Virtual gateways and implicit routing in distributed overlay virtual environments

1. A method comprising:

encapsulating, by a first virtual switch, a packet from a first virtual machine (VM) into a tunneled packet by appending the packet with a tunnel header that is addressed for a second virtual switch, wherein the packet includes a first destination address for a virtual default gateway; and

forwarding, by the first virtual switch, an inner packet of the encapsulated packet to a second VM,

wherein the first virtual switch acts as a virtual default gateway based on replacement of a first destination address for the virtual default gateway with a second destination address for the second VM, the first VM and the second VM are part of a distributed overlay virtual Ethernet (DOVE) network, and a plurality of virtual gateways in the DOVE network share a same MAC address.

2. The method of claim 1 , wherein the first destination address comprises a media access control (MAC) address for the virtual default gateway.

3. The method of claim 2 , further comprising:

receiving, by the first virtual switch, the packet;

obtaining, by the first virtual switch, a second destination address for the second VM based on information in the packet; and

replacing, by the first virtual switch, the first destination address for the virtual default gateway in the packet with the second destination address for the second VM.

4. The method of claim 3 , wherein all virtual gateways in the DOVE network share the same MAC address, and use of the same MAC address reduces amount of configuration and facilitates VM detection and troubleshooting.

5. The method of claim 4 , wherein all destinations in the DOVE network appear as one routing hop away irrespective of how many underlay routing hops a tunneled packet traverses.

6. The method of claim 5 , wherein an address resolution protocol (ARP) table of VMs has a static configuration for a gateway Internet Protocol ARP.

7. The method of claim 6 , wherein the tunnel header of the encapsulated packet comprises an Ethernet header, a user datagram protocol (UDP) header, and a DOVE header.

8. A computer program product comprising a non-transitory computer readable storage medium having program code embodied therewith, the program code being executable by a first switch to implement a method comprising:

encapsulating, by the first virtual switch, a packet from a first virtual machine (VM) into a tunneled packet by appending the packet with a tunnel header that is addressed for a second virtual switch, wherein the packet includes a first destination address for a virtual default gateway; and

forwarding, by the first virtual switch, an inner packet of the encapsulated packet to a second VM,

wherein the first virtual switch acts as a virtual default gateway based on replacement of a first destination address for the virtual default gateway with a second destination address for the second VM, the first VM and the second VM are part of a distributed overlay virtual Ethernet (DOVE) network, and a plurality of virtual gateways in the DOVE network share a same MAC address.

9. The computer program product of claim 8 , wherein the first destination address comprises a media access control (MAC) address for the virtual default gateway.

10. The computer program product of claim 9 , wherein the method further comprising:

receiving, by the first virtual switch, the packet;

obtaining, by the first virtual switch, a second destination address for the second VM based on information in the packet; and

replacing, by the first virtual switch, the first destination address for the virtual default gateway in the packet with the second destination address for the second VM.

11. The computer program product of claim 10 , wherein all virtual gateways in the DOVE network share the same MAC address, and use of the same MAC address reduces amount of configuration and facilitates VM detection and troubleshooting.

12. The computer program product of claim 11 , wherein all destinations in the DOVE network appear as one routing hop away irrespective of how many underlay routing hops a tunneled packet traverses.

13. The computer program product of claim 12 , wherein an address resolution protocol (ARP) table of VMs has a static configuration for a gateway Internet Protocol ARP.

14. The computer program product of claim 13 , wherein the tunnel header of the encapsulated packet comprises an Ethernet header, a user datagram protocol (UDP) header, and a DOVE header.

15. A method comprising:

encapsulating, by a source virtual switch, a packet from a source virtual machine (VM) by appending the packet with a tunnel header that is addressed for a destination virtual switch, wherein the packet is an inner packet of the encapsulated packet; and

forwarding, by the source virtual switch, the inner packet of the encapsulated packet to a destination VM,

wherein the source virtual switch acts as a virtual default gateway based on replacement of a media access control (MAC) address for the virtual default gateway with a MAC address for the destination VM, the source VM and the destination VM are part of a distributed overlay virtual Ethernet (DOVE) network, and a plurality of virtual gateways in the DOVE network share a same MAC address.

16. The method of claim 15 , further comprising:

receiving, by the source virtual switch, the packet including the MAC address for the default virtual gateway;

obtaining, by the source virtual switch, the MAC address for the destination VM based on an internet protocol (IP) address in the packet; and

replacing, by the source virtual switch, the MAC address for the virtual default gateway in the packet with the MAC address for the destination VM,

wherein the source VM and the destination VM appear as part of different subnets from one another in the DOVE network.

17. The method of claim 16 , wherein all virtual gateways in the DOVE network share the same MAC address, and use of the same MAC address reduces amount of configuration and facilitates VM detection and troubleshooting.

18. The method of claim 17 , wherein all destinations in the DOVE network appear as one routing hop away irrespective of how many underlay routing hops a tunneled packet traverses.

19. The method of claim 18 , wherein an address resolution protocol (ARP) table of VMs has a static configuration for a gateway Internet Protocol ARP.

20. The method of claim 19 , wherein the tunnel header of the encapsulated packet comprises an Ethernet header, a user datagram protocol (UDP) header, and a DOVE header.