Skystone Systems was a synchronous optical networking company based in Canada.

In synchronous optical networking, this is modified slightly.

Synchronous optical networking (SONET)

DS3 signals are rare except within buildings, where they are used for interconnections and as an intermediate step before being multiplexing onto a Synchronous optical networking circuit.

Resolute Networks is a provider of sub-system solutions for Circuit Emulation Services (CES) and Synchronous optical networking solutions.

MPLS also offers a robust recovery framework that goes beyond the simple protection rings of synchronous optical networking (SONET/SDH).

The synchronous digital hierarchy (SDH)/synchronous optical networking (SONET) network transmission standards that have replaced PDH.

PDH is typically being replaced by synchronous digital hierarchy (SDH) or synchronous optical networking (SONET) equipment in most telecommunications networks.

Data Communication Channel, a part of data traffic in synchronous optical networking (SDH/PDH/SONET)

The System Packet Interface family of Interoperability Agreements from the Optical Internetworking Forum specify chip-to-chip, channelized, packet interfaces commonly used in synchronous optical networking and ethernet applications.

Synchronous optical networking (SONET) and Synchronous Digital Hierarchy (SDH) are standardized multiplexing protocols that transfer multiple digital bit streams over optical fiber using lasers.

DTM specifies that channels may be switched, which sets it apart from common transmission techniques such as Synchronous Digital Hierarchy (SDH) or Synchronous optical networking (SONET).

It resembles the TDM carried out in synchronous optical networking, but the "TDM Bus" term is more commonly used when the bus is inside a single unit like a telecommunications switch or a PC.

The modern tendency in systems engineering is towards using systems that are either fundamentally asynchronous (such as Ethernet), or fundamentally synchronous (such as synchronous optical networking), and layering these where necessary, rather than using a mixture between the two in a single technology.