PDF of this tutorialThe process starts with the service provider defining a set of services and identifying their capabilities. Ethernet can offer support for many services, enabling providers to create an environment for advanced services that best suit their customers' needs.
Metro Ethernet services fall into two major categories-Ethernet connectivity services and Ethernet access-based value-added services. Each of these areas will be described below.
Ethernet Connectivity Services
This category of services provides Ethernet connectivity between two locations or multiple geographically separated locations. Ethernet connectivity services include point-to-point, point-to-multipoint, and multipoint-to-multipoint services.
"Point-to-point" and "point-to-multipoint" services are also called Ethernet Line Services (E-Line) by the Metro Ethernet Forum (MEF). A point-to-point Ethernet Line Service forms an Ethernet connection between two subscriber locations. It is symmetrical, providing the same bandwidth performance for sending or receiving. A point-to-point E-Line service is equivalent to a Frame Relay permanent virtual circuit (PVC) but with a greater range of bandwidth, the ability to provision bandwidth in increments, and more service options. In addition, it is also less expensive and easier to manage than a Frame Relay PVC, because the customer premises equipment (CPE) costs are lower for subscribers, and subscribers do not need to purchase and manage a Frame Relay switch or a WAN router with a Frame Relay interface.
Point-to-multipoint services provide connections between a single location and two or more customer-specified sites. For instance, a headquarters location of an enterprise may have a point-to-multipoint connection to two remote offices. In this case, all traffic between sites, including between the two remote offices flows through the headquarters. This type of service also provides Ethernet access to other Layer 2 services (Frame Relay and ATM) so that the service provider's customers can begin using Ethernet services without replacing their existing systems.
Multipoint-to-multipoint services are also called Ethernet LAN (E-LAN) services by the MEF, and are also often called transparent LAN services (TLSs). E-LAN services provide Ethernet connectivity among geographically separated customer locations, creating a VLAN that spans those locations. Typically, enterprises deploy E-LAN services within a metro area to interconnect multiple enterprise locations. However, these services can be extended to locations worldwide. Used this way, E-LAN services convert wide-area connectivity into a VLAN so that the enterprise customer does not need to own and maintain CPE with wide-area interfaces. E-LAN frees customers from the burden of managing, or even knowing anything about, the WAN connection that links their separate LANs.
E-LAN is much less expensive and simpler to implement on Ethernet than on a Frame Relay or ATM network. The lower cost results primarily from lower equipment costs. Cost savings are a primary reason that E-LAN accounted for more than 63 percent of metro Ethernet revenue in 2002 and is expected to account for 60.3 percent in 2007, according to IDC.
Another advantage of implementing E-LAN on Ethernet is that service providers gain the flexibility to provision more bandwidth, and with varying QoS capabilities and SLAs. Because E-LAN is a low-cost service, the service provider can use it as a draw for bundled services, which increase margins and strengthen the customer relationship. Typical value-added services include Ethernet interface to the Internet, storage transport, and data center connectivity.
Ethernet Access-based Value Added Services
After deploying the infrastructure for Ethernet connectivity services, service providers can generate new revenue streams by offering additional value-added services (Table 1). These services can be accessed using the Ethernet connectivity provided by the E-Line or E-LAN service. Value-added services include:
- Ethernet access to Internet
- Ethernet access to Layer 3 VPN
- Ethernet VPN with Frame Relay/ATM
- Voice
- Video
- Small/midsize business bundles (data, voice, and video)
- Residential broadband
- Storage transport
- Data center access
- Wholesale transport
| Ethernet Connectivity Services | Ethernet Access-based Value-Added Services | |
| Point-to-point (E-Line*) |
|
Access through ERS/EWS
|
| Point-to-multipoint (E-Line*) |
|
Access through ERS
|
| Multipoint-to-multipoint (E-LAN*; TLS) |
|
Access through ERMS/EMS
|
| *MEF terminology | ||
Table 1
Metro Ethernet Services
Ethernet Private-Line Service
Ethernet Private-Line (EPL) service is a dedicated point-to-point connection from one customer-specified location to another, with guaranteed bandwidth and payload transparency end to end. This service is ideal for transparent LAN interconnection and data center integration, for which wire-speed performance and VLAN transparency are important.
Although time-division multiplexing (TDM) and STM-x/OC-y-based facilities have been the traditional means of providing EPL service, EPL can now also support wavelength, Ethernet over SONET/SDH, and dedicated Ethernet platforms interconnected over fiber.
Ethernet Wire Service
Ethernet Wire Service (EWS) is a point-to-point connection between a pair of sites. It is typically provided over a shared switched infrastructure within the service provider network , can be shared between one or more other customers and is typically offered with a wider choice of committed bandwidth levels-up to wire speed. To help ensure privacy, the service provider segregates each subscriber's traffic by applying VLAN tags. This service is also ideal for customers who do not want to pay the expensive cost of a dedicated private line.
EWS is a port-based service. All customer packets are transparently transmitted to the destination port and customer VLAN tags are preserved from the customer equipment through the service provider network. This capability is called all-to-one bundling.
Ethernet Relay Service
Ethernet Relay Service (ERS) enables multiple instances of service to be multiplexed onto a single customer UNI so that the UNI can belong to multiple ERSs. The resulting "multiplexed UNI" supports point-to-multipoint connections between two or more customer-specified sites, similar to Frame Relay service. ERS can also provide Ethernet access to other Layer 2 services (Frame Relay and ATM) so that the service provider's customers can begin using Ethernet services without replacing their existing legacy systems.
ERS is ideal for interconnecting routers in an enterprise network, and for connecting to ISPs and other service providers for dedicated Internet access, VPN services, and other value-added services. Service providers can multiplex connections from many end customers onto a single Ethernet port at the point of presence (POP), for efficiency and ease of management.
Ethernet Multipoint Service
Ethernet Multipoint Service (EMS) shares the same technical access requirements and characteristics. The service provider network acts as a virtual switch for the customer, providing the ability to connect multiple customer sites and allow for any-to-any communication. In many cases, the enabling technology is virtual private label service (VPLS), implemented at the network-provider edge.
Service providers can also implement Layer 3 VPN service, based on IP/MPLS. This service provides excellent scaling capability and enables providers to offer services such as hosted IP telephony, storage hosting, integrated network security, and scalable multicast services.
Ethernet Relay Multipoint Service
Ethernet Relay Multipoint Service (ERMS) is a hybrid of EMS and ERS. It offers the any-to-any connectivity characteristics of EMS, as well as the service multiplexing of ERS. This combination enables a single UNI to support a customer's intranet connection as well as one or more additional EVCs for connection to outside networks, ISPs, or content providers.
