Explanation
VMware HCX Network Extension is a layer-two bridging function initiated at the source site1. It allows customers to extend their on-premises networks to a VMware Cloud SDDC without changing the IP addresses of the virtual machines2. When extending a network, a corresponding NSX segment is created at the destination site1. The network segment type that HCX Network Extension creates in the VMware Cloud SDDC is Extended2. This means that the network is stretched across both sites and the routing is handled at the source site2. The Extended network segment type preserves the network identity and connectivity of the virtual machines that are migrated or created on the extended segment at the remote site2. References: 1:
Extending Networks Using VMware HCX, 2: About VMware HCX Network Extension