JP2939584B1 - Search circuit - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To store each unit data constituting search data in each block of a register and to search based on the stored search data when the storage order of the unit data in each block is different for each search data. Search the searched data in the table at high speed. SOLUTION: Selectors 31 to 34 for commonly inputting each unit data of each block of a register 11 and selection for controlling the selector so that each unit data input to each selector corresponds to each block of a search table 12. Circuit 35
And a register 36 for storing designation information of each block of the register in association with the input search data,
Each time the search data is stored in each block of the register 11, the selection circuit 35 controls the switching of each selector by inputting the designation information of the register 36, and makes a one-to-one correspondence between each block of the register and each block of the search table. Correspond.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a search circuit provided in a gateway device for searching a transfer destination of a frame based on received frame information.

[0002]

2. Description of the Related Art Generally, in a gateway device such as a router / switch, when a frame is received, in order to determine a destination to which the frame is to be transferred from received frame information, a content addressable memory (CAM) is used to determine the destination of the transfer. Perform a search.

FIG. 3 is a block diagram showing a main configuration of such a search circuit. Reference numeral 11 denotes a register for holding search data a for searching a transfer destination of a received frame;
Is a search table, and 13 is a software interface for comparing the data registered in the search table in advance with the search data in the register 11 and outputting the result as a flag or data.

Next, the operation of the search circuit configured as described above will be described. When a frame is received by the gateway device, destination information included in the received frame is stored in the register 11 as search data a of 32 bits, for example.
In this case, the 32-bit search data a is stored in each of the blocks A, B, C, and D as unit data divided into 8-bit units. Here, the search table 12 stores 32-bit transfer destination information corresponding to each of the entries e1 to en. Also, the 32-bit transfer destination information of one entry e is stored in each of the blocks E, F, G, and H, divided into eight bits.

In this case, the soft interface 13
The data of the block A of the register 11 is compared with the data of the block E of each of the entries e1 to en of the search table 12. The data of the block B of the register 11 is compared with the data of the block F of each entry e1 to en of the search table 12. Further, register 11
Is compared with the data of the block G of each of the entries e1 to en of the search table 12.
Further, the data of the block D of the register 11 is compared with the data of the block H of each entry e1 to en of the search table 12.

As a result of such a comparison, each block E that matches all the data of each block A to D of the register 11
The entry e of the search table 12 having .about.H is obtained as entry data, and the entry data is determined as the transfer destination of the received frame. When the data of each of the blocks E to H does not match the data of each of the blocks A to D of the register 11 (including the case where the data does not partially match).
Sends the mismatch information to a higher-level device (not shown) inside the device to notify that the transfer destination cannot be determined.

[0007]

In such a conventional search circuit, the input order of unit data of one search data a stored in each of the blocks A to D of the register 11 is as shown in FIG.
As shown in (a), if the storage order in each block, that is, the order of “A, B, C, D” is fixed, the search circuit 14 including the software interface 13 etc. Even when input, the data of the search table 12 can be easily searched from the search data. However, in the series of search data stored in each of the blocks A to D of the register 11, the code shown in FIG.
, The unit data is assigned to each block in the order of “B, C, D, A” or “C,
When input sequence search data stored in the order of “B, D, A” or “A, D, C, B” is mixed, the search circuit 14 searches for search data corresponding to this portion. Table 12 cannot be searched.

For this purpose, as shown in FIG. 4C, a format conversion unit 15 composed of software is provided.
The format conversion unit 15 converts the format of the data of the array indicated by the symbol in the search data a ′ in FIG. 4B into an array like the search data a shown in FIG. By passing, the search circuit 14
Can easily search the data in the search table 12 from the format-converted search data a.
Therefore, even when a plurality of search data are continuously input, the data of the conversion table 12 can be easily searched from the search data.

However, the above-described configuration using the format conversion unit 15 performs format conversion by executing software, so that it takes a long time for format conversion, and therefore, there is a problem that a high-speed search operation cannot be performed. there were. Therefore, an object of the present invention is to perform a high-speed search when searching for data to be searched for in a search table based on search data.

[0010]

SUMMARY OF THE INVENTION In order to solve such a problem, the present invention has a plurality of blocks, and one search data composed of a plurality of input unit data is provided for each unit data. A first storage unit stored in each block, and a search having a plurality of blocks, wherein search target data including a plurality of unit data searched by the search data is stored in each block for each unit data. A search circuit for comparing the search data in the first storage unit and the plurality of data to be searched in the search table for each block and searching for the data to be searched. A block for designating each block of the first storage unit in association with each block of the search table each time each unit data of the search data is stored in each block of the first storage unit between the search table and the search table It is provided with a tough. Also,
The block designator controls a plurality of selectors for commonly inputting each unit data of each block of the first storage unit, and controls the selectors so that each unit data input to each selector corresponds to each block of the search table. And a second storage unit in which the designation information of each block of the first storage unit is stored in association with the input search data, and the selection circuit stores each unit data of the search data in the first storage unit. Each time the data is stored in each block of the storage unit, the designation information of the second storage unit is input to switch and control each selector. The search circuit is provided in a gateway device connected to the network and configured to transfer a frame received from the network to a transfer destination according to a destination included in the frame. The destination is used as search data. The search data is searched, and the transfer destination of the frame is determined based on the searched data.

