Find Sporting Goods on eBay
Video and Audio], Broadcasting and podcasting Broadcast On the Net

[description], Story, any other text you want to use.

Cisco CCNA Certification: Introduction to ISDN, Part I

 by: Chris Bryant, CCIE #12933

From the CCNA to the CCIE, ISDN is one of the most important technolgies you'll work with. It's also very common in the field; ISDN is frequently used as a backup connection in case an organization's Frame Relay connections go down. Therefore, it's important to know ISDN basics not only for your particular exam, but for job success.

ISDN is used between two Cisco routers that have BRI or PRI interfaces. Basically, with ISDN one of the routers places a phone call to the other router. It is vital to understand not only what causes one router to dial another, but what makes the link go down.

Why? Since ISDN is basically a phone call from one router to another, you're getting billed for that phone call -- by the minute. If one of your routers dials another, and never hangs up, the connection can theoretically last for days or weeks. The network manager then receives an astronomical phone bill, which leads to bad things for everyone involved!

Cisco routers use the concept of interesting traffic to decide when one router should call another. By default, there is no interesting traffic, so if you don't define any, the routers will never call each other.

Interesting traffic is defined with the dialer-list command. This command offers many options, so you can tie interesting traffic down not only to what protocols can bring the link up, but what the source, destination, or even port number must be for the line to come up.

One common misconception occurs once that link is up. Interesting traffic is required to bring the link up, but by default, any traffic can then cross the ISDN link.

What makes the link come down? Again, the concept of interesting traffic is used. Cisco routers have an idle-timeout setting for their dialup interfaces. If interesting traffic does not cross the link for the amount of time specified by the idle-timeout, the link comes down.

To summarize: Interesting traffic brings the link up; by default, any traffic can cross the link once it's up; a lack of interesting traffic is what brings the link down.

In tomorrow's article, we'll take a look at some common scenarios that make the ISDN link stay up, and what can be done about it. Keep studying, and I'll see you tomorrow!

Chris Bryant


Cisco Certified Internetwork Expert #12933

About The Author

Chris Bryant, CCIE (TM) #12933, has been active in the Cisco certification community for years. He has written several books that have helped CCNA candidates around the world achieve the coveted CCNA certification, including several concentrating on binary math conversions and subnetting questions that the average CCNA candidate will need to answer on their CCNA exams.

He is the owner of The Bryant Advantage (http://www.thebryantadvantage.com) where he teaches affordable world-class CCNA courses via the Internet. He's proud to have helped CCNA candidates around the world achieve their career goals. Mr. Bryant's books and courses are sold on his site, on eBay, and on several other major Cisco certification sites.

chris@thebryantadvantage.com


video production

Brodcast On the Net - streaming video, streaming audio, video conferencing, audio
Broadcast On the Net. If you are running a search for video conferencing and are looking for audio streaming or video streaminng and web conferenceing then you have come to the proper place. You can find many of the finest sites with the best conferencing services. Even find video studios or maybe the video talent to produce your program, no matter what you are looking for you can see the best streaming media here.
Brodcast On the Net - streaming video, streaming audio, video conferencing, audio

video production - a high stand of information


When you’re seeking information about video production the results can seem extremely overwhelming. But relax, because we’ve sifted through all the video production web sites we could find and have discovered the finest ones that will produce the results you want, and how you want them.
We know how crucial good results are when you’re searching for video production. Some Internet sites are superior than others and will meet your video production requirements in a better fashion.

If you’re looking for a high standard video production site you know you can count on, we suggest the above web site. We have taken the tiresome task out of your video production shopping and reduced our list of video production web sites down to only finest around.

Being assured you’re receiving value for money is crucial in buying video production, so by visiting our web site you can expect the assurance that you are getting the video production you paid for.

By purchasing through our suggested links you can also rest assured your video production will be of a high standard. How do we know? Because when we’re shopping for video production ourselves it’s where we go.

You might be pondering why we’re suggesting you visit outside links rather than stay on our own video production site. Well it’s because we’ve only recently created our site so it's early days. Our goal is to be the best site for video production info on the net, and real soon we’ll achieve it. So please bookmark us and come back soon.

Main Menu
Broadcast On the Net
Site Map

Affiliate Ads, Links, news, etc.

News for 08-Oct-25

Source: BBC News - Home
US issues Jordan travel warning after deadly attacks

Source: BBC News - Home
500 years later

Source: BBC News - Home
All heart

Source: BBC News - Home
Libya Malta hijack: Hijackers arrested as drama ends peacefully

Source: BBC News - Home
Preserving Mali's rural life

Source: BBC News - Home
Kim Ghattas: Trump's Syria conundrum

Source: BBC News - Home
Carrie Fisher: Star Wars actress suffers heart attack

Source: BBC News - Home
Chile anger as jailed Pinochet reign abusers ask forgiveness

Source: BBC News - Home
Wedding gift alpaca has 'surprise' baby

Source: BBC News - Home
Rockettes set for Trump inauguration


Links
Links
Links
Google

Present On The Net | Talk On The Net | Go Meetings | Take Medicine Correctly
Copyright © 2005. Name of Site here. Last Updated: Wednesday, 08-Oct-2025 00:00:29 MDT.
Medical Presentations   Real Time Media On The Net   Medical Meetings On The Net