Method and apparatus for segmenting network traffic variable length frames

A network adapter comprising:

• a data mover component to store input network variable length packet data received from the network data as words in a first storage unit, said data mover also creating input queues of said moved packets;
• a frame process component reading enqueued packets and creating queues of packets directed to the same destination and storing frame information in a second storage unit;
• a frame segmenting process component for segmenting said enqueued packets into fixed length cells, said frame segmenting process component comprising:
• a first input bus accessing the packet words of said first storage unit;
• a second connecting bus accessing said second storage unit;
• a finite state machine reading through said first bus the packet words in said first storage unit of the enqueued packets to be segmented;
• an Add/substract unit, activated by said finite state machine through an internal bus, receiving input data from said finite state machine and from said second storage unit, said Add/substract unit computing the cell content, storing in said second storage unit cell information describing the cell content, said cell content comprising a defined fixed length cell header, data from one packet and data from other packets of said succession of packets if they are found in said first data store and if there is space enough in the cell to enter at least a defined fixed length new packet header after the last data of the previous packet;
• a third connecting bus, connected to said finite state machine, through which a signal is received by said finite state machine requesting a new cell information, said finite state machine sending back through said third bus an acknowledgment when storing of cell information in said second storage unit is completed;
• a cell assembler sending through a connecting bus request for cell information and receiving acknowledgment from said segmenting process component that cell information is ready;
• said cell assembler further building the cell reading cell information from said second storage unit and packet data from said first storage unit;
• and
• an output interface receiving on a bus connected to said cell assembler component the cells built by said cell assembler component and sending them on an output bus.

A method for preparing cell information describing the cell content to build the cells resulting from the segmenting of a succession of variable length packets stored as words in a first storage unit into fixed length cells, said method comprising:

• reserving in the cell content the cell data for a defined fixed length cell header;
• reading the packet data stored in said storage unit and reserving the cell space following the cell header for said packet data;
• if the packet data does not completely fill the cell, checking if the remaining space in the cell is sufficient to contain at least a defined fixed length packet header;
• if the remaining space in the cell is sufficient to contain at least said packet header, reserving the cell space for the next packet data;
• repeating the previous two steps until the packet data completely fills the cell or the remaining space in the cell is not sufficient to contain at least one packet header;
• if the packet data completely fills the cell, storing information describing the cell content, signaling to an outside interface that this information is ready and restarting the method at the first step until the last cell is written for said succession of packets.

An apparatus to segment packets into fixed length cell comprising:

• a storage storing variable length packets;
• a control block storing control information including addresses of packets within said storage;
• a finite state machine operably coupled to said storage and reading packets to be segmented therefrom;
• an add/subtract unit operably coupled to the finite state machine, said add/subtract unit being responsive to signals from said finite state machine to compute cell contents and storing in said control block cell information describing said cell contents;
• a bus, operably coupled to said finite state machine, through which a signal is received by said finite state machine requesting a new cell information, said finite state machine sending back through said bus an acknowledgment when storing a cell information in said control block is complete.