Overlay tunnel in a fabric switch

1. A switch, comprising:

a tunnel management module configurable to:

operate the switch as a tunnel gateway capable of terminating an overlay tunnel;

learn a MAC address of a virtual machine via a tunnel initiated by a first hypervisor associated with the virtual machine; and

construct a message for a second hypervisor comprising an Internet Protocol (IP) address of the first hypervisor in response to receiving a data frame with unknown destination from a virtual machine associated with the second hypervisor; and

a packet processor configurable to identify in a data packet a virtual IP address associated with a virtual tunnel gateway, wherein the virtual tunnel gateway is associated with the switch; and

a forwarding module configurable to determine an output port for an inner packet in the data packet based on a destination address of the inner packet.

2. The switch of claim 1 , wherein the tunnel management module is further configurable to identify a hypervisor controlling a virtual machine, wherein the virtual machine initiates the overlay tunnel by encapsulating the inner packet using the virtual IP address.

3. The switch of claim 1 , wherein the packet processor is further configurable to identify in the data packet a virtual media access control (MAC) address corresponding to the virtual IP address.

4. The switch of claim 1 , further comprising a device management module configurable to generate a configuration message comprising the virtual IP address as a tunnel gateway address in response to detecting a hypervisor.

5. The switch of claim 4 , wherein the virtual IP address in the configuration message corresponds to a default gateway router.

6. The switch of claim 1 , wherein the virtual IP address is further associated with a remote switch, wherein the remote switch operates as a tunnel gateway and is associated with the virtual tunnel gateway.

7. The switch of claim 1 ,

wherein the packet processor is further configurable to:

encapsulate the data packet in an encapsulation packet; and

including a virtual switch identifier as an ingress switch identifier of the encapsulation packet; and

wherein the switch identifier is associated with the switch.

8. The switch of claim 1 , further comprising a switch management module configurable to maintain a membership in a network of interconnected switches.

9. The switch of claim 8 , wherein the packet processor is further configurable to identify the inner packet to be a broadcast, unknown unicast, or multicast packet; and

wherein the tunnel management module is further configurable to select a multicast tree in the network to distribute the inner packet based on one or more of: multicast group membership, virtual local area network (VLAN) membership, and network load.

10. The switch of claim 8 , wherein the virtual tunnel gateway appears as a member switch of the network.

11. The switch of claim 1 , wherein the packet processor is further configurable to construct an Address Resolution Protocol (ARP) response message comprising a virtual MAC address associated with the switch in response to an ARP query message for the virtual IP address.

12. A computer-executable method, comprising:

operating a switch as a tunnel gateway capable of terminating an overlay tunnel;

learning a MAC address of a virtual machine via a tunnel initiated by a first hypervisor associated with the virtual machine;

constructing a message for a second hypervisor comprising an Internet Protocol (IP) address of the first hypervisor in response to receiving a data frame with unknown destination from a virtual machine associated with the second hypervisor; and

identifying in a data packet a virtual IP address associated with a virtual tunnel gateway, wherein the virtual tunnel gateway is associated with the switch; and

determining an output port for an inner packet in the data packet based on a destination address of the inner packet.

13. The method of claim 12 , further comprising identifying a hypervisor controlling a virtual machine, wherein the virtual machine initiates the overlay tunnel by encapsulating the inner packet using the virtual IP address.

14. The method of claim 12 , further comprising identifying in the data packet a virtual media access control (MAC) address corresponding to the virtual IP address.

15. The method of claim 12 , further comprising generating a configuration message comprising the virtual IP address as a tunnel gateway address in response to detecting a hypervisor.

16. The method of claim 15 , wherein the virtual IP address in the configuration message corresponds to a default gateway router.

17. The method of claim 12 , wherein the virtual IP address is further associated with a remote switch, wherein the remote switch operates as a tunnel gateway and is associated with the virtual tunnel gateway.

18. The method of claim 12 , further comprising:

encapsulating the data packet in an encapsulation packet; and

identifying a virtual switch identifier as an ingress switch identifier of the encapsulation packet; and

wherein the virtual switch identifier is associated with the switch.

19. The method of claim 12 , further comprising maintaining a membership in a network of interconnected switches.

20. The method of claim 19 , further comprising:

identifying the inner packet to be a broadcast, unknown unicast, or multicast packet; and

selecting a multicast tree in the network to distribute the inner packet based on one or more of: multicast group membership, virtual local area network (VLAN) membership, and network load.

21. The method of claim 19 , wherein the virtual tunnel gateway appears as a member switch of the network.

22. The method of claim 12 , further comprising constructing an Address Resolution Protocol (ARP) response message comprising a virtual MAC address associated with the switch in response to an ARP query message for the virtual IP address.