Scalable multi-tenant underlay network supporting multi-tenant overlay network

1. A method comprising:

configuring, by an underlay network controller for a virtualized computing infrastructure, a plurality of Virtual Extensible Local Area Network (VXLAN) segments in a switch fabric, the switch fabric comprising network switches for the virtualized computing infrastructure, thereby enabling orchestration of respective tenants in the plurality of VXLAN segments,

wherein each VXLAN segment of the plurality of VXLAN segments provides underlay network connectivity among a different subset of host computing devices of the virtualized computing infrastructure, and

wherein a plurality of overlay networks are configured in a first subset of the host computing devices having underlay network connectivity by operation of a first VXLAN segment of the plurality of VXLAN segments, thereby enabling orchestration of multiple subtenants of a first tenant in the first subset of the host computing devices; and

provisioning, by the underlay network controller and for the first VXLAN segment, a Source Network Address Translation (SNAT) gateway between a VXLAN Tunnel Endpoint (VTEP) of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment.

2. The method of claim 1 , wherein provisioning, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment comprises:

provisioning, in a virtual router of the first subset of the host computing devices, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment.

3. The method of claim 1 , wherein provisioning, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment comprises:

configuring the SNAT gateway to perform address translation of network traffic exchanged between the VTEP of the first VXLAN and a virtual router of the first subset of the host computing devices.

4. The method of claim 3 , wherein configuring the SNAT gateway to perform address translation of network traffic comprises:

configuring, via Border Gateway Protocol (BGP), the SNAT gateway to perform address translation of network traffic exchanged between the VTEP of the first VXLAN and the virtual router of the first subset of the host computing devices; and

configuring, via Extensible Messaging and Presence Protocol (XMPP), the virtual router of the first subset of the host computing devices to exchange network traffic with a virtual machine of an overlay network of the plurality of overlay networks of the first VXLAN segment.

5. The method of claim 1 , wherein provisioning, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment comprises:

configuring the SNAT gateway to advertise at least one subnet address for the first VXLAN segment into an overlay network of the plurality of overlay networks of the first VXLAN segment.

6. The method of claim 1 , further comprising:

assigning, by the underlay network controller and to each VXLAN segment of the plurality of VXLAN segments, a different tenant of the tenants; and

controlling, by the underlay network controller, forwarding of network traffic for each tenant to the VXLAN segment of the plurality of VXLAN segments to which the tenant is assigned.

7. The method of claim 1 , further comprising:

assigning, by the underlay network controller and to the first subset of the host computing devices having underlay network connectivity by operation of the first VXLAN segment, a plurality of floating IP (FIP) addresses; and

assigning, by the underlay network controller and to a first overlay network of the plurality of overlay networks of the first VXLAN segment, a subset of the plurality of FIP addresses,

wherein each FIP address of the subset of the plurality of FIP addresses is assigned to a virtual router of a plurality of virtual routers of the first overlay network.

8. The method of claim 7 , wherein the plurality of FIP addresses comprises a first plurality of FIP addresses, the method further comprising:

assigning, to a second subset of the host computing devices having underlay network connectivity by operation of a second VXLAN segment of the plurality of VXLAN segments, a second plurality of FIP addresses that are different from the first plurality of FIP addresses.

9. The method of claim 7 , wherein the plurality of FIP addresses comprises a first plurality of FIP addresses, the method further comprising:

assigning, to a second subset of the host computing devices having underlay network connectivity by operation of a second VXLAN segment of the plurality of VXLAN segments, a second plurality of FIP addresses that is the same as the first plurality of FIP addresses.

10. An underlay network controller for a virtualized computing infrastructure, the underlay network controller executed by processing circuitry and configured to:

configure a plurality of Virtual Extensible Local Area Network (VXLAN) segments in a switch fabric, the switch fabric comprising network switches for the virtualized computing infrastructure, thereby enabling orchestration of respective tenants in the plurality of VXLAN segments,

wherein each VXLAN segment of the plurality of VXLAN segments provides underlay network connectivity among a different subset of host computing devices of the virtualized computing infrastructure, and

wherein a plurality of overlay networks are configured in a first subset of the host computing devices having underlay network connectivity by operation of a first VXLAN segment of the plurality of VXLAN segments, thereby enabling orchestration of multiple subtenants of a first tenant in the first subset of the host computing devices; and

provision, for the first VXLAN segment, a Source Network Address Translation (SNAT) gateway between a VXLAN Tunnel Endpoint (VTEP) of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment.

