Flexible and scalable virtual network segment pruning

1. A method comprising:

identifying a segment as being supported by a segment bundling device, the segment supporting a first host connected to a first bridging device and a second host connected to a second bridging device within a network;

receiving, using the segment bundling device, virtual network address information describing the virtual network segmentation identifier (ID) for the segment that is used to receive virtual network traffic for the first and second host, wherein the virtual network ID comprises an upper ID and a lower ID;

generating, using the segment bundling device, a segment bundling table associating a bundle ID with the virtual network segmentation identifier based on the upper ID and the lower ID of the virtual network ID; and

distributing, using the segment bundling device, the segment bundling table to traffic forwarding devices in the network that interface with the first bridging device and the second bridging device.

2. The method of claim 1 , wherein receiving virtual network addressing information comprises receiving, within a link state packet, an Interested Bundles Sub-TLV (type-length-value) from the first or second bridging device, the Interested Bundles Sub-TLV listing bundles in which the first or second bridging device is interested.

3. The method of claim 1 , wherein receiving virtual network addressing information comprises receiving, from the first or second bridging device and within a link state packet, a select bit in an Interested Labels Sub-TLV and a list of virtual network segmentation identifiers in which the first or second bridging device is interested.

4. The method of claim 3 , wherein the select bit indicates that the list of virtual network segmentation identifiers should be used to forward network traffic to the first or second bridging device instead of an upper ID.

5. The method of claim 1 , further comprising forwarding, by at least one of the traffic forwarding devices, traffic to the first or second bridging device for the first or second host based on (i) a bundle ID associated with the virtual network segmentation identifier in which the first or second host is interested, (ii) a particular upper ID identifying a subset of virtual network segmentation identifiers that at least one of the first or second host is interested in, or (iii) a particular virtual network segmentation identifier in which the first or second host is interested.

6. The method of claim 1 , wherein generating the segment bundling table comprises generating a segment bundling table checksum,

wherein distributing the segment bundling table comprises distributing the checksum to the traffic forwarding devices in the network so as to verify consistency in the segment bundling table, and

further comprising:

incorporating the checksum into a link state packet;

distributing the link state packet to the traffic forwarding devices; and

verifying, by the traffic forwarding devices, based on the checksum, that the segment bundling table previously received by the traffic forwarding devices is consistent with a traffic forwarding device that sent the link state packet.

7. The method of claim 1 , wherein the virtual network segmentation identifier is encapsulated in a Transparent Interconnect of Lots of Links (TRILL) frame format.

8. The method of claim 1 , wherein the virtual network segmentation identifier is encapsulated in a FabricPath frame format.

9. The method of claim 1 , wherein the virtual network segmentation identifier is encapsulated in a Native Ethernet frame format.

10. An apparatus, comprising:

one or more processors; and

logic encoded in one or more tangible non-transitory machine-readable media for execution on the one or more processors, and when executed operable to:

identify a segment as being supported by a segment bundling device, the segment supporting a first host connected to a first bridging device and a second host connected to a second bridging device within a network;

receive, using the segment bundling device, virtual network address information describing the virtual network segmentation identifier (ID) for the segment that is used to receive virtual network traffic for the first and second host, wherein the virtual network ID comprises an upper ID and a lower ID;

generate, using the segment bundling device, a segment bundling table associating a bundle ID with the virtual network segmentation identifier based on the upper ID and the lower ID of the virtual network ID; and

distribute, using the segment bundling device, the segment bundling table to traffic forwarding devices in the network that interface with the first bridging device and the second bridging device.

11. The apparatus of claim 10 , wherein the logic when executed to receive virtual network addressing information comprises receiving, within a link state packet, an Interested Bundles Sub-TLV from the first or second bridging device, the Interested Bundles Sub-TLV listing bundles in which the first or second bridging device is interested.

