A digital switch is a device that handles digital signals generated at or passed through a telephone company central office and forwards them across the company's backbone network. It receives the digital signals from the office's channel banks that have been converted from users' analog signals and switches them with other incoming signals out to the wide area network.
Digital switches are described in terms of classes based on the number of lines and features that are provided. A private branch exchange (PBX) is a digital switch owned by a private company. A centrex is a digital switch at the central office that manages switching for the private company from the central office.
Softswitch (software switch) is a generic term for any open application program interface (API) software used to bridge a public switched telephone network (PSTN) and Voice over Internet Protocol (VOiP) by separating the call control functions of a phone call from the media gateway (transport layer).
Switching fabric is the combination of hardware and software that moves data coming in to a network node out by the correct port (door) to the next node in the network.
Switching fabric includes the switching units (individual boxes) in a node, the integrated circuits that they contain, and the programming that allows switching paths to be controlled. The switching fabric is independent of the bus technology and infrastructure used to move data between nodes and also separate from the router. The term is sometimes used to mean collectively all switching hardware and software in a network.
The term uses a fabric metaphor to suggest the possible complexity and web-like structure of switching paths and ports within a node. The switching fabric typically includes data buffers and the use of shared memory.
An intelligent switch is a high-level storage area network (SAN) routing switch that provides features such as storage virtualization, quality of service (QoS), remote mirroring, data sharing, protocol conversion, and advanced security. Intelligent switches are an important part of storage area management (SAM), a methodology that is gaining in importance as networks become increasingly complex and expensive to deploy, operate, and maintain.
Intelligent switches can make it possible to manage storage in heterogeneous environments, reduce SAM costs, and provide expandability and scalability for existing SANs in large and growing businesses. However, intelligent switches are still in the evolutionary stage, and may not be an ideal solution for smaller enterprises, or in SANs not expected to grow or change substantially in the immediate future.
The intelligent switches in some sophisticated SANs are the latest product in a technology that is decades old. Primitive intelligent switches first appeared in telephone networks during the 1980s, and were used for automatic call routing. Similar switches found applications in other communications networks, including the Internet as it evolved during the 1990s.