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Re: [EFM] RE: Pause frame usage in transport networks

On Friday 21 February 2003 17:06, Roy Bynum wrote:
> The "link" that you are referring to is, from the data communications view,
> is at the transmission convergence sublayer of the Physical Media layer, a
> part of what 802.3 would refer to as the PHY.  What was being discussed
> here is the functionality that exists at the Data Link layer which is part
> of the customer's data link frame traffic.

Sure - it was a simplification of mine. Bad choice of words, I think. I used 
the term 'link' to refer in generic terms to the point-to-point entity that 
connects the ONU to the OLT. My intention was to point out that OAM is 
limited to 'link management' functions, where 'link' is roughly defined as 
described above, and so is restricted to the access space.

> In the case of 802.3ah OAM it functions at the Data Link layer, not the
> transmission convergence sublayer.  As such it is available to the service
> provider only for "packet" type services.  And for "packet" services the
> OAM frames should be for the use of and controlled by the service
> provider.  For all other services, the OAM frames belong only to the
> customer and are not accessible to the service provider.

What happens is that OAM 'shares' the same space occupied by user traffic 
(dedicated for frame-based traffic, in this case). So it's easy to see where 
did the confusion start: although both types of traffic are frames, only one 
of them is seen by the customer, and the other one is reserved for the 
operator. This separation must be made clear, to avoid people to mistakenly 
assume that OAM frames can be seen/used by the customer for whatever purpose.

[btw, coming from a similar background I think I understand why you are always 
so cautious when refering to definitions such as 'OAM', 'leased line 
services', 'packet based services', etc. But my intention was to refer to the 
'link level' as a generic entity, in opposition to the 'user traffic'; it was 
a generalization, and I assumed that no precise definitions were needed.]

> Thank you.
> Roy Bynum

Best regards,

Carlos Ribeiro