US 5,317,198 A · Optically controlled remote by-pass switch

Abstract

An optical bypass switch for a fiber optic local area communications network (LAN) with a ring topology allows an optical signal carried on the ring to by pass a node, which includes terminal equipment and a stub cable, associated with the switch. In a non-bypass mode, the optical signal is transmitted to and from the associated terminal. The switch assembly is remote from its associated terminal and includes optical couplers and associated optical receivers and activity detectors to produce electrical signals indicative of an optical input to and output from the terminal. Logic circuitry analyzes these signals and produces an appropriate drive signal for a switch controller. The remote switch has a local power supply and is preferably located at the junction of the ring and an associated, purely dielectric stub cable. The terminal can include a dual path transceiver and bridging equipment to provide cross links between terminals in the event of a link failure to complement the node failure protection of the bypass switch.

Claims14

Dependent claims

A bypass switch that increases the survivability and performance of a local area optical communications network having a ring carrying periodic optical signals, a plurality of nodes optically coupled into the ring through the bypass switch, each node connecting the ring via the bypass switch and a stub cable to a terminal having an optical receiver and an optical transmitter that regenerates the received signals, the stub cable alone optically connecting the ring and the terminals through the bypass switch, comprising

means associated with each node for passively monitoring and detecting the average optical power output from the associated one of said terminals and generating a first control signal if there is a diminution of said optical power output as compared to a threshold value,
logic means responsive to said first control signal that generates a second control signal,
a plurality of optical switches each optically coupled to said ring and to the associated terminal through the associated stub cable, said switches each being bistable and latching between bypass and non-bypass states, and
means for generating a signal to switch the state of said optical switch in response to said second control signal,
said passive monitoring means, logic means, optical switch and switch signal generating means being located remotely from the associated terminal at a node of the ring, and said stub cable being purely dielectric.

2 more elements

An intelligent optical bypass switch that enhances the survivability and performance of a ringtype LAN where the switch is remote from an associated terminal and optically connected at a node to a ring that carries periodic optical communication signals among a plurality of said terminals and also optically connected by a stub cable alone to a receiver and a transmitter of said terminal, said remote optical bypass switch comprising,

an optical switch set by a directional pulse into 1) a bypass mode where the optical signal carried on the ring bypasses the associated terminal or 2) a non-bypass mode where the optical signal carried on the ring is directed to and from said receiver and transmitter, respectively,
a first coupler connected between said ring and said switch to divert a portion of the input optical signal carried on said ring,
a second coupler connected between said transmitter and said switch to divert a portion of the output optical signal of said terminal to said ring,
switch control means to drive said switch between said bypass and non-bypass modes,
switch logic and driver means that produces an output signal that controls said switch control means, and
first and second optical receivers and activity detectors connected to receive said diverted input and output optical signal portions, respectively, and to produce output signals to said switch logic and driver means indicative of whether there is optical activity input to the terminal from the ring and to the ring from the terminal and indicative of the average optical power of said optical output signal portion from the terminal,
and said stub cable being purely dielectric.

4 more elements

Dependencies are inferred from the claim text.

Optically controlled remote by-pass switch

Life of this patent

Optically controlled remote by-pass switch

Life of this patent

Abstract

Claims14