ATM cell interface and method for dispatching an ATM cell

摘要

An ATM cell interface for dispatching an ATM cell having a header. The interface is comprised of N input ports, where N>/=1 and is an integer. The cell is also comprised of a table lookup mechanism that directs a cell from an input port to any desired destination. The table lookup mechanism has entries which identify desired destination for corresponding cells. The number of possible entries in the table lookup mechanism is less than a total number of entries supported by the ATM cell header. Preferably, a cell includes a VCI field having a value and a VPI field having a value. The table lookup mechanism preferably includes a first table which produces a first signal based on the value of the VPI field and a second level table which produces a second signal based on the value of the VCI field. The first and second signals are used to route the cell from an input port to a desired destination. Additionally, there is a method for dispatching an ATM cell. The method comprises the steps of locating a table entry in a first level table corresponding to a value of a VPI field of the cell. Then there is the step of producing a first signal corresponding to the table entry. Next, there is the step of locating a connection entry in a second level table corresponding to a value of a VCI field of the cell and the first signal. Then there is the step of producing a second signal corresponding to the connection entry. Next there is the step of directing a cell to a desired destination corresponding to the second signal. Preferably, the step of producing the first signal include the step of producing the first signal corresponding to a value of a INDEX field of the table entry. Preferably, the step of producing the second signal includes the step of producing the second signal corresponding to a value of a CONNECTION INFORMATION field of the connection entry.