Multi-homing in an extended bridge

1. A system, comprising:

a controlling bridge device of an extended bridge, the controlling bridge device comprising circuitry configured to:

receive a packet via an ingress port;

determine a destination virtual port link aggregation group according to a destination media access control (MAC) address of an end station identified in the packet;

select one of a plurality of egress virtual ports of the destination virtual port link aggregation group, a destination virtual port of a destination port extender being reachable through any of the plurality of egress virtual ports, the destination port extender reachable through any of a plurality of intermediate port extenders;

determine a source virtual port link aggregation group from the packet;

drop the packet when the source virtual port link aggregation group is the destination virtual port link aggregation group; and

forward the packet, when the source virtual port link aggregation group is not the destination virtual port link aggregation group, through the selected one of the plurality of egress virtual ports, the forwarded packet including an identifier that identifies the destination virtual port.

2. The system of claim 1 , wherein

the packet received via the ingress port includes a source identifier of the source virtual port link aggregation group, and

the source virtual port link aggregation group corresponds to an extended port.

3. The system of claim 1 , wherein

the packet is received from an intermediate port extender via the ingress port, and

the circuitry is further configured to receive another packet from the intermediate port extender via the ingress port, the other received packet including a second identifier that identifies a different source virtual port of a different source port extender.

4. The system of claim 1 , wherein the packet is forwarded to an intermediate port extender, the intermediate port extender being configured to forward the packet to the destination port extender based at least in part on the identifier of the destination virtual port.

5. The system of claim 1 , wherein the packet is forwarded to the destination port extender having the destination virtual port.

6. The system of claim 5 , wherein the end station is connected to the destination port extender and another port extender of the extended bridge.

7. The system of claim 1 , wherein the circuitry is further configured to:

receive a second packet via the ingress port;

determine a second destination virtual port link aggregation group based at least in part on a second destination MAC address of the end station in the second packet;

select a second egress virtual port of the plurality of egress virtual ports of the second destination virtual port link aggregation group; and

forward the second packet through the second egress virtual port, the second forwarded packet including a second identifier that identifies the second egress virtual port.

8. A method, comprising:

receiving, in a controlling bridge device of an extended bridge, a packet via an ingress port;

determining, by circuitry of the controlling bridge device, a destination virtual port link aggregation group according to a destination media access control (MAC) address identified in the packet;

selecting, by the circuitry, one of a plurality of egress virtual ports of the destination virtual port link aggregation group, a destination virtual port of a destination port extender being reachable through any of the plurality of egress virtual ports, the destination port extender reachable through any of a plurality of intermediate port extenders;

determining, by the circuitry, a source virtual port link aggregation group from the packet;

dropping the packet when the source virtual port link aggregation group is the destination virtual port link aggregation group; and

forwarding the packet, when the source virtual port link aggregation group is not the destination virtual port link aggregation group, through the selected one of the plurality of egress virtual ports, the forwarded packet including an identifier that identifies the destination virtual port.

9. The method of claim 8 , wherein the forwarding comprises forwarding the packet to the destination port extender.

10. The method of claim 8 , wherein the forwarding comprises forwarding the packet to an intermediate port extender different from the destination port extender.

11. The method of claim 8 , further comprising embedding, in the controlling bridge device, the identifier in the forwarded packet when the destination MAC address corresponds to a multicast group.

12. The method of claim 8 , further comprising maintaining, in the controlling bridge device, a plurality of loop-free multicast distribution trees in the extended bridge.

13. A method, comprising:

receiving, in a first port extender of an extended bridge, a packet from an end station;

determining, in the first port extender, a destination virtual port link aggregation group according to a destination media access control (MAC) address identified in the packet;

selecting, in the first port extender, one of a plurality of second port extenders, a destination virtual port being reachable through any of second port extenders;

determining, in the first port extender, a source virtual port link aggregation group from the packet;

dropping the packet, in the first port extender, when the source virtual port link aggregation group is the destination virtual port link aggregation group; and

forwarding, in the first port extender when the source virtual port link aggregation group is not the destination virtual port link aggregation group, the packet through the selected one of the plurality of second port extenders, the forwarded packet including an identifier that identifies the destination virtual port.

14. The method of claim 13 , further comprising:

receiving, in the selected one of the plurality of second port extenders, the forwarded packet from the first port extender; and

forwarding, in the selected one of the plurality of second port extenders, the forwarded packet to a controlling bridge device of the extended bridge.

15. The method of claim 13 , further comprising:

receiving, in the selected one of the plurality of second port extenders, the forwarded packet from the first port extender;

receiving, in the selected one of the plurality of second port extenders, another packet from a third port extender; and

forwarding, in the selected one of the plurality of second port extenders, the other packet to a controlling bridge device of the extended bridge.

16. The method of claim 15 , further comprising receiving, in the third port extender, the other packet from the end station.

17. The method of claim 13 , further comprising:

receiving, in the selected one of the plurality of second port extenders, another forwarded packet from a controlling bridge device; and

forwarding, in the selected one of the plurality of second port extenders, the other forwarded packet to the first port extender based at least in part on a destination port identifier included in the other forwarded packet.

18. The system of claim 1 , wherein the forwarded packet further includes a selection identifier that identifies the selected one of the plurality of egress virtual ports.

19. The system of claim 1 , wherein the forward packet further includes a source identifier that identifies the source virtual port link aggregation group.

20. The system of claim 1 , wherein the circuitry is further configured to embed the identifier in the forwarded packet when the destination MAC address corresponds to a multicast group.