Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1998-03-31
2001-09-04
Ton, Dang (Department: 2661)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S364000, C370S465000, C370S474000
Reexamination Certificate
active
06285673
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates generally to telephone networks, and more particularly to an interface between fiber optic transport media and a switching system designed for electrical signals.
BACKGROUND OF THE INVENTION
As multimedia applications increase the demand for high-bandwidth, high-bit-rate communications, fiber optics technology is rapidly advancing to supply the capacity. A family of standards for optical fiber transmissions is known as the Synchronous Optical Network (SONET) standards. SONET was born as an extension to the DS1 hierarchy, which is a hierarchy of “electrical” as opposed to “optical” signals and consists of levels of signals formed by multiplexing lower level TDM (time division multiplex) signals.
The SONET standard establishes a multiplexing format for using any number of 51.84 Mbits/s signals as building blocks. An OC-3 (Optical Carrier, Level 3) is a 155.52 Mbits/s signal (3×51.84 Mbits/s), and its electrical signal counterpart is referred to as an STS-3 signal. The STS-1 signal carries a DS3 signal or a number of DS1 or other lower level signals. A SONET STS-3 signal is created by concatenating STS-1 signals. Each SONET STS-N electrical signal has a corresponding OC-N “optical signal”. The OC-N signals are created by converting the STS-N electrical signal to an optical signal.
Although optical switching techniques have been developed, telecom companies are eager to provide as much performance as possible from their existing infrastructure. Switching systems based on the DS1 electrical signal hierarchy are in place and continue to be used for signals carrying that type of signal. Essentially these switching systems use DS0 data, which is derived from the DS1 hierarchy. For example, a DS1 signal is comprised of 24 multiplexed DS0 voice channels. Thus, there is a demand for interfaces that will permit SONET signals to be switched through switching systems designed for the DS1 hierarchy of signals.
SUMMARY OF THE INVENTION
One aspect of the invention is a bus control module for a delivery unit, which interfaces high level network signals to a switching matrix. The bus control module handles transport between application modules that perform various network data transport functions, sending out network data and control data in subframes on an ingress bus and receiving network data and control data in subframes on an egress bus. The bus control module has application circuitry operable to control access to the ingress bus for the subframes, to multiplex incoming subframes to the egress bus, and to format egress subframes to be carried on the egress bus. It also has a bus interface that receives subframes containing control data on the egress bus and that delivers subframes containing control data to the application circuitry, a controller in communication with the bus interface that originates and terminates subframes containing control data, and a timebase that receives timing signals to be used by the application circuitry.
An advantage of the invention is that control data and network data may be transported on the same busses within the delivery unit. The use of the ingress and egress busses permits common bus interface circuitry on the application modules whose transport is controlled by the bus control module.
REFERENCES:
patent: 5526344 (1996-06-01), Diaz et al.
patent: 5809021 (1998-09-01), Giaz et al.
patent: 5959987 (1999-09-01), Humphrey et al.
patent: 6157657 (2000-12-01), Humphrey et al.
Blackburn Bracey J.
Cooper Thomas E.
Fourcand Serge F.
Gammenthaler, Jr. Robert S.
Hay Donald B.
Alcatel USA Sourcing L.P.
Baker & Botts L.L.P.
Ton Anthony T.
Ton Dang
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