ITU-T Recommendations

This Recommendation defines a V-interface (V5.2) for the connection of an Access Network (AN) and the Local Exchange (LE) for the support of the following access types- analogue telephone access;- ISDN basic access with an NT1 separate from the AN, or integrated in the AN, based on ITU-T G.960 and I.430;- ISDN primary rate access with an NT1 separate from the AN, or integrated in the AN, based on ITU-T G.962 and I.431;- other analogue or digital accesses for semi-permanent connections without associated outband signalling information,with flexible information channel (bearer channel) allocation by use of a bearer channel connection protocol providing concentration capability within the AN.This Recommendation is based on ITU-T G.964 and refers to it for those parts which are common in both Recommendations.The electrical and functional interface specification for the interface links uses the 2048 kbit/s parts of ITU-T G.703, G.704 and G.706. Up to 16 interface links may be operated in parallel forming the V5.2 interface.The signalling from the PSTN user port is converted into a stimulus protocol with a functional part for the signalling path using layer 3 multiplexing for the information from the different user ports.The information from the ISDN D-channels is frame relayed in the Access Network using the mechanisms defined in ITU-T Q.933.A control protocol defined in this Recommendation is used for the exchange of the individual port status and control functions required for the coordination with the call control procedures in the Local Exchange.A bearer channel connection protocol establishes and de-establishes bearer connections required on demand, identified by the signalling information, under the control of the Local Exchange.A link control protocol is defined for the mult-link management to control link identification, link blocking and link failure conditions.In order to coordinate the traffic demands in the various protocols, up to three communication channels can be provisioned per interface link to transport the various protocols and frame relayed information. The data link layer for the protocols is defined on the bases of ITU-T Q.920 and Q.921.A protection protocol, operated on two separate data links for security reasons, is defined to manage the protection switching of communication channels in case of link failures.