120 Labs for Cisco CCNA 200-125 and CCENT Exams

Lab 93: Configuring PPP Encapsulation

Lab Objective:

The objective of this lab exercise is to enable PPP encapsulation on Cisco router Serial interfaces and verify the state of the PPP-encapsulated interfaces. This lab also covers debugging PPP links to see the different states of PPP negotiation

Lab Purpose:

PPP configuration and verification is a fundamental skill. PPP is one of the most popular Layer 2 protocols used on WANs. As a Cisco engineer, as well as in the Cisco CCNA exam, you will be expected to know how to configure and verify PPP encapsulation.

Certification Level:

This lab is suitable for both ICND2 and CCNA certification exam preparation.

Lab Difficulty:

This lab has a difficulty rating of 4/10.

Readiness Assessment:

When you are ready for your certification exam, you should complete this lab in no more than 10 minutes.

Lab Topology:

Please use the following topology to complete this lab exercise:

Task 1:

Configure hostnames on R1 and R2 as illustrated in the topology.

Task 2:

Enable Serial interfaces on R1 and R2. The Serial0/0 interface on R2 is identified as the DCE in the topology. Use the appropriate show command to verify that this interface is indeed the DCE. Configure the DCE interface on R2 to provide clocking to R1. The clock speed should be 512 Kbps. Verify that R1 receives clocking information from R2.

Task 3:

Enable PPP encapsulation on R1 and R2 Seriaol0/0 interfaces. Configure IP addressing on R1 and R2 Serial0/0 interfaces as illustrated in the topology. Verify your interface encapsulation, which should now be PPP. Test connectivity between R1 and R2 by pinging between the routers over the PPP link.

Task 4:

Enable PPP link negotiation debugging on R1. Next, issue the shutdown command, followed by the no shutdown command on Serial0/0. As the interface goes down and comes back up, you should see the different phases of PPP link negotiation. Disable debugging when you are done.

Configuration and Verification

Task 1:

For reference information on configuring hostnames, please refer to earlier labs.

Task 2:

For reference information on verifying DTE/DCE status, please refer to earlier labs.

Task 3:

 R1#conf t 
Enter configuration commands, one per line.  End with CTRL/Z. 
R1(config)#int s0/2 
R1(config-if)#encapsulation ppp 
R1(config-if)#ip address 10.0.254.1 255.255.255.240 
R1(config-if)#^Z 
R1# 

R2#conf t 
Enter configuration commands, one per line.  End with CTRL/Z. 
R2(config)#interface s0/0 
R2(config-if)#encapsulation ppp 
R2(config-if)#ip add 10.0.254.2 255.255.255.240 
R2(config-if)#end 
R2# 

R1#show interfaces s0/0 
Serial0/0 is up, line protocol is up 
 Hardware is PowerQUICC Serial 
 Internet address is 10.0.254.1/28
 MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec, reliability 255/255, txload 1/255, rxload 1/255   
Encapsulation PPP, LCP Open 
 Open: IPCP, CDPCP, loopback not set 
 Keepalive set (10 sec) 

R1#ping 10.0.254.2 

Type escape sequence to abort. 
Sending 5, 100-byte ICMP Echos to 10.0.254.2, timeout is 2 seconds: 
!!!!! 
Success rate is 100 percent (5/5), round-trip min/avg/max = 4/5/8 ms

Task 4:

R1#debug ppp negotiation 
PPP protocol negotiation debugging is on 
R1#conf ter 
Enter configuration commands, one per line.  End with CNTL/Z. 
R1(config)#int s0/0 
R1(config-if)#shut 
*Mar  1 02:00:08.949: %LINK-5-CHANGED: Interface Serial0/0, changed state to administratively down 
*Mar  1 02:00:08.949: Se0/0 PPP: Sending Acct Event[Down] id[4] 
*Mar  1 02:00:08.949: Se0/0 CDPCP: State is Closed 
*Mar  1 02:00:08.949: Se0/0 IPCP: State is Closed 
*Mar  1 02:00:08.953: Se0/0 PPP: Phase is TERMINATING 
*Mar  1 02:00:08.953: Se0/0 LCP: State is Closed 
*Mar  1 02:00:08.953: Se0/0 PPP: Phase is DOWN 
*Mar  1 02:00:08.953: Se0/0 IPCP: Remove route to 10.0.254.2 
*Mar  1 02:00:09.951: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to down 

