CN1281034C - Data translating device and method from coated-mode bus to CCLL mode bus - Google Patents

Abstract

The present invention relates to a retransmission unit for translating data from packet mode bus to CELL mode bus and a method. The data retransmission unit comprises a Cell header generating module 301, a data buffer unit 302, a Cell header buffer unit 303 and a Cell generating module 304, wherein the Cell header generating module 301 is connected with an input end of the data buffer unit 302 and a data output of the packet mode output bus, Cell header generated by the Cell header module 301 is fed to the Cell header buffer unit 303, and the Cell generating module combines the input information group to a complete Cell. Owing to that mode conversion job is completed while the package enters FIFO(First Input First Output) and that the reading of the Cell header from the FIFO and the combination of the Cell header and the data package into one Cell is required in the Cell mode bus end, the mode conversion system has relatively high overall bus bandwidth utilization.

Description

A kind of data forwarding device and method from the pack mode bus to CELL pattern bus

Technical field:

The present invention relates to data in retransmission unit and the method for pack mode bus, realize the transfer of data of different mode bus to CELL pattern bus.

Background technology:

Different network processing units has different data transmission bus, and different interface chips also has own unique data/address bus simultaneously.But generally speaking the most frequently used just has only two kinds: a kind of transmission that is based on pack mode, another is based on the transmission of CELL pattern.The difference of these two kinds of pattern maximums is that pack mode (as shown in Figure 1) is to adopt dedicated signal line to indicate information such as beginning SOP (start of package), end-of-packet EOP (end of package), the data of bag are effective, and bag fractionation the becoming littler unit (CELL) that the CELL pattern will be complete and head (Cell header) and data that relevant information adds CELL are together transmitted.The data structure of CELL pattern as shown in Figure 2, a CELL is made up of data division (Data) and Cell header.Two important field: Type, Length are arranged in Cell Header.What the Length field was represented is the length of this CELL data division, and Type represent this CELL at the position of complete packet as information such as the centre of the beginning of bag, the end of bag, bag, the beginning of bag and end.Accepting to survey the CELL that separates to be reconfigured by these information becomes a complete bag.The key that the realization data are changed from the pack mode bus to CELL pattern bus is the generation of Cell header information, does not also have a kind of relatively effective method to realize this data forwarding in the prior art.

Summary of the invention:

The technical problem that the present invention solves provide a kind of use independently Cell header fifo (first-infirst-out) realize the method for forwarding from the pack mode bus to CELL pattern bus.

Data forwarding device from the pack mode bus to CELL pattern bus of the present invention, as shown in Figure 3, comprising: Cell generation module 301, data buffer unit 302 (Data FIFO), a Cell buffer cell 303 (Cell header FIFO) and Cell generation module 304;

The input of Cell generation module 301 and data buffer unit 302 (Data FIFO) links to each other with the data output end of pack mode output bus, the Cell head of Cell generation module 301 generations is input to Cell buffer cell 303, the input of Cell generation module 304 links to each other with the output of Cell buffer cell 303 with data buffer unit 302 (Data FIFO) respectively, with the synthetic complete Cell of the information sets of input.

Data forwarding method from the pack mode bus to CELL pattern bus of the present invention comprises following treatment step:

The first step, the data of pack mode bus are imported Cell generation module 301 and data buffer unit 302 respectively;

In second step, Cell generation module 301 generates the Cell head with the data of importing, and sends to Cell buffer cell 303;

In the 3rd step, Cell generation module 304 reads the Cell head earlier from Cell buffer cell 303, and reading of data part from data buffer unit 302 is combined into a complete Cell then again.

Data forwarding device and method from the pack mode bus to CELL pattern bus of the present invention, because being operated in when bag enters FIFO of mode switch finished, only need simply from FIFO, to read Cell header and the synthetic Cell of bag data at Cell pattern bus end.So the bus bandwidth utilance of whole mode switch system can reach very high.In actual applications, the bus of Cell pattern is 16, the bus of 100Mhz, and data traffic can reach 1.58Gbit/s, and total line use ratio reaches 98.75%.

Description of drawings:

Fig. 1 is the sequential chart of pack mode transmission;

Fig. 2 is the data structure of Cell pattern;

Fig. 3 realizes the structural representation of pack mode to the Cell mode switch;

Fig. 4 is the type in the Cell head, the flow chart that the Length territory generates;

Fig. 5 is to use the FPGA specific implementation.

