Cell Relay Archive

[Nuzhath Shereen <shereen@chequemail.com>]

Hello Saso,

Can you explain more about this SDT format. The ITU-T I.363.1  says that the pointer format may be used only if the sequence count value is 0,2,4 or 6. This is because the 1,3,5 and 7 values are reserved for SRTS.

 I didn't understand the rest of the explanation in the standard. What is this 93-octet payload it refers to. By octet, Is it referring to one 64kps channel (I had read that somewhere) or is the digital 8 bits.

Please give links or references , if you have any

Regards,
Shereen@chequemail.com

On Wed, 26 July 2000, "Saso Stojanovski" wrote:

> 
> 
> hi rajagopalan,
> 
> when using AAL-1 for circuit emulation, you either care to specify to the
> receiver where the TDM frame boundary is or you don't.
> 
> in the former case you would use SDT, and in the latter case you would
> rely on the sync mechanism which is built in the TDM frame itself.
> 
> for instance, if you emulate a whole E-1 circuit, then you could use UDT,
> since the first timeslot (out of 32) in the E-1 frame contains a sync
> pattern.
> 
> on the other hand, if you are to emulate a fractional E-1 circuit (say
> only k 64 kbit/s channels), then you must use SDT in order to tell the
> receiver where exactly in the ATM payload the TDM frame (whose length is
> only k octets) starts. that is exactly what the pointer points at.
> 
> cheers,
>     v
> --saso
> 
> 
> 
> 
> rajagopalan.sampath@wipro.com wrote:
> 
> > Hi,
> >
> > Can somebody help me in implementing AAL type 1  ( ITU-T I.363.1 )?
> >
> > What's SDT ( Structured Data Transfer ) and why it's used?
> > How SDT is performed at transmitting and receiving end? It's basically
> > about when to select P-format and when to select Non-P format PDUs?
> > What does the pointer value represent in the P-format PDUs?
> >
> > Thanks.
> >
> > Regds,
> > Rajagopalan Sampath.


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