System and method for detecting unidirectional links

• US 7,480,251 B2
• Filed: 06/04/2004
• Issued: 01/20/2009
• Est. Priority Date: 08/30/1999
• Status: Expired due to Fees

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Annaamalai, Alagu, Fung, Hei Tao, Foschiano, Marco
• Primary Examiner(s): PATEL, JAYANTI K
• Assistant Examiner(s): Hoang; Thai D.
• Application Number:
  US10/860,816
• Publication Number:
  US 20040218540A1
• Time in Patent Office: 1,691 Days
• Field of Search: 370242-251
• US Class Current: 370/248
• 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 is disclosed. The method includes inserting into an echo packet an originating device identifier in an originating device field and a primary device identifier in a primary device field, and transmitting the echo packet from the primary device. Two-way communication is detected if a reply packet received at the primary device contains the originating device identifier in the originating device field and the primary device identifier in the primary device field. A system for testing a primary device for two-way communication between the primary device and neighbor 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:

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

transmitting the echo packet containing the originating device identifier and the 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 one-way communication if the reply packet does not contain one of the originating device identifier and the primary device identifier.

4. The method of claim 3 further comprising notifying a user of the primary device of the one-way communication.

5. The method of claim 3 further comprising notifying a network manager of the one-way communication.

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

7. 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.

8. 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 message generator configured to generate an echo message with an originating device identifier located in an originating device field and a primary device identifier located in a primary device field;

a transmitter configured to transmit from the primary device the echo message containing the originating device identifier and the primary device identifier; and

a receiver configured to receive a reply packet at the primary device and detect 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.

9. The system of claim 8 wherein the receiver receives messages from a data link layer and the transmitter transmits messages to the data link layer.

10. The system of claim 8 further comprising a cache table for storing the originating device identifier in the primary device.

11. The system of claim 8 further comprising an error message generator operable to generate a message that a one-way communication condition exists if the reply packet does not contain the originating device identifier in the originating device field.

12. The system of claim 8 wherein the primary device is in communication with the one or more other devices through a fiber medium.

13. The system of claim 8 wherein the primary device is in communication with the one or more other devices through fiber optic cable.

14. The system of claim 8 wherein the echo message generator is configured to generate a plurality of echo messages and the transmitter is operable to transmit the plurality of echo messages.

15. The system of claim 8 wherein the primary device is in communication with the one or more other devices through copper media.

16. The system of claim 8 further comprising a detector configured to detect an error selected from the group consisting of unidirectional link, bi-directional link, neighbor mismatch, and a loop.

17. The system of claim 8 wherein the device identifiers are encapsulated in a header of the packet.

18. 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:

means for generating an echo message with an originating device identifier located in an originating device field and a primary device identifier located in a primary device field;

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

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.

19. The system of claim 18 wherein the receiver means receives messages from a data link layer and the transmitter transmits messages to the data link layer.

20. The system of claim 18 further comprising a cache table for storing the originating device identifier in the primary device.

21. The system of claim 18 wherein means for transmitting the packet further comprises means for starting a timer and setting a time limit for detecting two-way communication.

22. The system of claim 18 further comprising means for removing the originating device identifier from cache of the primary device after a predetermined period of time.