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Cisco Certification Introduction To ISDN Part IVIn part III of this ISDN primer, we learned that PPP has two main methods of authentication that Cisco certification candidates need to know how to configure: PAP and CHAP. Cisco Certification Building Your Own Home Lab Part I Cisco Certification: Building Your Own Home Lab, Part I CCNAs and CCNA candidates hear it all the time: Get some handson experience. From my personal experience climbing the Cisco certification la.. int bri0 encapsulation ppp ppp authentication chap R2: username R1 password CISCO int bri0 encapsulation ppp Cisco Certification Taking Your First Certification Exam Cisco Certification: Taking Your First Certification Exam Youve studied hard; youve practiced your configurations; youve used your flash cards over and over again; and finally, the big day is here.. ppp authentication chap Why CHAP Authentication Requires The Same Password On Both Routers Remember how PAP sends the password over the line in clear-text? CHAP does not actually send the password over the line at all. Instead, CHAP runs a hash algorithm using the password and a random number. It is the result of this hash that is passed over the link. The remote router receives the hash result, and runs the exact same algorithm. If the result is the same, the authentication attempt will be successful. If the result is different, the authentication will fail. For this reason, the passwords must be the same. Debug The Connection If Authentication Fails Since two passwords are involved, the chances of one of the passwords being mistyped doubles. If you configure CHAP and the link dials but drops almost immediately, there's an authentication problem. Run debug ppp negotiation and attempt to dial the line again. The output of this particular debug will show you where the problem is. Chris Bryant, CCIE #12933, is the owner of The Bryant Advantage, home of freeCCNA andCCNP tutorials, The Ultimate CCNA Study Package, and Ultimate CCNP Study Packages. For a FREE copy of his latest e-books, ,How To Pass The CCNA, and ,How To Pass The CCNP,, visit the website and download your free copies. You can also get FREE CCNA and CCNP exam questions every day! Pass theCCNA exam with The Bryant Advantage!
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