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Cisco 2900 Series and 3900 Series Hardware Installation Guide
OL-18712-02
Chapter 2 Preparing for Router Installation
Power Guidelines and Requirements
Power Guidelines and Requirements
Check the power at your site to ensure that you are receiving “clean” power (free of spikes and noise).
Install a power conditioner if necessary.
The AC power supply includes the following features:
•
Autoselects either 110 V or 220 V operation.
•
All units include a 6-foot (1.8-meter) electrical power cord. (A label near the power inlet indicates
the correct voltage, frequency [AC-powered systems only], current draw, and power dissipation for
the unit.)
For the power requirements for the Cisco 2900 and 3900 series routers, see the specifications table for
each router model, which can be found at the following link:
http://www.cisco.com/en/US/docs/routers/access/2900/hardware/installation/guide/Overview.html#wp
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Network Cabling Specifications
The following sections describe the cables needed to install your Cisco 2900 and 3900 series ISR in the
following sections:
•
Console and Auxiliary Port Considerations, page 2-6
•
Preparing for Network Connections, page 2-9
Console and Auxiliary Port Considerations
The router includes an asynchronous serial console port and an auxiliary port. The console and auxiliary
ports provide access to the router 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 router 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
The router has both EIA/TIA-232 asynchronous (RJ-45) and USB 5-pin mini Type B, 2.0 compliant
serial console ports. The console ports 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 DTE or DCE device at the end of the
cable. Only one port can be used at the same time.
