Console Port Connections, C H A P T E R | Cisco Systems CISCO1841-HSEC/K9-RF

•Console and Auxiliary Port Considerations, page 5-1

C H A P T E R 5

Cable Information and Specifications for Cisco 1800 Series Routers (Modular)

This chapter gives cable information and specifications for the console port, auxiliary port, and network ports on your Cisco 1800 series integrated services router (modular). It contains the following sections:

•Console and Auxiliary Port Considerations, page 5-1

•Preparing to Connect to a Network, page 5-2

For cable connection procedures, see “Cable Connection Procedures for Cisco 1800 Series Routers (Modular)”.

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 provides 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 flow control, whereas 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 slower speeds than modems; therefore, the console port is ideally suited for use with console terminals.