Method and apparatus for event detection in a switching system

• US 6,741,558 B1
• Filed: 06/30/1999
• Issued: 05/25/2004
• Est. Priority Date: 06/30/1998
• Status: Expired due to Term

• Current Assignee: Mitel Networks Corporation
• Original Assignee: Mitel Corporation (Microchip Technology Incorporated)
• Inventors: Gresham, Paul
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): Ferris, Derrick W
• Application Number:
  US09/343,227
• Time in Patent Office: 1,791 Days
• Field of Search: 370/216, 370/218, 370/241, 370/243, 370/245, 370/250, 370/400, 370/410, 370/229, 370/230, 370/389, 709/200, 709/201, 709/202, 709/203, 709/318, 710/40, 710/58
• US Class Current: 370/230
• CPC Class Codes: H04L 69/324 in the data link layer [OSI layer 2], e.g. HDLC
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

An event detector for detecting a plurality of different possible asynchronous events from any of a plurality of source addresses and nodes, debouncing the events and, once a valid event has been identified and confirmed, formatting and transmitting a message via a message transport system to a predetermined destination address for further appropriate action. According to the preferred embodiment, each event is time-stamped so that latency in the message transport system does not affect time-critical events. Thus, the transmitted message identifies the source address, source node, an event number for identifying the event, and a time-stamp associated with the event.

Claims

1. Apparatus for detecting an asynchronous event in a communication system and signaling occurrence of said event by transmitting a message to a predetermined device, comprising:

an input device for sampling at least one input signal location of said communication system for the occurrence of said event;

a message transmitter for creating and transmitting said message to said predetermined device for each said occurrence of said event; and

an event detector connected to said input device and said message transmitter for (i) delaying activation of said message transmitter for a first predetermined time period in order to ensure validity of the occurrence of said event at said input device, and (ii) causing said message transmitter to re-transmit said message in the event said event persists at said input device after a second predetermined time period has elapsed following said transmitting of said message.

2. The apparatus of claim 1, wherein said event detector further comprises:

a memory having a plurality of memory locations each containing an event identifier field for storing an event number for identifying said event, a time-stamp field for storing a time-stamp value indicative of when said event has occurred, and an event state field for storing a plurality of event state values; and

a state machine connected to said memory, said input device and said message transmitter for (i) scanning said memory for previous storage of said event number in said event identifier field of said memory locations, (ii) in the event said event number is not located after said first predetermined time period then selecting a first one of said memory locations containing a first order one of said state values in its event state field, writing said event number and said time-stamp value into said event identifier and time-stamp fields and advancing said first order state value to a second order state value in the event state field of said first memory location, (iii) in the event said event number is located after said first predetermined time period then advancing said second order state value to a third order state value, (iv) scanning said memory for any location having said third order state value stored in its event state field, (v) upon locating a memory location having said third order state value stored in its event state field activating said message transmitter for creating and transmitting said message, wherein said message includes said event number and time-stamp value, and advancing said third order state value to a fourth order state value once said message has been transmitted, (vi) repeating step (i) and (a) in the event said event number is not located then advancing said fourth order state value to a fifth order state value and (b) in the event said event number is located after said second predetermined time period then advancing said fourth order state value to said third order state value and repeating step (vi), (vii) repeating step (i) and (a) in the event said event number is not located then advancing said fifth order state value to said first order state value and (b) in the event said event number is located then advancing said fifth order state value to said fourth order state value and repeating step (vii).

3. A method for detecting an asynchronous event in a communication system and signaling occurrence of said event by transmitting a message to a predetermined device, comprising the steps of:

sampling at least one input signal location of said communication system for the occurrence of said event;

creating and transmitting said message to said predetermined device after a first predetermined time period sufficient to ensure validity of the occurrence of said event at said input; and

causing said message transmitter to re-transmit said message in the event said event persists at said input device after a second predetermined time period has elapsed following said transmitting of said message.

4. The method of claim 3, comprising the further steps of:

(i) scanning a memory for previous storage of an event number in an event identifier field thereof, wherein said event number identifies said event;

(ii) in the event said event number is not located after said first predetermined time period then selecting a first memory location containing a first order state value in an event state field, writing said event number and a time-stamp value indicative of when said event has occurred into respective event identifier and time-stamp fields of said memory location and advancing said first order state value to a second order state value in the event state field of said first memory location;

(iii) in the event said event number is located after said first predetermined time period then advancing said second order state value to a third order state value;

(iv) scanning said memory for any location having said third order state value stored in its event state field;

(v) upon locating a memory location having said third order state value stored in its event state field activating said message transmitter for creating and transmitting said message, wherein said message includes said event number and time-stamp value, and advancing said third order state value to a fourth order state value once said message has been transmitted;

(vi) repeating step (i) and (a) in the event said event number is not located then advancing said fourth order state value to a fifth order state value and (b) in the event said event number is located after said second predetermined time period then advancing said fourth order state value to said third order state value and repeating step (vi); and

(vii) repeating step (i) and (a) in the event said event number is not located then advancing said fifth order state value to said first order state value and (b) in the event said event number is located then advancing said fifth order state value to said fourth order state value and repeating step (vii).