Console Port on a Cisco Router

In order to perform the initial configuration of a Cisco router, you will need to create a terminal session with the router via its console port. On a Cisco 2501, the console port uses an RJ-45 connection and is an asynchronous serial port that uses the common EIA/TIA-232 communications standard. Asynchronous serial differs from synchronous in that it doesn’t require synchronized clocking between the two systems. Instead, systems use what are known as start and stop bits to mark the beginning and end of a character.

While the console port may look like it should be used for a standard Ethernet connection, do not make this mistake – it is not an Ethernet port, and a straight-through or crossover cable will not provide a proper connection. Instead, connections to this port are made using what is referred to as a rollover cable. This cable is usually included when you purchase the router, but we’ll look at how to create our own rollover cable shortly.

The physical connection to the console port is made via a standard PC COM port. Since the COM port on a PC is usually accessed via a DB-9 or DB-25 serial interface, a small RJ-45 to DB-9 (or DB-25) adapter is required. Again, this adapter is usually included with the router, and is labeled “TERMINAL”. Once the rollover cable is connected to both the PC COM port and the console port on the router, the router can be configured using a terminal emulation program like Windows HyperTerminal. The communications settings are the same as those looked at in Chapter 3 for connecting to the console port on a Cisco 1900 switch. As a reminder, the settings remain:

  • Bits per second – 9600
  • Data bits – 8
  • Parity – None
  • Stop bits – 1
  • Flow Control – None

We’ll discuss the initial connection to and configuration of a Cisco 2500 router in Chapter 7.

Author: Dan DiNicolo

Dan DiNicolo is a freelance author, consultant, trainer, and the managing editor of He is the author of the CCNA Study Guide found on this site, as well as many books including the PC Magazine titles Windows XP Security Solutions and Windows Vista Security Solutions. Click here to contact Dan.