Hardware switch controller (HSC)


The switch can function as a hardware layer 2 gateway, which enables the switch to extend VXLAN networks to a remote controller (such as VMware NSX-V 6.4.4).

The hardware layer 2 gateway encapsulates/decapsulates VXLAN traffic between the virtual machine and VLANs connected to the switch. It supports up to 4096 VNIs, 2048 hosts per VNI, 32000 hosts on a device, and 10 replicators.

Communication between the remote controller and the hardware layer 2 gateway is managed by the remote controller. It communicates with a software module on the switch called the hardware switch controller (HSC). The HSC runs an open source OVSDB server, and the remote controller connects to it as an OVSDB client. OVSDB is the Open vSwitch Database Management Protocol detailed in RFC 7047.


  • HSC is mutually exclusive with EVPN.

  • Broadcast, Unknown unicast and Multicast (BUM) traffic is not replicated by HSC. Instead, the NSX Controller provides a list of Service Replication Nodes (RSNs) that the HSC will leverage for replication.