NSX Controller

The NSX Controller manages the control plane for both Layer 2 and Layer 3 networking within the NSX domain.

For Layer 2, it maintains logical switch tables such as VTEP, MAC, and ARP tables.

For Layer 3, it maintains routing information for Distributed Logical Routers (DLRs).

It ensures that consistent network state information is distributed across all ESXi hosts, enabling proper forwarding and routing behavior.

For each logical switch, the NSX Controller maintains three primary tables:

• VTEP Table: Contains information about VTEPs that have at least one VM connected to that logical switch. (One VTEP table per logical switch.)

• MAC Table: Stores MAC addresses of VMs connected to logical switches, as well as physical devices in the same broadcast domain.

• ARP Table: Maintains IP-to-MAC mappings for VMs and physical systems in the same broadcast domain.

These tables help optimize forwarding decisions and reduce unnecessary broadcast traffic.

For production deployments, three NSX Controllers per standalone NSX Manager are recommended.

Having three controllers ensures:

• High availability

• Proper cluster quorum

• Balanced distribution of control-plane responsibilities

This design provides redundancy and operational stability.

NSX Controllers must have the following connectivity:

• TCP 443 between NSX Controller and NSX Manager

• TCP 443 between all NSX Controllers (controller-to-controller communication)

• Port 1234 between each NSX Controller and the ESXi host VMkernel interfaces

Proper connectivity ensures synchronization of control-plane data and cluster health.

Each NSX Controller requires:

• 4 vCPUs

• 4 GB RAM (with 2 GB reservation)

• 20 GB disk space

• 1 vNIC

• VM hardware version 10

It must be deployed as a virtual appliance in the same vCenter Server associated with the NSX Manager.

After deployment, NSX Controllers automatically form a cluster.

Within the cluster:

• One controller is elected as the API provider.

• One controller is elected as the L2/L3 master.

The Master controller is responsible for distributing Layer 2 and Layer 3 control-plane responsibilities across the cluster members.

This ensures efficient routing, switching coordination, and failover management throughout the NSX domain.