A VLSI implementation of a broadband ISDN internetworking unit

The broadband integrated services digital network (B-ISDN) is intended to be the future standard for high speed wide area digital networks. It will allow for almost any type of services through a single network interface. Its line rate ranges from 155 Mbps to 2.4 Gbps and beyond. ATM (asynchronous transfer mode) and SDH (synchronous digital hierarchy) are the techniques used in this network. Here we present the implementation of an internetworking unit called UNICORN which is used to interconnect LANs as Ethernet and MANs as DQDB over a B-ISDN based on SDH and ATM. The system architecture is based on a general purpose high speed bus which interconnects the different elements on it. The object of this paper is to explain a network attachment unit (NAU) for B-ISDN and the two ASICs developed for it