Ethernet VPN

Ethernet VPN (EVPN) is a technology for carrying layer 2 Ethernet traffic as a virtual private network using wide area network protocols. EVPN technologies include Ethernet over MPLS and Ethernet over VXLAN.^[1][2]

EVPN uses encapsulation methods to ensure efficient and scalable transmission of Ethernet traffic over MPLS or IP-based networks. The Ethernet frames are encapsulated within MPLS or VXLAN headers for transport.

MPLS encapsulation

In MPLS-based EVPN, Ethernet frames are encapsulated with:

1. MPLS label stack: Each EVPN instance is associated with a unique label that helps in identifying the destination bridge domain.
2. Control word (optional): Provides additional information for synchronization and alignment in certain scenarios.

The encapsulated packet flow includes:

• Original Ethernet frame
• MPLS labels
• Outer IP header (in case of IP/MPLS networks)

EVPNs are covered by a number of Internet RFCs, including:

• RFC 7209 – Requirements for Ethernet VPN (EVPN),^[3] Informational.
• RFC 7432 – BGP MPLS-Based Ethernet VPN,^[4] Proposed Standard.
• RFC 8317 – Ethernet-Tree (E-Tree) Support in Ethernet VPN (EVPN) and Provider Backbone Bridging EVPN (PBB-EVPN),^[5] Proposed Standard.
• RFC 8365 – A Network Virtualization Overlay Solution Using Ethernet VPN (EVPN),^[6] Proposed Standard.
• RFC 9161 – Operational Aspects of Proxy ARP/ND in Ethernet Virtual Private Networks,^[7] Proposed Standard.