The thought is not to increase the efficiency of SONET, but rather the
of the edge device that fills the SONET frames. The drive to doing this
comes from
the emergence of "integrated SONET multiplexers" that accept native
traffic as
input, and output to a OC-n network. There is NO talk of changing the
STS payload
size or the 125us transmit time. Those parameters are fixed and
generally cannot
be manipulated. But, the actual payload (2340 bytes) can be completely
filled, thus
optimizing the *utilization* of the SONET.

Like I mentioned, the project was focused on ATM and Frame relay. The
idea was to
provide the inetgrated SONET mux with information on the input traffic
protocol. Based
on the input protocol's cell/frame/packet size, the mux would attempt to
completely fill
a STS payload. There is a large amout of wasted bandwidth in today's
systems where
the STS is very much underutilized. This is because today's SONET
systems tie one
particular input to a specific STS. Optimization occurs by filling the
payload with cells/
frames/packets from multiple sources that use the same protocol. In
essence, this
begins to treat SONET as a shared transport system rather than the
dedicated, virtual
point-to-point system that it is today. Of course, the source and the
destination of the
multiple sources would have to be the same for this to work.

Gotcha. This seems to be the next step in the evolution of SONET transport systems,
i.e. putting the muxing functionality in the same box as the switching/routing

You guess right. In telephony, carriers want to use every bit that can
possibly be used.
Brings to mind a project where a certain carrier actually sold the
protect channels on a
ring to a customer.... but that's another e-mail altogether :wink:

Actually, I hear that that practice is becoming more common. Depending upon the
discount, I may choose unprotected transport, especially if I knew that my edge
devices failed much more often than the carrier network. :slight_smile: