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.

bmw rental chicago Bath .. Lockport Chicago limo O’Hare

In The News:

Spambots, data thieves, and other bad actors run rampant online — more so now than ever before. Here's what to do if one gets ahold of you.

Tech expert Kurt “CyberGuy" Knutsson says the Super Bowl's huge audience makes it a prime target for many types of cybersecurity scams.

It's not just about freeing up space on your computer, Kurt “CyberGuy" Knutsson says. It's about protecting your digital memories and important documents.

From proofreading and research to brainstorming and data analysis, you can use generative AI as a sidekick for just about any task you can dream of.

Tech expert Kurt “CyberGuy" Knutsson says Super Bowl 2025 ads promise star power and laughs, featuring Beckham's twin reveal.

First driverless semi delivers 100 loads in Texas, transforming logistics with AI. Tech expert Kurt “CyberGuy" Knutsson gives his takeaways.

A new scam using Elon Musk's name is making the rounds, promoting "energy-saving" devices and falsely linking the Tesla and SpaceX leader to the products.

China recently unveiled a new bullet train prototype with a test speed of 280 mph that is poised to break records and set new standards.

Hackers sometimes find ways to exploit iPhones, and Apple recently discovered a vulnerability in iOS that may have been exploited for over a year.

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

Lynx the robot dog from China is pushing boundaries of what autonomous mobile robots can achieve with a groundbreaking design and unique mobility.

A startup claims to have developed the world's first entirely artificial intelligence-designed and 3D-printed shoe, the brainchild of a 25-year-old.

Creating an email alias can help clean up your inbox by organizing emails based on purpose, like creating different aliases for shopping, newsletters and work.

A multipurpose robotic system promises to transform how items are stacked onto pallets, aiming to maximize space utilization and reduce shipping costs.

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

The number of people affected by a UnitedHealth data breach in February 2024 was actually higher than previously reported and was the largest medical data breach in U.S. history.

A phishing campaign uses Google Calendar to schedule fake meeting invitations that appear legitimate, redirecting targets to phishing sites.

Toll road text scam: Fake messages claim unpaid fees, seek payment via fraudulent links. Kurt “CyberGuy" Knutsson says this scam is becoming increasingly sophisticated and widespread.

Kurt “CyberGuy" Knutsson says these steps ensure that your friends and family get to the exact moment you want them to see. Try it out and streamline your sharing experience.

Tech expert Kurt “CyberGuy" Knutsson offers tips on how to protect your identity: Be vigilant, monitor accounts, use smart security, know theft response.

Tech expert Kurt “CyberGuy" Knutsson says cybercriminals are exploiting iMessage phishing protection, tricking users to reactivate links.

It's hard to imagine life without in-flight Wi-Fi these days – but sky-high web surfing comes with its own set of privacy concerns. Here's how to protect yourself.

Over 400,000 cases of credit card fraud were reported in 2024 to the Federal Trade Commission. The CyberGuy explains how to protect against becoming another victim.

A nondescript metal box transforms into a fully functional electric motorcycle that blurs the line between vehicle and urban infrastructure.

Many apps unrelated to location still ask users for tracking permission, and Texas Attorney General Ken Paxton has filed a lawsuit seeking to end this alleged practice by Allstate.

Cisco Certification: Introduction To ISDN, Part III

Software