Multiplex communications – Pathfinding or routing – Through a circuit switch
Reexamination Certificate
1998-03-31
2001-05-29
Olms, Douglas (Department: 2661)
Multiplex communications
Pathfinding or routing
Through a circuit switch
C370S353000, C370S354000, C370S463000, C379S441000
Reexamination Certificate
active
06240087
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 delivery unit that interfaces telecommunications media and a switching system. The delivery unit has a number of application modules, each having application circuitry operable to perform functions associated with conversions between high level signals carried by the telecommunications media and electrical signals switched by the switching system. A bus control module has application circuitry that controls access to ingress and egress buses carrying network data represented by said electrical signals. These ingress and egress buses provide transport of the network data between the application modules. Each of the application modules has a controller, whose circuitry is substantially the same for each the application modules. These controllers originate and terminate control datagrams containing control messages, and each has a processor that processes incoming control messages and generates outgoing control messages.
An advantage of the invention is that the common controller contributes to a “building block” design for the delivery unit. This increases economy of manufacture and reliability in operation.
REFERENCES:
patent: 4513390 (1985-04-01), Walter et al.
patent: 4993017 (1991-02-01), Bachinger et al.
patent: 5111497 (1992-05-01), Bliven et al.
patent: 5712903 (1998-01-01), Bartholomew et al.
Cummings David C.
Jones Alan A.
Alcatel USA Sourcing L.P.
Baker & Botts L.L.P.
Hom Shick
Olms Douglas
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