 |
|
| Video and Audio], Broadcasting and podcasting Real Time Media 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
adelphia
Once you're at the adelphia site it's a simple matter of selecting the exact product or service you want to purchase. Nothing to it really. Whether you're just looking for information, or you're looking for something to buy right now, we've got the links to the exact adelphia website you need. As you can tell from all the effort we've put into building our adelphia site, it's something that we care about. You can be certain, when you follow one of the hyperlinks in the middle of this web page, or click on the pop up which might have appeared when you entered our site, we've chosen the best site about adelphia for you to go to. Thank you for coming to our adelphia information page. Real Time Media On The Net Index
|
Main Menu News for 04-Jan-09 Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Source: BBC News | News Front Page | World Edition Links Links Links |
Copyright © 2005. Name of Site here. Last Updated: Sunday, 04-Jan-2009 00:15:11 MST.