An administrator is responsible for managing a VMware Cloud Foundation (VCF) Private Cloud.

Site A = Data Site; Site B = Witness Site; Site C = Data Site; Site A ↔ Site C = Layer 3, RTT < 5 ms; Site A ↔ Site B = Layer 3, RTT < 200 ms; Site B ↔ Site C = Layer 3, RTT < 200 ms

Site A and Site C should be the data sites because Site A hosts production services and Site C has been commissioned to replace the capacity-constrained Site B. Site B should be used as the witness site because it has no space for additional physical hosts, and a vSAN witness appliance does not run workload VMs. A vSAN Stretched Cluster requires two availability zones for data nodes and a third site for the witness appliance. The data-site-to-data-site connection carries synchronous vSAN data traffic and must meet less than 5 ms RTT. The witness site carries metadata traffic only, so the data-site-to-witness links support higher latency, with less than 200 ms RTT for up to 10 hosts per site. Because the requirement specifically calls out minimizing disruption from STP, Layer 3 is the preferred network type between sites. VMware states that Layer 3 helps avoid STP redirecting traffic across undesirable links, such as constrained witness links. Reference topics: vSAN Stretched Cluster Network Design, Data Site and Witness Site Placement, Layer 3 Recommendation, RTT Requirements.