.12 Hierarchical layer to layer relationship (Fig. 3/1.311) for establishing signalling communication paths. It examines the Establish, maintain and release VCCs and VPCs. May be on- capabilities required to control ATM VC and VP connections for demand, semi-permanent or permanent, but must comply with information transfer and (implicitly acknowledging the distinction requested connection characteristics. between connection and call) further examines the capabilities 2. Support point-to-point, multipoint and broadcast configura- required to support simple multi-party and multi-connection calls. tions. Capabilities include: 3. Negotiation of traffic characteristics at set-up and during calls. Transmission Path A Transmission Path C VPI x VPI x(A) VPI p(C) VPI p VCI a VCI a VCI b VCI b VCI b VCI a VCI c VCI b VPI y(A) VPI q(C) VPI q Transmission Path B Transmission Path D VPI x VPI x(B) VPI r(D) VPI r VCI a VCI b VCI b VCI c VCI b VCI b VCI c VCI c VPI y VPI z(B) VPI q(D) VPI q VP Switch Figure 41.13 Representation of VP switching (an elaboration of Fig. 4/1.311) Standards for ATM 41/13 VC Switch VCI a VCI b VCI m Endpoint of VPC Transmission Path A Transmission Path C VPI x (A) VPI p(C) VPI p VCI a VCI n VCI b VCI b VCI m VCI c VPI y VPI y (A) VPI q(C) VPI q Transmission Path B Transmission Path D VPI (B) VPI r(D) VPI r VCI a VCI b VCI b VCI C VCI b VCI b VCI c VCI c VPI Z VPI Z (B) VPI q(D) VPI q VP Switch Figure 41.14 Representation of VP and VC switching (an elaboration of Fig. 4/1.311) 4. Support of symmetric and asymmetric calls. equipment (CEQ) and local or transit connection related functions 5. Addition/removal/reconfiguration of connections and parties (CRFs) or exchanges. from multi-connection and multi-party calls. 6. Support interworking between different coding schemes and with non B-ISDN services. 41.4.5.3 Traffic control and resource management Signalling principles also examines the requirements for signall- ing virtual channels on the user access and in the network and also This deals with the sev