This is the clearest most concise explanation of this i've ever seen. Bravo. -----Original Message----- From: [EMAIL PROTECTED] [mailto:[EMAIL PROTECTED]] Sent: Tuesday, May 22, 2001 10:53 AM To: [EMAIL PROTECTED] Subject: Re: Cisco Certification Digest V2 #1296 [7:5442] I'm not sure why this came up on ISDN material, since it is most often used in T1's. AMI is "alternate mark inversion," and it is a way of varying a continuous pattern of 1's or 0's so that the receiving device can separate them out. When you're pulling clock signal from the line, you are relying on a relatively steady "pulse" to break out your bits. If a bunch of 1's comes across, represented by a long period of positive voltage, ++++++++++++++++++ , the device has a hard time figuring out where to break the bits out of that signal. What AMI does is vary the polarity of every other 1, for instance +-+-+-+-+-+-+-. That allows discrete 1's to be picked out of the signal. But what happens when you have a bunch of zeroes? Same problem. Enter B8ZS, Binary 8 Zeroes Suppression. It becomes necessary if you are sending a long string of 0's across the wire, which is often done by a lack of signal. What B8ZS does, is replace a string of eight zeroes with a known pattern of voltage ( +-0-+ ) The other device recognizes this, and says, "Oh, you must be sending eight zeroes." This technique is called "maintaining the 1's density." This is it in a rough explanation, don't quote me on this ;) But the good news is that this is as much as you'll likely ever have to know about B8ZS and AMI, unless your job involves desinging CSU/DSU's or something. Kenneth Mays Sr. Network Analyst AutoZone Date: Mon, 21 May 2001 20:51:54 -0400 From: "Lists Wizard" Subject: ISDN line transition and the linecode command [7:5353] Hi group. I am using the CISCO CIM for ISDN. There is talk about line transition and line-level changes and how the linecode command prvent the loss of synchronization. Can some one explain this better. The information transmitted is intended only for the person or entity to which it is addressed and may contain confidential and/or privileged material. Any review, retransmission, dissemination or other use of, or taking of any action in reliance upon, this information by persons or entities other than the intended recipient is prohibited. If you received this in error, please contact the sender and delete the material from any computer. FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED] Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=5450&t=5450 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
