Datasheet

Lab – Configuring Basic PPP with Authentication
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.Jun 20 05:05:16.089: Se0/0/1 PPP: Received SENDAUTH Response PASS
.Jun 20 05:05:16.089: Se0/0/1 CHAP: Using hostname from configured hostname
.Jun 20 05:05:16.089: Se0/0/1 CHAP: Using password from AAA
.Jun 20 05:05:16.089: Se0/0/1 CHAP: O RESPONSE id 1 len 28 from "Central"
.Jun 20 05:05:16.093: Se0/0/1 CHAP: I RESPONSE id 1 len 28 from "Branch3"
.Jun 20 05:05:16.093: Se0/0/1 PPP: Sent CHAP LOGIN Request
.Jun 20 05:05:16.093: Se0/0/1 PPP: Received LOGIN Response PASS
.Jun 20 05:05:16.093: Se0/0/1 CHAP: O SUCCESS id 1 len 4
.Jun 20 05:05:16.097: Se0/0/1 CHAP: I SUCCESS id 1 len 4
.Jun 20 05:05:16.097: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/1,
changed state to up
.Jun 20 05:05:16.165: %OSPF-5-ADJCHG: Process 1, Nbr 192.168.3.1 on Serial0/0/1 from
LOADING to FULL, Loading Done
h. Issue the undebug all (or u all) command on the Central and Branch3 routers to turn off all debugging.
Central# undebug all
All possible debugging has been turned off
Step 3: Intentionally break the serial link configured with authentication.
a. On the Central router, configure a username for use with Branch1. Assign cisco as the password.
Central(config)# username Branch1 password cisco
b. On the Central and Branch1 routers, configure CHAP authentication on interface S0/0/0. What is
happening with the interface?
____________________________________________________________________________________
The interface S0/0/0 is going up and down.
Note: To speed up the process, shut down the interface and enable it again.
.Jun 20 05:23:55.032: %LINK-3-UPDOWN: Interface Serial0/0/0, changed state to up
Central(config-if)#
.Jun 20 05:23:57.064: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0,
changed state to up
.Jun 20 05:23:57.076: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0,
changed state to down
Central(config-if)#
.Jun 20 05:24:03.144: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0,
changed state to up
.Jun 20 05:24:03.156: %LINEPROTO-5-UPDOWN: Line protocol on Interface Serial0/0/0,
changed state to down
Central(config-if)#
c. Use a debug ppp negotiation command to examine what is happening.
Central# debug ppp negotiation
PPP protocol negotiation debugging is on
Central(config-if)#
.Jun 20 05:25:26.229: Se0/0/0 PPP: Missed a Link-Up transition, starting PPP
.Jun 20 05:25:26.229: Se0/0/0 PPP: Processing FastStart message
.Jun 20 05:25:26.229: PPP: Alloc Context [29F9F32C]
.Jun 20 05:25:26.229: ppp145 PPP: Phase is ESTABLISHING
.Jun 20 05:25:26.229: Se0/0/0 PPP: Using default call direction
.Jun 20 05:25:26.229: Se0/0/0 PPP: Treating connection as a dedicated line