Redundant control architecture for a network device

• US 20020097672A1
• Filed: 11/05/2001
• Published: 07/25/2002
• Est. Priority Date: 01/25/2001
• Status: Active Grant

• Current Assignee: Ericsson AB (Telefonaktiebolaget LM Ericsson)
• Original Assignee: Crescent Networks, Inc.
• Inventors: Schwalbe, James C., Barbas, Steve N.
• Granted Patent: US 7,010,715 B2
• Time in Patent Office: Days
• US Class Current: 370/216
• CPC Class Codes: G06F 11/2005 using redundant communication controllers
• CPC Class Codes: G06F 11/2007 using redundant communication media
• CPC Class Codes: G06F 11/2028 eliminating a faulty processor or activating a spare
• CPC Class Codes: G06F 11/2038 with a single idle spare processing component

Abstract

A redundant control plane for a network device such as a network switch or a router. The control plane is isolated from a data plane for the network device that carries network traffic. The redundant control plane includes first and second Router Control Processor (RCP)/Bridge Hotswap Card (BHC) pairs, and first and second switch cards (SCs). A first RCP/BHC pair is selected as the master and the second pair becomes the master in the event of a failure or the need to perform maintenance on the first pair. Redundant control paths are provided from each RCP/BHC pair to first and second pluralities of line cards to allow for downloading of forwarding tables, control and configuration information. Redundant Switch cards are provided and one of the Switch Cards is selected as the master Switch card to permit communication between the RCPs. The control plane may continue to function in the event of a single failure of any component or bus within the control plane.

Claims

1. A network device having a redundant control plane comprising:

a switch fabric;

first and second data paths associated with and coupled to said switch fabric, a plurality of line cards having input and output ports for receiving data from and transmitting data over corresponding communication links, wherein said line cards are each communicably coupled to said switch fabric via said first and second data paths;

said line cards, said first and second data paths and said switch fabric forming a data plane for forwarding data units received at an input port of a first line card to an output port of a second line card via said switch fabric over the associated data path;

first and second control processors, wherein one of said first and second control processors comprises an active control processor and the other one of said first and second control processors comprises a standby control processor during normal operation of said network device; and

first and second control paths associated with and communicably coupling the first and second control processors, respectively, to said plurality of line cards, said first and second control paths being isolated from said first and second data paths;

said active control processor being operative to selectively transmit control information to said plurality of line cards over the corresponding control path and out of band with respect to said data plane.

2. The network device of claim 1 wherein said first and second line cards comprise the same line card.

3. The network device of claim 1 further including:

first and second bridge logic;

first and second primary control plane buses operative in accordance with a predetermined bus protocol, said first primary control plane bus communicably coupling said first control processor to said first bridge logic, said second primary control plane bus communicably coupling said second control processor to said second bridge logic; and

first and second secondary control plane buses operative in accordance with said predetermined bus protocol, said first secondary control plane bus communicably coupling said first bridge logic to said plurality of line cards, and said second secondary control plane bus communicably coupling said second bridge logic to said plurality of line cards,

wherein said first control path includes said first primary control plane bus, said first bridge logic, and said first secondary control plane bus, and said second control path includes said second primary control plane bus, said second bridge logic, and said second secondary control plane bus.

4. The network device of claim 3 wherein said predetermined protocol generally comprises the compact PCI bus protocol.

5. The network device of claim 3 wherein said first and second bridge logic each include a first bridge device, said first bridge device within said first bridge logic communicably coupling said first primary control plane bus to said first secondary control plane bus, and said first bridge device within said second bridge logic communicably coupling said second primary control plane bus to said second secondary control plane bus.

6. The network device of claim 4 wherein said first and second primary control buses and said first and second secondary control plane buses are generally compatible with the compact PCI bus protocol, and said first bridge devices comprise PCI-to-PCI bus bridges.

7. The network device of claim 1 further including:

first interface logic communicably coupling said first and second control processors,

at least said standby control processor being operative to obtain configuration information from the active control processor via said first interface logic.

8. The network device of claim 1 wherein said line card control information includes at least one forwarding table.

9. The network device of claim 1 wherein said line card control information includes line card configuration information.

10. The network device of claim 1 wherein said line card control information includes at least one software image for execution on at least one line card.

11. The network device of claim 1

wherein said plurality of line cards includes first and second sets of line cards, and wherein each set of line cards includes at least one line card;

wherein said first and second control paths are communicably coupling said first set of line cards to said first and second control processors respectively; and

said network device further includes third and fourth control paths communicably coupling said second set of line cards to said first and second control processors respectively, said third and fourth control paths being isolated from said data plane.

12. The network device of claim 11 further including

first and second bridge logic;

first and second primary control plane buses operative in accordance with a predetermined bus protocol, said first primary control plane bus communicably coupling said first control processor to said first bridge logic, said second primary control plane bus communicably coupling said second control processor to said second bridge logic; and

first, second, third, and fourth secondary control plane buses operative in accordance with said predetermined bus protocol, said first secondary control plane bus communicably coupling said first bridge logic to said first set of line cards, said second secondary control plane bus communicably coupling said second bridge logic to said first set of line cards, said third secondary control plane bus communicably coupling said first bridge logic to said second set of line cards, and said fourth secondary control plane bus communicably coupling said second bridge logic to said second set of line cards,

wherein said first control path includes said first primary control plane bus, said first bridge logic, and said first secondary control plane bus, and said second control path includes said second primary control plane bus, said second bridge logic, and said second secondary control plane bus,

wherein said third control path includes said first primary control plane bus, said first bridge logic, and said third secondary control plane bus, and said fourth control path includes said second primary control plane bus, said second bridge logic, and said fourth secondary control plane bus.

13. The network device of claim 12 wherein said predetermined protocol comprises the compact PCI bus protocol.

14. The network device of claim 12 wherein said first and second bridge logic each include first and second bridge devices, said first bridge device within said first bridge logic communicably coupling said first primary control plane bus to said first secondary control plane bus, said second bridge device within said first bridge logic communicably coupling said first primary control plane bus to said third secondary control plane bus, said first bridge device within said second bridge logic communicably coupling said second primary control plane bus to said second secondary control plane bus, and said second bridge device within said second bridge logic communicably coupling said second primary control plane bus to said fourth secondary control plane bus.

15. The network device of claim 14 wherein transmissions by said first control processor traverse said first and third control paths and wherein transmission by said second control processor traverse said second and fourth control paths.

16. The network device of claim 1 further including:

first and second interface logic each communicably coupling said first and second control processors to permit inter-control processor communication;

interface selection logic for selecting one of said first and second interface logic as an active interface logic for inter-control processor communication and for selecting the other one of said first and second interface logic as the standby interface logic; and

wherein at least said standby control processor is operative to obtain configuration information from the active control processor via said selected one of said first and second interface logic.