R1(config-if)#no shut
*Mar  1 02:00:14.746: Se0/0 PPP: Outbound cdp packet dropped 
*Mar  1 02:00:16.746: %LINK-3-UPDOWN: Interface Serial0/0, changed state to up 
*Mar  1 02:00:16.746: Se0/0 PPP: Using default call direction 
*Mar  1 02:00:16.746: Se0/0 PPP: Treating connection as a dedicated line 
*Mar  1 02:00:16.746: Se0/0 PPP: Session handle[A7000001] Session id[2] 
*Mar  1 02:00:16.746: Se0/0 PPP: Phase is ESTABLISHING, Active Open 
*Mar  1 02:00:16.750: Se0/0 LCP: O CONFREQ [Closed] id 22 len 10 
*Mar  1 02:00:16.750: Se0/0 LCP:    MagicNumber 0x05CC8E89 (0x050605CC8E89) 
*Mar  1 02:00:16.750: Se0/0 LCP: I CONFREQ [REQsent] id 2 len 10 
*Mar  1 02:00:16.750: Se0/0 LCP:    MagicNumber 0x052E783E (0x0506052E783E) 
*Mar  1 02:00:16.754: Se0/0 LCP: O CONFACK [REQsent] id 2 len 10 
*Mar  1 02:00:16.754: Se0/0 LCP:    MagicNumber 0x052E783E (0x0506052E783E) 
*Mar  1 02:00:16.754: Se0/0 LCP: I CONFACK [ACKsent] id 22 len 10 
*Mar  1 02:00:16.754: Se0/0 LCP:    MagicNumber 0x05CC8E89 (0x050605CC8E89) 
*Mar  1 02:00:16.754: Se0/0 LCP: State is Open 
*Mar  1 02:00:16.758: Se0/0 PPP: Phase is FORWARDING, Attempting Forward 
*Mar  1 02:00:16.758: Se0/0 PPP: Queue IPCP code[1] id[1] 
*Mar  1 02:00:16.758: Se0/0 PPP: Discarded CDPCP code[1] id[1] 
*Mar  1 02:00:16.762: Se0/0 PPP: Phase is ESTABLISHING, Finish LCP 
*Mar  1 02:00:16.762: Se0/0 PPP: Phase is UP 
*Mar  1 02:00:16.762: Se0/0 IPCP: O CONFREQ [Closed] id 1 len 10 
*Mar  1 02:00:16.762: Se0/0 IPCP:    Address 10.0.254.1 
*Mar  1 02:00:16.774: Se0/0 IPCP: State is Open 
*Mar  1 02:00:16.778: Se0/0 IPCP: Install route to 10.0.254.2 
*Mar  1 02:00:17.763: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0, changed state to up 
*Mar  1 02:00:18.741: Se0/0 CDPCP: I CONFREQ [ACKrcvd] id 2 len 4 
*Mar  1 02:00:18.741: Se0/0 CDPCP: O CONFACK [ACKrcvd] id 2 len 4 
*Mar  1 02:00:18.741: Se0/0 CDPCP: State is Open 
R1(config-if)#end 
*Mar  1 02:00:25.777: %SYS-5-CONFIG_I: Configured from console by console 
R1#undebug all
All possible debugging has been turned off

Related Articles

Subscribe
Notify of
guest

This site uses Akismet to reduce spam. Learn how your comment data is processed.

0 Comments
Inline Feedbacks
View all comments
Back to top button