more data on this
b8zs/esf leads to 64k time slots
ami/sf leads to 56k time slots, because 1 bit out of each slot is used for
location tracking.
usually these days, I have only seen ami used in cases where people wanted
to use some portion for a pbx.
Brian
----- Original Message -----
From:
To:
Sent: Tuesday, May 22, 2001 7:52 AM
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.
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