernet ports
—
The maximum segment distance for Gigabit Ethernet is 330 feet (100 meters)
(specified in IEEE 802.3).
•
FXS analog voice ports
—
The maximum distance is established by a total allowable loop resistance,
including the phone or terminal equipment, of 600 Ohms.
Console Port and Auxiliary Port Considerations
Cisco VG310 and Cisco VG320 include an asynchronous serial console port and an auxiliary port. The console
and auxiliary ports provide access to the unit either locally using a console terminal connected to the console
port, or remotely, using a modem connected to the auxiliary port. This section discusses important cabling
information to consider before connecting the unit to a console terminal or modem.
The main difference between the console and auxiliary ports is that the auxiliary port supports hardware flow
control and the console port does not. Flow control paces the transmission of data between a sending device
and a receiving device. Flow control ensures that the receiving device can absorb the data sent to it before the
sending device sends more. When the buffers on the receiving device are full, a message is sent to the sending
device to suspend transmission until the data in the buffers has been processed. Because the auxiliary port
supports flow control, it is ideally suited for use with the high-speed transmissions of a modem. Console
terminals send data at speeds slower than modems do; therefore, the console port is ideally suited for use with
console terminals.
Console Port Connections
Cisco VG310 and Cisco VG320 have EIA/TIA-232 asynchronous (RJ-45) and USB 5-pin mini Type B,
2.0-compliant serial console ports. The console port do not have any hardware flow control. Shielded USB
cables with properly terminated shields are recommended.
EIA/TIA-232
Depending on the cable and the adapter used, this port appears as a Date Terminal Equipment (DTE) or Data
Circuit-Terminating Equipment (DCE) device at the end of the cable. Only one port can be used at the same
time.
The default parameters for the console port are 9600 baud, 8 data bits, 1 stop bit, and no parity. The console
port does not support hardware flow control.
USB Serial Console
Use the USB console port on the chassis to access the Cisco IOS CLI and perform configuration tasks. A
terminal emulation program, such as Microsoft HyperTerminal for Windows, is required to establish
communication between the voice gateway and a PC. The USB serial console port connects directly to the
USB connector of a PC using a 5-pin mini USB Type A or USB Type-B cable. The USB console supports
full-speed (12 Mbps) operation.
Cisco VG310 and Cisco VG320 Voice Gateways Hardware Installation Guide
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Planning Your Installation
Distance Limitations for Interface Cables
