Network controller and method

A method for passing supervisory control from a first station to a second station of a plurality of stations, said method comprising steps of:

• (a) providing a message header in an interstation message;
• (b) transmitting the interstation message from the first station to the second station;
• (c) receiving the interstation message in the second station;
• (d) processing in the second station a received message header from the interstation message to extract data;
• and
• (e) determining in the second station the present identification of a network controller from the extracted data, wherein:
• said step (a) further comprises substeps of:
• (a1) providing in the message header a first field containing message identification information;
• (a2) providing in the message header a second field containing supervisor station identification information;
• (a3) providing in the message header a third field comprising update count information;
• and
• (a4) providing in the message header a fourth field comprising sending station identification information;
• and said step (d) comprises substeps of:
• (d1) extracting message identification information from the first field of the received message header to provide extracted message identification information;
• (d2) extracting supervisor station identification information from the second field of the received message header to provide extracted supervisor station identification information;
• (d3) extracting update count information from the third field of the received message header to provide extracted update count information;
• and
• (d4) extracting sending station identification information from a fourth field of the received message header to provide extracted sending station identification;
• (d5) comparing the extracted update count information to stored update count information to obtain a first agreement, when the extracted and the stored update count informations agree;
• (d6) comparing the extracted update count information to stored update count information to obtain a first disagreement, when the extracted and stored update count informations disagree;
• (d7) comparing the extracted supervisor station identification information to stored supervisor station information to obtain a second agreement, when the extracted and the stored supervisor station identification information agree;
• and
• (d8) comparing the extracted supervisor station identification information to stored supervisor station information to obtain a second disagreement, when the extracted and stored supervisor station identification information disagree.

A communications network including at least a first terminal, said terminal comprising:

• means for receiving a first message including a first message header, said first message header having first, second, third and fourth fields, said first field containing information describing message identification, said second field containing information describing supervisor station identification, said third field containing information describing an update count, said fourth field containing information describing sending station identification;
• means for storing information, said stored information describing message identification, supervisor station identification, update count and sending station identities;
• means, coupled to said receiving means and to said storing means, for comparing said second and third fields from a received message to stored information from said means for storing information;
• and
• means, coupled to said means for comparing, for updating information stored in said means for storing information in response to signals from said means for comparing.