Accessing Cisco router or switch

Cisco routers or switches are commonly accessed either via Virtual TTY line (VTY) telnet or ssh or line console port.

Console port is a physical dedicated port, and does not route packets. A special flat cable, typically blue is used to connect your PC or Mac to the router.
Use clients like Putty or SecureCRT, establish a serial connection with following settings:

Baud rate 9600
Data bits 8
parity None
Stop bits 1
  • Cisco console access settings

When accessing the router via telnet or ssh, you are coming in through a routed port.  telnet or ssh session can be initiated from another router or most likely a management station. Management or jump station, is a server which has access to all of your network devices, allowing access to you or your scripts. Because the jump station is so critical, it must be secured to allow access to network cleared staff.

The caveat is, before you can telnet/ssh to a router, these access methods must be permitted. This requires that the 1st log in is via console, which is what the following demos will cover.

Our demo tasks will consist of the following steps:

  • Access RTR1 & RTR2 via console.

  • Configure hostnames.

  • Configure link IP addresses on both RTRs interfaces.

  • Check interfaces status and reachability.

  • Check line VTY configuration and enable login via VTY (use username LAB and password cisco, enable password CCNA).

  • Test telnet access from RTR1 from RTR2 .

  • Save your configurations.

STEP1

On accessing the router for the 1st time, if it does not have a startup configuration, it would ask you to enter an initial configuration dialogue. Here just type”no” and take control of configuring the device yourself.

STEP2

Type enable , or “ena” to access privilege mode, followed by “conf t” for executive mode and then set your hostname.

STEP3

Access the interface sub-level and assign the ip address and mask, then end to exit return to main exec level prompt.

STEP4

Run a “show ip interface brief” command to see a list of all interfaces, and note how GE0/1 has the configured IP, as well as an UP status and protocol UP.
If protocol was down, it would suggest link at the other end is either down or whole router is powered off. This is one of the most common issues you will encounter in the field.

Our test ping to remote end of the link 10.1.1.2 on RTR2 responds fine, so we know we have full connectivity

STEP5

Do a  “show run” for show running configuration, and scroll down to the end. Here you will see the section related to line console and line vty.
line vty has transport input set to none. This means neither telnet, nor ssh will be accepted from a remote source !

Let’s configure RTR2 to accept telnet, ensure it will use a local user credentials for login and set CCNA as enable password.

STEP6

Back to RTR1, we telnet to RTR2 on its link IP address 10.1.1.2, and when prompted to login, use our passwords.

STEP7

Saving the configuration in Cisco IOS platforms, is saving the running config (which is the config you are working on), to nvram(which is non volatile RAM). This action will ensure the router’s configuration persists, and I become to startup config the router has if rebooted.

3 commands can lead to the same results, write memory, wr, or copy running-config to startup-config.

For more examples on assign ip addresses to Cisco router or switch interface, take a look at Assigning IP addresses