Method and system for incorporating non-redundant components in a redundant system in a communications network

1. A method for incorporating a non-redundant component in a redundant system in a communications network, the redundant system having first and second redundant components providing first and second data streams and activity signals, respectively, the activity signals indicating which of the first and second data streams is an active data stream, the first and second data streams being unsynchronized, the method comprising:

determining whether an activity switch has occurred from the activity signals;

responsive to the determining, selecting an input data stream from among the first and second data streams;

filtering the selected input data stream to produce an output data stream by nullifying any incorrect control information inserted into a packet in the input data stream due to the selecting; and,

providing the output data stream to the non-redundant component.

2. The method of claim 1 and further comprising determining whether any incorrect control information has been inserted into the packet.

3. The method of claim 2 wherein the nullifying comprises blocking one or more control indications in packets being transmitted during the activity switch.

4. The method of claim 2 wherein the nullifying comprises, if the incorrect control information pertains to a first start of packet indication followed by a second start of packet indication, inserting an end of packet indication between the first and second start of packet indications.

5. The method of claim 2 wherein the nullifying comprises inserting abort information in the output data stream to instruct the non-redundant component to discard one or more packets.

6. The method of claim 2 wherein the nullifying comprises, if the incorrect control information pertains to a first end of packet indication followed by a second end of packet indication, discarding packets until a start of packet indication is received.

7. The method of claim 1 wherein the redundant system is a router, switch, or gateway.

8. The method of claim 1 wherein the non-redundant component is an input/output device.

9. The method of claim 1 wherein the non-redundant component is a buffer management device, network processor, Ethernet device, physical layer device, framer device, or first-in-first-out (“FIFO”) device.

10. The method of claim 1 wherein the packet is an Internet Protocol (“IP”) packet, a multiprotocol label switching (“MPLS”) packet, an asynchronous transfer mode (“ATM”) packet, or a packet of another cell/packet format.

11. A system for incorporating a non-redundant component in a redundant system in a communications network, the redundant system having first and second redundant components providing first and second data streams and activity signals, respectively, the activity signals indicating which of the first and second data streams is an active data stream, the first and second data streams being unsynchronized, the system comprising:

a processor coupled to the non-redundant component and to the first and second redundant components; and,

a program executed by the processor, the program including:

a module for determining whether an activity switch has occurred from the activity signals;

a module for, responsive to the determining, selecting an input data stream from among the first and second data streams;

a module for filtering the selected input data stream to produce an output data stream by nullifying any incorrect control information inserted into a packet in the input data stream due to the selecting; and,

a module for providing the output data stream to the non-redundant component.

12. The system of claim 11 and further comprising a module for determining whether any incorrect control information has been inserted into the packet.

13. The system of claim 12 wherein the nullifying comprises blocking one or more control indications in packets being transmitted during the activity switch.

14. The system of claim 12 wherein the nullifying comprises, if the incorrect control information pertains to a first start of packet indication followed by a second start of packet indication, inserting an end of packet indication between the first and second start of packet indications.

15. The system of claim 12 wherein the nullifying comprises inserting abort information in the output data stream to instruct the non-redundant component to discard one or more packets.

16. The system of claim 12 wherein the nullifying comprises, if the incorrect control information pertains to a first end of packet indication followed by a second end of packet indication, discarding packets until a start of packet indication is received.

17. The system of claim 11 wherein the redundant system is a router, switch, or gateway.

18. The system of claim 11 wherein the non-redundant component is an input/output device.

19. The system of claim 11 wherein the non-redundant component is a buffer management device, network processor, Ethernet device, physical layer device, framer device, or first-in-first-out (“FIFO”) device.

20. The system of claim 11 wherein the packet is an Internet Protocol (“IP”) packet, a multiprotocol label switching (“MPLS”) packet, an asynchronous transfer mode (“ATM”) packet, or a packet of another cell/packet format.