Network communication protocol including a reliable multicasting technique

• US 5,297,143 A
• Filed: 12/03/1990
• Issued: 03/22/1994
• Est. Priority Date: 12/03/1990
• Status: Expired due to Term

• Current Assignee: Echelon Systems Corp.
• Original Assignee: Echelon Systems Corp.
• Inventors: Riley, Glen M., Dolin, Robert A. Jr., Fridrich, Marek J.
• Primary Examiner(s): Olms, Douglas W.
• Assistant Examiner(s): HOM, SHICK C
• Application Number:
  US07/621,739
• Time in Patent Office: 1,205 Days
• Field of Search: 370/85.3, 370/13, 370/110.1, 370/77, 370/51, 370/52, 370/67, 370/85.1, 370/94.1, 370/76, 455/57, 340/825.47, 371/32, 371/33
• US Class Current: 370/445
• CPC Class Codes: H04L 1/14 in which the signals are sent back to the transmitter to be checked ; echo systems
• CPC Class Codes: H04L 1/1614 using bitmaps
• CPC Class Codes: H04L 1/1685 the supervisory signal being transmitted in response to a specific request, e.g. to a polling signal
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 12/1868 Measures taken after transmission, e.g. acknowledgments
• CPC Class Codes: H04L 2001/0093 Point-to-multipoint
• CPC Class Codes: H04L 2001/125 Arrangements for preventing errors in the return channel
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

An improved network for communication of message packets. The present invention provides for improved reliable multicast messaging wherein messages may be reliably multicast to members of a multicast group and acknowledgements may be handled in an improved and efficient manner. In particular, a message may be transmitted to all members of a group, each member of the group responding to receipt of the message with an acknowledgement message. Further, facility is provided to allow for transmissions of reminder messages in the event one or members of a group do not respond to a message with an acknowledgement.

Claims

1. In a network system allowing for communication, sensing and control comprising a plurality of nodes coupled to a medium, said plurality of nodes comprising at least one group of nodes which may be referred to herein as Group 1, a method for reliably communicating with members of said Group 1 comprising the steps of:

a) a first device preparing a first message packet for transmission on said medium, said first message packet addressed to members of said Group 1;

b) said first device transmitting said first message on said medium;

c) said first message being received by a first member of said Group 1, said first member of said Group 1 referred to herein as Member 1;

d) said first device setting a timer;

e) if said timer expires prior to said first device receiving a first acknowledgement of receipt of said first message on said medium, then said first device transmitting a reminder message of a format different than said first message for transmission at least to said Member 1, said Member 1 receiving said reminder message;

f) said Member 1 transmitting said first acknowledgement of receipt of said first message on said medium;

g) said first device receiving said first acknowledgement;

h) said first message being received by a second member of said Group 1, said second member of said Group 1 referred to herein as Member 2;

i) said Member 2 transmitting a second acknowledgement of receipt of said first message on said medium;

j) said first device receiving said second acknowledgement.

2. The method as recited in claim 1 wherein said reminder message includes a field ML comprising information representative of whether said first device has received an acknowledgement from said Member 1.

3. A method for ensuring reliable delivery of messages to a plurality of members of a group, Group 1, in a network comprising the steps of:

a) a first device transmitting a message packet having a message field for transmission to members of said Group 1, Group 1 including a member M;

b) said first device waiting a predetermined period of time for an acknowledgement of receipt of said message packet by said member M;

c) if said first device does not receive said acknowledgement within said predetermined period of time, said first device transmitting a reminder message in a format of a re-transmitted message packet, said format of said re-transmitted message packet including a field F comprising a plurality of subfields, F₁ through F_n, corresponding to said plurality of members of said Group 1;

said subfields for indicating whether an acknowledgement has been received by said first device from said corresponding member of said Group 1, said subfields including a subfield F_m corresponding to said member M;

d) said format of said re-transmitted message packet further includes a field in which a copy of said message field is enclosed.

4. The method as recited by claim 3 further comprising the step of said member M responding to receipt of said message packet.

5. The method as recited by claim 3 further comprising the step of said member M responding to receipt of said re-transmitted message packet if said subfield F_m indicates an acknowledgement was not received by said first device from said member M.

6. The method as recited by claim 5 wherein said subfield F_m is a bit which is set to a 0 if said first device has not received an acknowledgement from said member M and is set to a 1 if said first device has received an acknowledgement from said member M.

7. The method as recited by claim 3 further comprising the step of said first device computing an expected number of acknowledgement messages to be transmitted responsive to transmission of said message packet, said first device transmitting said expected number as a field of said message packet.

8. A method for ensuring reliable delivery of messages to a plurality of members of a group, Group 1, in a network comprising the steps of:

a) a first device transmitting a message packet having a message field for transmission to members of said Group 1, Group 1 including a member M, said first device computing an expected number of acknowledgement messages to be transmitted responsive to transmission of said message packet, said first device transmitting said expected number as a field of said message packet;

b) said first device waiting a predetermined period of time for an acknowledgement of receipt of said message packet by said member M;

c) if said first device does not receive said acknowledgement within said predetermined period of time, said first device transmitting a reminder message in a format of a re-transmitted message packet, said format of said re-transmitted message packet including a field F comprising a plurality of subfields, F₁ through F_n, corresponding to said plurality of members of said Group 1;

said subfields for indicating whether an acknowledgement has been received by said first device from said corresponding member of said Group 1, said subfields including a subfield F_m corresponding to said member M;

d) said format of said re-transmitted message packet further includes a field in which a copy of said message field is enclosed;

e) said member M responding to receipt of said re-transmitted message packet if said subfield F_m indicates an acknowledgement was not received by said first device from said member M.