Understand Carrier Ethernet Services.

Carrier Ethernet Services are connectivity services based on Ethernet User Network Interfaces (UNI) and packet formats. Defined by Metro Ethernet Forum (MEF) in a number of recommendations, Carrier Ethernet Services are proposed as an alternative to traditional leased line services as well as layer 3 services (IP/MPLS) services, such as Virtual Private Networks (VPN).

There are three basic Carrier Ethernet Services:

• E-Line - a point-to-point connectivity service
• E-LAN - a multipoint-to-multipoint connectivity service
• E-TREE - a point-to-multipoint connectivity service

Common for all of these services is the use of a stndardized User Network Interface (UNI) based on Ethernet, where service payload data is transported in Ethernet packets. However, the actual transport of these Ethernet packets can be performed over multiple technologies. For currently deployed Carrier Ethernet Services, the predominant transport mechanisms are:

• Ethernet over NG-SONET/SDH
• Ethernet over IP/MPLS using pseudowires and VPLS

In this context, it should be noted that the IETF have defined a Virtual Private Wire Service (VPWS) and Virtual Private LAN Service (VPLS), which are point-to-point and multipoint-to-multipoint connectivity services respectively based on Ethernet over MPLS. Both of these would be considered example implementations of MEF Carrier Ethernet Services.

It should also be noted that ITU-T has defined Carrier Ethernet Services as:

• Ethernet Private Line Service (EPLS)
• Ethernet Virtual Private Line Service (EPLS)
• Ethernet Private LAN Service (EPLAN)
• Ethernet Virtual Private LAN Service (EVPLAN)

The first two definitions correspond to E-Line services, while the last two correspond to E-LAN services. These definitions and associated ITU-T standards are used as a basis for Carrier Ethernet Service certification testing, which is provided by MEF.

For more information on Carrier Ethernet and MEF see:

Metro Ethernet Forum