JP2005252954A - Table retrieval apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology for improving a degree of freedom in designing a device or for simplifying the device by retrieving a plurality of tables using one retrieval section according to a predetermined order. <P>SOLUTION: A packet type is identified from a received packet, an identification code corresponding to the packet type is generated, and information of a field required for retrieval is extracted from the packet. A search key corresponding to a type of the field is generated, a plurality of tables are retrieved for the search key in an order corresponding to the identification code, and result information is generated and outputted from a retrieval result relating to the packet. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a technique for searching a plurality of tables. For example, the present invention relates to a destination table search process necessary for determining a packet relay destination in a network relay device.

  In recent years, speeding up of the Internet and corporate networks has progressed, and high-speed processing of relay devices has been demanded. Along with this, the destination table search processing unit mounted on the relay apparatus is also required to be faster, smaller, and consume less power.

  FIG. 7 is a diagram illustrating a conventional destination table search processing unit. The destination table search processing unit is mounted on the network relay device as a part of the packet processing unit together with the destination table.

  The destination table is generally built on a memory such as CAM or RAM, and is generally mounted separately from the packet processing unit. For this reason, as shown in FIG. 7, when processing corresponding to packet types A and B is performed, the destination table requires three types for each of packet types A and B, for a total of six types, each of which is an independent memory 4A. -1-4A-3, 4B-1-4B-3. A plurality of table search processing units A-1 to A-3, B-1 to B-3 corresponding to these are provided via individual interface circuits 8A-1 to 8A-3, 8B-1 to 8B-3. Search processing is performed independently.

Further, as a prior art related to the present invention, for example, there is a technique disclosed in Patent Document 1 below.
JP 2002-335275 A

The conventional technology described above has the following problems.
When a packet processing unit including a plurality of destination table search processing units is mounted on a device such as an FPGA or ASIC or a general-purpose device typified by a network processor, it is possible to mount interfaces with all types of destination tables on one device. In many cases, this is not possible due to physical factors such as the number of pins on the device.

  For example, in the apparatus of FIG. 7, as indicated by the dotted line, the destination table search processing unit is divided into three devices and mounted in two. For this reason, the problem that the enlargement of an apparatus and the increase in power consumption and cost will arise.

  In the conventional destination table search processing unit, if the search order is determined by the circuit configuration and FIG. 7 is used, the order is 4A-1 → 4A-2 → 4A-3 or 4B-1 → 4B-2. The search can be performed only in the order of 4B-3, and there has been a problem that the search contents and the search order cannot be changed due to the user's request or the response to the new technology.

  In addition, since the destination table search processing unit in the prior art performs each table search sequentially, it can only search in the order of arrival of the search request. There arises a problem that priority control cannot be performed.

Furthermore, in the prior art, an external device (CAM, RAM, etc.) used as a destination table
Since the interface signal specialized for the device is generated, the device is fixed to a specific type, and there arises a problem that the user cannot freely select a table device or change to a new device.

  Therefore, an object of the present invention is to provide a technique for improving the degree of freedom in device design and simplifying the device by allowing a single search unit to search a plurality of tables in a predetermined order.

In order to solve the above problems, the present invention includes the following means. That is, the table search apparatus of the present invention identifies the packet type from the received packet, generates an identification code corresponding to the packet type, and extracts field information necessary for the search from the packet. Generating a search key according to the type of the field, and transmitting the identification code and the search key;
A search unit that searches a plurality of tables for the search key in the order according to the identification code, and outputs the search results;
A result information generating unit that generates and outputs result information from a search result relating to the packet;
The search identification unit, the search unit, and the result information generation unit are mounted on one device, and the search is performed on a table outside the device.

The search unit
An order determining unit that determines a search order corresponding to the identification code based on a predetermined search sequence;
A search request unit that provides search keys in the order determined by the order determination unit;
May be provided.

The order determination unit may store the search sequence in a rewritable manner.
The table search device has a plurality of queues for storing the search key in the search request unit,
The search unit may further include a search arbitration unit that reads a search key from each queue according to priority.

The search unit may include an interface unit that searches the table based on a predetermined interface sequence for the search key.
The interface unit may store the interface sequence in a rewritable manner.

