Load sharing and redundancy scheme

• US 8,077,604 B1
• Filed: 07/26/2005
• Issued: 12/13/2011
• Est. Priority Date: 06/29/1999
• Status: Active Grant

• Current Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Original Assignee: Cisco Technology, Inc. (Cisco Systems, Inc.)
• Inventors: Kanekar, Bhushan Mangesh, Rajendran, Saravanakumar, Davar, Jonathan
• Primary Examiner(s): Jagannathan, Melanie
• Application Number:
  US11/190,696
• Time in Patent Office: 2,331 Days
• Field of Search: None
• US Class Current: 370/219
• CPC Class Codes: H04L 12/4641 Virtual LANs, VLANs, e.g. virtual private networks [VPN] LAN interconnection over a bridge based backbone H04L12/462; encapsulation techniques H04L12/4633; routing of packets H04L45/00; packet switches H04L49/00; virtual private networks for security H04L63/0272
• CPC Class Codes: H04L 45/02 Topology update or discovery
• CPC Class Codes: H04L 45/58 Association of routers

Abstract

Methods and apparatus for providing a device for forwarding packets in a network are disclosed. A first router and a second router having a shared set of interfaces are provided, enabling the first router and the second router to share forwarding data for forwarding packets on the shared set of interfaces.

Claims

1. A system for forwarding packets received at a set of interfaces, the system comprising:

a first router having a first processor and a first memory associated therewith, wherein the first memory and the first processor are adapted to run a first layer 2 spanning tree protocol only when the first router is operating in active mode and a first layer 3 protocol, the first memory storing a first database; and

a second router having a second processor and a second memory associated therewith, wherein the second memory and the second processor are adapted to run a second layer 2 spanning tree protocol only when the second router is operating in the active mode and a second layer 3 protocol, the second memory storing a second database, wherein the second database is updated with updates received from the first router when the first router is operating in the active mode and the second router is operating in standby mode, wherein the updates include spanning tree updates;

a first forwarding engine coupled to the first router, the first forwarding engine being associated with a first forwarding information for facilitating forwarding of packets in hardware; and

a second forwarding engine coupled to the second router, the second forwarding engine being associated with a second forwarding information for facilitating forwarding of packets in hardware;

wherein the first forwarding engine and the second forwarding engine obtain information from packets at the set of interfaces in order to update the first and second forwarding information;

wherein the first forwarding information and second forwarding information are not transmitted between the first router and the second router;

wherein the first forwarding information includes a first layer 2 table and the second forwarding information includes a second layer 2 table, wherein the first and second layer 2 tables associate one or more MAC addresses with the first router or the second router;

wherein the first forwarding information further includes a first layer 3 table and the second forwarding information further includes a second layer 3 table, wherein the first and second layer 3 tables specify one or more shortcuts specifying layer 3 forwarding information, each one of the one or more shortcuts being associated with a flow associated with a source IP address and destination IP address, each of the first and second layer 2 tables enabling packets to be forwarded by a specified router when an entry specifying a particular flow is not stored in the corresponding one of the first and second layer 3 tables;

wherein when the second router is operating in active mode, the first router is operating in standby mode;

wherein when the first router is operating in active mode, the second router is operating in standby mode;

wherein the first router and the second router share the set of interfaces.

2. The system as recited in claim 1, wherein the updates received from the first router when the first router is operating in the active mode do not include layer 3 protocol updates.

3. The method as recited in claim 1, wherein the first layer 3 protocol is different from the second layer 3 protocol.

4. A method of enabling a slave router to forward packets received at a set of interfaces, comprising:

maintaining a routing table;

receiving updates from a master router running a protocol, the updates including at least one of synchronized state information indicating states of ports associated with the set of interfaces or VLAN membership of the master router; and

updating a database with the updates received from the master router, thereby enabling the slave router to forward packets received at the set of interfaces upon failure of the master router.

5. The method as recited in claim 4, further comprising:

obtaining information from a packet at the shared set of interfaces by

the slave router; and

updating a set of forwarding data maintained by the slave router with the obtained information, the set of forwarding data for facilitating forwarding of packets.

6. The method as recited in claim 5,

wherein the information obtained from the packet at the shared set of interfaces by the slave router includes a shortcut created by the master router, the shortcut specifying layer 3 forwarding information.

7. The method as recited in claim 5, further comprising:

modifying the set of forwarding data maintained by the slave router in response to a failure of the master router.

8. The method as recited in claim 7, further comprising:

forwarding a packet by the slave router;

wherein forwarding the packet by the slave router is performed using a source MAC address of the master router.

