m Business Frame relay networks MPLS NETWORK networks Frame relay Ethernet networks networks Ethernet networks ATM networks Label switching router (LSR) Label switched path (LSP) Source: ITU-T SG 13 Figure 12.10 The MPLS principle to create paths in the backbone network Billing Telecom business Service Service layer Service, security, QoS management Numbering Dimensioning Charging Routing Control layer Signalling Dependability Mobility management Switching Frequency Traffic resources Transmission in connectivity Organization Synchronization layer M = Management system Traffic system = Network Figure 12.11 The FP is refined with connectivity control signalling, routing, numbering, QoS and security functions in the connectivity layer 12.4.3 DESIGN SPLIT The functional split corresponds to a design split, where a core network design is normally split into: Control layer design, including MGW from the connectivity layer ATM and IP network design and dimensioning SDH/SONET/PDH network design Packet Backbone Note: No service enablers in this figure Voice, video Signaling Voice, video, codec H.323 QoS, Media Encapsu- lation (FAST) Diffserv PNNI, AINI OSPF, RIP, BGP IPv4, IPv6 IPsec UNI, B-ICI AAL 1 Encapsu- lation IP/ATM) IP/WLAN IP/GPRS (SDH/ PLMN/PSTN/ IP/WCDMA SONET) IP/CDMA Addition Ethernet PDH/SDH/ Radio bearers, SONET PDH/SDH/SONET/xDSL GMPLS WDM + Radio fiber Figure 12.12 Examples of stack combinations: IP/ATM/SDH or SONET, IP/PPP/SDH or SONET (called PoS, packet over SONET/SDH), IP/MPLS/WDM and IP/Integrated Shim layer/WDM. A main task of the shim layer is framing With a new standard GMPLS a more integrated planning is necessary. See next section. 12.4.4 LAYERING OF THE PACKET BACKBONE See Figure 12.12. A similar figure has been used before, but protocols to the left and right have been added. With all possibilities and layers, facilities management becomes somewhat cumbersome. An overall approach for multi-layer traffic engineering is called GMPLS, generalized MPLS, from IETF. GMPLS is briefly described in sec