The table search method of the present invention includes:
Identifying the packet type from the received packet and generating an identification code according to the packet type;
Extracting field information necessary for the search from the packet and generating a search key according to the type of the field;
Searching a plurality of tables for the search key in the order according to the identification code, and outputting the search results;
Generating and outputting result information from a search result relating to the packet;
Is performed by the apparatus.

The table search method includes the step of performing the search,
Determining a search order corresponding to the identification code based on a predetermined search sequence;
Providing a search key in the order;
May be performed.

  The table search method may refer to a storage unit that stores the search sequence in a rewritable manner in the step of determining the order.

  The table search method may perform a step of reading a search key from a plurality of queues storing the search key according to priority.

  The table search method may include a step of searching the table based on a predetermined interface sequence for the search key.

  The table search method may refer to a storage unit that stores the interface sequence in a rewritable manner when performing the search.

  FIG. 6 is a diagram for explaining the principle of the present invention. As shown in the figure, the table search apparatus 10 of the present invention includes a search identification unit 1, a search unit 2, and a result information generation unit 3. The search unit 2 includes a search request unit 5, a search mediation unit 6, a search control unit 7, an interface unit 8, and a search result identification unit (order determination unit) 9.

Specific operations will be described below.
(1) The search and identification unit 1 identifies the type of packet from the received packet, and generates an identification code that is an identification result. Further, a field necessary for the search is extracted from the packet, and a search key is generated. The identification code and the search key are stored in the search request unit 5 together with the search request.

  (2) The search request unit 5 is a FIFO composed of a memory or the like. That is, the search request unit (FIFO) stores the identification code and the search key so that they can be read out in the stored order.

  (3) The search arbitration unit 6 monitors the search request storage status of the search request unit 5, and when there is a search request, reads the identification code and the search key from the FIFO and transmits them to the search control unit 7.

  (4) The search control unit 7 identifies the type of search from the identification code, rearranges the search key into a predetermined format for the corresponding table search, and transmits it to the interface unit 8. Also, identification codes are held in the order of transmission.

  (5) The interface unit 8 generates an interface signal corresponding to the external device 4 and transmits the search key from the search control unit 7 to the external device.

  (6) A search result that is a result of the destination search is transmitted from the destination table of the external device.

  (7) The interface unit 8 receives the search result from the external device 4 and transmits it to the search control unit 7.

  (8) The search control unit 7 receives the search result from the interface unit 8 and transmits it to the search result identification unit 9 together with the held identification code.

(9) The search result identification unit 9 identifies whether further search is necessary or the search is completed based on the identification code.
If a search is necessary, a new identification code and search key are generated and stored in the search FIFO. Thereafter, (3) to (9) are repeated.
If the search is completed, the identification code and the search result are transmitted to the result information generation unit 3.

(10) The result information generation unit 3 generates destination information from the search result and transmits it.
The table retrieval apparatus 1 according to the present invention is a means for solving the problem that the contents of retrieval and the retrieval order cannot be changed by responding to the request of the apparatus / user and the new technology when performing the destination table retrieval. Taking advantage of the processing that can be performed by one search control unit, the destination table search sequence can be set, and the table search contents and search order can be changed.

  The search unit 2 includes a search order setting register 12 as a storage unit that stores a search sequence. In the above (9), the search result identifying unit 9 refers to the search order setting register from the search type code and identifies whether the search is completed. If the search is not finished, the next search identification code is determined from the search order setting register.

  In addition, in order to solve the conventional problem that destination search priority control cannot be performed in table search, the table search apparatus of the present invention takes advantage of the ability to process all destination table searches with a single search control unit. Priority control is possible. In the table search apparatus 1 of the present invention, for example, the search request unit 5 of the search unit 2 is configured by a plurality of FIFOs, and the queue configuration is such that each packet or search is stored in an individual FIFO. The search identification unit 1 and the search result identification unit 9 are provided with a function of selecting a FIFO for storing a search request for each packet and each search type. In addition, the search arbitration unit 6 is provided with a function of giving priority to the FIFO that reads the search request.

