When you create a VI workload domain or add a host or vSphere cluster to an existing workload domain (management or VI), you do not need to enter IP addresses manually. Network pools automatically assign static IP addresses to vSAN, NFS, iSCSI, and vMotion VMkernel ports.

A network pool is a collection of subnets within an layer-2 network domain. Depending on the storage option, it includes information about subnets reserved for the vMotion and vSAN, NFS, or iSCSI networks that are required for adding a host to the SDDC Manager inventory.
Table 1. Information Required for a Network Pool
Storage Being Used Required Networks in Network Pool
vSAN vMotion and vSAN
vSAN Max vMotion and vSAN
NFS vMotion and NFS
vSAN and NFS vMotion, vSAN, and NFS
VMFS on FC vMotion only or vMotion and NFS
vVols on FC vMotion only or vMotion and NFS
vVols on iSCSI vMotion and iSCSI
vVols on NFS vMotion and NFS

The network pool also contains a range of IP addresses, called an inclusion range. IP addresses from the inclusion ranges are assigned to the VMkernel ports on the host. The use of inclusion ranges allows you to limit the IP addresses that are consumed from a given subnet. You can add more inclusion ranges to expand the use of the provided subnet.

A default network pool is created during bring-up. This network pool is automatically associated with the management domain. Network information for this network pool is based on the deployment parameter workbook you provided during bring-up. This network pool contains vMotion and vSAN networks only - an NFS network is not supported in this network pool. If the vSAN and vMotion networks in your management domain are in the same layer-2 network domain, you can expand the default network pool. You can also expand the default network pool if you expand the management domain by adding a host.

To create a VI workload domain with hosts in a different layer-2 network domain than the management domain, you must create a new network pool. Also, if you want to use external NFS or VMFS on FC storage, you must create a new network pool. A network pool can contain both vSAN and NFS networks.

You can also create a workload domain with multiple vSphere clusters, each with its own network pool. You can have multiple vSphere clusters within a workload domain to provide a separate fail over domain (a VM only fails over between hosts in a cluster). Multiple vSphere clusters also provide isolation for security reasons and are also useful for grouping servers of a particular type of configuration together. Multiple vSphere clusters can also be used to handle the growth. The original servers used in the default vSphere cluster can get outdated at some point. Newer server models can then be added to a new cluster in the workload domain and workloads can be migrated at a leisurely pace.