Embodiment:

Wherein of paramount importance is Cell generation module 301 (Cell header generator).Introduce the generative process in TYPE among the Cell header, LENGTH territory below in detail.As shown in Figure 4:

Step 401 is unwrapped the beginning to write FIFO, by counter LENGTH_COUNTER the packet length that writes is counted simultaneously, and SOP_PTR (unwrapping the beginning pointer) signal is set to 1 when packet header signal (SOP) when importing into;

Step 402, EOP comes when SOP_PTR is 1, and at this moment execution in step 403, and TYPE=" beginning of bag and end " represents that this Cell includes a complete bag, and the value that LENGTH=LENGTH_COUNTER counts to get finishes this time conversion then;

Otherwise, execution in step 404, if EOP arrives, but SOP_PTR is not 1 o'clock, changes step 405, and TYPE=" end of bag " represents that this Cell belongs to the ending of a bag, and LENGTH=LENGTH_COUNTER finishes this time conversion simultaneously; If EOP does not arrive, then execution in step 406;

Step 406, if LENGTH=LENGTH_SET (LENGTH_SET is expressed as the length restriction of a Cell who sets in advance) SOP_PTR simultaneously is 1, TYPE=" centre of bag " represents that this Cell belongs to the mid portion of a complete packet so, LENGTH=LENGTH_SET, it is 0 that SOP_PTR is set simultaneously;

Otherwise change 407, if LENGTH=LENGTH_SET, simultaneously SOP_PTR is 0, TYPE=" centre of bag " so, and LENGTH=LENGTH_SET jumps to step 404, finishes when having EOP to come.

The FIFO that specific implementation of the present invention can adopt FPGA and internal RAM (random memory) to constitute.As shown in Figure 5, the bag of PPP (Peer-Peer Protocal) uses PTM Packet Transfer Mode to enter module 501.In 501, finish the generation in Type among the Cell header, Length territory and deposit among the 503 Cell Header FIFO.501 finish the operation that data deposit 502 data FIFO in simultaneously.The degree of depth of Cell Header FIFO has relation with the minimum packet length of the degree of depth of DataFIFO, the setting of Cell length (LENGTH_SET among Fig. 4) and PPP.The calculating aspect is as follows:

1. if the length of Cell is less than the minimum packet length of PPP, so the length of the degree of depth/Cell of the degree of depth of Cell Header FIFO=Data FIFO.

2.PPP minimum packet length less than the length of Cell, the minimum packet length of the degree of depth/PPP of the degree of depth=DataFIFO of Cell Header FIFO so.

In 504, at first from Cell header FIFO, read Cell header at last, and then the data that read regular length from Data FIFO are formed a complete Cell and are exported from bus.

Claims (3)

1. data forwarding device from the pack mode bus to CELL pattern bus, it is characterized in that described device comprises: Cell generation module (301), data buffer unit (302), a Cell buffer cell (303) (Cell header FIFO) and Cell generation module (304);

The input of Cell generation module (301) and data buffer unit (302) links to each other with the data output end of pack mode output bus, the Cell head that Cell generation module (301) generates is input to Cell buffer cell (303), the input of Cell generation module (304) links to each other with the output of Cell buffer cell (303) with data buffer unit (302) respectively, with the synthetic complete Cell of the information sets of input.

2. the data forwarding method from the pack mode bus to CELL pattern bus is characterized in that, comprises following treatment step:

The first step, the data of pack mode bus are imported Cell generation module (301) and data buffer unit (302) respectively;

In second step, Cell generation module (301) generates the Cell head with the data of input, and sends to Cell buffer cell (303);

In the 3rd step, Cell generation module (304) reads the Cell head earlier from Cell buffer cell (303), and reading of data part from data buffer unit (302) is combined into a complete Cell then again.

3. the data forwarding method from the pack mode bus to CELL pattern bus according to claim 2 is characterized in that, affiliated second step also comprises following treatment step:

Step 401 is unwrapped and is begun to write FIFO, by counter LENGTH_COUNTER the packet length that writes is counted simultaneously, and the SOP_PTR signal is set to 1 when the packet header signal imports into;

Step 402, EOP comes when SOP_PTR is 1, and at this moment execution in step 403, and TYPE=" beginning of bag and end " represents that this Cell includes a complete bag, and the value that LENGTH=LENGTH_COUNTER counts to get finishes this time conversion then;

Otherwise, execution in step 404, if EOP arrives, but SOP_PTR is not 1 o'clock, changes step 405, and TYPE=" end of bag " represents that this Cell belongs to the ending of a bag, and LENGTH=LENGTH_COUNTER finishes this time conversion simultaneously; If EOP does not arrive, then execution in step 406;

Step 406, if LENGTH=LENGTH_SET while SOP_PTR is 1, TYPE=" centre of bag " represents that this Cell belongs to the mid portion of a complete packet so, LENGTH=LENGTH_SET, it is 0 that SOP_PTR is set simultaneously;

Otherwise change 407, if LENGTH=LENGTH_SET, simultaneously SOP_PTR is 0, TYPE=" centre of bag " so, and LENGTH=LENGTH_SET jumps to step 404, finishes when having EOP to come.

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