Runtime detection of network loops

• US 6,298,456 B1
• Filed: 09/24/1998
• Issued: 10/02/2001
• Est. Priority Date: 12/05/1997
• Status: Expired due to Fees

• Current Assignee: Hewlett-Packard Development Company, L.P. (HP Inc.)
• Original Assignee: Hewlett-Packard Company (HP Inc.)
• Inventors: McGuire, Robert Michael, OʼNeil, Douglas E.
• Primary Examiner(s): Myers, Paul R.
• Application Number:
  US09/160,054
• Time in Patent Office: 1,104 Days
• Field of Search: 714/48, 714/716, 370/224, 370/234, 370/249, 709/223
• US Class Current: 714/48
• CPC Class Codes: H04L 12/44 Star or tree networks
• CPC Class Codes: H04L 41/24 using dedicated network management hardware
• CPC Class Codes: H04L 41/5019 Ensuring fulfilment of SLA
• CPC Class Codes: H04L 43/00 Arrangements for monitoring or testing data switching networks
• CPC Class Codes: H04L 43/0847 Transmission error
• CPC Class Codes: H04L 43/10 Active monitoring, e.g. heartbeat, ping or trace-route
• CPC Class Codes: H04L 43/16 Threshold monitoring

Abstract

Runtime detection of network loops is performed. It is detected when for a network segment a ratio of duplicate packets to total packets exceeds a first predetermined threshold. Also it is detected when traffic load on the network segment exceeds a second predetermined threshold. When the ratio of duplicate packets to total packets exceeds the first predetermined threshold and the traffic load on the network segment exceeds the second predetermined threshold, a network loop has been detected.

Claims

1. A method for runtime detection of network loops comprising the following steps:

(a) detecting when, for a network segment, a ratio of duplicate packets to total packets exceeds a first predetermined threshold;

(b) detecting when traffic load on the network segment exceeds a second predetermined threshold; and

,

(c) when in step (a) it is detected that a ratio of duplicate packets to total packets exceeds the first predetermined threshold and in step (b) it is detected that the traffic load on the network segment exceeds the second predetermined threshold, indicating that a network loop has been detected.

2. A method as in claim 1 wherein step (a) includes the following substeps:

(a.1) acquiring sampled packets from all network packets sent over the network segment;

(a.2) using the sampled packets to generate packet identification statistics; and

,

(a.3) calculating the ratio of duplicate packets to total packets using the packet identification statistics.

3. A method as in claim 2 wherein in substep (a.2) a cyclical redundancy check is used to identify packets when generating packet identification statistics.

4. A method as in claim 2 wherein in substep (a.2) entire contents of each sampled packet are used to identify packets when generating packet identification statistics.

5. A method as in claim 1 wherein in step (a) the first predetermined threshold is equal to one half.

6. A method as in claim 1 wherein in step (b) the second predetermined threshold is equal to one half bandwidth for the network segment.

7. A device for runtime detection of network loops comprising:

first detection means for detecting when a ratio of duplicate packets to total packets exceeds a first predetermined threshold for a network segment;

second detecting means for detecting when traffic load on the network segment exceeds a second predetermined threshold; and

,

indication means for indicating that a network loop has been detected when the first detecting means detects that a ratio of duplicate packets to total packets exceeds the first predetermined threshold the second detection means detects that the traffic load on the network segment exceeds the second predetermined threshold.

8. A device as in claim 7 wherein the first detection means includes:

an acquiring process which acquires sampled packets from all network packets sent over the network segment;

a generating process which generates packet identification statistics from the sampled packets acquired by the acquiring process; and

,

a calculating process which calculates the ratio of duplicate packets to total packets using the packet identification statistics.

9. A device as in claim 8 wherein the generating processes uses a cyclical redundancy check to identify packets when generating packet identification statistics.

10. A device as in claim 8 wherein the generating processes uses entire contents of each sampled packet to identify packets when generating packet identification statistics.

11. A device as in claim 7 wherein the first predetermined threshold is equal to one half.

12. A device as in claim 7 wherein the second predetermined threshold is equal to one half bandwidth for the network segment.

13. A method for runtime detection of network loops comprising the following steps:

(a) detecting when, for a network segment, a plurality of indicators have each exceeded predetermined thresholds; and

(b) when in step (a) all of the plurality of indicators have each exceeded predetermined thresholds, indicating that a network loop has been detected.

14. A method as in claim 13 wherein in step (a) the plurality of indicators includes broadcast and multicast traffic levels exceeding a predetermined threshold.

15. A method as in claim 13 wherein in step (a) the plurality of indicators includes high collision rate level exceeding a predetermined threshold.

16. A method as in claim 13 wherein in step (a) the plurality of indicators includes duplicate packets exceeding a predetermined threshold.

17. A method as in claim 13 wherein in step (a) the plurality of indicators includes traffic load exceeding a predetermined threshold.

18. A computer implemented method for runtime detection of network loops comprising the following steps:

(a) detecting by a computing system when, for a network segment, a performance indicator has exceeded a predetermined threshold; and

(b) when in step (a) the performance indicator has exceeded the predetermined threshold, noting that a network loop has been detected.

19. A method as in claim 18 wherein in step (a) the performance indicator is one of the following:

broadcast and multicast traffic levels exceeding a predetermined threshold;

high collision rate level exceeding a predetermined threshold;

duplicate packets exceeding a predetermined threshold; and

,

traffic load exceeding a predetermined threshold.