11. The underlay network controller of claim 10 , wherein to provision, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment, the underlay network controller is configured to:

provision, in a virtual router of the first subset of the host computing devices, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment.

12. The underlay network controller of claim 10 , wherein to provision, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment, the underlay network controller is configured to:

configure the SNAT gateway to perform address translation of network traffic exchanged between the VTEP of the first VXLAN and a virtual router of the first subset of the host computing devices.

13. The underlay network controller of claim 12 , wherein to configure the SNAT gateway to perform address translation of network traffic, the underlay network controller is configured to:

configure, via Border Gateway Protocol (BGP), the SNAT gateway to perform address translation of network traffic exchanged between the VTEP of the first VXLAN and the virtual router of the first subset of the host computing devices; and

configure, via Extensible Messaging and Presence Protocol (XMPP), the virtual router of the first subset of the host computing devices to exchange network traffic with a virtual machine of an overlay network of the plurality of overlay networks of the first VXLAN segment.

14. The underlay network controller of claim 10 , wherein to provision, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment, the underlay network controller is configured to:

configure the SNAT gateway to advertise at least one subnet address for the first VXLAN segment into an overlay network of the plurality of overlay networks of the first VXLAN segment.

15. The underlay network controller of claim 10 , further configured to:

assign, to each VXLAN segment of the plurality of VXLAN segments, a different tenant of the tenants; and

control forwarding of network traffic for each tenant to the VXLAN segment of the plurality of VXLAN segments to which the tenant is assigned.

16. The underlay network controller of claim 10 , further configured to:

assign, to the first subset of the host computing devices having underlay network connectivity by operation of the first VXLAN segment, a plurality of floating IP (FIP) addresses; and

assign, to a first overlay network of the plurality of overlay networks of the first VXLAN segment, a subset of the plurality of FIP addresses,

wherein each FIP address of the subset of the plurality of FIP addresses is assigned to a virtual router of a plurality of virtual routers of the first overlay network.

17. The underlay network controller of claim 16 ,

wherein the plurality of FIP addresses comprises a first plurality of FIP addresses, and

wherein the underlay network controller is further configured to assign, to a second subset of the host computing devices having underlay network connectivity by operation of a second VXLAN segment of the plurality of VXLAN segments, a second plurality of FIP addresses that are different from the first plurality of FIP addresses.

18. The underlay network controller of claim 16 ,

wherein the plurality of FIP addresses comprises a first plurality of FIP addresses, and

wherein the underlay network controller is further configured to assign, to a second subset of the host computing devices having underlay network connectivity by operation of a second VXLAN segment of the plurality of VXLAN segments, a second plurality of FIP addresses that is the same as the first plurality of FIP addresses.

19. A non-transitory, computer-readable medium comprising instructions that, when executed, are configured to cause processing circuitry to execute an underlay network controller for a virtualized computing infrastructure, the underlay network controller configured to:

configure a plurality of Virtual Extensible Local Area Network (VXLAN) segments in a switch fabric, the switch fabric comprising network switches for the virtualized computing infrastructure, thereby enabling orchestration of respective tenants in the plurality of VXLAN segments,

wherein each VXLAN segment of the plurality of VXLAN segments provides underlay network connectivity among a different subset of host computing devices of the virtualized computing infrastructure, and

wherein a plurality of overlay networks are configured in a first subset of the host computing devices having underlay network connectivity by operation of a first VXLAN segment of the plurality of VXLAN segments, thereby enabling orchestration of multiple subtenants of a first tenant in the first subset of the host computing devices; and

provision, for the first VXLAN segment, a Source Network Address Translation (SNAT) gateway between a VXLAN Tunnel Endpoint (VTEP) of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment.

20. The computer-readable medium of claim 19 , wherein to provision, for the first VXLAN segment, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment, the underlay network controller is configured to:

provision, in a virtual router of the first subset of the host computing devices, the SNAT gateway between the VTEP of the first VXLAN segment and the plurality of overlay networks of the first VXLAN segment.