Abstract: A transfer layer of an ATM type used between a switch (216) and a number N of communication channels (218). Each communication channel (218) has second storage arrangement B.sub.0, . . . , B.sub.N-1 for storing cell queues having a length of up to P cells each, one of the second storage arrangements being in a busy condition if a minimum number M of cells is stored therein, where M is lesser of equal P. Each communication channel is assigned to one of the switch queues. The transfer layer (217) has third storage arrangement T for storage of a cell queue having a length of up to L cells. Furthermore the transfer layer (217) selectively disables the input of a cell from one of the switch queues into the third storage arrangement if the second storage arrangement is in a busy condition.

Abstract: A method (FIGS. 5-6) and a structure (FIGS. 3-4) are taught herein for prioritizing and transmitting forward monitoring cells (FMCs) for performance monitoring in an asynchronous transfer mode (ATM) system. An ATM system may have multiple physical lines which have many virtual paths which have multiple virtual connections. These paths/connections may be performance monitored by transmitting an FMC each time N ATM data cells are received for the connection/path (wherein N is number which may be different for each connection/path). The number of data cells are stored via a counter for each connection/path being monitored. Once N ATM cells are received on a given connection/path, an FMC descriptor is queued which indicates that the FMC cell for the given connection/path must be transmitted before receipt of N/2 subsequent cells received by the given connection/path. A priority (which is a function of one of the counters) is used to ensure that the N/2 requirement is satisfied.

Abstract: An asynchronous transfer mode (ATM) system has a plurality of physical layers (24, 50, 52, and 26) coupled to one ATM layer (12) for communicating ATM data cells. In order to allow bi-directional communication, both the receive interface and the transmit interface of FIGS. 14 and 15 are coupled between the ATM layer and each physical (PHY) layer in the plurality of physical layers. In order to identify which physical layer of the plurality of physical layers is to either receive or transmit a data cell, a physical layer ID byte is transmitted along with the UTOPIA protocol multi-byte ATM data cell to address one physical layer in the plurality of physical layers.

Abstract: An asynchronous transfer mode (ATM) address compression method uses a PHY ID (14). The PHY ID (14) is provided before the transmission of a 53-byte ATM data cell (12, 16, and 18). The PHY ID (14) (also referred to as a link) is used to access a link table (20). The link table (20) contains address compression mode information which allows for many address compression modes and an enable bit, an address pointer, and a mask value which are used to both reduce ATM addressing bits and identify a virtual path table/entry in the ATM system. In some address compression modes, the identified virtual path contains the ingress connection identifier (ICI) which identifies a physical data routing path in the ATM system. In other address compression modes, further address compression of virtual channel identifiers is required beyond the virtual path tables in order to identify a virtual channel table/entry which then contains the ICI.