The new ICND2 book takes extra care to map out the configuration required for PPPoE, along with the somewhat complex verification and troubleshooting details as well. This lab is meant to be straightforward so that you get practice on getting the configuration correct. The lab also lists a copy of a figure from the book that details the main configuration steps. (Here’s the lab post link.)
Answers
Figure 1: Typical Lab Network for Testing PPPoE Configurations
Example 1: Client Config
interface GigabitEthernet0/1 pppoe enable pppoe-client dial-pool-number 5 ! interface Dialer10 mtu 1492 ! layer 3 ip address negotiated ! layer 3 encapsulation ppp ! layer 2 ppp chap hostname Wendell ppp chap password Odom dialer pool 5 ! layer 1 ! ip route 0.0.0.0 0.0.0.0 Dialer10
Commentary
The new ICND2 200-105 book’s Chapter 15 (published 2016) takes a close look at PPPoE configuration. Interestingly, the client side configuration can look scary, with several unfamiliar commands. However, for parameters, all you have to do is select two parameters that just need to be unique on the local router, and then configure those numbers in the correct places. The numbers are the dialer interface number and the dialer pool number.
This particular lab told you what values to use for each parameter, mainly to make it easier to list a single answer configuration here in the lab. Once armed with the dialer interface number of choice (10 in this case) and dialer pool number (5 in this case), you can just follow a template. You also need to know the same username/password combination that the ISP is expecting to hear from the client router as part of the PPP CHAP authentication exchange (Wendell/Odom in this case). Figure 2 shows the template:
Figure 2: Figure 15-28 from the ICND2 200-105 Cert Guide
If you use the template in the figure, and compare it to the answer in Example 1, you will find all the commands. Here are some important highlights:
- The physical interface (G0/1 in this case) has no layer 3 parameters at all, and even shows the no ip address command to emphasize that IP is not enabled on the physical interface.
- IPv4 is enabled on the dialer interface, but in a way to use PPP address assignment, not DHCP address assignment, by using the ip address negotiated
- The CHAP user and password sit under the dialer interface, which actually has more to do with the one-way authentication configured here (the ISP authenticates the client, but not vice versa).
- The numbers that must match here are the dialer pool numbers (5 in this case).
Note that no one dialer interface number or dialer pool number is better than another. (Note that often an engineer will use the same dialer pool and dialer interface number just to make operations a little simpler.)