As a result, the search arbitration unit 6 reads the search requests in order from the FIFO with the highest priority in (3).
Further, as a means for solving the problem that the user can freely select a device for a table and cannot change to a new device, the table search apparatus 1 of the present invention sets an interface signal with an external device by setting. It is possible to control and select a device. Therefore, the search unit 2 includes an interface sequence setting register 13. A signal level (0, 1) according to a predetermined sequence is set in the register 13.
In the above (7), the interface unit 8 reads the interface sequence setting register 13 every clock and sends it out as an interface signal.

  According to the present invention, there is provided a technique for improving the degree of freedom in device design and simplifying a device by allowing a single search unit to search a plurality of tables in a predetermined order.

The best mode for carrying out the present invention will be described below with reference to the drawings. The configuration of the following embodiment is an exemplification, and the present invention is not limited to the configuration of the embodiment.
FIG. 1 is a schematic configuration diagram of a packet processing apparatus 10 according to the present invention. The packet processing apparatus 10 searches the destination table according to the type of packet, and performs bridge relay or IPv4 relay based on the search result.

  As shown in FIG. 1, the packet processing apparatus 10 includes a search identification unit 1, a search unit 2, a result information generation unit 3, and a destination table 4. The search unit 2 includes a search request unit 5, a search mediation unit 6, a search control unit 7, an interface unit 8, and a search result identification unit (order determination unit) 9.

  The search identifying unit 1 identifies the packet type from the received packet, generates an identification code corresponding to the packet type, extracts field information necessary for the search from the packet, A search key is generated according to the type, and the identification code and the search key are transmitted.

  The search unit 2 searches the table for the search key in the order corresponding to the identification code, and outputs the search result. The search unit 2 includes a search request unit 5, a search mediation unit 6, a search control unit 7, an interface unit 8, and a search result identification unit (order determination unit) 9.

  The search request unit 5 provides search keys and identification codes in the order determined by the search result identification unit 9. The search request unit 5 of this example is a FIFO memory and provides a search key and an identification code in the order stored by the search result identification unit 9. The search request unit 5 has a plurality of queues corresponding to the table to be searched. In the figure, a learning request queue is a queue for requesting a search for a learning table, an R request queue is a queue for requesting a search for an IPv4 routing table, an MFL request queue is a queue for requesting a search for a MAC flow table, and an IPFL request queue Are queues for requesting retrieval of IPv4 flow tables, MFI request queues are queues for requesting retrieval of MAC filtering tables, and IPFI request queues are queues for requesting retrieval of IPv4 filtering tables.

  The search arbitration unit 6 reads the search key from each queue of the search request unit 5 according to the priority and performs priority control. This priority is stored in advance in the search arbitration unit 6 so as to be rewritable. This priority control is performed in preference to the search order determined by the order determination unit based on the search sequence. That is, the order determination unit searches for the type A packet in the order of the tables A-1, A-2, and A-3, and searches for the type B packet in the tables B-1, B-2, and B-3. When the search arbitration unit 6 is set to give priority to the packet of type B and the search request for the table B-1 is made while searching the tables A-1 to A-3. The search arbitration unit 6 causes the search of the tables B-1, B-2, and B-3 to be performed with priority, and then performs the remaining searches of the tables A-1, A-2, and A-3.

  The search control unit 7 identifies the type of search from the identification code, rearranges the search key into the corresponding table search format, and transmits it to the interface unit 8. Also, identification codes are held in the order of transmission.

  The interface unit 8 includes the table based on a predetermined interface sequence for the search key. The interface unit 8 includes a storage unit (interface sequence setting register) 13 that stores the interface sequence in a rewritable manner. The interface sequence is obtained by reference. Search for.

  When the search result identification unit (including the order determination unit) 9 receives the search result and the identification code from the search control circuit, the search result identification unit 9 determines whether further search is necessary based on the identification code or whether the search is completed. If a search is necessary, an identification code and a search key are newly generated and stored in the search request unit 5. As described above, the search result identification unit 9 determines the search order by creating search keys in the order based on a predetermined search sequence and storing them in the search request unit 5.

In this embodiment, the search request unit 5 is a FIFO, and the search result identification unit 9 stores information such as a search key so as to request a search in the order determined by the search request unit 5. However, the present invention is not limited to this, and any configuration that can perform a search according to a predetermined search sequence may be used.
The result information generation unit 3 generates and outputs result information from a plurality of search results relating to the packet.

