Cisco WS-C2950T-24 Hardware Installation Guide - Page 73

Chapter 2 Preparing for Router Installation Network Cabling Specifications 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 2-7 • 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. 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. For detailed information about installing a console terminal, see the "Connecting to a Console Terminal or Modem" section on page 3-31. For cable and port pinouts, see the Cisco Modular Access Router Cable Specifications document located at Cisco.com. USB Serial Console The USB serial console port connects directly to the USB connector of a PC using a USB Type A to 5-pin mini USB Type-B cable. The USB Console supports full speed (12Mb/s) operation. The console port does not support hardware flow control. Note Always use shielded USB cables with a properly terminated shield. OL-18712-02 Cisco 2900 Series and 3900 Series Hardware Installation Guide 2-7