A study on the architecture of a network adapter

We show the need for the network adapter (NA) function and discuss problems with its role as a channel processing NA that is important to the introduction of B-ISDN. We discuss a suitable module structure and an experimental system. This system can provide inter-connection between the STM-channels on STM-1 and ATM virtual channels on ATM-NNI. To reduce the amount of hardware, the NA should provide the multiplexed multi-bit-rate AAL type 1 function. An integrated testing circuit also can reduce the amount of hardware. It can check the connectivity and normality of the ATM layer, the AAL, and the STM channels. We roughly estimated the performance of ATM circuit emulation services for voice, modem, and facsimile communication under normal conditions and cell loss conditions using real terminals