Dynamic forwarding plane reconfiguration in a network device

• US 9,049,148 B1
• Filed: 09/28/2012
• Issued: 06/02/2015
• Est. Priority Date: 09/28/2012
• Status: Active Grant

• Current Assignee: Juniper Networks Incorporated
• Original Assignee: Juniper Networks Incorporated
• Inventors: Singh, Ravi
• Primary Examiner(s): Thier, Michael
• Assistant Examiner(s): Wang, Yaotang
• Application Number:
  US13/631,738
• Time in Patent Office: 977 Days
• Field of Search: 370/401
• US Class Current: 1/1
• CPC Class Codes: H04L 45/50 using label swapping, e.g. multi-protocol label switch [MPLS]
• CPC Class Codes: H04L 45/54 Organization of routing tables

Abstract

A network router dynamically reconfigures representations of forwarding structures used within a forwarding unit of the router. The forwarding structures comprise a plurality of forwarding next hops associated with the routes and stored in a first representation within the forwarding unit. The router further comprises a control unit having a processor to install the forwarding structures within the forwarding unit. In response to input directing the router to change from a first operating mode to a second operating mode, the control unit installs, within the forwarding unit, one or more new forwarding next hops that are associated with none of the routes by the forwarding structures and are stored in a second representation within the forwarding unit that is different from the first representation and, after installing the new forwarding next hop, updates the forwarding structures to associate at least one of the routes to the new forwarding next hop.

Claims

1. A method comprising:

installing, within a forwarding unit of a router, forwarding structures for forwarding packets in accordance with routing information for a set of routes through a network, wherein the forwarding structures comprise a plurality of forwarding next hops associated with the routes, and wherein the forwarding next hops are stored in a first representation within the forwarding unit;

while forwarding the packets with the forwarding unit in accordance with the forwarding structures, installing, within the forwarding unit, one or more new forwarding next hops that are not associated with any routes by the forwarding structures and are stored within the forwarding unit in a second representation that is different from the first representation, the second representation comprising composite next hops; and

after installing the new forwarding next hops within the forwarding unit, updating the forwarding structures to associate at least one of the routes of the set of routes to the new forwarding next hops;

wherein the forwarding next hops and the new forwarding next hops specify operations to be performed on the packets by the forwarding unit,

wherein, for the at least one of the routes, the forwarding next hops in the first representation and the new forwarding next hops in the second representation specify the same operations to be performed on the packets, and

wherein, for at least one of the routes, the operations for the composite next hops are arranged in a memory of the forwarding unit as shared by multiple ones of the composite next hops such that some operations in the first representation are linked differently in the memory of the forwarding unit than the same operations in the second representation.

2. The method of claim 1, wherein installing forwarding structures comprises installing the forward data structures to comprise forwarding next hops in the first representation as flat next hops within the memory of the forwarding unit, wherein each of the flat next hops store operations to be performed on the packets by the forwarding unit and none of the operations are shared by multiple ones of the flat next hops within the memory of the forwarding unit.

3. The method of claim 1, wherein installing forwarding structures comprises installing the forward data structures to comprise forwarding next hops in the first representation as composite next hops within the memory of the forwarding unit, wherein the composite next hops store operations to be performed on the packets by the forwarding unit and the operations are arranged within the memory of the forwarding unit as shared by multiple ones of the composite next hops.

4. The method of claim 1, further comprising, after updating the forwarding structures to associate the at least one route with the new forwarding next hops, directing the forwarding unit to discard one of the forwarding next hops previously associated with the at least one of the routes.

5. The method of claim 1, further comprising:

outputting a message from a routing engine to the forwarding unit to direct the forwarding unit to install the one or more new forwarding next hops in the second representation;

in response to the message, installing the one or more forwarding next hops in the second representation by executing operations within the forwarding unit to create the one or more new forwarding next hops within an internal memory of the forwarding unit in accordance with the second representation;

outputting an acknowledgement message from the forwarding unit to the routing engine upon creating the one or more new forwarding next hops within the internal memory of the forwarding unit; and

outputting a message from the routing engine to direct the forwarding unit to update the forwarding structures to associate at least one of the routes to the new forwarding next hops only upon receiving the acknowledgment from the forwarding unit that the new forwarding next hops have been created in the internal memory of the forwarding unit.

6. The method of claim 1, further comprising:

receiving an input directing the router to change from a first operating mode in which the forwarding structures in the forwarding unit are stored in the first representation to a second operating mode in which the forwarding structures in the forwarding unit are stored in the second representation; and

in response to the input to change from the first operating mode to the second operating mode, installing the one or more new forwarding next hops in the forwarding unit and updating the forwarding structures to associate at least one of the routes to the new forwarding next hops while continuing to forward packets with the forwarding unit.

