y, if more than two UNIs are associated they can form a multipoint-to-multipoint EVC, and in this form of EVC it is possible to add or remove UNIs as the service evolves. The behavior of a multipoint-to-multipoint EVC depends on the traffic type, which is deter- mined by the Ethernet address in any individual frame. Ethernet frames with the broadcast address or with multicast addresses that are inserted into the EVC at one UNI are delivered Chapter 14 Next Generation Ethernet Customer Customer Fig. 14.2 Examples of EVCs: (a) point-to-point line service and (b) E-LAN service (multipoint-to- multipoint). to all other UNIs. On the other hand, frames with unicast addresses can be delivered to all other UNIs in the EVC only when the address is unknown, or they can be learned, via MAC learning, and when learned are delivered to the required UNI. The simplest form of service is a dedicated point-to-point Ethernet connection, which is referred to as an E-Line Service by the MEF and as an Ethernet Private Line (EPL) by the ITU-T (MEF 6, 2004a; ITU-T G.8011, 2004a; ITU-T G.8011.1, 2004b). The service is analogous to existing private circuits and to two LANs attached by an EPL: It looks like a wire. An EPL can be subdivided into two classes. In EPL type 1 the information transferred between the UNIs is at the Ethernet MAC frame level. Everything else, such as the preamble and interframe gap, is discarded. The presentation to the EPL is an Ethernet interface, and the Ethernet frames are mapped into the underlying server technology that provides the EPL. For transport over SDH, for example, the MAC frames are mapped into the appropriately sized virtual container via frame-based GFP (GFP-F). In EPL type 2 an 8B/10B-line-coded signal is mapped using transparent GFP (GFP-T) and provides low latency combined with transparency to control-codes. EPL type 2 is only defined for Gigabit Ethernet. In an EPL a resource is reserved for each service instance and is therefore dedicated to a customer. It is also possible to share network re