9. The method as recited in claim 8, wherein forwarding the packet by the slave router is performed using a source MAC address of the master router when a shortcut associated with the packet and established by the master router has not been invalidated by the slave router, the shortcut specifying layer 3 forwarding information.

10. The method as recited in claim 7, wherein the set of forwarding data includes shortcuts established by the master router and modifying includes invalidating selected shortcuts established by the master router, wherein each of the shortcuts specifies layer 3 forwarding information.

11. The method as recited in claim 10, further comprising:

forwarding a packet by the slave router;

creating a shortcut associated with the slave router, the shortcut specifying layer 3 forwarding information; and

entering the shortcut in the set of forwarding data.

12. The method as recited in claim 11, wherein forwarding the packet by the slave router is performed using a source MAC address of the slave router.

13. The method as recited in claim 12, wherein forwarding the packet by the slave is performed using a source MAC address of the slave router when a shortcut associated with the packet and established by the master router has been invalidated by the slave router, the shortcut specifying layer 3 forwarding information.

14. The method as recited in claim 5, wherein only the master router runs a layer 2 spanning tree protocol, wherein the master router sends spanning tree updates to the slave router.

15. The method as recited in claim 4, further comprising:

configuring a number of ports in a first router and a second router, wherein the number of ports in the first router and the second router is identical;

configuring a type of the ports associated with the first router and the second router, wherein the type of ports associated with the first router is identical to the type of ports of the second router; and

configuring a set of security information associated with both the first router and the second router.

16. The method as recited in claim 5, wherein the packet is not transmitted between the master router and the slave router.

17. A non-transitory computer-readable medium storing thereon computer-readable instructions for enabling a slave router to forward packets received at a set of interfaces, comprising:

instructions for maintaining a routing table;

instructions for receiving updates from a master router running a protocol, the updates including at least one of synchronized state information indicating states of ports associated with the set of interfaces or VLAN membership of the master router; and

instructions for updating a database with the updates received from the master router, thereby enabling the slave router to forward packets received at the set of interfaces upon failure of the master router.

18. An apparatus for enabling a slave router to forward packets received at a set of interfaces, comprising:

a processor; and

a memory, at least one of the processor or the memory being configured for;

maintaining a routing table;

receiving updates from a master router running a protocol, the updates including at least one of synchronized state information indicating states of ports associated with the set of interfaces or VLAN membership of the master router; and

updating a database with the updates received from the master router, thereby enabling the slave router to forward packets received at the set of interfaces upon failure of the master router.

19. The apparatus as recited in claim 18, further comprising:

at least one of the processor or the memory being further configured for;

obtaining information from a packet at the set of interfaces by the slave router; and

updating a set of forwarding data maintained by the slave router with the obtained information, the set of forwarding data for facilitating forwarding of packets.

20. The apparatus as recited in claim 19, wherein the information obtained from the packet at the set of interfaces by the slave router includes a shortcut created by the master router, the shortcut specifying layer 3 forwarding information.

21. The apparatus as recited in claim 19, further comprising:

at least one of the processor or the memory being further configured for;

modifying the set of forwarding data maintained by the slave router in response to a failure of the master router.

22. The apparatus as recited in claim 21, further comprising:

at least one of the processor or the memory being further configured for;

forwarding a packet by the slave router;

wherein forwarding the packet by the slave router is performed using a source MAC address of the master router.

23. The apparatus as recited in claim 22, wherein forwarding the packet by the slave router is performed using a source MAC address of the master router when a shortcut associated with the packet and established by the master router has not been invalidated by the slave router, the shortcut specifying layer 3 forwarding information.

24. The apparatus as recited in claim 21, wherein the set of forwarding data includes shortcuts established by the master router and modifying includes invalidating selected shortcuts established by the master router, wherein each of the shortcuts specifies layer 3 forwarding information.

25. The apparatus as recited in claim 24, further comprising:

at least one of the processor or the memory being further configured for;

forwarding a packet by the slave router;

creating a shortcut associated with the slave router, the shortcut specifying layer 3 forwarding information; and

entering the shortcut in the set of forwarding data.

26. The apparatus as recited in claim 25, wherein forwarding the packet by the slave router is performed using a source MAC address of the slave router.

27. The apparatus as recited in claim 26, wherein forwarding the packet by the slave is performed using a source MAC address of the slave router when a shortcut associated with the packet and established by the master router has been invalidated by the slave router, the shortcut specifying layer 3 forwarding information.