Multiplex communications – Pathfinding or routing – Through a circuit switch
Patent
1996-10-01
1999-02-02
Olms, Douglas W.
Multiplex communications
Pathfinding or routing
Through a circuit switch
370421, 370463, 370468, 370545, 379 9305, 379399, H04Q 1104, H04M 1100
Patent
active
058674969
DESCRIPTION:
BRIEF SUMMARY
This invention relates to interface devices, and more particularly to an drop/add switch device serving as a bridge between a telephone bus with a plurality of TDM (time division multiplex) channels and a high speed synchronous time division multiplexed (TDM) network to permit the transport of mixed data, voice, and video signals.
Many businesses now have installed local area networks (LANs). A typical LAN is Ethernet, which is a 10 Mb/s asynchronous communications medium permitting the exchange of data between many users. Particularly, a LAN is used to interconnect personal computers so as to permit many users to work with the same data. However, multi-media applications cannot be networked with an acceptable quality and they are incompatible with existing telephone applications. Furthermore, the available bandwidth is insufficient for evolving applications.
In an attempt to address this problem, a new LAN referred to as "Iso-Ethernet" has been introduced. This adds an extra 6 Mb/s of isochronous bandwidth to the existing 10 Mb/s asynchronous network. Although Iso-Ethernet makes use of the existing cabling, the scheme has an inherent bandwidth limitation.
Today, speeds of up to 155 Mb/s can be achieved using transmission links based on twisted pair wires or optical fiber links. These are isochronous TDM (time division multiplex) backbones capable of carrying mixed, data, voice and video signals. The high speed devices used to perform the framing functions are serial-to-parallel and parallel-to-serial converters having an up-front line interface circuit designed in ECL or Bipolar technologies to handle the high speed serial link and CMOS circuitry to transmit and receive data on a parallel backbone plane.
Popular framers currently available that perform such functions are Transwitch SYN-155 and AMCC/PMC S3005/6. One widely used telephone backplane is the present applicants Mitel STBUS, which operates at a speed of 2.048 Mb/s. This has thirty-two 64 Kb/s channels.
An object of the present invention is to permit existing telephone buses, such as the Mitel STBUS, to be interfaced with high speed TDM networks ranging from 16 Mb/s to 155 Mb/s.
Accordingly, the present invention provides an interface device serving as a bridge between a telephone-based bus with a plurality of TDM channels and a high speed synchronous digital network and providing per channel direction control to permit mixed data, voice, and video signals to be exchanged between the telephone bus and the high speed synchronous digital network, comprising a serial port for connection to the telephone bus; bidirectional serial-to-parallel/parallel-to-serial converter means connected to said serial port; a port for connection to a high speed framer that assembles frames for said high speed synchronous digital network, said port for connection to a high speed framer being a parallel port for direct connection to a parallel backplane of the high speed framer over a parallel bus; a rate converter circuit provided between said bidirectional converter means and said parallel port, said rate converter circuit including time-slot interchange means adapted to permit rate adaptation with constant throughput delay and switching between said TDM channels; and a microprocessor controlling time slot assignments in said time-slot interchange means.
The device can be described as a switch that allows both voice and data to be time-slot interchanged with constant delay within a frame. It will work as the interface between existing 2 Mb/s STBUS interface (from DNICs, Trunks, codecs) to different Fiber Interface Modules with serial backplanes operating at 16, 51 or 155 Mb/s. Since existing high speed framers provide an 8-bit parallel backplane as user data interface, the device can interface to the framers using an 8-bit parallel backplane that will transmit/receive 64 Kb/s channels at 2.048, 6.48 or 19.44 Mbyte/s. Narrowband 64 kbit/s channels can be mapped to accommodate the required bandwidth pipe for the application.
The device may also incorporate a direct inte
REFERENCES:
patent: 5497373 (1996-03-01), Hulen et al.
patent: 5533017 (1996-07-01), Thor
Peres Mauricio
Roberts Mel
Mitel Corporation
Olms Douglas W.
Rao Seema S.
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