EVPn

EVPN, or Ethernet VPN, is a family of networking technologies that provide scalable Layer 2 and Layer 3 VPN services over an IP/MPLS or IP network. It uses a control plane based on multiprotocol BGP (MP-BGP) to distribute reachability information about Ethernet segments, MAC addresses, and IP prefixes among provider edge devices, enabling bridged domains and routed networks to be extended across data centers and wide-area networks.

Key concepts in EVPN include Ethernet Segments, which represent multi-homed attachments, and Ethernet Segment Identifiers (ESIs) used to support active-active multi-homing. EVPN uses MP-BGP to advertise MAC addresses and IP reachability, as well as IP prefixes and multicast information, allowing data plane learning to be performed in the control plane. This reduces unknown traffic floods and improves convergence in large networks. EVPN can operate over MPLS, where labels carry L2/L3 traffic, or over VXLAN overlays, where the EVPN control plane populates MAC and IP reachability for VXLAN tunnels.

In practice, EVPN provides L2 connectivity across distributed data centers and WANs and also supports L3 VPN services. It enables scalable MAC learning, fast failover for multi-homed devices, and efficient multicast replication through dedicated EVPN multicast mechanisms. Typical deployments include data center interconnects, campus networks needing L2 extension, and cloud/Data Center Interconnect scenarios that use VXLAN or MPLS as the data plane.

Standards and adoption originate from IETF work on EVPN, beginning with RFCs that define the EVPN control plane and its use with MP-BGP. Over time, extensions have added IPv4/IPv6 prefix advertisement and multicast capabilities, making EVPN a widely deployed solution for scalable L2/L3 VPNs.