Example 6-8 Disabling | CCNA Practical Studies (Cisco Certification & Training)

Console Port Configuration

In the lab, you need to ensure that your connection to the console port does not time out, consequently disconnecting the reverse Telnet session. This is done from the line configuration mode of the console port using the following command:

 Router(config-line)#  no exec-timeout

Example 6-8 demonstrates how to prevent your connection to the console port on R1 from timing out.

Example 6-8 Disabling exec-timeout on the Console Port

 R1  #configure terminal  Enter configuration commands, one per line.  End with CNTL/Z. R1(config)#  line con 0  R1(config-line)#  no exec-timeout  R1(config-line)#

Note

In Example 6-8, the command exec-timeout 0 0 is the same as no exec-timeout. The exec-timeout command also can be set to an arbitrary number of minutes and seconds. For example, you could set the timeout value to 10 minutes and 5 seconds using the command exec-timeout 10 5. In live environments, it is recommended that you avoid using the no exec-timeout command because this provides unlimited access on the console port and the potential for a security breach.

In addition, another useful command helps with readability. Often when you are configuring a router, you will receive a console message that is generated by the router. If this happens while you are typing a command, your command is interrupted and the console message is inserted from where you entered your last keystroke. Example 6-9 highlights an occurrence of this. As you begin to type the command configure terminal, the console message inserts itself and the configure command is split between two lines of screen output.

Example 6-9 Console Message Interrupts When Typing the configure terminal Command

 R1(config-line)#  ^Z  R1#   confi   %SYS-5-CONFIG_I: Configured from console by console  gure  Enter configuration commands, one per line.  End with CNTL/Z. R1(config)#

This becomes problematic when typing long commands because you might lose track of where you left off in the command syntax, consequently typing an erroneous command. To prevent this, enable synchronous logging on the console port. This is done from line configuration mode of the console port using the following command:

 Router(config-line)#  logging synchronous

Example 6-10 demonstrates enabling synchronous logging on the console port of R1.

Example 6-10 Enabling Synchronous Logging on the Console Port

 R1(config)#  line con 0  R1(config-line)#  logging synchronous  R1(config-line)#

With synchronous logging enabled on the console port, when you begin to type the same configure terminal command, the console message is displayed; however, this time it does not interrupt the command flow. Instead, the keystrokes that you have entered to that point (that is, confi ) are redrawn on the line following the console message. Then you can finish typing and the completed command appears uninterrupted on the screen. Example 6-11 demonstrates this.

Example 6-11 With Logging Synchronous Enabled, Command Flow Is Not Interrupted when a Console Message Is Displayed

 R1#   confi   %SYS-5-CONFIG_I: Configured from console by console R1#   configure

Synchronous logging has now been successfully enabled on R1.

Top