Hi Ole,
Let me take the case of T1. In T1 all the 24 channel are used for
sending data. There will be one framing bit which constitiute to 193 bits. So
193 * 8000 = 1544 kbps. And one bit from every sixth frame in case of
superframe(which consists of 12 T1/DS1 frames) will be robbed for signalling.
The robbed bit will be the least significant bit and this concept is known as
robbed-bit signalling. If I am wrong then please correct me.
Thanks,
-Subbi.
Ole Drews Jensen wrote:
> Hi Subbi,
>
> That would still only leave 184 * 8000 = 1472000 bps or (1472000/1024)
> 1437.5 kbps for data.
>
> Ole
>
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
> Ole Drews Jensen
> Systems Network Manager
> CCNA, MCSE, MCP+I
> RWR Enterprises, Inc.
> [EMAIL PROTECTED]
> ~~~~~~~~~~~~~~~~~~~~~~~~~~
>
> -----Original Message-----
> From: Subramanian Nallasivam [mailto:[EMAIL PROTECTED]]
> Sent: Tuesday, July 11, 2000 3:54 PM
> To: Ole Drews Jensen
> Cc: [EMAIL PROTECTED]
> Subject: Re: Some ISDN PRI questions
>
> Hi,
>
> I am new to ISDN concepts, but here they are....
>
> We have 23 DSO for carrying data. Each channel carries 8 bit word or
> something. So
>
> 23 * 8 = 184
>
> One channel is used for carrying signal . So the number comes out to be
>
> 184 + 8 = 192
>
> Since 8000 samples are sampled per second , the calculation comes to be
>
> 192 * 8000 = 1536 Kbps.
>
> T1 uses in-band signalling ( uses same data channel for signalling also)
> where
> as ISDN PRI uses out-band signalling (uses seperate channels for signals).
>
> I am new to ISDN cocepts. If I am wrong please correct me.
>
> Thanks,
> -Subbi.
>
> Ole Drews Jensen wrote:
>
> > The ISDN BRI has two 64 kbps B channels and one 16 kbps D channel. That
> > gives us a maximum of 128 kbps bandwidth for data which makes sense.
> >
> > The ISDN PRI has twenty three 64 kbps B channels and one 64 kbps D
> channel.
> > That should give us a maximum of 1472 kbps bandwidth for data, and not
> 1536
> > kbps as normally specified unless it is possible to use the D channel for
> > data too ???
> >
> > The ISDN PRI in Europe has thirty 64 kbps B channels and one 64 kbps D
> > channel. That should give us a maximum of 1920 kbps for data, and not 2048
> > kbps as normally specified even if the D channel is used for data too.
> >
> > Are these numbers just used because it's easier to remember the 1536 and
> > 2048 values, or is there a hidden factor here???
> >
> > A last question: I sometimes hear people refer to an ISDN PRI as a T1. The
> > T1 has the same amount of channels and bandwidth, so the question is - are
> > there really a big difference between these two specifications, or is it
> > more or less the same???
> >
> > Some or all of these questions might be answered later on in my book, but
> I
> > can't wait any longer - I want to know NOW :-)
> >
> > Thanks for any comments on this.
> >
> > Ole
> >
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~
> > Ole Drews Jensen
> > Systems Network Manager
> > CCNA, MCSE, MCP+I
> > RWR Enterprises, Inc.
> > [EMAIL PROTECTED]
> > ~~~~~~~~~~~~~~~~~~~~~~~~~~
> >
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