Method and apparatus for the secure switching of a packet within a communications network

• US 6,289,015 B1
• Filed: 09/17/1998
• Issued: 09/11/2001
• Est. Priority Date: 09/17/1998
• Status: Expired due to Term

• Current Assignee: ARRIS Enterprises LLC (CommScope Holding Company, Inc.)
• Original Assignee: Tut Systems, Inc. (Motorola Solutions, Inc.)
• Inventors: Miller, Mark S., Warner, Thomas E., Corder, Patrick L., Ethier, Steven L.
• Primary Examiner(s): Olms, Douglas
• Assistant Examiner(s): MEHRA, INDER P
• Application Number:
  US09/156,570
• Time in Patent Office: 1,090 Days
• Field of Search: 370/351, 370/389, 370/396, 370/398, 370/400, 370/422, 370/535, 370/537, 370/902, 370/352
• US Class Current: 370/392
• CPC Class Codes: H04L 49/351 for local area network [LAN], e.g. Ethernet switches

Abstract

A switch for switching a packet within a communications network includes a switching core that services a number of ports. The switch also includes address matching logic, coupled to the switching core, that implements an address lookup scheme according to which the switching core may switch to packet received at the switch. Override logic, that is also coupled to the switching core, determines with a packet received at any one of the number of ports serviced by the switching core is received at a predetermined port. This may be done by snooping a bus within the switch that provides an indication of an active port. If the packet was not received at the predetermined port, the override logic override the address matching logic to cause the switching core to route the packet exclusively to the first port.

Claims

1. Switching apparatus for switching a packet within a communications network, the switching apparatus comprising:

a switching core servicing a plurality of ports;

address matching logic, coupled to the switching core, to implement an address look-up scheme according to which the switching core switches a packet; and

override logic, coupled to the switching core, to determine whether a packet, received at any one of the plurality of ports serviced by the switching core, was received at a first port and, if not, to override the address matching logic to cause the switching core to route the packet exclusively to the first port.

2. The switching apparatus of claim 1 wherein the override logic snoops a bus on which an indication of an active port is provided to determine whether the packet was received at the first port.

3. The switching apparatus of claim 1 wherein the override logic receives an indication from the address matching logic as to whether the packet was received at the first port.

4. The switching apparatus of claim 1 wherein the override logic performs an address matching operation in parallel with an address matching operation performed by the address matching logic to determine whether the packet was received at the first port.

5. The switching apparatus of claim 4 wherein the override logic determines whether or not a source address of the packet received corresponds to a network address associated with any one of the plurality of ports serviced by the switching core other than the first port.

6. The switching apparatus of claim 5 wherein the override logic accesses a memory resource storing network address and port association information maintained by the address matching logic.

7. The switching apparatus of claim 1 wherein the address matching logic is external to the switching core.

8. The switching apparatus of claim 7 wherein the address matching logic propagates a port-indicating signal to an external address matching interface of the switching core, and wherein the override logic disables propagation of the port-indicating signal from the address matching logic to the external address matching interface of the switching core.

9. The switching apparatus of claim 8 wherein the override logic propagates an override port-indicating signal to the external address matching interface of the switching core, the override port-indicating signal indicating the first port as an exit port of the switching core from which the packet is to be propagated over the communications network.

10. The switching apparatus of claim 9 wherein the override logic performs a multiplexing operation between the port-indicating signal propagated from the address matching logic and the override port-indicating signal according to whether the packet was received at the first port.

11. Switching apparatus for switching a packet within a communications network, the switching apparatus comprising:

a switching core servicing a plurality of ports; and

switching logic, coupled to the switching core, to determine whether a packet received at any one of the plurality of ports serviced by the switching core was received at a first port and;

if so, to route the packet according to a default switching scheme within the switch; and

if not, to route the packet to the port service by the switch.

12. The switching apparatus of claim 11 wherein the switching logic comprises address matching logic to implement the default switching scheme, and override logic to route the packet to the first port.

13. The switching apparatus of claim 12 wherein the override logic snoops a bus on which an indication of an active port is provided to determine whether the packet was received at the first port.

14. The switching apparatus of claim 12 wherein the override logic receives an indication from the address matching logic as to whether the packet was received at the first port.

15. The switching apparatus of claim 12 wherein the override logic performs an address matching operation in parallel with the default switching scheme performed by the address matching logic to determine whether the packet was received at the first port.

16. The switching apparatus of claim 15 wherein the override logic accesses address look-up information maintained by the address matching logic to determine whether the packet was received at the first port.

17. The switching apparatus of claim 15 wherein the override logic determines whether or not a source address of the packet received corresponds to a network address associated with any one of the plurality of ports of the switching core other than the first port.

