By Chris July 25, 2016 13:05

Getting reps with connecting two router serial interfaces helps build confidence. This lab gives you another chance, this time with PAP authentication on the link. The goal: get the link working so both routers can ping each other.


PAP Authentication provides one way to authenticate two routers on the ends of a serial link. This lab gives you the parameters, and you then need to remember the configuration steps and get a link working. The lab begins with all the interfaces shown in Figure 1 connected and enabled using default parameters. Your job is to get the serial link working per the following parameters:

  • Use PPP
  • Use PAP Authentication
  • Use bidirectional PAP Authentication.
  • Usernames and passwords:
    • R1 claims to be ciscouser1 with username/password of ciscouser1/cisco
    • R2 claims to be ciscouser2 with username/password of ciscouser2/cisco
  • Use the IP addresses indicated in the figure
  • Assume R2 connects to the DCE end of the cable, and that the link should run at T1 speed


Figure 1: Two Routers with IP Subnets


Initial Configuration

While you might be able to configure this lab using the information supplied so far, the initial configurations of the two routers can also be helpful. Example 1 and 2 show the beginning configuration state of R1 and R2.

Example 1: R1 Config

Example 2: R2 Config


Answer on Paper, or Maybe Test in Lab

Next, write your answer on paper. Or if you have some real gear or other tools, configure the lab using them.

To test your solution if you happen to try it with real gear, all you need to do is cable the back-to-back cable and configure both ends. If both serial interfaces remain in an up/up state, and you can ping the other router’s serial interface IP address, then the link is up.

Answers: GRE Tunnel 3
Answers: PAP 1
By Chris July 25, 2016 13:05
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