Network interfacing method and a network interface for a digital transmission network

A user-network interface in a digital transmission network for a cell-based digital signal comprising cells of fixed length and having a high nominal bit rate, the interface comprising:

• an input buffer means for receiving and buffering the cell-based signal;
• a policing means for controlling said buffer means to adapt the rate of the received cell-based signal to the actual transmission speed of the transmission network;
• a mapping means for forming cell blocks of N consecutive cells from the cell-based signal and for adding N overhead bytes to each cell block;
• a first multiplexing means for multiplexing the output signal of the mapping means byte by byte into N separate output signals of about 1.5 Mbit/s, 2 Mbit/s, 6 Mbit/s or 8 Mbit/s, N being an integer which is greater than 1.

A method for establishing a user-network interface in a digital transmission network for a cell-based digital signal comprising cells of fixed length and having a high nominal bit rate, for an ATM signal, said method comprising the steps of:

• adapting the rate of the cell-based signal by a policing function to an actual transmission speed lower than said nominal bit rate;
• generating empty cells;
• generating control cells;
• combining said empty cells and said control cells with the rate-adapted cell-based signal,
• mapping the rate-adapted cell-based signal into a group of N separate lower-speed transmission signals for transmission over the transmission network, N being an integer higher than 1.

A user-network interface in a digital transmission network for a cell-based digital signal comprising cells of fixed length and having a high nominal bit rate, said interface comprising:

• an input buffer means for receiving and buffering the cell-based signal;
• a policing means for controlling said buffer means to adapt the rate of the received cell-based signal to the actual transmission speed of the transmission network;
• a mapping means for forming cell blocks of N consecutive cells from the cell-based signal and for adding N overhead bytes to each cell block;
• a first multiplexing means for multiplexing the output signal of the mapping means byte by byte into N separate output signals of about 1.5 Mbit/s, 2 Mbit/s, 6 Mbit/s or 8 Mbit/s, N being integer higher than 1;
• a first generator means for generating empty cells;
• a second generator means for generating control cells;
• and
• a combiner means for combining cells from the first and the second generator means with the rate-adapted cell-based signal before applying the signal to the mapping means.