Switch protection arrangement

Details Switch protection arrangement Switch protection arrangement

1995-12-08

1998-01-20

Olms, Douglas W.

Multiplex communications

Diagnostic testing

Fault detection

370248, H04J 116

Patent

active

057107599

DESCRIPTION:

BRIEF SUMMARY
BACKGROUND OF THE INVENTION

This invention relates to a switch protection arrangement in or for a switching network and in particular to a synchronous digital hierarchy system (SDH) in which information is carried in bit form in a framework in which the framework comprises a plurality of bytes of information each byte comprising in turn a plurality of bits in serial form. The bytes in the framework are assigned titles and references depending on their situation in the framework and the structure of the framework is defined in accordance with standards such as CCITT (now ITU) specification G708 and G709. Within the framework certain bytes are allocated to the path overhead frame and others to the section overhead frame for data transmission purposes.
In order to ensure correct functioning of the switch information, the information to the input of the switch is re-arranged and presented to the output. In this re-arrangement the data may be re-written and be corrupted or misrouted and it is an object of the present invention to check for parity of information between the input and the output of the switch.


SUMMARY OF THE INVENTION

EP-A-0 477 553 discloses an apparatus for testing ATM switches by inputting a test cell to an ATM channel at a free cell timing on an input highway. Test cell detectors are provided in the switches forming the ATM channel for detecting if the test cell has been correctly switched in accordance with a switch path information written in the cell.
According to the present invention a telecommunications switch protection arrangement includes a switch including switch paths, means for establishing switched connections, a plurality of interface cards which include the capability of generating and monitoring multiple test data fields and reporting any discrepancies found, the format of a switched connection including a test data byte which is reserved for transporting a multiplicity of different test data fields which are used to assist in the determination of whether the switch paths are routed and operating correctly, and wherein the contents of the data fields comprise data which is characteristic of the originating interface cards and of the channel used by the switched connection to enter the switch.
According to the present invention a switch protection arrangement includes a switch, means for establishing switched connections, a plurality of interface cards which include the capability of generating and monitoring multiple test data fields and reporting any discrepancies found, the format of a switched connection including a test data byte which is reserved for transporting a multiplicity of different test data fields which are used to assist in the determination of whether the switch paths are routed and operating correctly, and wherein the contents of the data fields comprise: a multiframe synchronisation pattern; a plurality of parity check bits generated from the data carried by that switched connection; the number of the shelf containing the originating interface card of the switched connection; the number of a card position containing the originating interface card; the type number of the originating interface card; and the channel number used by the switched connection to enter the switch.
Means may be provided to distribute data to the interface card at the destination of a switched connection; the data containing: the shelf number; the card number; the card type; and the channel number of the source of a switched connection.
Means may also be provided to inhibit the reporting of some or all of the detected discrepancies.
The test data byte is preferably the V4 byte of an SDH tributary.
It is preferred that TU1/2 structured data utilises the V4 byte of the associated path overhead. TU3/AU4 structured data utilises bytes within the section overhead of the frame.
A glossary of terms used in this specification and the drawings appears in an Appendix at the end of the specification.
The detailed description following is specific to the TU12 checking mechanism. The same princ

REFERENCES:
patent: 5500851 (1996-03-01), Kozaki et al.
patent: 5524106 (1996-06-01), Tremel et al.

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