Datasheet

Lab – Troubleshooting Basic PPP with Authentication

0 packets input, 0 bytes, 0 no buffer

Received 0 broadcasts, 0 runts, 0 giants, 0 throttles

0 input errors, 0 CRC, 0 frame, 0 overrun, 0 ignored, 0 abort

0 packets output, 0 bytes, 0 underruns

0 output errors, 0 collisions, 0 interface resets

0 unknown protocol drops

0 output buffer failures, 0 output buffers swapped out

0 carrier transitions

DCD=down DSR=up DTR=down RTS=down CTS=down

From the show interfaces results for S0/0/0 and S0/0/1, what are possible issues with the PPP links?

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The output indicates: Both S0/0/0 and S0/0/1 are shut down. PPP encapsulation has been applied to both

S0/0/0 and S0/0/1 interfaces. Besides the fact that the serial interface are administratively down, there

are still issues with the PPP configurations, such as mismatched authentication.

b. Use the debug ppp authentication command to view real-time PPP authentication output during

troubleshooting.

R1# debug ppp authentication

PPP authentication debugging is on

c. Use the show run interface s0/0/0 command to examine the settings on S0/0/0.

R1# show run interface s0/0/0

Building configuration...

Current configuration : 143 bytes

interface Serial0/0/0

ip address 192.168.12.1 255.255.255.252

encapsulation ppp

shutdown

ppp authentication chap

clock rate 128000

end

Resolve all problems found for S0/0/0. Record the commands used to correct the configuration.

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R1(config)# interface s0/0/0

R1(config-if)# no shutdown

After correcting the issue, what information does the debug output provide?

R1(config-if)# no shutdown

*Jun 18 12:01:23.931: %LINK-3-UPDOWN: Interface Serial0/0/0, changed state to up

*Jun 18 12:01:23.931: Se0/0/0 PPP: Using default call direction

*Jun 18 12:01:23.931: Se0/0/0 PPP: Treating connection as a dedicated line

*Jun 18 12:01:23.931: Se0/0/0 PPP: Session handle[F900005A] Session id[90]

*Jun 18 12:01:23.943: Se0/0/0 CHAP: O CHALLENGE id 1 len 23 from "R1"

*Jun 18 12:01:23.947: Se0/0/0 CHAP: I CHALLENGE id 1 len 23 from "R2"

*Jun 18 12:01:23.947: Se0/0/0 PPP: Sent CHAP SENDAUTH Request