Cell Relay Archive

[Ahmed Mehaoua <amehaoua@crim.ca>]

Hal Murray wrote:
> 
> In article <327A615B.3C4A@crim.ca>, you write:
> 
> >       Since the source should generate one byte every 125 micro-sec,
> >       the packetization delay to fill a 48-byte cell is exactely 6 ms
> >       (48*125micro-sec = 6ms).
> >
> >       The same time is needed by the destination to depacketize the
> >       cell (another 6 ms).
> 
> Why does it take twice 6 ms?
> 
> Consider the first byte of the cell.  After I put it into the cell
> I have to wait for 47 more bytes.  That's about 6 ms.
> 
> When the cell gets to the other end, I can take the first byte out
> with no delay.
> 
> Similar arguments work for other byte positions.


	Technically you are right, but don't miss to take into account
	AAL-1 layer in the transmission process. The standard proposed to use 
	AAL-1 as the ATM adaptation layer to perform several tasks, such as 
	integrity check, synchronization, ... in relation with voice
transmission.
	Therefore, at the destination, all the ATM payload (48 bytes) should be 
	extracted to rebuilt the AAL-1 PDU. 

	Best regards,
	Ahmed. M.

-- 
________________________________________________________________

Ahmed Mehaoua
Telecommunications & Distributed Systems
Computer Research Institute of Montreal (CRIM)

mailto:Ahmed.Mehaoua@crim.ca
________________________________________________________________