Packet mode data communications in NUMERIS, the French ISDN

How to introduce packet switching into ISDN and, in particular, whether frame switching should be privileged are addressed in the context of NUMERIS. In addition to 64-kb/s access to Transpac, the national packet-switching public data network (PSPDN), it has been decided to offer packet-mode data communications services on the D channel of the user access to provide access to switching facilities as well as other applications and services such as telex, videotex, or teleactions through so-called access points. Layer-2 frame-switching capabilities are being developed for this purpose in Alcatel E10 switching systems to operate permanent logical links (PLLs) in a first stage, to be complemented by switched logical links at a second stage. The implementation of the switched access to a PSPDN gateway known as the packet access point (PAP) in Transpac is reviewed, and a description is given of the network equipment and interfaces being implemented in the E10 switching system to support the PLL services in conformance with CCITT Recommendation X.31 (maximum integration on the D channel, without incoming call notification).<>