[0011]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a block diagram showing a configuration of a main part of a search circuit according to the present invention. The search circuit is arranged in a gateway device, and when a frame is received, the frame is transferred from destination information included in the received frame. This is a circuit for searching for a transfer destination in order to determine a destination.

In FIG. 1, the search circuit includes a register 11 for holding search data a for searching for a transfer destination of a received frame, and a search table 12 in which the transfer destination data (ie, data to be searched) is registered. And register 11
And a data comparison unit 21 for comparing and collating the search data with the data in the search table 12.

When the search circuit configured as described above receives a frame from a network (not shown), the destination information included in the received frame is stored in the register 11 as, for example, 32-bit search data a. In this case, the 32-bit search data a is stored in each of the blocks A, B, C, and D of the register 11 as unit data divided into 8-bit units. The search table 12 stores 32-bit transfer destination information corresponding to each of the entries e1 to en. The 32-bit transfer destination information of one entry e is:
Each of the blocks E, F, G, and H is divided into eight bits and stored.

Here, when the search data a is stored in the register 11, the data comparison section 21 converts the data stored in each of the blocks A, B, C, and D of the register 11 into the search data a.
In synchronization with the search point designation information b output when the data is stored in the register 11, the data is compared with the corresponding block data of the search table 12 for each block. That is, as an example, when the search point designation information b is input, the contents of the selection signal of the selection circuit described later are the data of the blocks A, B, C, and D of the register 11 and the blocks H and E of the search table 12 at this time. , F, and G, the data of the block A of the register 11 is compared with the data of the block H of each of the entries e1 to en of the search table 12, respectively. The data of the block B of the register 11 is stored in each entry e1 of the search table 12.
Ｅｎen is compared with the data of the block E.
Further, the data of the block C of the register 11 is compared with the data of the block F of each of the entries e1 to en of the search table 12 for matching. Furthermore, the data of the block D of the register 11 is stored in each entry e of the search table 12.
The data is compared with the data of the blocks G of 1 to en.

As a result of such a comparison, each block E corresponding to each data of each block A to D of the register 11
The data of the entry e of the search table 12 having .about.H is determined as the transfer destination of the received frame. As described above, when the search data of each block of the register 11 is input, a block to be compared in the search table 12 is selected based on the search point designation information b instructed in synchronization with the storage of the search data. By providing the data comparison unit 21 for comparing the coincidence of both data, the data search operation of the search table 12 can be performed at high speed.

FIG. 2 is a block diagram showing a specific configuration of the data comparing section 21. The data comparing unit 21 includes a block specifying unit that specifies each block of the register 11 and each block of the search table 12 in association with each other, and a data comparing circuit. The block specifying unit includes a selector as shown in FIG. The selector circuit 31 includes a selection circuit 35 for selecting each of the selectors 31 to 34 by a selection signal d, and a register 36 for outputting selection information to the selection circuit 35. Here, the data of the blocks A, B, C, and D of the register 11 are commonly output to the input sides of the selectors 31 to 34. In the register 36, a plurality of setting data c are stored in advance in correspondence with a plurality of search data by software setting.

Next, the operation of the data comparing section 21 shown in FIG. 2 will be specifically described. When the selection circuit 35 receives the search point designation information b output from an output unit (not shown) when the search data a is stored in the register 11, the selection circuit 35
6, and outputs a selection signal d corresponding to the setting data c to each of the selectors 31-34. That is, as an example, when the setting data c indicates a comparison instruction between the data of the blocks A, B, C, and D of the register 11 and the data of the blocks H, E, F, and G of the search table 12, , The selector 34 is controlled so that each data of the block A of the register 11 and the data of the block H of the search table 12 are compared. Further, the selector 31 is controlled so that each data of the block B of the register 11 and each data of the block E of the search table 12 are compared.
Further, the block C of the register 11 and the search table 12
The selector 32 is controlled so that each data of the block F is compared with each other. Furthermore, the selector 33 is controlled so that each data of the block D of the register 11 and each data of the block G of the search table 12 are compared.

In a data comparing circuit (not shown) of the data comparing section 21, data of each block of the register 11 is compared with data of a designated block of the search table 12 for each of the entries e1 to en. As a result of the comparison, an entry e of the search table 12 having each of the blocks E to H that matches all the data of each of the blocks A to D of the register 11 is obtained as entry data, and the entry data is used as a transfer destination of the received frame. It is determined. Each data of each block A to D of the register 11 is added to each block E.
If the data of .about.H do not match (including the case where the data does not partially match), the mismatch information is sent to a higher-level device (not shown) inside the device to notify that the transfer destination cannot be determined.

After the comparison and collation of all the blocks A to D of the first search data a are performed, the second search data is stored in the register 11, and the search point instruction information b is output. And the selection circuit 35
6, the setting data c corresponding to the second search data is input to each selector 3 as a selection signal d.
Output to 1-34. Then, this selector 31 compares the data of the blocks A, B, C, and D of the register 11 with the data of the blocks G, H, E, and F of the search table 12, respectively. ~
34 is controlled.

