HCX sites used in site pairing can be vSphere-based or non-vSphere based, which is selected during the site pairing process.
Understanding vSphere-based sites
A vSphere-based site is a vSphere installation where HCX Connector or HCX Cloud has been deployed and activated. For these sites, HCX supports a full range of management and mobility services when paired with other vSphere-based sites.
VMware vSphere-based sites can be either private (on-premises) or public clouds. HCX Connector sites serve as the source of mobility and network extension operations. HCX Cloud sites serve as the target of HCX operations, or as the source and target site in cloud-to-cloud configurations.
For each vSphere site, you must configure a Compute Profile (CP) and Network Profile (NP). The CP and NP define the resources that HCX Connector or HCX Cloud Manager uses to deploy the appliances for management and data plane connectivity, and specifies the networks to use for the management and the mobility operations. The CP and NP information is used for creating the Service Mesh, which is required for each site pair.
In HCX Connector to HCX Cloud site pairs, HCX Connector is deployed at the legacy or source vSphere environment. HCX Connector creates a unidirectional site pairing to an HCX Cloud system. In this type of site pairing, all HCX Service Mesh connections, Migration and Network Extension operations, including reverse migrations, are always initiated from HCX Connector.
In HCX cloud-to-cloud deployments, site pairing can be unidirectional or bidirectional:
In unidirectional site pairing, the HCX Cloud manager containing the virtual machine inventory and networks (similar to HCX Connectors) will site pair to the destination HCX Cloud. In this type of site pairing, all HCX Service Mesh connections, Migration and Network Extension operations, including reverse migrations, are always initiated from the source HCX Cloud system. In this case, an administrator might see the message URL not available when viewing site pairing from the destination site. This is expected behavior because HCX Connector to HCX Cloud site pairing is unidirectional.
In bidirectional site pairing, HCX Cloud systems are site paired with each other, share a common Service Mesh, and can initiate Migration and Network Extension operations from either HCX Cloud system.
In the case of unidirectional site pairing, an administrator may see the message URL not available when viewing site pairing from the destination site. This is expected behavior because HCX Connector to HCX Cloud site pairing is unidirectional. In the case of bidirectional site pairing, the URLs for the paired sites are visible from either the source or destination.
It is still supported to use OSAM with HCX Connector and HCX Cloud Manager. Using OSAM with HCX Connector and Cloud Manager provides the ability to use WAN Optimization if migrations are happening across data centers.
An HCX Connector cannot be the target for a site pairing.
Understanding non-vSphere based sites
Non-vSphere based sites do not run VMware vSphere and HCX is not installed in those environments. Examples of non-vSphere based sites include sites running on non-vSphere hypervisors like KVM and Hyper-V. A typical scenario for pairing non-vSphere based sites is for the purpose of migrating Guest OS workloads to VMware vSphere-based environments using OS Assisted Migration (OSAM).
For non-vSphere based sites, the process of adding a site pair generates a "pseudo site" that appears in the HCX Site Pairs interface along with any vSphere-based sites. Because a non-vSphere site has no installed HCX from which to gather management information, the Site Pairs interface provides only limited information about the psuedo-site, including the site name and type.
