Another step towards all optical networks (AON) has been achieved with
the consent of the new Recommendation G.680 by ITU-T's Study Group 15.
The Recommendation will allow operators to take optical add/drop
multiplexers (OADMs) and photonic cross-connects (PXCs) from different
vendors and integrate them in to an all optical network without having
to add expensive optical/electrical/optical conversion (O/E/Os).
achievement is made possible as the Rec gives operators a way to
evaluate the end-to-end quality of a signal where photonic
cross-connects (PXC) and optical add/drop multiplexers (OADMs) are
deployed. In addition, experts say that the evolution towards an AON
could significantly reduce costs for operators by reducing the need for
costly optical/electrical/electrical (O/E/O) conversion.
As optical transport networks (OTN) evolve, the number of - expensive -
O/E/O conversions within their boundaries is coming down.
The two main
reasons for the reduction in the number of O/E/O conversions are that
DWDM systems are becoming capable of carrying light signals for
thousands of kilometers without electrical regeneration and that PXCs
and OADMs are becoming available with the capacity, space requirements,
power consumption, reliability and cost, suitable for their use in the
With this evolution experts predict that AONs could extend to all
potential routes of the backbone network of a medium size country -
optical paths up to around 2,000 km.
The Recommendation defines a "degradation function" of optical network
elements (ONEs) such as photonic cross connects (PXCs), optical add-drop
multiplexers (OADMs), etc. making up an optical network. It enables the
degradation of the signal quality in an all-optical network consisting
of ONEs including DWDM line segments to be assessed.