Editing Synchronous optical networking (section)

==Equipment==
With advances in SONET and SDH chipsets, the traditional categories of network elements are no longer distinct. Nevertheless, as network architectures have remained relatively constant, even newer equipment (including [[add-drop multiplexer|multi-service provisioning platforms]]) can be examined in light of the architectures they will support. Thus, there is value in viewing new, as well as traditional, equipment in terms of the older categories.

===Regenerator===
Traditional regenerators terminate the section overhead, but not the line or path. Regenerators extend long-haul routes in a way similar to most regenerators, by converting an optical signal that has already traveled a long distance into electrical format and then retransmitting a regenerated high-power signal.

Since the late 1990s, regenerators have been largely replaced by [[optical amplifier]]s. Also, some of the functionality of regenerators has been absorbed by the transponders of wavelength-division multiplexing systems.

===STS multiplexer and demultiplexer===
STS multiplexer and demultiplexer provide the interface between an electrical tributary network and the optical network.

===Add-drop multiplexer===
[[Add-drop multiplexer]]s (ADMs) are the most common type of network elements. Traditional ADMs were designed to support one of the network architectures, though new generation systems can often support several architectures, sometimes simultaneously. ADMs traditionally have a ''high-speed side'' (where the full line rate signal is supported), and a ''low-speed side'', which can consist of electrical as well as optical interfaces. The low-speed side takes in low-speed signals, which are multiplexed by the network element and sent out from the high-speed side, or vice versa.

===Digital cross connect system===
Recent [[digital cross connect system]]s (DCSs or DXCs) support numerous high-speed signals, and allow for cross-connection of DS1s, DS3s and even STS-3s/12c and so on, from any input to any output. Advanced DCSs can support numerous subtending rings simultaneously.