Multiple node dual level error recovery system and method

• US 5,958,064 A
• Filed: 10/23/1997
• Issued: 09/28/1999
• Est. Priority Date: 06/20/1992
• Status: Expired due to Fees

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Beer, Reginald, Judd, Ian David
• Primary Examiner(s): Palys, Joseph E.
• Assistant Examiner(s): Baderman, Scott T.
• Application Number:
  US08/956,919
• Time in Patent Office: 705 Days
• Field of Search: 395/182.02, 395/182.13, 395/182.14, 395/182.15, 395/182.16, 395/182.17, 370/216, 370/217, 370/218, 370/219, 370/220, 370/221, 370/222, 370/223, 370/224, 370/225, 370/226, 370/227, 370/228
• US Class Current: 714/4.4
• CPC Class Codes: H04L 1/0083 Formatting with frames or packets; Protocol or part of protocol for error control
• CPC Class Codes: H04L 1/1874 Buffer management
• CPC Class Codes: H04L 12/28 characterised by path configuration, e.g. LAN [Local Area Networks] or WAN [Wide Area Networks] wireless communication networks H04W ; arrangements for dividing the transmission path H04W40/00
• CPC Class Codes: H04L 69/40 for recovering from a failure of a protocol instance or entity, e.g. service redundancy protocols, protocol state redundancy or protocol service redirection management of faults, events, alarms or notifications in data switching networks H04L41/06

Abstract

An error recovery method for use in an information communication system which comprises a plurality of nodes connected by links. Information is transferred between the nodes in frames of predefined types, including at least a first frame type used to transfer data and a second frame type used for error recovery. Each node has at least a first and a second mode of operation. In the first mode frames of both first and second types are accepted. In the second mode frames of the first type are discarded and only frames of the second type are accepted. A master node which controls error recovery is selected from amongst those nodes which can initiate transfers.

Claims

1. An error recovery method for use in an information communication system network comprising a plurality of nodes connected by links, information being transferred in frames of predefined types between the nodes via one or more of the links, the predefined types including a data frame for transferring data and an error recovery frame for transferring error information, each node including a buffer for receiving the frames, the plurality of nodes including a plurality of initiator nodes capable of initiating the transfer of information, the method comprising the steps of:

selecting one of the initiator nodes to be a master node for controlling data error recovery;

if a link fails between a first and a second node of the network at least one node of the first and second nodes asynchronously discarding data frames received over the failed link and initiating an error recovery mode by transmitting to the master node error information identifying the failed link;

the master node, upon receiving the error information, transmitting to the initiator nodes an error recovery frame including the error information; and

each initiator node that has transferred data frames for receipt by another node of the network over the failed link, upon receiving the second error recovery frame, transmitting instructions to the receiving node to discard the data frames in its buffer to prevent transmission of incomplete or erroneous data.

2. The error recovery method of claim 1, further comprising the step of conditioning the at least one node, after the link failure, to accept only frames of the error recovery frame type.

3. The error recovery method of claim 2, further comprising, after the preceding steps, the step of transmitting by the master node to the at least one node an error recovery frame for conditioning the at least one node to accept frames of both the data and error recovery frame types, thereby terminating the error recovery mode.

4. The error recovery method of claim 1, wherein the step of defining a master node further comprises selecting a master node by agreement of all initiator nodes using predetermined criteria.

5. The error recovery method of claim 1, wherein each initiator node is associated with a unique value, and wherein the initiator node having the highest unique value is selected to be the master node.

6. The error recovery method of claim 1, further comprising the steps of:

after the link failure and prior to transmitting error information to the master node, retransmitting by the at least one node of any data frames previously transmitted over the failed link;

determining whether the retransmitted data frames are received by the other node without error; and

if the retransmitted frames are received without error, terminating the error recovery method.

7. The error recovery method of claim 1, further comprising the steps of:

upon addition of a new node to the system by the establishment of a new link between the new node and one of the system nodes, the system node transmitting to the master node information identifying the new link; and

the master node, upon receiving the information, transmitting to the new node the location of the master node and a unique identifier to be associated with the new node, and transmitting to the initiator nodes an error recovery frame for causing each initiator node to configure the new node.

8. The error recovery method of claim 1, further comprising, after the preceding steps, the step of transmitting by the master node to each initiator node an error recovery frame to cancel the error information.

