You can create an L2 bridge between a logical switch and a VLAN, which enables you to migrate virtual workloads to physical devices with no impact on IP addresses.
A Layer 2 bridge enables connectivity between the virtual and physical network by enabling virtual machines (VMs) to be connected to a physical server or network. Use cases include:
Physical to virtual, or virtual to virtual migration. L2 bridging allows you to maintain connectivity between workloads inside NSX and outside NSX, without requiring IP re-addressing.
Insertion into NSX of an appliance that cannot be virtualized, and that require L2 connectivity with its clients. This is common for some physical database servers.
Service insertion. An L2 Bridge allows integrating transparently into NSX any physical appliance such as a router, load balancer or firewall
A logical network can leverage a physical L3 gateway and access existing physical networks and security resources by bridging the logical switch broadcast domain to the VLAN broadcast domain. The L2 bridge runs on the host that has the NSX DLR control virtual machine. An L2 bridge instance maps to a single VLAN, but there can be multiple bridge instances. The VLAN port group and VXLAN logical switch that is bridged must be on the same vSphere distributed switch (VDS) and both must share same physical NICs.
VXLAN (VNI) network and VLAN-backed port groups must be on the same distributed virtual switch (VDS).
Note that you should not use an L2 bridge to connect a logical switch to another logical switch, a VLAN network to another VLAN network, or to interconnect datacenters. Also, you cannot use a universal logical router to configure bridging and you cannot add a bridge to a universal logical switch.