Arrangement for testing packet switching networks

• US 4,745,593 A
• Filed: 11/17/1986
• Issued: 05/17/1988
• Est. Priority Date: 11/17/1986
• Status: Expired due to Term

• Current Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Original Assignee: American Telephone & Telegraph Company (AT&T, Inc.)
• Inventors: Stewart, Gilbert M.
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Marcelo, Melvin
• Application Number:
  US06/931,685
• Time in Patent Office: 547 Days
• Field of Search: 370/13, 370/14, 370/15, 370/16, 370/60, 370/94, 370/13.1, 371/33, 371/62
• US Class Current: 370/244
• CPC Class Codes: H04L 12/56 Packet switching systems
• CPC Class Codes: H04L 43/0811 by checking connectivity
• CPC Class Codes: H04L 43/50 Testing arrangements

Abstract

A packet network test arrangement where a test packet is transmitted from a test source to a test destination via successive nodes of the packet network. Any node that fails to receive acknowledgement within a predetermined time of transmitting the test packet to a subsequent node responds by transmitting information to the test source concerning the failure and particularly defining the involved nodes. Accordingly, a single test can be used advantageously both to detect faults and to localize such faults between two network nodes. The test arrangement also provides for the loop-around of test packets received at the test destination thus enabling the test source to verify successful packet communications.

Claims

1. In a test arrangement for testing communication from a test source to a test destination via a packet switching network comprising a plurality of packet switching nodes and a plurality of bidirectional links each interconnecting a distinct pair of said nodes, a test method comprising

in response to a receipt of a test packet from said test source, one of said nodes transmitting said test packet to another of said nodes via the one of said links interconnecting said one node and said another node and

in response to a failure to receive acknowledgment via said one link from said another node within a predetermined time interval of said one node transmitting said test packet, said one node transmitting information to said test source defining said failure as concerning packet transmission between said one node and said another node via said one link.

2. A method in accordance with claim 1 wherein said information comprises a test result packet defining a reverse route from said one node to said test source comprising ones of said plurality of nodes traversed by said test packet.

3. A method in accordance with claim 2 wherein said test packet from said test source specifies said predetermined time interval.

4. A method in accordance with claim 1 wherein said test packet from said test source specifies said predetermined time interval.

5. A method in accordance with claim 1 further comprising

said one node retransmitting said test packet to said another node more than a fixed number of times and

upon retransmitting said test packet to said another node more than a fixed number of times, said one node transmitting information to said test source concerning said retransmissions of said test packet.

6. A method in accordance with claim 5 wherein said test packet from said test source specifies said fixed number.

7. A method for testing a packet switching network comprising a plurality of packet switching nodes and a plurality of bidirectional links each interconnecting a distinct pair of said nodes, said method comprising

transmitting a test packet from a test source to a test destination via said network,

upon receiving said test packet from said test source, a first one of said nodes transmitting said test packet to a second one of said nodes via the one of said links interconnecting said first node and said second node,

upon receiving said test packet from said first node, said second node acknowledging receipt of said test packet to said first node via said one link, and

upon a failure to receive acknowledgment via said one link from said second node within a predetermined time interval of said first node transmitting said test packet, said first node transmitting information to said test source defining said failure as concerning packet transmission between said first node and said second node via said one link.

8. A method in accordance with claim 7 further comprising

upon receiving said test packet, said test destination looping said test packet back to said test source.

9. A method in accordance with claim 8 wherein said information comprises a test result packet defining a reverse route from said first node to said test source comprising ones of said plurality of nodes traversed by said test packet.

10. A method in accordance with claim 9 wherein said test packet transmitted from said test source specifies said predetermined time interval.

11. A method in accordance with claim 7 wherein said test packet transmitted from said test source defines a route from said test source to said test destination comprising ones of said plurality of nodes.

12. A method in accordance with claim 7 further comprising

as said test packet is transmitted from said test source via ones of said plurality of nodes, adding information into said test packet defining said ones of said nodes.

