Time-synchronized multi-layer network switch for providing quality of

Abstract

A network system for providing efficient transmission of real-time data and non-real-time data between a plurality of network devices, including an arbitration mechanism that provides a low cost and high performance mechanism for delivery of quality of service guarantees for time-sensitive data sharing a local area with non-time-sensitive data. Device adapters are placed at all access points to a local network. The device adapters limit admission rates and control the timing of all packets entering the network. An X-Hub placed at the center of the network provides for transparent, concurrent transport of signals transmitted by device adapters. Collisions may therefore be eliminated for time-sensitive traffic, thereby guaranteeing timely delivery. A common time reference is established for the device adapters and the X-Hub. The time reference defines a frame with a plurality of phases. Each of the phases defines a state of the X-Hub, and a state for each of the device adapters. Each device adapter is allowed to transmit packets of data onto the network directly to one or more destination device adapters, without the possibility of collisions, during a phase in which it is in a cross-connect mode. Each device adapter can also broadcast unscheduled transmissions, usinig a conventional network protocol (such as CSMA/CD), when it is not in the cross-connect mode. The scheduling of phases to support transport of signals in the cross-connect mode can be dynamically altered, in accordance with a signaling protocol, based on unscheduled transmissions using the conventional network protocol when the X-Hub is so configured.