The Foster City, California-based ATM Forum has approved three physical layer specifications. These comprise the 155Mbps Asynchronous Transfer Mode Physical Medium-Dependent Interface Unshielded Twisted Pair-5 copper wiring, the 1.544Mbps DS1 Physical Layer Interface and the Universal Test and Operation PHY Interface for Asynchronous Transfer Mode. The 155Mbps Physical Medium Dependent specification is intended for use in high-performance multi-station networks. It provides point-to-point communication between Asynchronous Transfer Mode user devices and network equipment. The DS1 Physical Layer Interface applies to the public User-to-Network Interface. The specification is based on documents from the American National Standards Institute T1 and ITU-T, and is fully compatible with existing standards for Asynchronous Transfer over DS1. The Universal Test and Operation PHY Interface specification defines the interface between the physical layer and upper layer Asynchronous Transfer Mode modules. The Universal Test and Operation PHY Interface specification provides a common functional interface for a wide range of speeds and media types, interconnecting devices supporting Asynchronous Transfer Mode specifications ranging from sub-100Mbps to 155Mbps.