7. The method of claim 6, further comprising:

repeatedly and concurrently, installing a plurality of new forwarding next hops in the forwarding unit and updating different portions of the forwarding structures to associate routes for the different portions of the forwarding structures to the new forwarding next hops until all of the forwarding structures in the forwarding unit are stored in the second representation while continuing to forward packets with the forwarding unit.

8. A router comprising:

a forwarding unit to forward packets in accordance with forwarding structures programmed into a memory in accordance with routing information for routes through a network, wherein the forwarding structures comprise a plurality of forwarding next hops associated with the routes and stored in a first representation within the forwarding unit;

a control unit having a processor to install the forwarding structures within the forwarding unit, wherein, in response to input directing the router to change from a first operating mode to a second operating mode, the control unit installs, within the forwarding unit, one or more new forwarding next hops that are associated with no routes by the forwarding structures and are stored in a second representation within the forwarding unit that is different from the first representation, the second representation comprising composite next hops, and, after installing the new forwarding next hops, updates the forwarding structures to associate at least one of the routes to the new forwarding next hops;

wherein the forwarding next hops and the new forwarding next hops specify operations to be performed on the packets by the forwarding unit,

wherein, for the at least one of the routes, the forwarding next hops in the first representation and the new forwarding next hops in the second representation specify the same operations to be performed on the packets, and

wherein, for at least one of the routes, the operations for the composite next hops are arranged in the memory of the forwarding unit as shared by multiple ones of the composite next hops such that some operations in the first representation are linked differently in the memory of the forwarding unit than the same operations in the second representation.

9. The router of claim 8, wherein forwarding next hops in the first representation are stored within the memory of the forwarding unit as flat next hops, wherein each of the flat next hops store operations to be performed on the packets by the forwarding unit and none of the operations are shared by multiple ones of the flat next hops within the memory of the forwarding unit.

10. The router of claim 8, wherein forwarding next hops in the first representation are stored within the memory of the forwarding unit as composite next hops, wherein the composite next hops store operations to be performed on the packets by the forwarding unit and the operations are arranged within the memory of the forwarding unit as shared by the composite next hops.

11. The router of claim 8, wherein the control unit is configured to, after updating the forwarding structures to associate the at least one route with the new forwarding next hop, direct the forwarding unit to discard one of the forwarding next hops previously associated with the at least one of the routes.

12. The router of claim 8,

wherein the forwarding unit outputs an acknowledgement message from the forwarding unit to the routing engine upon creating the one or more new forwarding next hops within the memory, and

wherein the routing engine outputs a message to direct the forwarding unit to update the forwarding structures to associate at least one of the routes to the new forwarding next hops only upon receiving the acknowledgment from the forwarding unit that the new forwarding next hops have been created in the internal memory of the forwarding unit.

13. The router of claim 8, wherein the input comprises an event triggers that triggers an automatic change from the first operating mode to the second operating mode.

14. A non-transitory computer-readable storage medium comprising instructions that, when executed by a processor, cause the processor to:

install, within a forwarding unit of a router, forwarding structures for forwarding packets in accordance with a routing information for routes through a network, wherein the forwarding structures comprises a plurality of forwarding next hops associated with the routes that specify operations to be performed on the packets by the forwarding unit, and wherein the operations of the forwarding next hops are stored in a first representation within the forwarding unit;

install, within the forwarding unit, one or more new forwarding next hops that are not associated with any routes by the forwarding structures, wherein operations specified by the new forwarding next hops to be performed on the packets are stored in a second representation within the forwarding unit that is different from the first representation, the second representation comprising composite next hops; and

after installing the new forwarding next hop within the forwarding unit, update the forwarding structures to associate at least one of the routes to the new forwarding next hops;

wherein, for the at least one of the routes, the forwarding next hops in the first representation and the new forwarding next hops in the second representation specify the same operations to be performed on the packets, and

wherein, for at least one of the routes, the operations for the composite next hops are arranged in a memory of the forwarding unit as shared by multiple ones of the composite next hops such that some operations in the first representation are linked differently in the memory of the forwarding unit than the same operations in the second representation.

15. The non-transitory computer-readable storage medium of claim 14, wherein the operations include label swapping operations to be performed by the forwarding unit on the packets.

16. The non-transitory computer-readable storage medium of claim 14, wherein the operations are instructions executable by the forwarding unit.