Re: CBR without AAL1?

[Paul Koning <pkoning@xedia.com>]

>>>>> "Alfonso" == Alfonso Gonzalez <e0192388@brookes.ac.uk> writes:

 Alfonso> If I understood well, only AAL0 and AAL5 are
 Alfonso> supported. Then, what AAL does CBR use?

Whatever you want.

Service category (ABR, CBR, etc.) and AAL type (AAL1, AAL5, etc.) are
independent decisions.  In principle, you can use any of the former
with any of the latter.  In practice, some combinations are unlikely
or silly.  (For example, AAL1 over ABR is rather nonsensical.)

But it makes perfect sense to run AAL5 over any of the four service
categories, CBR included.  Which service category you pick depends on
what sort of real time guarantees you need and what sort of data rate
controls are applicable.  Which AAL you pick depends on the nature of
your application data.  If you have packet data, use AAL5; if those
packets come at a pretty constant rate, and you want low jitter, run
them over CBR.

By the way, there is really no such thing as AAL0.  "AAL0" is a term
generally used to mean "no AAL at all" -- i.e., raw cell service.  You
can use this to implement any AAL you want yourself.  So if your
application needs AAL1, use AAL0 and write your own AAL1 code...

	paul