ISDN ACCESS LINE DATA LINK LAYER & NET\VORI< LAkFR MAINTENANCE

Integrated Services Digital Network (ISDN) is a new network architecture that enables the operating telephone companies (OTCs) to provide various services to customers over a single access line. ISDNs use a %layer protocol structure on the user/network interface to exchange user-network signaling information and to establish end-user to end-user communication connections (both circiiit. mode and DBC~P~. mode). Experience from ISDN trials conducted by various Bell Operating Companies (L3OCs) has indicated that centralized Maintenance tools for all three layers are needed to support ISDN operations. This paper presents a means to monitor data link and network layer performance while the access line 1s In-service. The need for each layer to be monitored separately and the tools that may be used to maintain these layers (including testing tools) are identified.