Lab 5-1: Setting up a Serial Connection

Physical Topology Diagram

  • Visual Topology
  • Command Line
  • Task 1: Using HDLC
  • Task 2: Configuring PPP
  • Task 3: Setting up PPP authentication

Visual Topology

Command Line

Command Description
debug ppp authentication Displays the PPP authentication process in real time
debug ppp negotiation Displays the PPP negotiation packet exchange
encapsulation HDLC Enables HDLC encapsulation on an interface
encapsulation PPP Enables PPP encapsulation on an interface
Hostname Sets a system name and changes the prompt output
PPP authentication chap Enable PPP authentication CHAP in an interface
no debug all Turns off all current debugging screens
username username password password Sets up a local user account

Task 1: Using HDLC

Step 1: Access the CLI on the router.

Step 2: Shutdown the ethernet interface connecting the two routers together, for this exercise we are going to configure a serial link between the two.

Step 3: Using the information contained in the visual topology diagram configure your serial interface with the appropriate IP address.

Step 4: Run the sh int s0/0/0 or s0/0 command and study the output to ascertain the layer 2 frame encapsulation, default should be HDLC.

Step 5: In the classroom we are using a back-to-back serial cable and one end will act as the DTE and the other end will be the DCE.

The DCE provides the synchronous clocking signal and requires the clock rate to be set.

R(config-if)clock rate 256000

Step 6: Enable the serial interface and PING the IP address of the peer end.

The PING should be successful!

Task 2: Configuring PPP.

Once you are happy with the connection disable the serial interface so we can change the encapsulation to PPP.

PPP provides optional features not available with HDLC such as authentication and will allow communication with a non-Cisco peer device unlike the default Cisco version of HDLC.

Step 1: Disable the serial interface and apply a command which changes the encapsulation to PPP, enable the serial interface and check you once again have connectivity between the two routers.

Task 3: Setting up PPP Authentication.

PPP supports different types of authentication, PAP and CHAP, in this task we are going to configure the more secure option out of the two, CHAP.

Step 1: Create a local user account

R1 only....
R1(config)#username R2 password cisco

R2 only....
R2(config)#username R1 password cisco

The username will need to match the hostname of the peer end and the password needs to be the same at both ends of the connection.

Step 2: Shutdown the serial interface.

Step 3: Run a debug command to observe the authentication handshaking process

Step 4: Enable the serial interface

Step 5: Save your running-config

Lab Answer Keys:

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