The physical network of a VSA cluster consists of Gigabit Ethernet switches and network interface cards (NICs) that are installed on each host.

All hosts in the VSA cluster must have two dual-port or four single-port network interface cards. You can use a single Gigabit Ethernet switch for the VSA cluster network. To ensure network redundancy, you should use two Gigabit Ethernet switches.

The following illustrations depict network redundancy in a VSA cluster with 2 and 3 members.

Network Redundancy in a VSA Cluster with 2 Members
physical network of a 2-member cluster
Network Redundancy in a VSA Cluster with 3 Members
physical network of a 3-member cluster

In a VSA cluster, the network traffic is divided into front-end and back-end traffic.

Front-end network traffic

Communication between each VSA cluster member and the VSA Manager

Communication between ESXi and the VSA volumes

Communication between each VSA member cluster and the VSA cluster service

vMotion traffic between the hosts

Back-end network traffic

Replication between a volume and its replica that resides on another host

Clustering communication between all VSA cluster members

Each vSphere Storage Appliance has two virtual NICs: one handles the front-end traffic, and the other handles back-end traffic. The back-end virtual NIC has an IP address from a private subnet. The front-end virtual NIC can have up to 3 assigned IP addresses.

IP address for VSA management network

IP address of the exported NFS volume

IP address of the VSA cluster (assigned only when the VSA cluster member is elected as the cluster leader)

The IP address of the VSA cluster can move between VSA cluster members. It is assigned to the front-end virtual NIC of a VSA cluster member only when that VSA cluster member is elected as the cluster leader. If the cluster leader becomes unavailable, the VSA cluster IP address is assigned to another VSA cluster member that becomes the leader.

The VSA cluster installation creates two vSphere standard switches on each ESXi host to isolate front-end and back-end traffic. The physical NICs act as an uplink for each vSphere standard switch so that each NIC handles either front-end or back-end traffic. The standard switches use ESXi NIC teaming to provide link failover.

The following illustration depicts the logical network of a VSA cluster member that is the leader in the VSA cluster. The logical network of other VSA cluster members is the same with the exception of the assigned VSA cluster IP address.

Logical Network Architecture of a VSA Cluster Member
logical network architecture