In an EVPN-VXLAN fabric, the VXLAN Tunnel End Point (VTEP) is the functional entity responsible for data plane operations. Its primary role is to encapsulate Layer 2 Ethernet frames from a source endpoint into VXLAN packets, which are then transported over the Layer 3 IP underlay network. At the receiving end, the destination VTEP de-encapsulates the VXLAN packet to retrieve the original Ethernet frame and forwards it to the destination endpoint. This process allows for the extension of Layer 2 segments over a Layer 3 infrastructure, which is fundamental to the operation of a campus fabric.

A. VLAN: A VLAN is a Layer 2 broadcast domain. Traffic from a VLAN is the payload that gets encapsulated into a VXLAN packet, but the VLAN itself does not perform the encapsulation.

C. EVPN route reflector: This is a control plane component. It uses BGP to distribute EVPN reachability information (MAC and IP addresses) between VTEPs, but it does not handle data plane traffic or perform encapsulation.

D. GBP tag: A Group-Based Policy (GBP) tag is a metadata field carried within the VXLAN header to enable micro-segmentation and policy enforcement. It is part of the encapsulated data, not the component performing the encapsulation.

1. Juniper Networks TechLibrary, EVPN-VXLAN Campus Fabric: Core-Distribution. (2023). In the "Campus Fabric Overview" section, it states, "The access switches act as VXLAN tunnel endpoints (VTEPs) and are responsible for encapsulating and de-encapsulating VXLAN traffic."

2. Juniper Networks TechLibrary, Understanding EVPN with VXLAN Data Plane Encapsulation. (2023). Under the "VXLAN" section, it defines the VTEP: "A VTEP is a device that is capable of VXLAN encapsulation and de-encapsulation. Each VTEP has an IP interface with an IP address on the transport IP network."

3. Juniper Networks Day One+ Guide, Deploying a Campus Fabric with EVPN-VXLAN. (2023). In Chapter 2, "Campus Fabric Architecture," the role of the VTEP is described as the device that "encapsulates Ethernet frames in VXLAN packets and de-encapsulates VXLAN packets to Ethernet frames." The guide also clarifies the role of the route reflector as a control plane element.