Home
>
Software
>
Cisco Certification: Introduction To ISDN, Part III

Cisco Certification: Introduction To ISDN, Part III

Configuring PPP PAP Authentication

Now we know how the ISDN link comes up (interesting traffic), and some scenarios that might cause the link to stay up, we need to look at ISDN authentication schemes. The two methods Cisco certification candidates must be familiar with are PAP and CHAP.

Password Authentication Protocol (PAP) sends the username and password over the ISDN link in clear-text. Sending any passwords over any WAN link in clear-text is generally a bad idea, but it???s important to know you have this option.

Regarding both PAP and CHAP, it???s a common misunderstanding that each side must authenticate the other. PAP and CHAP both support bidirectional and unidirectional authentication that is, R1 can authenticate R2 without R2 necessarily authenticating R1. It???s more common to use unidirectional authentication in a lab environment than a production network, but keep in mind that bidirectional authentication is an option, not a requirement.

The configurations of PAP and CHAP do have their similarities. For both, you???ll configure a username/password combination in global configuration mode. Newcomers to ISDN sometimes put the local router name in for the username remember that the remote router name is the username.

The only real advantage of PAP over CHAP comes in the password configuration. Since PAP actually sends the password as a whole over the link, the two routers can send different passwords during authentication. The operation of CHAP requires that both routers use the same password, and we???ll see why in tomorrow???s article.

Under the BRI interface, you???ll enter encapsulation ppp and ppp authentication pap. So far, your authentication scheme looks like this:

username R2 password CCNA

Int bri0

encapsulation ppp

ppp authentication pap

PAP requires an extra command at this point. The ppp pap sent-username command is required under the interface, indicating the username and password this router will be sending to the remote router.

Int bri0

encapsulation ppp

ppp authentication pap

ppp pap sent-username R1 password CISCO

I always encourage CCNA and CCNP candidates to use as many debugs as possible when working in their lab, since these commands show us how things work. For any PPP authentication, always run debug ppp negotiation before sending interesting traffic to trigger the call. Watching exactly how PAP and CHAP work give you a much better understanding of what???s going on ???behind the command???, and makes you a stronger candidate and a stronger networking engineer.

Tomorrow, we???ll take a look at CHAP, and why routers cannot use the same password on both ends of the link.

Keep studying!

About The Author:

Chris Bryant, CCIE (TM) #12933, has been active in the Cisco certification community for years. He worked his way up from the CCNA to the CCIE, and knows what CCNA and CCNP candidates need to know to be effective on the job and in the exam room.

He is the owner of http://www.thebryantadvantage.com, where he teaches CCNA and CCNP courses to small groups of exam candidates, ensuring they each receive the individual attention they deserve. Classes are offered over the Internet and in person in select cities. Chris has custom-written the Study Guide and Lab Workbook used in each course - no third-party training materials or simulators are used. You're invited to visit our site and check out our CCNA and CCNP Courses, Flash Card Books, and to sign up for our weekly newsletter written personally by Chris. Chris is always glad to hear from Cisco certification candidates at http://www.thebryantadvantage.com.

Riverside Chicago charter limousine .. Lockport Chicago limo O’Hare

In The News:

NASA's Ingenuity helicopter, which flew on Mars in April 2021, became the first aircraft to achieve powered, controlled flight on a planet other than Earth.

Stay up to date on the latest AI technology advancements and learn about the challenges and opportunities AI presents now and for the future.

Thieves who have iPhones can usually detect a hidden AirTag in vehicles they are attempting to steal, and an RFID wallet may not help you.

Genmoji, the latest addition to Apple's Apple Intelligence suite, uses artificial intelligence to generate customized emoji based on text descriptions.

It's easy to find yourself swamped in unread emails. Here are a few simple steps to archiving them and clearing out some of your digital clutter.

Keep your retirement plan safe from data brokers selling your personal information. Kurt the CyberGuy explains how to protect yourself and your retirement.

Turo faces scrutiny after tragic incidents involving rented vehicles, raising questions about security measures and regulatory frameworks.

A Chinese company has developed a spherical, 276-pound law enforcement robot that has been chasing down criminals at impressive speeds.

Here are some powerful online sleuthing tricks you can use to check the credibility of a website, see old pictures of places you've lived and even learn more about your neighbors.

Beware scam calls: Avoid unknown numbers and protect your personal information. Tech expert Kurt “CyberGuy" Knutsson talks about the increasingly common scam.

Tech expert Kurt “CyberGuy" Knutsson helps you crush your New Year's goals with these 12 apps to help you stay on track and succeed.

There are many untapped safeguards and tips you can learn to take your Wi-Fi knowledge to the next level, technology expert Kim Komando shares her tricks.

VPNs ensure privacy; antivirus stops malware. Tech expert Kurt “CyberGuy" Knutsson says both are essential for online security.

Tech expert Kurt “CyberGuy" Knutsson cites a new report that says many people still use weak passwords like "123456," risking their accounts.

Tech expert Kurt “CyberGuy" Knutsson says a tech support scam used a fake Windows Defender pop-up, tricking the victim to call and download software.

Tech expert Kurt “CyberGuy" Knutsson reveals ways to restore accidentally deleted text messages on your Android phone.

A new study says outdoor security camera apps are among the biggest collectors of user data, including phone numbers, payment details and precise location.

In iOS 18.2 and later, Apple's Mail app enhances email management by automatically sorting messages into distinct categories to help find emails faster.

A virtual private network (VPN) allows computer and smartphone users to mask an IP and create a secure, encrypted connection between a device and the internet.

Android 15's latest feature, Private Space, is like a private vault helping to keep your personal or sensitive apps away from prying eyes.

Cybercriminals have more ways than ever to target teenagers; here are some of the most widespread scams and tricks to watch in order to keep your loved ones safe.

Stay up to date on the latest AI technology advancements and learn about the challenges and opportunities AI presents now and for the future.

A humanoid robot named CUE6 has got game. The basketball-playing robot, produced by Toyota, claimed a Guinness World Record for longest shot.

With electronic signatures becoming more common, Kurt the CyberGuy explains how to produce your digital John Hancock for online documents.

Kurt the CyberGuy walks through steps he recommends immediately taking after getting new electronics — like phones or TVs — as gifts this holiday season.

Cisco Certification: Introduction To ISDN, Part III

Software