13. A method in accordance with claim 7 wherein said information comprises a test result packet defining a reverse route from said first node to said test source comprising ones of said plurality of nodes traversed by said test packet.

14. A method in accordance with claim 7 wherein said test packet transmitted from said test source specifies said predetermined time interval.

15. A method in accordance with claim 7 further comprising

said first node retransmitting said test packet to said second node more than a fixed number of times and

upon retransmitting said test packet to said second node more than said fixed number of times, said first node transmitting information to said test source concerning said retransmissions of said test packet.

16. A method in accordance with claim 15 wherein said test packet transmitted from said test source specifies said fixed number.

17. A method in accordance with claim 7 wherein said test source and said test destination are packet switching nodes of said network.

18. In a test arrangement for testing communication from a test source to a test destination via a packet switching network comprising a plurality of packet switching nodes and a plurality of bidirectional links each interconnecting a distinct pair of said nodes, a test method comprising

in response to a receipt of a test packet from said test source, one of said nodes transmitting said test packet to other ones of said nodes via the ones of said links interconnecting said one node and said other ones of said nodes and

in response to a failure to receive acknowledgment from each of said other ones of said nodes via the one of said links interconnecting said one node and said each other node within a predetermined time interval of said one node transmitting said test packet, said one node transmitting information to said test source defining said failure as concerning packet transmission between said one node and said each other node.

19. A method in accordance with claim 18 wherein the number of said other nodes is at most M, where M is a positive integer greater than one.

20. A method in accordance with claim 19 wherein said test packet from said test source specifies said integer M.

21. A method for testing a packet switching network comprising a plurality of packet switching nodes and a plurality of bidirectional links each interconnecting a distinct pair of said nodes, said method comprising

broadcasting a test packet from a first one of said nodes to other ones of said nodes,

any of said nodes receiving said test packet, broadcasting said test packet to other ones of said nodes,

any of said nodes receiving said test packet, acknowledging receipt of said test packet to the one of said nodes from which said test packet is received,

any of said nodes other than said first node, upon a failure to receive acknowledgment via ones of said links from ones of said nodes to which said any node other than said first node has broadcast said test packet, transmitting information to said first node defining said failure as concerning packet transmission via said ones of said links between said any node other than said first node and said ones of said nodes to which said any node other than said first node has broadcast said test packet.

22. In a test arrangement for testing communication from a test source to a test destination via a packet switching network comprising a plurality of packet switching nodes and a plurality of bidirectional links each interconnecting a distinct pair of said nodes, each of said nodes comprising

means responsive to a receipt of a test packet from said test source for transmitting said test packet to said test destination via one of said links and

means responsive to a failure to receive via said one link acknowledgment of receipt of said transmitted test packet for transmitting information to said test source defining said failure as concerning packet transmission from said each node via said one link.

23. A packet switching node in accordance with claim 22 wherein said means for transmitting said information comprises

timer means for defining elapsed time from the transmission of said test packet by said means for transmitting said test packet,

means for detecting acknowledgment of receipt of said transmitted test packet and

means responsive to said timer means and said detecting means for transmitting said information to said test source when said timer means defines an elapsed time exceeding a predetermined time without a detection of acknowledgment of receipt of said transmitted test packet by said detecting means.

24. A packet switching node in accordance with claim 23 further comprising

means responsive to a receipt of a test packet defining said node as said test destination, for looping said test packet defining said node as said test destination back to said test source.

25. In a test arrangement for testing communication of a test packet from a test source to a test destination, a packet switching network interconnecting said source and destination and comprising a plurality of packet switching nodes and a plurality of bidirectional links each interconnecting a distinct pair of said nodes each of said nodes comprising

means for acknowledging receipt of said test packet to one of said nodes from which said test packet is received,

means for transmitting said test packet received from said one node to another one of said nodes via one of said links and

means responsive to a failure to receive via said one link acknowledgment of receipt of said test packet from said another node for transmitting information via said network to said test source defining said failure between said each node and said another node via said one link.