Backward congestion notification

• US 8,804,529 B2
• Filed: 01/24/2012
• Issued: 08/12/2014
• Est. Priority Date: 08/21/2007
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Bergamasco, Davide, Dutt, Dinesh
• Primary Examiner(s): Russell, Wanda Z
• Assistant Examiner(s): Banthrongsack, Jeff
• Application Number:
  US13/357,443
• Publication Number:
  US 20120307638A1
• Time in Patent Office: 931 Days
• Field of Search: 370/236, 370/229, 370/235
• US Class Current: 370/236
• CPC Class Codes: H04L 47/10 Flow control; Congestion control
• CPC Class Codes: H04L 47/11 Identifying congestion
• CPC Class Codes: H04L 47/17 Interaction among intermediate nodes, e.g. hop by hop
• CPC Class Codes: H04L 47/263 Rate modification at the source after receiving feedback
• CPC Class Codes: H04L 47/33 using forward notification

Abstract

In one embodiment, an apparatus comprises a network interface system having at least one input port configured for receiving frames and a logic system comprising at least one logic device. The logic system may be configured to perform the following functions: determining a source address and a destination address of a frame received at an ingress port; calculating a flow hash based at least upon the source address and the destination address; forming a congestion management (“CM”) tag that includes the flow hash; inserting the CM tag in the frame; and forwarding the frame to the destination address.

Claims

1. A method, comprising:

receiving, at an ingress port of a core switch of a first Data Center Ethernet portion of a network, a first frame from an Ethernet portion of the network, the first frame comprising a congestion management (“

CM”

) tag and a first destination address;

determining that the CM tag indicates a first hierarchical media access control (“

MAC”

) address of a device in a second Data Center Ethernet portion of the network;

determining that the first hierarchical MAC address matches a second hierarchical MAC address of the ingress port;

modifying the CM tag to indicate that a second frame should be forwarded to the device in the second Data Center Ethernet portion of the network, wherein the second frame indicates the first hierarchical MAC address as a second destination address for the second frame and wherein the second frame comprises a backwards congestion notification (“

BCN”

) message; and

forwarding the first frame to the first destination address of the first frame.

2. The method of claim 1, wherein the modifying comprises modifying the CM tag to indicate that the second frame indicating the first hierarchical MAC address as the second destination address should not be terminated by the core switch.

3. The method of claim 1, wherein the modifying comprises setting a bit in the CM tag.

4. The method of claim 1, wherein determining that the CM tag indicates the first hierarchical MAC address of the device in the second Data Center Ethernet portion of the network comprises:

determining that the CM tag indicates the first hierarchical MAC address by inspecting an H bit of the CM tag.

5. The method of claim 1, wherein the CM tag comprises congestion point information.

6. The method of claim 1, wherein the CM tag comprises a flow hash.

7. The method of claim 6, wherein the flow hash identifies a flow corresponding to a source address and the first destination address of the first frame.

8. The method of claim 1, wherein the ingress port is not configured to provide backwards congestion notification (“

BCN”

) reaction point functionality.

9. The method of claim 8, wherein modifying comprises:

forming an indication for a second ingress port of the device in the second Data Center Ethernet portion of the network to add a BCN address in the CM tag.

10. An apparatus, comprising:

a network interface system including at least one input port configured for receiving frames; and

a logic system including at least one logic device configured to

receive, at an ingress port of a core switch of a first Data Center Ethernet portion of a network, a first frame from an Ethernet portion of the network, the first frame comprising a congestion management (“

CM”

) tag and a first destination address;

determine that the CM tag indicates a first hierarchical media access control (“

MAC”

) address of a device in a second Data Center Ethernet portion of the network;

determine that the first hierarchical MAC address matches a second hierarchical MAC address of the ingress port;

modify the CM tag to indicate that a second frame should be forwarded to the device in the second Data Center Ethernet portion of the network, wherein the second frame indicates the first hierarchical MAC address as a second destination address for the second frame and wherein the second frame comprises a backwards congestion notification (“

BCN”

) message; and

forward the first frame to the first destination address of the first frame.

11. The apparatus of claim 10, wherein modifying the CM tag comprises modifying the CM tag to indicate that the second indicating the first hierarchical MAC address as the second destination address should not be terminated by the core switch.

12. The apparatus of claim 10, wherein modifying the CM tag comprises setting a bit in the CM tag.

13. The apparatus of claim 10, wherein determining that the CM tag indicates the first hierarchical MAC address of the device in the second Data Center Ethernet portion of the network comprises:

determining that the CM tag indicates the first hierarchical MAC address by inspecting an H bit of the CM tag.

14. The apparatus of claim 10, wherein the CM tag comprises congestion point information.

15. The apparatus of claim 10, wherein the CM tag comprises a flow hash identifying a flow corresponding to a source address and the first destination address of the first frame.

16. The apparatus of claim 10, wherein the ingress port is not configured to provide backwards congestion notification (“

BCN”

) reaction point functionality.

17. The apparatus of claim 10, wherein an egress port of the core switch is configured to provide BCN reaction point functionality, wherein modifying comprises:

forming, by the egress port, an indication for a second ingress port of the device in the second Data Center Ethernet portion of the network to add a BCN address in the CM tag.

18. An apparatus, comprising:

means for receiving, at an ingress port of a core switch of a first Data Center Ethernet portion of a network, a first frame from an Ethernet portion of the network, the first frame comprising a congestion management (“

CM”

) tag and a first destination address;

means for determining that the CM tag indicates a first hierarchical media access control (“

MAC”

) address of a device in a second Data Center Ethernet portion of the network;

means for determining that the first hierarchical MAC address matches a second hierarchical MAC address of the ingress port;

means for modifying the CM tag to indicate that a second frame should be forwarded to the device in the second Data Center Ethernet portion of the network, wherein the second frame indicates the first hierarchical MAC address as a second destination address for the second frame and wherein the second frame comprises a backwards congestion notification (“

BCN”

) message; and

means for forwarding the frame to the first destination address of the first frame.

19. The apparatus of claim 18, wherein determining that the CM tag indicates the first hierarchical MAC address of the device in the second Data Center Ethernet portion of the network comprises:

determining that the CM tag indicates the first hierarchical MAC address by inspecting an H bit of the CM tag.

20. The apparatus of claim 18, wherein the ingress port is not configured to provide backwards congestion notification (“

BCN”

) reaction point functionality.