Spanning-tree based loop detection for an ethernet fabric switch

• US 9,350,564 B2
• Filed: 12/19/2014
• Issued: 05/24/2016
• Est. Priority Date: 06/28/2011
• Status: Expired due to Fees

• 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
• Primary Examiner(s): Lee, Andrew
• Application Number:
  US14/577,785
• Publication Number:
  US 20150117266A1
• Time in Patent Office: 522 Days
• US Class Current: 1/1
• 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 process of;

extracting a first path cost to a root switch of

a spanning tree from a first message received via a local edge port of the one or more ports;

extracting a second path cost to the root switch from a second message from a second switch via an inter-switch port of the one or more ports, wherein the second message is encapsulated in an encapsulation header, and wherein the switch and the second switch participate in the spanning tree using a same source identifier associated with a network of interconnected switches;

assigning a state of the local edge port based on the first and second path costs.

2. The switch of claim 1, wherein the root switch is a second network of interconnected switches, wherein the first and second messages include an the identifier of the root switch, and wherein the identifier of the root switch is a media access control (MAC) address associated with the second network of interconnected switches.

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

and

wherein the method further comprises determining a state of the remote port based on the first and second path costs.

4. The switch of claim 1, wherein the method further comprises assigning a discarding state to the local edge port in response to determining the first and second path costs to be equal and that the local edge port has a lower priority value than a port of the second switch, wherein the second path cost is a path cost via the port 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 state to the local edge port in response to detecting unavailability of a port of the second switch, wherein the port of the second switch has been in a forwarding state and the local edge port has been in a discarding state.

7. The switch of claim 1, wherein the method further comprises generating an agreement message acknowledging the state of the local edge port in response to identifying a synchronization message from the second switch, wherein the synchronization message indicates that edge ports 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 process of;

maintaining a membership in a network of interconnected switches, wherein the network of interconnected switches is associated with a unique identifier, and wherein a respective switch of the network of interconnected switches is associated with the unique identifier;

identifying the network of interconnected switches as a root switch of a spanning tree, wherein a respective switch of the network of interconnected switches participates in the spanning tree using the unique identifier as a source identifier;

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

identifying a respective local edge port 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.

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

11. A method, comprising:

extracting a path cost to a root switch of a spanning tree from a first message received via a local edge port of a switch;

extracting a second path cost to the root switch from a second message from a second switch via an inter-switch port, wherein the second message is encapsulated in an encapsulation header, and, wherein the switch and the second switch participate in the spanning tree using a same source identifier associated with a network of interconnected switches;

assigning a state of the local edge port based on the first and second path costs.

12. The method of claim 11, wherein the root switch is a second network of interconnected switches, wherein the first and second messages include an the identifier of the root switch, and wherein the identifier of the root switch is a media access control (MAC) address associated with the second network of interconnected switches.

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

and

wherein the method further comprises determining a state of the remote interface port based on the first and second path costs.

14. The method of claim 11, further comprising assigning a discarding state to the local edge port in response to determining the first and second path costs to be equal and that the local edge port has a lower priority value than a port of the second switch, wherein the second path cost is a path cost via the port 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 state to the local edge port in response to detecting unavailability of a port of the second switch, wherein the port of the second switch has been in a forwarding state and the local edge port has been in a discarding state.

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

18. A method, comprising:

maintaining a membership of a switch in a network of interconnected switches, wherein the network of interconnected switches is associated with a unique identifier, and wherein a respective switch of the network of interconnected switches is associated with the unique identifier;

identifying the network of interconnected switches as a root switch of a spanning tree, wherein a respective switch of the network of interconnected switches participates in the spanning tree using the unique identifier as a source identifier;

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

identifying a respective local edge port 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.

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