12. The apparatus of claim 10 , wherein the logic when executed to receive virtual network addressing information comprises receiving, from the first or second bridging device and within a link state packet, a select bit in an Interested Labels Sub-TLV and a list of virtual network segmentation identifiers in which the first or second bridging device is interested.

13. The apparatus of claim 12 , wherein the select bit indicates that the list of virtual network segmentation identifiers should be used to forward network traffic to the first or second bridging device instead of an upper ID.

14. The apparatus of claim 10 , wherein the logic when executed is further operable to forward, by at least one of the traffic forwarding devices, traffic to the first or second bridging device for the first or second host based on (i) a bundle ID associated with the virtual network segmentation identifiers in which the first or second host is interested, (ii) a particular upper ID identifying a subset of virtual network segmentation identifiers that at least one of the first or second host is interested in, or (iii) a particular virtual network segmentation identifier in which the first or second host is interested.

15. The apparatus of claim 10 , wherein the logic when executed to generate the segment bundling table comprises generating a checksum,

wherein the logic when executed to distribute the segment bundling table comprises distributing the checksum to the traffic forwarding devices in the network so as to verify consistency in the segment bundling table, and

wherein the logic when executed is further operable to:

incorporate the checksum into a link state packet;

distribute the link state packet to the traffic forwarding devices; and

verify, by the traffic forwarding devices, based on the checksum, that the segment bundling table previously received by the traffic forwarding devices is consistent with a traffic forwarding device that sent the link state packet.

16. A non-transitory computer-readable medium comprising instructions to cause a processor to perform operations comprising:

identifying a segment as being supported by a segment bundling device, the segment supporting a first host connected to a first bridging device and a second host connected to a second bridging device within a network;

receiving, using the segment bundling device, virtual network address information describing the virtual network segmentation identifier (ID) for the segment that is used to receive virtual network traffic for the first and second host, wherein the virtual network ID comprises an upper ID and a lower ID;

generating, using the segment bundling device, a segment bundling table associating a bundle ID with the virtual network segmentation identifier based on the upper ID and the lower ID of the virtual network ID; and

distributing, using the segment bundling device, the segment bundling table to traffic forwarding devices in the network that interface with the first bridging device and the second bridging device.

17. The non-transitory computer-readable medium of claim 16 , wherein receiving virtual network addressing information comprises receiving, within a link state packet, an Interested Bundles Sub-TLV from the first or second bridging device, the Interested Bundles Sub-TLV listing bundles in which the first or second bridging device is interested.

18. The non-transitory computer-readable medium of claim 16 , wherein receiving virtual network addressing information comprises receiving, from the first or second bridging device and within a link state packet, a select bit in an Interested Labels Sub-TLV and a list of virtual network segmentation identifiers in which the first or second bridging device is interested.

19. The non-transitory computer-readable medium of claim 16 , wherein the select bit indicates that the list of virtual network segmentation identifiers should be used to forward network traffic to the first or second bridging device instead of an upper ID.

20. The non-transitory computer-readable medium of claim 16 , further comprising forwarding, by at least one of the traffic forwarding devices, traffic to the first or second bridging device for the first or second host based on (i) a bundle ID associated with the virtual network segmentation identifiers in which the first or second host is interested, (ii) a particular upper ID identifying a subset of virtual network segmentation identifiers that at least one of the first or second host is interested in, or (iii) a particular virtual network segmentation identifier in which the first or second host is interested.

21. The non-transitory computer-readable medium of claim 16 , wherein generating the segment bundling table comprises generating a segment bundling table checksum,

wherein distributing the segment bundling table comprises distributing the checksum to the traffic forwarding devices in the network so as to verify consistency in the segment bundling table, and

further comprising:

incorporating the checksum into a link state packet;

distributing the link state packet to the traffic forwarding devices; and

verifying, by the traffic forwarding devices, based on the checksum, that the segment bundling table previously received by the traffic forwarding devices is consistent with a traffic forwarding device that sent the link state packet.