Accessing a Cisco IOS Device

Unlike computers and smartphones, networking devices do not support video output, which makes it necessary for network professionals to use alternative methods, such as remote access, to interact with Cisco IOS for administration and troubleshooting. Whenever you purchase a new Cisco IOS device, you will find a special blue cable within the box, known as a console cable. The console cable enables network professionals to gain initial access to Cisco IOS from a computer using a terminal emulator application.

Figure 2.3 shows a Cisco console cable:

Figure 2.3: Cisco console cable

As shown in the preceding figure, there’s an RS-232 connector that connects to a serial interface (DB-9) on a computer. However, modern computers and laptops no longer have a DB-9 interface to support the RS-232 connector. Therefore, network professionals may need to acquire an RS-232-to-USB converter cable to bridge the connection.

Figure 2.4 shows an RS-232-to-USB converter cable:

Figure 2.4: RS-232 converter cable

Additionally, the RJ45 connector on the console cable connects to the console port of a Cisco IOS device, as shown:

Figure 2.5: Console port

The console port of a Cisco IOS device will always be labeled to help network professionals easily identify the interface.

Note

Keep in mind that you will need to use a console cable to gain initial access to a device that has not been configured for remote access and management.

Upon making the connection between the PC and the Cisco IOS device using the console cable, a serial connection is created between the PC and the device via the RS-232-to-USB cable. To access the CLI of Cisco IOS, a terminal emulation application is required.

The following are some common terminal emulation applications:

• PuTTY (free): https://www.putty.org/
• SecureCRT (paid): https://www.vandyke.com/products/securecrt/

To access the CLI, please take the following steps:

1. Connect the console cable to your laptop and the Cisco IOS device.
2. If you’re using Microsoft Windows, open Control Panel and click on Device Manager.
3. Expand the Port (COM & LPT) category to view which COM interface is assigned to the cable.
4. Figure 2.6 shows COM3 is being utilized on the computer:

Figure 2.6: Device Manager on Windows

Note

If the serial connection does not appear, ensure the latest drivers are installed for the cable on your computer. Additionally, the COM port number may be different when the cable is connected to your computer.

5. Next, download PuTTY on your computer and launch the application. Once PuTTY opens, use the following settings:
   • Connection type: Serial
   • Serial line: COM3 (change this accordingly)
   • Speed: 9600
   • Data bits: 8
   • Parity: None
   • Stop bit: 1
   • Flow control: None

Note

PuTTY can be downloaded via the Microsoft Store application on Microsoft Windows operating systems.

6. Figure 2.7 shows the PuTTY Configuration window:

Figure 2.7: PuTTY on Windows

7. Next, click on Open to establish the serial connection from PuTTY through the console cable to Cisco IOS.
8. Figure 2.8 shows the typical welcome screen when connecting to Cisco IOS:

Figure 2.8: CLI of a Cisco IOS router

Now that you have learned how to access a Cisco IOS device using the console cable, take a look at acquiring the Cisco Packet Tracer application, a network simulator built by Cisco for learning for the Cisco Certified Network Associate (CCNA) certification.