A network pool is a group of undifferentiated networks that is available for use in an organization VDC to create vApp networks and certain types of organization VDC networks.
A network pool is backed by vSphere network resources, such as VLAN IDs or port groups, by NSX Data Center for vSphere resources, or by NSX-T Data Center resources.
vCloud Director uses network pools to create NAT-routed and internal organization VDC networks and all vApp networks. Network traffic on each network in a pool is isolated at layer 2 from all other networks.
Each organization VDC in vCloud Director can have one network pool. Multiple organization VDCs can share a network pool. The network pool for an organization VDC provides the networks created to satisfy the network quota for an organization VDC.