Then, the data comparison circuit compares the data of each block of the register 11 with the data of the designated block of the search table 12 in the same manner, and determines whether the transfer destination of the received frame or the transfer destination cannot be determined. Is determined. After that, when the third search data is stored in the register 11, the same selector control, transfer destination determination, and other processing are performed.

As described above, a plurality of setting data c corresponding to a plurality of search data are registered in the register 36 in advance, and when the search data is stored in the register 11, the selection circuit 35
Outputs the setting data c of the register 36 as the selection signal d to the selectors 31 to 34 in synchronization with the search point designation information b output based on the storage of the search data, and switches the selectors 31 to 34. Each selector 31-34
Is configured to compare and collate the data of each block of the register 11 with any data of each block of the search table 12, so that a plurality of search data arrives continuously and the unit data constituting the search data Even if the storage order (input order) of the search data stored in the register 11 differs for each search data, the search target data of the search table 12 can be searched at high speed from each search data stored in the register 11. .

In this embodiment, the unit data stored in one block is 8 bits, and the selectors are provided in units of 8 bits. 1 for each unit
One block and a selector may be provided.
Furthermore, one block and one selector may be provided for each bit unit of 1 bit unit or 4 bit unit. Further, the selectors 31 to 34 can be easily configured by a normal logic circuit, that is, a gate circuit such as an AND circuit or an OR circuit. Further, since the present search circuit is provided in the gateway device connected to the network and transferring the frame received from the network to the transfer destination according to the destination included in the frame, the gateway device determines the transfer destination of the frame at high speed. can do. It should be noted that the same effect can be obtained when the present search circuit is applied to a device other than the gateway device.

[0023]

As described above, according to the present invention, one search data having a plurality of blocks and including a plurality of input unit data is stored in each block for each unit data. A first storage unit, a search table having a plurality of blocks, and a search table in which search target data including a plurality of unit data searched by the search data is stored in each block for each unit data; In a search circuit for comparing the search data in the first storage unit and the plurality of data to be searched in the search table for each block and searching for the data to be searched, a search circuit is provided between the first storage unit and the search table. , A block designating unit is provided, and the block designating unit associates each block of the first storage unit with each block of the search table each time each unit data of the search data is stored in each block of the first storage unit. Even if a plurality of pieces of search data arrive continuously and the storage order of the unit data constituting the search data in the first storage unit differs for each search data, the first It is possible to search the search target data of the search table at high speed from each search data stored in the storage unit. Further, the block designating unit includes a plurality of selectors for commonly inputting each unit data of each block of the first storage unit, and a selector so that each unit data input to each selector corresponds to each block of the search table. And a second storage unit in which the designation information of each block of the first storage unit is stored in association with the input search data, so that a simple and economical configuration is provided. Thus, each block in the first storage unit can be associated with each block in the search table. Further, since the search circuit is applied to a gateway device connected to the network and transferring a frame received from the network to a transfer destination according to a destination included in the frame, the gateway device determines a frame transfer destination at high speed. can do.

[Brief description of the drawings]

FIG. 1 is a diagram schematically showing a search circuit according to the present invention.

FIG. 2 is a block diagram illustrating a main configuration of the search circuit.

FIG. 3 is a diagram schematically showing a conventional search circuit.

FIG. 4 is a diagram showing a state of a search operation of a conventional search circuit.

[Explanation of symbols]

11 register (first storage unit), 12 search table, 21 data comparison unit, 31-34 selector, 35
... Selection circuit, 36 ... Register (second storage unit), A,
B, C, D, E, F, G, H ... block, a ... search data, b ... search point designation information, c ... setting data, d ...
Select signal.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) G06F 17/30 G11C 15/04 631 H04L 12/28 H04L 12/46 H04L 12/56 JICST file (JOIS)

Claims (3)

(57) [Claims] A first storage unit having a plurality of blocks, wherein one search data including a plurality of input unit data is stored in each block for each unit data; A search table in which search target data including a plurality of unit data searched by the search data is stored in each block for each unit data, and the search data in the first storage unit and In a search circuit for searching for data to be searched by comparing a plurality of pieces of data to be searched for in a search table with each block for each block, each of the search data is provided between the first storage unit and the search table. A block designating unit for designating each block of the first storage unit in association with each block of the search table each time unit data is stored in each block of the first storage unit; Search circuit. 2. The block specifying unit according to claim 1, wherein the block specifying unit searches for a plurality of selectors commonly inputting each unit data of each block of the first storage unit and each unit data input to each of the selectors. A selection circuit that controls a selector so as to correspond to each block of the table; and a second storage unit that stores designation information of each block in the first storage unit in association with input search data, A selector circuit for inputting specification information of a second storage unit and controlling switching of each selector each time each unit data of the search data is stored in each block of the first storage unit; . 3. The search device according to claim 1, wherein the search circuit is provided in a gateway device connected to a network and configured to transfer a frame received from the network to a transfer destination in accordance with a destination included in the frame. A search circuit that searches the searched data for the searched data in the search table, and determines a transfer destination of the frame based on the searched searched data.