Method for switching ATM, TDM and packet data through a single communications switch

Abstract

A network switch includes at least one port processor and at least one switch element. The port processor has an SONET OC -x interface (for TDM traffic), a UTOPIA interface (for ATM and packet traffic), and an interface to the switch element. In one embodiment, the port processor has a total I / O bandwidth equivalent to an OC-48, and the switch element has 12x12 ports for a total bandwidth of 30 Gbps. A typical switch includes multiple port processors and switch elements. A data frame of 9 rows by 1700 slots is used to transport ATM, TDM, and Packet data from a port processor through one or more switch elements to the same or another port processor. Each frame is transmitted in 125 microseconds; each row in 13.89 microseconds. Each slot includes a 4-bit tag plus a 4-bnyte payload. The slot bandwidth is 2.592 Mbps which is large enough to carry an E-1 signal with overhead. The 4-bit tag is a cross connect pointer which is set up when a TDM connection is provisioned. The last twenty slots of the frame are reserved for link overhead. Thus, the frame is capable of carrying the equivalent of 1,680 E-1 TDM signals. For ATM and packet data, a PDU (protocol data unit) of 16 slots is defined for a 64-byte payload. The PDUs are self-routed through the switch with a 28-bit routing tag which allows routing through seven switch stages using 4-bits per stage. Bandwidth is arbitrated among ATM and Packet connections while maintaining TDM timing.

Description

technical field [0001] The invention relates to telecommunications networks. More specifically, the present invention relates to methods and devices aimed at exchanging ATM (Asynchronous Transfer Mode), TDM and packet data through a single communication switch. Background technique [0002] One of the earliest technologies aimed at utilizing broadband telecommunication networks was called Time Division Multiplexing (TDM). The working principle of TDM is simple and easy to understand. Divide a high frequency signal into time slots within which multiple low frequency signals can be transmitted from one point to another. However, the actual implementation of TDM is very complex, requiring complex framing techniques and buffers in order to accurately multiplex and demultiplex signals. The North American standard for TDM (called T1 or DS1) utilizes 24 interleaved channels with an aggregate rate of 1.544 Mb / s. The European standard for TDM is called E-1, which utilizes 30 inte...

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Problems solved by technology

Another difference is that, unlike channels in TDM, the packet length is not necessarily fixed

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