Using a midlay in a software defined networking (SDN) fabric for adjustable segmentation and slicing

1. A method comprising:

configuring, by a device, a plurality of subinterfaces for each of a plurality of physical ports of a software defined network (SDN);

allocating, by the device, a fixed amount of bandwidth to each of the subinterfaces to construct a plurality of midlays for the SDN;

forming, by the device, the plurality of midlays by assigning subsets of the plurality of subinterfaces to each of the midlays, wherein the plurality of midlays operate as an intermediate layer between a physical layer of the SDN and an overlay layer of the SDN to implement network slicing; and

assigning, by the device, a network slice to one or more of the midlays, based on a bandwidth requirement of the network slice.

2. The method as in claim 1 , wherein a particular one of the plurality of midlays comprises one or more Fat Trees between one or more leaves of the SDN and a spine of the SDN.

3. The method as in claim 1 , further comprising:

allocating, by the device, more bandwidth to the slice by assigning at least one additional subinterface to the one or more midlays to which the network slice is assigned.

4. The method as in claim 1 , wherein the one or more of midlays to which the network slice is assigned span multiple physical pods of the SDN.

5. The method as in claim 1 , wherein the device uses Flexible Ethernet (FlexE) or Time Sensitive Networking (TSN) commands to allocate the fixed amount of bandwidth to each of the subinterfaces.

6. The method as in claim 1 , wherein forming the plurality of midlays for the SDN by assigning subsets of the plurality of subinterfaces to each of the midlays comprises:

using virtual routing and forwarding (VRF) to establish routes in the SDN for the midlays.

7. The method as in claim 1 further comprising:

indicating the midlays in a forwarding plane of the SDN using Multiprotocol Label Switching (MPLS) or virtual local area network (VLAN) tagging.

8. An apparatus, comprising:

one or more network interfaces to communicate with a software defined networking (SDN) fabric;

a processor coupled to the network interfaces and configured to execute one or more processes; and

a memory configured to store a process executable by the processor, the process when executed configured to:

configure a plurality of subinterfaces for each of a plurality of physical ports of a software defined network (SDN);

allocate a fixed amount of bandwidth to each of the subinterfaces to construct a plurality of midlays for the SDN;

form the plurality of midlays by assigning subsets of the plurality of subinterfaces to each of the midlays, wherein the plurality of midlays operate as an intermediate layer between a physical layer of the SDN and an overlay layer of the SDN to implement network slicing; and

assign a network slice to one or more of the midlays, based on a bandwidth requirement of the network slice.

9. The apparatus as in claim 8 , wherein a particular one of the plurality of midlays comprises one or more Fat Trees between one or more leaves of the SDN and a spine of the SDN.

10. The apparatus as in claim 8 , wherein the process when executed is further configured to:

allocate more bandwidth to the slice by assigning at least one additional subinterface to the one or more midlays to which the network slice is assigned.

11. The apparatus as in claim 8 , wherein the one or more of midlays to which the network slice is assigned span multiple physical pods of the SDN.

12. The apparatus as in claim 8 , wherein the apparatus uses Flexible Ethernet (FlexE) or Time Sensitive Networking (TSN) commands to allocate the fixed amount of bandwidth to each of the subinterfaces.

13. The apparatus as in claim 8 , wherein the apparatus forms the plurality of midlays for the SDN by assigning subsets of the plurality of subinterfaces to each of the midlays by:

using virtual routing and forwarding (VRF) to establish routes in the SDN for the midlays.

14. The apparatus as in claim 8 , wherein the process when executed is further configured to:

indicating the midlays in a forwarding plane of the SDN using Multiprotocol Label Switching (MPLS) or virtual local area network (VLAN) tagging.

15. A tangible, non-transitory, computer-readable medium storing program instructions that cause a device to execute a process comprising:

configuring, by the device, a plurality of subinterfaces for each of a plurality of physical ports of a software defined network (SDN);

allocating, by the device, a fixed amount of bandwidth to each of the subinterfaces to construct a plurality of midlays for the SDN;

forming, by the device, the plurality of midlays by assigning subsets of the plurality of subinterfaces to each of the midlays, wherein the plurality of midlays operate as an intermediate layer between a physical layer of the SDN and an overlay layer of the SDN to implement network slicing; and

assigning, by the device, a network slice to one or more of the midlays, based on a bandwidth requirement of the network slice.

16. The computer-readable medium as in claim 15 , wherein a particular one of the plurality of midlays comprises one or more Fat Trees between one or more leaves of the SDN and a spine of the SDN.

17. The computer-readable medium as in claim 15 , wherein the process further comprises:

allocating, by the device, more bandwidth to the slice by assigning at least one additional subinterface to the one or more midlays to which the network slice is assigned.

18. The method as in claim 1 , wherein the one or more of midlays to which the network slice is assigned span multiple physical pods of the SDN.