Ccna routing and Switching Complete Study Guide

sh int s0/0

Serial0/0 is up, line protocol is up

  Hardware is PowerQUICC Serial

  Internet address is 10.0.1.1/24

  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

     reliability 239/255, txload 1/255, rxload 1/255

  

Encapsulation PPP

  loopback not set

  Keepalive set (10 sec)

  

LCP Open

  

Open: IPCP, CDPCP

[output cut]

The first line of output is important because it tells us that Serial 0/0 is up/up. Notice 

that the interface encapsulation is PPP and that LCP is open. This means that it has 

negotiated the session establishment and all is well. The last line tells us that NCP is 

listening for the protocols IP and CDP, shown with the NCP headers IPCP and CDPCP.

But what would you see if everything isn’t so perfect? I’m going to type in the 

configuration shown in Figure 21.15 to find out.

f i g u r e   21.15     Failed PPP authentication

Pod1R1

Pod1R2

hostname Pod1R1

username Pod1R2 password Cisco

interface serial 0

ip address 10.0.1.1  255.255.255.0

clock rate 64000

bandwidth 512

encapsulation ppp

ppp authentication chap

hostname Pod1R2

username Pod1R1 password cisco

interface serial 0

ip address 10.0.1.2  255.255.255.0

bandwidth 512

encapsulation ppp

ppp authentication chap

What’s wrong here? Take a look at the usernames and passwords. Do you see the 

problem now? That’s right, the C is capitalized on the Pod1R2 username command found 

in the configuration of router Pod1R1. This is wrong because the usernames and passwords 

are case sensitive. Now let’s take a look at the 

show interface

 command and see what 

happens:

Pod1R1#

sh int s0/0

Serial0/0 is up, line protocol is down

  Hardware is PowerQUICC Serial

---

904

 

Chapter 21 

■

  Wide Area Networks

  Internet address is 10.0.1.1/24

  MTU 1500 bytes, BW 1544 Kbit, DLY 20000 usec,

     reliability 243/255, txload 1/255, rxload 1/255

  Encapsulation PPP, loopback not set

  Keepalive set (10 sec)