9. An error recovery apparatus for use in an information communication system network comprising a plurality of nodes connected by links, wherein information is transferred in frames of predefined types between the nodes via one or more of the links, the predefined types including a data frame for transferring data and an error recovery frame for transferring error information, each node including a buffer for receiving the frames, the plurality of nodes including a plurality of initiator nodes capable of initiating the transfer of information, the apparatus comprising:

means for selecting one of the initiator nodes to be a master node for controlling data error recovery;

means responsive to a link failure between a first and a second node of the network for at least one node of the first and second nodes asynchronously discarding data frames received over the failed link, and means for initiating an error recovery mode by asynchronously transmitting by the at least one node to the master node error information identifying the failed link;

means responsive to receipt of the error information, for transmitting by the master node to each initiator node of an error recovery frame including the error information; and

means associated with each initiator node and responsive to receipt of the error recovery frame, for transmitting by the initiator node to other nodes of the network to which it has transferred data frames over the failed link, instructions to discard the data frames in its buffer to prevent transmission of incomplete or erroneous data.

10. The apparatus of claim 9, further comprising means for conditioning the at least one node, after the link failure, to only accept frames of the error recovery frame type.

11. The apparatus of claim 10, further comprising means for transmitting, by the master node to the at least one node, an error recovery frame for conditioning the at least one node to accept frames of both the data and error recovery frame types, thereby terminating the error recovery mode.

12. The apparatus of claim 9, wherein the selecting means further comprises means for selecting a master node by agreement of all initiator nodes using predetermined criteria.

13. The apparatus of claim 9, wherein each initiator node is associated with a unique value, and further comprising means for selecting the initiator node having the highest unique value as the master node.

14. The apparatus of claim 9, further comprising:

means for retransmitting, after a link failure, by the at least one node data frames transmitted over the failed link; and

means for determining if the retransmitted frames are received without error.

15. The apparatus of claim 9, further comprising:

means, responsive to a new node added to the system by establishment of a new link between the new node and one of the system nodes, for transmitting by the system node to the master node information identifying the new link;

means for transmitting, by the master node to the new node, a unique identifier to be associated with the new node;

means for transmitting, by the master node to the new node, the location of the master node; and

means for transmitting, by the master node to each initiator node, an error recovery frame for causing each initiator node to configure the new node.

16. The apparatus of claim 9, further comprising means for transmitting, by the master node to each initiator node, an error recovery frame canceling the error information.

17. An information communication system network, comprising:

a plurality of nodes connected by links, wherein information is transferred in frames of predefined types between the nodes via one or more of the links, the predefined types including a data frame for transferring data and an error recovery frame for transferring error information, each node including a buffer for receiving the frames, the plurality of nodes including a plurality of initiator nodes capable of initiating the transfer of information;

means for selecting one of the initiator nodes to be a master node for controlling data error recovery;

means responsive to a link failure between a first and a second node of the network, for at least one node of the first and second nodes asynchronously discarding data frames received over the failed link, and means for initiating an error recovery mode by asynchronously transmitting by the at least one node to the master node error information identifying the failed link;

means responsive to receipt of the error information, for transmitting by the master node to each initiator node an error recovery frame including the error information; and

means associated with each initiator node and responsive to receipt of the error recovery frame, for transmitting by the initiator node to other nodes of the network to which it has transferred data frames over the failed link, instructions to discard the data frames in its buffer to prevent transmission of incomplete or erroneous data.

18. The system of claim 17, further comprising means for conditioning the at least one node, after the link failure, to only accept frames of the error recovery frame type.

19. The system of claim 18, further comprising means for transmitting, by the master node to the at least one node, an error recovery frame for conditioning the at least one node to accept frames of both the data and error recovery frame types, thereby terminating the error recovery mode.

20. The system of claim 17, wherein the selecting means further comprises means for selecting a master node by agreement of all initiator nodes using predetermined criteria.

21. The system of claim 17, wherein each initiator node is associated with a unique value, and further comprising means for selecting the initiator node having the highest unique value to be the master node.

22. The system of claim 17, further comprising:

means for retransmitting, after a link failure, by the at least one node data frames previously transmitted over the failed link; and

means for determining if the retransmitted frames are received without error.

23. The system of claim 17, further comprising:

means, responsive to a new node added to the system by establishment of a new link between the new node and one of the system nodes, for transmitting by the system node to the master node information identifying the new link;

means for transmitting, by the master node to the new node, a unique identifier to be associated with the new node;

means for transmitting, by the master node to the new node, the location of the master node; and

means for transmitting, by the master node to each initiator node, an error recovery frame for causing each initiator node to configure the new node.

24. The system of claim 17, further comprising means for transmitting, by the master node to each initiator node, an error recovery frame canceling the error information.