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Cisco IP Solution Center L2VPN and Carrier Ethernet User Guide, 6.0
Appendix E ISC Layer 2 VPN Concepts
L2VPN Service Provisioning
L2VPN Service Provisioning
This section provides and overview of ISC provisioning for L2VPN services that provide Layer 2
point-to-point connectivity over an MPLS core. Cisco’s Any Transport over MPLS (AToM) enables
supports these services. These implementations, in turn, support service types, as follows:
Ethernet Wire Service (EWS). The MEF term for this service is EPL.
Ethernet Relay Service (ERS). The MEF term for this service is EVPL.
ATM over MPLS (ATMoMPLS)
Frame Relay over MPLS (FRoMPLS)
Instructions on creating policies and service requests for these services are provided in other chapters of
the guide. For more information, see the following sections:
• Point-to-Point Ethernet (EWS and ERS) (EPL and EVPL), page E-5
• ATM over MPLS (ATMoMPLS), page E-8
• Frame Relay over MPLS (FRoMPLS), page E-9
Point-to-Point Ethernet (EWS and ERS) (EPL and EVPL)
The EWS and ERS services (also known as EPL and EVPL, respectively, in MEF terminology) are
delivered with the Cisco Metro Ethernet offering. The same network architecture can simultaneously
provide both ERS (EPL) and EWS (EVPL) connections to diverse customers. Additionally, this Metro
Ethernet infrastructure can be used for access to higher-level services, such as IP-based virtual private
networking, public internet communications, Voice over IP, or a combination of all applications.
Ethernet Wire Service (EWS or EPL)
An Ethernet Virtual Circuit (EVC) connects two physical User-to-Network Interfaces (UNI) such that
the connection appears like a virtual private line to the customer. VLAN transparency and control
protocol tunnelling are supplied by the implementation of 802.1Q-in-Q tag-stacking technology. Packets
received on one UNI are transported directly to the other corresponding UNI.
The MEF term for this service is EPL.
Ethernet Relay Service (ERS or EVPL)
An Ethernet Virtual Circuit (EVC) is used to logically connect endpoints, but multiple EVCs could exist
per single UNI. Each EVC is distinguished by 802.1q VLAN tag identification. The ERS network acts
as if the Ethernet frames have crossed a switched network, and certain control traffic is not carried
between ends of the EVC. ERS is analogous to Frame Relay where the CE-VLAN tag plays the role of
a Data-Link Connection Identifier (DLCI).
The MEF term for this service is EVPL.
Topology for L2VPN Ethernet Over MPLS (ERS and EWS) (EPL and (EVPL)
Ethernet Over MPLS (EoMPLS) is a tunnelling mechanism that allows the service provider to tunnel
customer Layer 2 traffic though a Layer 3 MPLS network. It is important to remember that EoMPLS is
a point-to-point solution only.
The following figures provide a reference for how EoMPLS is utilized. Ethernet Services can be
distributed to the end customer in two ways.