Nec Corporation

Tomoyoshi Shimizu

Hiroshi Ikeda

Yoshinori Yoshida

Masao Hashimoto

Hatsuho Murata

Masato Aoyagi

Tsutomu Okurano

Haruhiko Yamamura

Hideki Nakane

A data link layer processing (DLLP) system comprises a plurality of in-service DLLPs and a plurality of spare DLLPs. The switching between the in-service DLLP and the spare DLLP is effected by coupling both the DLLPs with the transmission line and transferring logical links from the in-service DLLP to the spare DLLP one by one while frame multiplexing the data from the spare DLLP with the data from the in-service DLLP. After all of the logical links are transferred, a switch decouples the in-service DLLP to leave the spare DLLP coupled with the transmission line for a normal operation.

Data link layer processor system for a local exchange system

A simple adapter for multiplexing ISDN (Integrated Services Digital Network) terminals adapter for an ISDN basic subscriber access system is connected by a connector to a subscriber's point-to-multipoint bus. The adapter allows a greater number of terminal equipment (TE) to be connected to the point-to-multipoint bus via S/T interfaces. By checking the type, subaddress or the like of a call coming in through the adapter, the adapter is capable of limiting the kind of acceptable calls.

Simple adapter for multiplexing ISDN terminals

An integrated service network ('ISDN') is structured to connect subscriber lines through a packet switching system to incoming or outgoing packet switching calls without passing them through a circuit switching system. This effectively uses the speech path of the circuit switching section instead of using it for packet switching calls. At the same time, the invention minimizes the influence of the introduction of the ISDN upon the software of the circuit switching section. The ISDN digital switching network applies to circuit switching calls which are switched at a local switch and to packet switching calls which are to be switched at a toll switch. The digital switching system separates calls into circuit switching calls which are transferred through B channels, packet switching calls which are transferred through B channels, and packet switching calls which are transferred through D channels in order to connect the circuit switching calls to a time division switch and the packet switching calls to a packet multiplexer. The packets are concentrated and multiplexed into separated packet switching calls. The circuit switching calls from the time division switch are multiplexed with the packet switching calls from the packed multiplexer and are placed in predetermined time slots in accordance with a band width designated corresponding to respective call traffic.

Digital local switching system for integrated service digital network

Growing community of inventors

Tokyo, Japan

Tomoyoshi Shimizu