MAPPING SYSTEM BETWEEN X25 LAYER 3 SOFTWARE AND OSI PROTOCOL NETWORK SERVICE ACCESS POINT SOFTWARE

摘要

PURPOSE:To communicate inter-network service point between DTEs without correction of lots of packet exchange stations by using a DTE address of the CCITT recommendations X25 as a selection index from a 3-layer subsequent software to a 3-layer host software. CONSTITUTION:An X25 protocol accommodation terminal equipment DTE 2 and a packet exchange station DCE 1 are interconnected by 4 connection lines C1-C4 and DTE addresses are A1, A2, A3 and A3. As the software processing an OSI 3 layer protocol for a packet, it consists of an X25 layer 3 software P and NSAP softwares N1-N3, and plural Ni (N1-N3) are set optionally to the software P. When a fault takes place in the lines C1-C4, the processing of replied Ni (such as N1 in case of the faulty C1) is processed by an enable/disable notice function software P1 in the X25 layer 3 software. Thus, the communication between the X25 layer 3 host software is attained without revision of the layer 3 software.