Frame-based Transport Services

Description: The Frame-based Transport Services provide the transport of frames or cells between two or more end-points, involving forwarding between frame/cell switches using associated switching protocols. In Frame-based Transport Services switching is performed on a per-frame, per-cell basis. The services’ “unit” is the virtual circuit, consisting of a flow of frames or cells, which share a given attribute coded in the frame or cell header (e.g. an MPLS tag, or stack of MPLS tags, or a Data Link Connection Identifier (DLCI) value in Frame Relay, or a VLAN tag in Carrier Ethernet). Frame-based Transport Services can interface to Transmission Services through various possible Cross-layer Adaptation Functions (CLAF) often by directly transporting frames (or cells) over fibre (e.g. Ethernet over SDH). Frame-based Transport Services can be native or emulated over higher layer protocols (e.g. over IP/MPLS). Frame-based Transport Services service classes (and various support protocols within) are * Native Frame-based Transport – Frame Relay, Asynchronous Transfer Mode (ATM); Multiprotocol Label Switching (MPLS); and Ethernet; or * Emulated Frame-based Transport – L2VPN (over IP, or IP/MPLS); Ethernet over MPLS; Virtual Private LAN Service (VPLS, multipoint to multipoint); and Virtual Private Wire Services (VPWS, point to point).