摘要:
An apparatus and method for transmitting X.25 communications over the D-channel of an ISDN link. This is achieved by terminal adapters connected between an X.25 terminal and an ISDN connection which contain converters to convert X.25 LAPB frames into LAPD frames and vice versa. The conversion process involves directly copying fields from the incoming LAPB frame into a LAPD frame with the minimum amount of verification. Essentially the only checking performed is to examine the number of octets in each field of the incoming frame to ensure that the conversion process itself does not fall down.
摘要:
A packet switching method in a digital network includes a calling equipment and called equipment connected to the digital network for communication by packet switching, and further includes a destination end system to be connected to the called equipment for communication. Upon occurrence of a call demand by the calling equipment, a sub-address of the called equipment and a network address of the destination end system are inserted in a call demand packet and the call demand packet is transmitted to the digital network. Upon reception of a call setup message by the called equipment from the digital network which receives the call demand packet, the sub-address from the call setup message is extracted and a judgement is made as to whether the incoming call is designated to own equipment by checking matching of the extracted sub-address and a given sub-address assigned to own equipment. A response message to the digital network is transmitted when the incoming call is judged to designate own equipment. Upon the called equipment's reception of an incoming call packet which was transmitted by the digital network after receiving the response message, the network address from the incoming call packet is extracted and incoming call processing is performed based on the extracted network address for establishing the call.
摘要:
A plurality of data terminals are connected to a plurality of ports in a data terminal control unit. A table representing correspondence in an extension number, a dial-in number and an ISDN subaddress of each data terminal equipment, the number of a port connected with each data terminal equipment, and so on is provided within the data terminal control unit. When one data terminal equipment calls another data terminal equipment, the extension number of the data terminal equipment to be called is set in a setup message. When one data terminal equipment is called from an outside line, an ISDN number thereof is set in a setup message. The setup message is then transmitted to the data terminal control unit. The data terminal control unit refers to the table, thereby to specify the data terminal equipment to be called and transmit the setup message to the corresponding data terminal equipment.