System and method for detecting unidirectional links

• US 6,765,877 B1
• Filed: 08/30/1999
• Issued: 07/20/2004
• Est. Priority Date: 08/30/1999
• Status: Expired due to Term

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Fung, Hei Tao, Foschiano, Marco, Annaamalai, Alagu
• Primary Examiner(s): Pham, Chi
• Assistant Examiner(s): HOANG, THAI D
• Application Number:
  US09/386,534
• Time in Patent Office: 1,786 Days
• Field of Search: 370/241, 370/242, 370/243, 370/244, 370/245, 370/248, 370/249, 370/252
• US Class Current: 370/250
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/18 Loop-free operations
• CPC Class Codes: H04L 45/26 Route discovery packet

Abstract

A method of testing a primary device for two-way communication between the primary device and one or more other devices in communication therewith in a network. The method may include receiving a packet containing an originating device identifier at the primary device; adding a primary device identifier to the packet; transmitting the packet containing the originating device identifier and the primary device identifier from the primary device; and receiving a reply packet and detecting two-way communication if the reply packet contains the originating device identifier and the primary device identifier. A system for testing a primary device for two-way communication between the primary device and the other devices coupled to the primary device is also disclosed.

Claims

1. A method of testing a primary device for two-way communication between the primary device and one or more neighbor devices in communication therewith in a network, the method comprising:

receiving at the primary device a probe packet from an originating device, the probe packet containing an originating device identifier and an originating device port identifier;

inserting into an echo packet the originating device identifier in an originating device field and a primary device identifier and a primary device port identifier in a primary device field in the echo packet;

transmitting the echo packet containing the originating device identifier and a primary device identifier from the primary device; and

receiving a reply packet at the primary device and detecting two-way communication if the reply packet contains the originating device identifier in the originating device field and the primary device identifier in the primary device field.

2. The method of claim 1 wherein receiving and transmitting the packet comprises receiving and transmitting the packet across a data link layer.

3. The method of claim 1 wherein receiving a reply packet further comprises detecting a transmitting and receiving loop if the primary device identifier is located in the originating device field.

4. The method of claim 1 wherein receiving a reply packet further comprises detecting one-way communication if the reply packet does not contain one of the originating device identifier and the primary device identifier.

5. The method of claim 4 further comprising notifying a user of the primary device of the one-way communication.

6. The method of claim 4 further comprising notifying a network manager of the one-way communication.

7. The method of claim 1 wherein transmitting the packet further comprises starting a timer and setting a time limit for detecting two-way communication.

8. The method of claim 1 further comprising storing the originating device identifier in cache of the primary device upon receiving the packet.

9. The method of claim 8 further comprising removing the originating device identifier from the cache of the primary device after a predetermined period of time.

10. The method of claim 1 wherein receiving a packet and transmitting a packet comprises receiving a plurality of packets and transmitting a plurality of packets, respectively.

11. The method of claim 1 further comprising detecting an error if the reply packet does not contain the originating device identifier and the primary device identifier in proper fields of the reply packet.

12. The method of claim 1 wherein the primary device is configured to detect a unidirectional link, bidirectional link, neighbor mismatch, or a loop.

13. The method of claim 1 wherein the device identifiers are encapsulated in a header of the packet.

14. A system for testing a primary device for two-way communication between the primary device and one or more other devices in communication therewith in a network, the system comprising:

a receiver operable to receive a probe message containing an originating device identifier and originating device port identifier;

a message generator operable to generate an echo message with the originating device identifier in an originating device field and a primary device identifier in a primary device field; and

a transmitter operable to transmit the echo message containing the originating device identifier and the primary device identifier to facilitate detection of one-way communication at the primary device based on the identifiers contained in the echo message and the location of the identifiers in the message.

15. The system of claim 14 wherein the receiver receives messages from a data link layer and the transmitter transmits messages to the data link layer.

16. The system of claim 14 further comprising a cache table for storing the originating device identifier in the primary device.

17. The system of claim 14 further comprising an error message generator operable to generate a message that a one-way communication condition exists.

18. The system of claim 14 wherein the primary device is in communication with the one or more other devices through a fiber medium.

19. The system of claim 18 wherein the primary device is in communication with the one or more other devices through fiber optic cable.

20. The system of claim 14 further comprising a detector operable to receive a reply message and detect whether the reply message contains the originating device identifier and the primary device identifier to determine if the primary device is in two-way communication with connected devices in the network.

21. The system of claim 20 wherein the detector is operable to identify field locations of the originating device identifier and the primary device identifier within the reply message.

22. The system of claim 20 further comprising a timer operable to limit detection time of the detector.

23. The system of claim 14 wherein the echo message generator is operable to generate a plurality of echo messages and the transmitter is operable to transmit the plurality of echo messages.

24. The system of claim 14 wherein the primary device is in communication with the one or more other devices through copper media.

25. The system of claim 14 further comprising a detector operable to receive a reply packet and detect a unidirectional link, bidirectional link, neighbor mismatch, and a transmitting or receiving loop.

26. A system for testing a primary device for two-way communication between the primary device and one or more neighbor devices in communication therewith in a network, the system comprising:

means for receiving at the primary device a probe packet from an originating device, the probe packet containing an originating device identifier and an originating device port identifier;

means for inserting into an echo packet the originating device identifier in an originating device field and a primary device identifier and a primary device port identifier in a primary device field in the echo packet;

means for transmitting the echo packet containing the originating device identifier and a primary device identifier from the primary device; and

means for receiving a reply packet at the primary device and detecting two-way communication if the reply packet contains the originating device identifier in the originating device field and the primary device identifier in the primary device field.

27. The system of claim 26 wherein means for transmitting the packet further comprises starting a timer and setting a time limit for detecting two-way communication.

28. The system of claim 26 further comprising means for storing the originating device identifier in cache of the primary device upon receiving the packet.

29. The system of claim 28 further comprising means for removing the originating device identifier from the cache of the primary device after a predetermined period of time.