Method and apparatus for rendering a cell-based switch useful for frame based protocols

A switch comprising:

• a) a source for a Fibre Channel frame;
• b) a cell-based switch fabric requiring cells having a data payload and a cell header, the cell header containing a packet length field that indicates the length of the Fibre Channel frame in cells;
• c) means for constructing a first data cell from the Fibre Channel frame, the first data cell containing a full data payload and a packet length value in the packet length field, the packet length value being set large enough to represent a maximum sized Fibre Channel frame;
• d) means for establishing a path through the cell based switch fabric and associating with the path a duration determined by the packet length value;
• e) means for constructing a second data cell from the Fibre Channel frame, the second data cell containing a partially filled data payload and a valid data value in the packet length field, the valid data value indicating the number of valid data bytes in the partially filled data payload;
• f) means for reconstructing the Fibre Channel frame at least in part from the transmitted first and second data cells, the reconstructed data frame containing data from the entire full data payload of the first data cell and the valid data bytes of the second data cell data payload.

A switch comprising:

• a) an input port for receiving a Fibre Channel frame;
• b) an input interface module in data communication with the input port, the input interface module segmenting the Fibre Channel frame into fixed-size data cells, the data cells each having a cell data payload and a cell header having a packet length field, the interface module containing logic for
• i) constructing a first data cell from the Fibre Channel frame containing a data payload filled with data from the Fibre Channel frame and a value in the packet length field set large enough to represent a maximum sized Fibre Channel frame, and
• ii) constructing a second data cell from the Fibre Channel frame, the second data cell containing a partially filled data payload and a valid data value in the packet length field;
• c) a cell-based crossbar in data communication with the input interface module, the crossbar capable of creating paths through the crossbar for data cells, the paths being maintained through the transmission multiple data cells comprising a data packet, the size of the data packet being determined by the packet length field in the first data cell;
• d) an egress interface module in data communication with the crossbar, the egress interface module having logic to reconstruct the Fibre Channel frame from the first and second data cells received from the crossbar;
• and
• e) an output port in data communication with the egress interface module.