Duplicate message detection method and apparatus

• US 5,856,972 A
• Filed: 09/06/1996
• Issued: 01/05/1999
• Est. Priority Date: 09/01/1994
• Status: Expired due to Term

• Current Assignee: Echelon Corporation (Renesas Electronics Corporation)
• Original Assignee: Echelon Corporation (Renesas Electronics Corporation)
• Inventors: Riley, Glen M., Dolin, Robert A. Jr.
• Primary Examiner(s): Lane, Jack A.
• Application Number:
  US08/706,683
• Time in Patent Office: 851 Days
• Field of Search: 370/218, 370/312, 370/349, 370/393, 370/397, 370/389, 370/409, 370/432, 370/475, 395/200.68
• US Class Current: 370/389
• CPC Class Codes: H04L 1/16 in which the return channel carries supervisory signals, e.g. repetition request signals
• CPC Class Codes: H04L 1/1848 Time-out mechanisms
• CPC Class Codes: H04L 1/1854 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 1/188 Time-out mechanisms
• CPC Class Codes: H04L 1/1887 Scheduling and prioritising arrangements
• CPC Class Codes: H04L 9/40 Network security protocols

Abstract

A method of determining a transaction identifier for a message to be sent from a node on a network. The node has an address table and a memory. The method comprising the steps of: accessing the address table to determine an address for the message; and accessing the transaction identifier at a memory location corresponding to the address.

Claims

1. An apparatus for communicating messages on a network, said apparatus including:

a memory including a plurality of addresses and representing a plurality of transaction spaces, each transaction space of said plurality of transaction spaces including a plurality of transaction identifiers, each address of said plurality of addresses corresponding to a different transaction space of said plurality of transaction spaces, wherein one of said transaction identifiers in each of said transaction spaces is a next transaction identifier)to be used for a corresponding one of said addresses; and

a processor for preparing a message, said message including an address of said plurality of addresses and a transaction identifier of said plurality of transaction identifiers.

2. The apparatus of claim 1 wherein said plurality of addresses includes a first address and a second address, said second address being a duplicate of said first address, and wherein said first address and said second address share a common transaction space.

3. The apparatus of claim 1 wherein said plurality of addresses are stored as an address table, wherein said plurality of transaction spaces is represented as a transaction identifier table, and wherein each entry in said address table corresponds to a different entry in said transaction identifier table.

4. A method for determining a transaction identifier for a message to be sent from a node on a network, said node having an address table and a memory, said method comprising the steps of:

accessing the address table to determine an address of a destination for said message; and

accessing said transaction identifier at a memory location corresponding to said address to determine the transaction identifier of the message to be sent.

5. The method of claim 4 wherein said step of accessing said address table includes the steps of:

determining an address table index corresponding to a variable;

accessing a memory location in said address table corresponding to said address table index.

6. The method of claim 5 wherein said node includes a variable configuration table, and wherein said node is executing an application, and said application includes a variable, said step of determining an address table index includes the steps of:

said application initiating a transmission of said variable; and

accessing said variable configuration table, at a memory location corresponding to said variable, to determine said address table index.

7. The method of claim 4 further comprising the steps of:

determining whether a duplicate address exists; and

if said duplicate address exists, then said step of accessing said transaction identifier at said memory location corresponding to said address includes a step of accessing said transaction identifier at a memory location corresponding to said duplicate address.

8. The method of claim 7 wherein said node includes a duplicate address table and wherein said step of determining whether a duplicate address exists includes the steps of:

accessing a duplicate indicator in said duplicate address table at a memory location corresponding to said memory location corresponding to said address; and

testing whether said duplicate indicator has been set.

9. The method of claim 7 wherein said step of accessing said transaction identifier at a memory location corresponding to said duplicate address includes the steps of:

searching said address table for a first occurrence memory location of an address matching said address; and

accessing said transaction identifier at a memory location corresponding to said first occurrence memory location.

