Loop detection in a communications network

• US 20070230357A1
• Filed: 03/31/2006
• Published: 10/04/2007
• Est. Priority Date: 03/31/2006
• Status: Active Grant

• Current Assignee: Avaya Management L.P. (Avaya Incorporated)
• Original Assignee: Nortel Networks Limited (Nortel Networks Corporation)
• Inventors: Lapuh, Roger, Lin, Chuh
• Granted Patent: US 8,107,382 B2
• Time in Patent Office: Days
• US Class Current: 370/241.100
• CPC Class Codes: H04L 43/50 Testing arrangements

Abstract

A first node includes ports and a controller to receive a test packet at a first one of the ports. The first node determines whether the received test packet has a destination address that matches one or more predefined addresses associated with a second node. Presence of a loop in a communications network in which the first and second nodes are located is indicated in response to detecting receipt of the test packet containing the matching destination address.

Claims

1. A method comprising:

transmitting, from a logical switch made up of at least two switching nodes, a test packet to a communications network;

detecting receipt of the test packet by at least one of the switching nodes in the logical switch; and

indicating presence of a loop in the communications network in response to detecting receipt of the test packet by the at least one switching node.

2. The method of claim 1, wherein transmitting the test packet to the communications network comprises transmitting the test packet to the communications network that has an arrangement of the plural switching nodes in which re-routing around failure points is enabled.

3. The method of claim 1, wherein transmitting the test packet comprises transmitting the test packet having a destination address that specifies the one of the switching nodes in the logical switch as a destination.

4. The method of claim 3, wherein the test packet further has a field indicating that the test packet is for loop detection, the method further comprising setting a value of the field.

5. The method of claim 3, wherein the test packet further has a field indicating an identifier of a virtual local area network, the method further comprising setting a value of the field.

6. The method of claim 1, further comprising determining whether the received test packet has a destination address of the at least one switching node, wherein indicating the presence of the loop is in response to determining that the received test packet has the destination address of the at least one switching node.

7. The method of claim 6, wherein the at least one switching node comprises a first one of the switching nodes in the logical switch, the method further comprising the first switching node detecting receipt of a second test packet having a destination address of a second one of the switching nodes in the logical switch;

and

indicating presence of a loop in response to detecting receipt of the second test packet that has the destination address of the second switching node.

8. The method of claim 1, further comprising effecting an action in response to the indicated presence of the loop.

9. The method of claim 8, wherein effecting the action comprises disabling one or more ports of the switching nodes in the logical switch.

10. The method of claim 1, further comprising storing configuration information relating to a time period at which transmission of test packets is to be repeated.

11. The method of claim 1, further comprising receiving user input from a user interface console to set configurations relating to transmission of test packets and processing of received test packets.

12. A first node comprising:

ports; and

a controller to;

receive a test packet at a first one of the ports;

determine whether the received test packet has a destination address that matches one or more predefined addresses associated with a second node; and

indicate presence of a loop in a communications network in which the first and second nodes are located in response to detecting receipt of the test packet containing the matching destination address.

13. The first node of claim 12, wherein the controller further determines whether the received test packet has a destination address that matches one or more predefined addresses associated with the first node, wherein presence of the loop in the communications network is also indicated in response to detecting receipt of the test packet that has a destination address matching the one or more predefined addresses of the first node.

14. The first node of claim 12, the controller to further send a request to the second node in response to detecting that the received test packet has a destination address that matches the one or more predefined addresses associated with the second node, wherein the request is a request to disable a port of the second node.

15. The first node of claim 12, the controller to write debugging information into a record, the debugging information including at least one of:

information pertaining to the port at which the test packet was received, an identifier of a virtual local area network from which the test packet was received, and an identifier of a sender from which the test packet was received.

16. The first node of claim 12, wherein the first node is a switching node that is part of a split multilink trunk (SMLT) architecture.

17. The first node of claim 12, the controller to disable a group of multilink trunk (MLT) ports in response to the indicated presence of the loop, wherein the first port belongs to the group of MLT ports.

18. The first node of claim 12, further comprising a storage to store a transmit list of virtual local area networks to which test packets are to be sent from the first node,

wherein the controller transmits test packets to virtual area networks indicated by the transmit list.

19. An article comprising at least one storage medium containing instructions that when executed cause a first network node to:

receive a test packet from a communications network; and

a controller to;

determine whether the test packet has a destination address that matches an address of the first network node;

determine whether the destination address in the test packet matches an address of a second network node; and

indicate presence of a loop in the communications network in response to detecting receipt of the test packet containing the destination address that matches either the address of the first network node or the address of the second network node.

20. The article of claim 19, wherein the instructions when executed cause the first network node to send a request to disable a port of the second network node in response to determining that the test packet contains the destination address that matches the address of the second network node, wherein the first and second network nodes comprise first and second switching nodes that form a logical switch.