18. The switching apparatus of claim 11 wherein the switching logic is external to the switching core, and propagates a port-indicating signal to the switching core indicating one of the plurality of ports of the switching core as being an exit port for the packet.

19. The switching apparatus of claim 18 wherein the switching logic performs a multiplexing operation between a first port-indicating signal generated according to the default switching scheme and a second port-indicating signal designating the first port as the exit port for the packet.

20. The switching apparatus of claim 11 wherein the default switching scheme comprises an external address look-up operation utilizing an address look-up table stored in a memory resource.

21. The switching logic for switching a packet within a communications network, the switching logic comprising:

determination logic to determine whether a packet received at any one of a plurality of ports of a switch was received at a designated upstream port of the switch; and

signal generation logic to output a port-indicating signal to indicate the designated upstream port as an exit port of the switch for the packet if the packet was received on any one of the plurality of ports of the switch other than the upstream port.

22. The switching logic of claim 21 wherein the determination logic snoops a bus on which an indication of an active port is provided to determine whether the packet was received at the designated upstream port.

23. The switching logic of claim 21 wherein the determination logic receives an indication from address matching logic as to whether the packet was received at the designated upstream port.

24. The switching logic of claim 21 wherein the determination logic performs an address matching operation in parallel with address matching logic of the switch to determine whether the packet was received at the designated upstream port or not.

25. The switching logic of claim 24 wherein the determination logic accesses address look-up information maintained by the address matching logic to determine whether the packet was received at the designated upstream port or not.

26. The switching logic of claim 24 wherein the determination logic determines whether or not a source address of the packet corresponds to a network address associated with any one of the plurality of ports of the switch other than the designated upstream port.

27. The switching logic of claim 21 wherein the signal generation logic outputs the port-indicating signal to a switching core of the switch.

28. The switching logic of claim 27 wherein the signal generation logic performs a multiplexing operation between a default port-indicating signal generated by address matching logic and the port-indicating signal outputted by the signal generation logic, the selected output of the multiplexing operation being propagated to the switching core of the switch.

29. Switching apparatus for switching a packet within a communications network, the switching apparatus comprising:

switch core means, servicing a plurality of ports, one of the plurality of ports comprising an upstream port, for switching packets between the plurality of ports; and

determination means, coupled to the switching core, for determining whether a packet received at any one of the plurality of ports of the switching core was received at the upstream port and;

if so, for routing the packet according to a default switching scheme within the switch; and

if not, for routing the packet to the upstream port within the switch.

30. A method of switching a packet through a multi-port switch having a plurality of ports, the method including the steps of:

determining whether a packet is received at a first port of the multi-port switch;

if so, routing the packet according to a default switching scheme within the switch; and

if not, then overriding the default switching scheme to route the packet to the first port for propagation over a communications network.

31. The method of claim 30 wherein the step of determining comprises snooping a bus on which an indication of an active port is provided to determine whether the packet was received at the first port.

32. The method of claim 30 wherein the step of determining comprises generating an indication from the address matching logic as to whether the packet was received at the first port.

33. The method of claim 30 wherein the step of determining comprises determining whether or not a source address of the packet corresponds to a network address associated with any one of the plurality of ports of the switch other than the first port.

34. The method of claim 33 including the step of determining that the packet was not received from the first port if the source address corresponds to a network address associated with any one of the plurality of ports of the switch other than the first port.

35. The method of claim 33 including the step of determining that the packet was received from the first port if the source address does not correspond to a network address associated with any one of the plurality of ports of the switch other than the first port.

36. The method of claim 30 wherein the default switching scheme comprises an address matching scheme.

37. The method of claim 36 wherein the address matching scheme is an external address matching scheme implemented by external address matching logic.

38. The method of claim 37 wherein the step of overriding the default switching scheme includes the step of disabling propagation of a port-indicating signal from the external address matching logic to an external address match interface of a switch fabric.

39. The method of claim 38 wherein the step of overriding includes the step of propagating an alternative port-indicating signal from override logic to the external address matching interface of the switch fabric.

40. The method of claim 39 wherein the step of overriding includes the step of performing a multiplexing operation with respect to the port-indicating signal from the external address matching logic and the alternative port-indicating signal.

41. The method of claim 33 wherein the step of determining whether or not a source address of the packet corresponds to a network address associated with any one of the plurality of ports of the switch other than the first port includes the step of accessing address-lookup information maintained by external address matching logic.

42. A machine-readable medium storing a sequence of instructions that, when executed by a machine, cause the machine to perform the steps of:

determining whether a packet is received at a first port of a switch servicing a plurality of ports;

if so, then switching the packet according to a default switching scheme; and

if not, then overriding the default switching scheme to route the packet to the first port for propagation over a communications network.