Ciena Corporation

Equipe Communications Corporation

Colin Bell

Brian Branscomb

Mike A Sluyski

Peter B Everdell

Corey Simons

Chris R Noel

Larry B Manor

The present invention reduces the cost of a minimally configured network device by providing a network device with a distributed switch fabric. Such a network device locates a portion of the switch fabric functionality on each forwarding card allowing the minimal network device configuration to include less than the entire switch fabric functionality. The cost of the minimal configuration is, therefore, reduced allowing network service providers to more quickly recover the initial cost of the network device. As new services are requested, additional functionality, including both forwarding cards and universal port cards may be added to the network device to handle the new requests, and the fees for the new services may be applied to the cost of the additional functionality. Consequently, the cost of the network device more closely tracks the service fees received by network providers.

Network device including central and distributed switch fabric subsystems

The present invention provides a central switch fabric timing subsystem and distributed switch fabric timing subsystems. Distributed switch fabric subsystems reduce the cost of a minimally configured network device by providing a network device with a distributed switch fabric. Such a network device locates a portion of the switch fabric functionality on each forwarding card allowing the minimal network device configuration to include less than the entire switch fabric functionality. The cost of the minimal configuration is, therefore, reduced allowing network service providers to more quickly recover the initial cost of the network device. As new services are requested, additional functionality, including both forwarding cards and universal port cards may be added to the network device to handle the new requests, and the fees for the new services may be applied to the cost of the additional functionality. Consequently, the cost of the network device more closely tracks the service fees received by network providers.

Network device with a distributed switch fabric timing system

The present invention provides a network device including a central timing subsystem for distributing one or more timing reference signals including a main timing signal and an embedded timing signal. Embedding one timing signal within another reduces the routing resources necessary to route the timing signal(s) within the network device. In addition, one central timing system, as opposed to two or more, may be used to provide multiple different synchronous clock signals. In one embodiment, the main timing signal is used for network data transfer while the embedded signal is used at least for processor synchronization. Consequently, a separate central timing subsystem is not required for generation and distribution of processor timing reference signals, and separate routing resources are not required for the processor timing reference signals. In addition, separate local timing subsystems for both the central timing and processor timing are not necessary. Embedding the processor timing reference signal within a highly accurate, redundant external timing reference signal also provides a highly accurate and redundant processor timing reference signal, and having a common local timing subsystem is more efficient resulting in less design time, less debug time, less risk, design re-use and simulation re-use.

Network device with embedded timing synchronization

The present invention provides a network device including redundant, synchronous central timing subsystems (CTSs) and local timing subsystems (LTSs) including control circuits for automatically selecting between reference signals from both central timing subsystems. Automatically selecting between reference timing signals allows each LTS to quickly switchover from a failing or failed reference timing signal to a good reference timing signal. Quick switchovers prevent data corruption errors that may result during slow switchovers where a failing or failed reference signal is used for a longer period of time prior to the switch over. In addition, since each LTS independently monitors its received reference timing signals, a problem on one reference timing signal is quickly detected by the LTS and the LTS switches over to the good reference timing signal regardless of whether any other LTSs detect a problem with their received reference timing signals. Consequently, each LTS that detects a problem with a timing reference signal may immediately switch over to a good reference signal and not be forced to wait for all LTSs to be switched over.

Network device with local timing systems for automatic selection between redundant, synchronous central timing systems

The present invention provides a network device including redundant, synchronous central timing subsystems (CTSs) each having a voltage controlled timing circuit for receiving a constant master voltage signal and variable slave voltage signal. Each CTS also includes a control logic circuit for selecting the constant master voltage signal for use by the voltage controlled timing circuit when the CTS is master and for selecting the variable slave voltage signal when the CTS is slave. Using a constant master voltage signal eliminates the need for a separate master oscillator in each CTS. Oscillators are typically expensive, consume significant space on the printed circuit board and have location restrictions on where they may be placed on the printed circuit board.

Growing community of inventors

Acton, MA, United States of America

Colin Bell