A Multiservice Access Concentrator (MAC) provides traffic shaping by
allocating at least one cell stream to at least one cell slot of a cell
scheduling table. A cell slot and a corresponding cell stream are
designated in response to a cell interrupt signal generated following
cell transmission. At least one counter and at least one credit buffer
are maintained, and a service class of the designated cell stream is
determined. The size of the credit buffer is determined by a maximum
burst cell size (MBC) of the corresponding cell stream and virtual
circuit (VC). A cell of the designated cell stream is transmitted in
response to the determined service class and a count of the at least one
counter and contents of the at least one credit buffer. Therefore, cells
are transmitted based on cell credits. A virtual circuit (VC) builds cell
credit based on the sustained cell rate (SCR) of the VC. Cell credit is
consumed as cells are transmitted. If no data is queued or transmitted,
the cell credit builds to a maximum burst cell size (MBC). When data is
queued again and credit is available, cell transmissions may burst to the
peak cell rate (PCR) until credit is exhausted. Cell transmission timing
is controlled using the cell interrupt signal, wherein the cell interrupt
signal emulates a clock signal.