MPLS Layer 2 VPNs

Cisco Jun 15, 2025

Service to allow Layer 2 connectivity between customer sites.

  • VPWS - Virtual Private Wire Service
    • Point-to-point connection
    • Can use L2TPv3 over an IP network
    • Can use MPLS for the transport (AToM)
  • AToM - Any Transport over MPLS
    • subset of VPWS
    • Supports Ethernet, PPP, HDLC, Frame Relay, and ATM.

Advantages to the customer,

  • Identical to traditional WAN services - engineers familiar with this model
  • Can have its own routing and service polices
  • Allows a single infrastructure for both IP and traditional services
  • Optimizes data center solution - same broadcast domain
  • Maintains enterprise autonomy

Advantages for the service provider

  • Migration path to MPLS or IP Core
  • Service continuity
  • Lower cost due to single infrastructure
  • Maintains customer autonomy

MPLS transport uses two labels in the stack

  • Top label (Tunnel Label) is used to transport the packet from the ingress PE to the egress PE
  • Second label (VC Label) is used on the egress PE to identify the egress interface

L2 VPN components

  • AC - Attachment Circuit - circuit between the CE and PE, mapped to the VC for transport
  • PW - Pseudowire - emulates the operation of a virtual wire
  • Underlying transport - MPLS with targeted LDP or IP with L2TPv3

L2 VPN Types

Metro Ethernet Forum (MEF) IETF Cisco
E-Line (P-to-P) Ethernet Private Line (EPL) Ethernet Virtual Private Line (EVPL) Virtual Private Wire Service (VPWS) Ethernet Wire Service (EWS) Ethernet Relay Service (ERS)
E-LAN (Multipoint) Transparent LAN Service (TLS) Ethernet Virtual Connection Service (EVCS) Virtual Private LAN Service (VPLS) Ethernet Multipoint Service (EMS) Ethernet Relay Multipoint Service (ERMS)

Cisco specific names not commonly used anymore.

Flexible Ethernet Mapping

  • Processes and classifies various Ethernet frame types (Ethertype, VLAN tag, CoS)
  • Cisco ASR 9000 used the Ethernet Flow Point (EFP) concept
  • Each Ethernet flow from the access side is mapped or connected to a service on the trunk side.

point-to-point (E-line)

Local connect

  • Two EFPs on the same platform
  • Uses native Ethernet

EoMPLS

  • Two EFPs on different platforms
  • Connected with Pseudowires (PW)

Multipoint differentE-LAN)

Local bridging

  • Two or more EFPs on the same platform
  • Uses native Ethernet in a bridge domain

VPLS bridging

  • Two or more EFPs on different platforms in a bridge domain
  • Connected with a full mesh of Pseudowires (PW)
VPLS
One or more emulated LANs can be created for each customer. * Each emulated LAN looks like a giant Ethernet switch to the customer. * Each emulated LAN is completed separate from others * For each LAN, the PE routers have a full mesh of PW When the PE receives a frame, it
EoMPLS
EoMPLS is the most popular form of VPWS/AToM. Some unneeded headers are removed from the frame in transit. * Preamble and Start of Frame Delimiter (SFD) * Frame Check Sequence (FCS) In Ethernet port mode, all VLAN information is transmitted, but the VLAN tag may be overwritten on the egress PE

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