flowControlCommand and packet overhead

[Stephen Casner]

On Wed, 28 Apr 1999, Paul Long wrote:

> Therefore, clarification text to the following effect should be added to
> 6.2.11.2 (in v2) of H.323:
>
>         "flowControlCommand applies to the information streams which are the
> content of logical channel(s), not including RTP headers, RTP payload headers,
> network headers and other overhead."

I'm mostly a lurker on this list, but I thought I would offer another
perspective.  The RTP spec, RFC 1889, says the following:

   Bandwidth calculations for control and data traffic include lower-
   layer transport and network protocols (e.g., UDP and IP) since that
   is what the resource reservation system would need to know. The
   application can also be expected to know which of these protocols are
   in use. Link level headers are not included in the calculation since
   the packet will be encapsulated with different link level headers as
   it travels.

At a minimum, I would expect the RTP payload header to be included
because that is specific to the encoding and would not be known by
lower layers.  The difficulty in pushing this problem off to lower
layers is that they need to know the packet rate in order to know how
much overhead the additional headers will add.
                                                        -- Steve