Internal interfaces are regular Layer 2 interfaces configured as access or trunk ports. Trunk configuration is typical given the need to concurrently extend more than one VLAN across the overlay. There is no need to apply OTV-specific configuration to these interfaces. Also, typical Layer 2 functions (like local switching, spanning-tree operation, data plane learning, and flooding) are performed on the internal interfaces. Figure 1-2 shows Layer 2 trunks that are considered internal interfaces which are usually deployed between the edge devices also.