10. The method of claim 4 wherein said node includes a priority transaction identifier table and a non-priority transaction identifier table and wherein the step of accessing said transaction identifier at a memory location includes the steps of:

determining a priority for said message;

if said message is a priority message, then accessing said transaction identifier at a memory location in said priority transaction identifier table; and

if said message is a non-priority message, then accessing said transaction identifier at a memory location in said non-priority transaction identifier table.

11. The method of claim 4 further including the step of incrementing said transaction identifier at said memory location corresponding to said address.

12. The method of claim 4 wherein said transaction identifier is four bits in length.

13. A node for preparing a message for transmission to one of a plurality of other nodes on a network, said node comprising:

a memory including an address table and a transaction identifier table, said address table including a plurality of addresses, said transaction identifier table including a plurality of transaction spaces each of said transaction spaces including at least one of a plurality of transaction identifiers, each of said addresses corresponding to one of said transaction spaces, said transaction identifiers including, for each of the other nodes on the network, a transaction identifier for a next transmission to such other node; and

a processor coupled to said memory, said processor for preparing said message, said message including one of said addresses and one of said transaction identifiers.

14. The node of claim 13 wherein a memory location in said transaction identifier table is indexed using an index used to access a memory location in said address table.

15. The node of claim 13 wherein:

said memory further includes a duplicate address table, said duplicate address table including a first duplicate indicator corresponding to said memory location in said address table; and

said processor is for accessing said first duplicate indicator to determine whether a duplicate address exists in said address table.

16. The node of claim 15 wherein said memory location in said address table includes an address, and wherein said duplicate address corresponds to a first occurrence of said address in said address table.

17. A method of generating a transaction identifier for a message, said message to be sent on a network from a node, said message including information for a second node in said network, said node including a processor and a memory, said processor being coupled to said memory, said node being coupled in communications with said network, said method comprising the steps of:

accessing a variable configuration table index stored in said memory;

using said variable configuration table index to determine an address table index;

accessing a duplicate address table stored in said memory, using said address table index, to determine whether a duplicate address exists for an address identified by said address table index;

accessing a transaction identifier table stored in said memory, as follows;

if a duplicate address exists, accessing said transaction identifier in said transaction identifier table at an index corresponding to a predetermined occurrence of said address in an address table, said address table being stored in said memory, and

if no duplicate address exists, accessing said transaction identifier in said transaction identifier table at an index corresponding to said address table index.

18. The method of claim 17 wherein said predetermined occurrence is a first occurrence of said address in said address table.

19. The method of claim 17 wherein said predetermined occurrence is a last occurrence of said address in said address table.

20. The method of claim 17 wherein said transaction identifier is four bits long.

21. The method of claim 17 wherein said step of accessing said variable configuration table includes a step of determining a priority for said message, and wherein said priority is used in said step of accessing said transaction identifier.

22. An apparatus for communicating messages on a network, said apparatus including:

a memory including a plurality of addresses and representing a plurality of transaction spaces, each transaction space including at least one of a plurality of transaction identifiers, each address corresponding to a different one of the transaction spaces, the transaction spaces including a next transaction identifier to be used for each of the addresses; and

a processor for preparing a message, said message including an address of said plurality of addresses and a transaction identifier of said plurality of transaction identifiers.

23. A method of generating a transaction identifier for a message to be sent from a first node to a second node on a network including a plurality of nodes, said first node including a processor and a memory coupled to said processor, said method comprising the steps of:

allocating a plurality of transaction spaces in said memory, such that each of said transaction spaces corresponds to one of a plurality of addresses, each of said addresses corresponding to one of said plurality of nodes with which said first node can communicate over said network; and

storing a transaction identifier in each of said transaction spaces, each of said transaction identifiers for identifying a message to be transmitted from said first node to a node on the network corresponding to the transaction space in which the transaction identifier is stored.