SHORTENING OF SERVICE PATHS IN SERVICE CHAINS IN A COMMUNICATIONS NETWORK

• US 20150138973A1
• Filed: 11/15/2013
• Published: 05/21/2015
• Est. Priority Date: 11/15/2013
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Kumar, Surendra M., Bagepalli, Nagaraj A., Devireddy, Dileep K., Patra, Abhijit
• Granted Patent: US 9,300,585 B2
• Time in Patent Office: Days
• US Class Current: 370/235
• CPC Class Codes: H04L 12/56 Packet switching systems
• CPC Class Codes: H04L 43/026 using flow identification
• CPC Class Codes: H04L 45/12 Shortest path evaluation
• CPC Class Codes: H04L 45/306 Route determination based on the nature of the carried application
• CPC Class Codes: H04L 45/38 Flow based routing
• CPC Class Codes: H04L 45/48 Routing tree calculation
• CPC Class Codes: H04L 45/64 using an overlay routing layer
• CPC Class Codes: H04L 47/12 Avoiding congestion; Recovering from congestion
• CPC Class Codes: H04L 47/17 Interaction among intermediate nodes, e.g. hop by hop
• CPC Class Codes: H04L 47/2475 for supporting traffic characterised by the type of applications

Abstract

A method is provided in one example embodiment and includes receiving at a network element a flow offload decision for a first service node comprising a portion of a service chain for processing a flow; recording the flow offload decision against the first service node at the network element; and propagating the flow offload decision backward on a service path to which the flow belongs if the first service node is hosted at the network element. Embodiments may also include propagating the flow offload decision backward on a service path to which the flow belongs if the flow offload decision is a propagated flow offload decision and the network element hosts a second service node that immediately precedes the service node on behalf of which the propagated flow offload decision was received and a flow offload decision has already been received by the network element from the second service node.

Claims

1. A method, comprising:

receiving at a network element a flow offload decision for a first service node comprising a portion of a service chain for processing a flow;

recording the flow offload decision against the first service node at the network element; and

propagating the flow offload decision backward on a service path to which the flow belongs if the first service node is hosted at the network element.

2. The method of claim 1 further comprising propagating the flow offload decision backward on a service path to which the flow belongs if the flow offload decision is a propagated flow offload decision and:

the network element hosts a second service node that immediately precedes the first service node; and

a flow offload decision has already been received by the network element for the second service node.

3. The method of claim 2 further comprising recording the flow offload decision against the first service node at each additional network element to which the flow offload decision is propagated.

4. The method of claim 1, wherein the network element comprises a Virtual Ethernet Module (“

VEM”

) including a distributed virtual switch (“

DVS”

).

5. The method of claim 2 further comprising providing at the network element a service forwarding table associated with the flow, the service forwarding table including an entry corresponding to each service node of the service chain hosted by the network element, wherein each entry indicates a next hop and a previous hop for the corresponding service node of the service chain.

6. The method of claim 5, wherein the propagating comprises propagating the flow offload decision to the previous hop indicated in the service forwarding table entry corresponding to the first service node.

7. The method of claim 5, wherein the recording comprises indicating in the service forwarding table that the first service node has been offloaded for the flow.

8. The method of claim 7 further comprising forwarding a packet of the flow received at the network element to a next hop service node as indicated by the service forwarding table, wherein if a corresponding service table entry indicates that the next hop service node has been offloaded, the packet is forwarded to a first next hop service node in the service chain that has not been offloaded.

9. One or more non-transitory tangible media that includes code for execution and when executed by a processor is operable to perform operations, comprising:

receiving at a network element a flow offload decision for a first service node comprising a portion of a service chain for processing a flow;

recording the flow offload decision against the first service node at the network element; and

propagating the flow offload decision backward on a service path to which the flow belongs if the first service node is hosted at the network element.

10. The media of claim 9 further including code for execution and when executed by a processor is operable to perform operations comprising:

propagating the flow offload decision backward on a service path to which the flow belongs if the flow offload decision is a propagated flow offload decision and;

the network element hosts a second service node that immediately precedes the service node on behalf of which the propagated flow offload decision was received; and

a flow offload decision has already been received by the network element from the second service node.

11. The media of claim 10 further including code for execution and when executed by a processor is operable to perform operations comprising recording the flow offload decision against the first service node at each additional network element to which the flow offload decision is propagated.

12. The media of claim 10 further including code for execution and when executed by a processor is operable to perform operations comprising providing at the network element a service forwarding table associated with the flow, the service forwarding table including an entry corresponding to each service node of the service chain hosted by the network element, wherein each entry indicates a next hop and a previous hop for the corresponding service node of the service chain.

13. The media of claim 12, wherein the propagating comprises propagating the flow offload decision to the previous hop indicated in the service forwarding table entry corresponding to the first service node.

14. The media of claim 12, wherein the recording comprises indicating in the service forwarding table that the first service node has been offloaded for the flow.

15. The media of claim 14 further including code for execution and when executed by a processor is operable to perform operations comprising forwarding a packet of the flow received at the network element to a next hop service node as indicated by the service forwarding table, wherein if a corresponding service table entry indicates that the next hop service node has been offloaded, the packet is forwarded to a first next hop service node in the service chain that has not been offloaded.

16. An apparatus, comprising:

a memory element configured to store data;

a processor operable to execute instructions associated with the data; and

a service path shortening module configured to;

receive at a network element a flow offload decision for a first service node comprising a portion of a service chain for processing a flow;

record the flow offload decision against the first service node at the network element; and

propagate the flow offload decision backward on a service path to which the flow belongs if the first service node is hosted at the network element.

17. The apparatus of claim 16, wherein the service path shortening module is further configured to:

propagate the flow offload decision backward on a service path to which the flow belongs if the flow offload decision is a propagated flow offload decision and;

the network element hosts a second service node that immediately precedes the service node on behalf of which the propagated flow offload decision was received; and

a flow offload decision has already been received by the network element from the second service node.

18. The apparatus of claim 17, wherein the service path shortening module is further configured to provide at the network element a service forwarding table associated with the flow, the service forwarding table including an entry corresponding to each service node of the service chain hosted by the network element, wherein each entry indicates a next hop and a previous hop for the corresponding service node of the service chain.

19. The apparatus of claim 18, wherein the propagating comprises propagating the flow offload decision to the previous hop indicated in the service forwarding table entry corresponding to the first service node and wherein the recording comprises indicating in the service forwarding table that the first service node has been offloaded for the flow.

20. The apparatus of claim 19, wherein the service path shortening module is further configured to forward a packet of the flow received at the network element to a next hop service node as indicated by the service forwarding table, wherein if a corresponding service table entry indicates that the next hop service node has been offloaded, the packet is forwarded to a first next hop service node in the service chain that has not been offloaded.