SPANNING-TREE BASED LOOP DETECTION FOR AN ETHERNET FABRIC SWITCH

• US 20150117266A1
• Filed: 12/19/2014
• Published: 04/30/2015
• Est. Priority Date: 06/28/2011
• Status: Active Grant

• Current Assignee: Avago Technologies International Sales Pte Limited (Broadcom, Inc.)
• Original Assignee: Brocade Communications Systems, Inc. (Broadcom, Inc.)
• Inventors: Lei, Tse Yu, Song, Ning, Venkatesh, Vardarajan, Raman, Mythilikanth
• Granted Patent: US 9,350,564 B2
• Time in Patent Office: Days
• US Class Current: 370/256
• CPC Class Codes: H04L 12/462 LAN interconnection over a bridge based backbone
• CPC Class Codes: H04L 45/66 Layer 2 routing, e.g. in Ethernet based MAN's
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches
• CPC Class Codes: H04L 49/354 for supporting virtual local area networks [VLAN]

Abstract

One embodiment of the present invention provides a switch. The switch includes a local database, a packet processor, a data management module, and a tree construction module. The packet processor extracts spanning tree information associated with a remote switch. The data management module stores the extracted spanning tree information in the local database. The tree construction module assigns an interface state associated with a spanning tree to a local interface based on the extracted spanning tree information.

Claims

1. A switch, comprising:

one or more ports;

processing circuitry;

a storage device coupled to the processing circuitry and storing instructions which when executed by the processing circuitry cause the processing circuitry to perform a method, the method comprising;

extracting an identifier of a root of a spanning tree and a first path cost to the root from a first message received via a local edge interface;

extracting the identifier of the root and a second path cost to the root from a second message received from a second switch, wherein the switch and the second switch are members of a first fabric switch, wherein a fabric switch includes a plurality of switches operating as a single switch;

assigning an interface state to the local edge interface based on the first and second path costs.

2. The switch of claim 1, wherein the root is a second fabric switch, and wherein the identifier of the root is a media access control (MAC) address associated with the second fabric switch.

3. The switch of claim 1, wherein the second message comprises an interface identifier of an interface of the second switch, and wherein the interface identifier of the interface includes a switch identifier of the second switch;

and

wherein the method further comprises determining an interface state of the interface of the second switch based on the first and second path costs.

4. The switch of claim 1, wherein the method further comprises assigning a discarding interface state to the local edge interface in response to determining the first and second path costs to be equal and that the local edge interface has a lower priority value than an interface of the second switch, wherein the second path cost corresponds to the interface of the second switch.

5. The switch of claim 1, wherein the method further comprises maintaining a zero-cost logical link between the switch and the second switch, wherein the second path cost includes cost of the logical link.

6. The switch of claim 1, wherein the method further comprises assigning a forwarding interface state to the local edge interface in response to detecting unavailability of an interface of the second switch, wherein the interface of the second switch has been in a forwarding interface state and the local edge interface has been in a discarding interface state.

7. The switch of claim 1, wherein the method further comprises generating an agreement message acknowledging the interface state in response to identifying a synchronization message from the second switch, wherein the synchronization message indicates that local edge interfaces of the second switch has been synchronized for the spanning tree.

8. A switch, comprising:

one or more ports;

processing circuitry;

a storage device coupled to the processing circuitry and storing instructions which when executed by the processing circuitry cause the processing circuitry to perform a method, the method comprising;

maintaining a membership in a fabric switch, wherein the fabric switch is associated with a unique identifier, and wherein a fabric switch includes a plurality of switches operating as a single switch;

identifying the fabric switch as a root of a spanning tree;

generating a notification message associated with the spanning tree, wherein the notification message includes the unique identifier; and

identifying a respective local edge interface as an egress identifier for the notification message.

9. The switch of claim 8, wherein the unique identifier is a media access control (MAC) address associated with a second switch, wherein the second switch is a member switch of the fabric switch.

10. The switch of claim 8, wherein the spanning tree is specific to a virtual local area network (VLAN).

11. A method, comprising:

extracting an identifier of a root of a spanning tree and a first path cost to the root from a first message received via a local edge interface of a switch;

extracting the identifier of the root and a second path cost to the root from a second message received from a second switch, wherein the switch and the second switch are members of a first fabric switch;

assigning an interface state to the local edge interface based on the first and second path costs.

12. The method of claim 11, wherein the root is a second fabric switch, and wherein the identifier of the root is a media access control (MAC) address associated with the second fabric switch.

13. The method of claim 11, wherein the second message comprises an interface identifier of an interface of the second switch, and wherein the interface identifier of the interface includes a switch identifier of the second switch;

and

wherein the method further comprises determining an interface state of the interface of the second switch based on the first and second path costs.

14. The method of claim 11, further comprising assigning a discarding interface state to the local edge interface in response to determining the first and second path costs to be equal and that the local edge interface has a lower priority value than an interface of the second switch, wherein the second path cost corresponds to the interface of the second switch.

15. The method of claim 11, further comprising maintaining a zero-cost logical link between the switch and the second switch, wherein the second path cost includes cost of the logical link.

16. The method of claim 11, further comprising assigning a forwarding interface state to the local edge interface in response to detecting unavailability of an interface of the second switch, wherein the interface of the second switch has been in a forwarding interface state and the local edge interface has been in a discarding interface state.

17. The method of claim 11, further comprising generating an agreement message acknowledging the interface state in response to identifying a synchronization message from the second switch, wherein the synchronization message indicates that local edge interfaces of the second switch has been synchronized for the spanning tree.

18. A method, comprising:

maintaining a membership of a switch in a fabric switch, wherein the fabric switch is associated with a unique identifier;

identifying the fabric switch as a root of a spanning tree;

generating a notification message associated with the spanning tree, wherein the notification message includes the unique identifier; and

identifying a respective local edge interface as an egress identifier for the notification message.

19. The method of claim 18, wherein the unique identifier is a media access control (MAC) address associated with a second switch, wherein the second switch is a member switch of the fabric switch.

20. The method of claim 18, wherein the spanning tree is specific to a virtual local area network (VLAN).