Cell Relay Archive

[Paul Koning <pkoning@lucent.com>]

efam@my-deja.com wrote:
> 
> I'm hoping someone out there can clarify some
> confusion I'm having related to "Framing".   I
> understand that framing is a link layer
> function.  For exmaple, ATM frames.   However,
> when I look at the Sonet specification, it too
> has a frame structure.   SONET, however, is
> traditionally designated as a physical layer
> protocol.    So is SONET a protocol containing
> both layer 1 and 2 functions or are SONET frames
> somehow different than those protocol frames
> traditionally designated as layer 2.

I've found that applying the 7 layer OSI model
religiously to WAN technologies gets you nowhere
in a hurry...

Rather than think in terms of the rigid 7 layer model,
generalize and apply a flexible number of layers with
flexible contents.

As for SONET, yes, it does framing -- bit and byte
framing, to be specific.  Above that you find ATM cell
framing.

	paul
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