vSAN uses the network to transport all information, including communication between the cluster nodes and virtual machine I/O operations. The required network transport is accomplished by a specially created VMkernel port group that must be configured on all hosts in the cluster, whether the hosts are contributing storage resources to the cluster or not.

When designing the network, the architect must consider how much replication and communication traffic is running between hosts, because with vSAN, the amount of traffic directly correlates to the number of virtual machines that are running in the cluster, how write-intensive the I/O is for the applications running, and whether an all-flash configuration is being used.

As with other communications, such as vSphere vMotion, isolate vSAN traffic on its own Layer 2 network segment. You can do this with dedicated switches or ports, or by using VLANs, as shown in the following figure.