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Cisco Certification: Introduction To ISDN, Part IV

Part III of this ISDN primer for PAP CHAP, We PPP, Cisco certification candidates have learned two methods of authentication will need to know how to configure.

PAP CHAP has the advantage of a very few through. PAP password is a very good idea in today's world, the line is done through plain text. PAP configuration "PPP uterine transfer - username" command, the running configuration, so you can see additional configuration is required, and a person can see the PAP password.

PAP CHAP to the one, the only advantage is slim. PAP, the authentication password of the router associated with each of the other one can be used. CHAP password must be the same. Why? We CHAP authentication, we can see through the test.

The first step in configuring CHAP

CHAP user name / password combination, you must configure authentication on the remote device is connected to. (We already have a router with global hostname command you in the name of the configuration is assumed to be or not). Two CISCO router password.


Name R2 password CISCO

INT bri0

PPP encapsulation

PPP authentication two people


The name of R1 password CISCO

INT bri0

PPP encapsulation

PPP authentication two people

Two routers need the same password for CHAP authentication, the reason to

PAP send plain text passwords over the line Do you remember? In fact, no wire does not send the password via CHAP. Instead, the password hashing algorithm using random numbers CHAP. It is the result of the hash through this link. Remote router receives the hash result of the same algorithm. If the result is the same, the authentication attempt is successful. If the authentication fails, the results are different. For these reasons, the password should be the same.

If authentication fails, the connection debugging

Because it contains the two password incorrect password is entered the chances of one of the ship. CHAP and you connect the phone, configure, but when it drops almost immediately, authentication problems. The PPP negotiation debugging and try to run the phone line again. This particular problem is, I shows the debug output location.

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