  The search identification unit 1, the search unit 2, and the result information generation unit 3 constitute a packet processing unit of the apparatus 10, and are mounted on a general-purpose device typified by a device such as an FPGA or an ASIC or a network processor. That is, in this example, the range indicated by the dotted line in FIG. 1 is mounted on one device.

  A destination table 4 is provided outside the device. The destination table 4 includes a CAM and a memory, and stores a plurality of tables such as a learning table, an IPv4 routing table, a MAC flow table, a MAC filtering table, an IPv4 flow table, and an IPv4 filtering table.

  An example of assignment of identification codes to the respective tables is shown in FIG. The assignment of the identification code is stored in the search result identification unit 9. Examples of setting the search sequence are shown in FIGS.

  In setting example-1 in FIG. 3, when the packet type is to be relayed by bridge, search is performed in the order of learning table → MAC flow table → MAC filtering table, and when the packet type is to relay IPv4, IPv4 This indicates that the setting is to search in the order of routing table → IPv4 flow table → IPv4 filtering table.

  Setting example-2 in FIG. 4 indicates that the setting is to search in the order of the IPv4 routing table → the IPv4 filtering table at the time of IPv4 relaying as in setting example-1 at the time of bridge relaying.

  FIG. 5 is an explanatory diagram of a table search method by the packet processing device (table search device) of the present embodiment. Each step (abbreviated as S1) of this table search method will be described below.

(S1) The search identifying unit 1 identifies the MAC header of the input Ethernet (registered trademark) packet, and identifies whether it is a bridge relay or an IPv4 routing relay. The search identification unit 1 generates an identification code indicating the identification result (for example, 0 for bridge, 1 for IPv4 routing), and a field required for search (MAC header for bridge, IP header for IPv4 routing). Is extracted from the input packet and a search key is generated.
When the identification result is a bridge, the search identification unit 1 first searches the queue for requesting the search of the learning table among the plurality of queues of the search request unit 5, that is, the learning request queue in the drawing and the identification code and the search Write the key. On the other hand, when the identification result is IPv4 routing, the search identifying unit 1 first identifies the queue for requesting the search of the IP routing table among the plurality of queues of the search requesting unit 5, that is, the R request queue in the figure. Write code and search key.

(S2) The search request unit 5 notifies the search arbitration unit 6 of the storage status of the search request for each queue (FIFO).

(S3) The search arbitration unit 6 monitors the storage status of the search request unit. If the identification code and the search key, that is, the search request is stored in the FIFO, the search request is sequentially read out from the FIFO with the highest priority. Send to part 7.

(S4) The search control unit 7 receives the identification code and the search key from the search arbitration unit 6, rearranges the search code corresponding to the identification code, and transmits it to the interface unit 8.
Also, an identification code and a search key are held.

(S5) The interface unit 8 receives the search key, reads the interface sequence setting register 13 for each clock, and transmits the search key to the external device that is the destination table 4 while generating an interface signal according to this interface sequence.

(S6) The external device receives the search key, and searches for destination information that matches the search key from a pre-registered table. If the comparison matches, the external device transmits the corresponding destination information together with the hit flag to the interface unit 8 as a search result. If the comparison does not match, the external device transmits a miss hit flag to the interface unit 8.

(S7) The interface unit 8 transmits the search result to the search control unit 7.

(S8) The search control unit 7 receives the search result and transmits it to the search result identification unit 9 together with the identification code and the search key held at the time of the search request.

(S9) When receiving the search result, the identification code, and the search key, the search result identifying unit 9 refers to the search order setting register 12 and obtains sequence information (search sequence). If the search end flag corresponding to the received identification code is “0” in the sequence information, the search result identification unit 9 determines that the search is continued, holds the identification code and the search result, and stores the sequence information. The next identification code is stored as a new identification code in the corresponding queue of the search request unit 5 to which the new identification code is assigned together with the search key (FIG. 2). When the search result identification unit 9 stores the new identification code and search key in the search request unit 5, the search request unit 5 repeats the processing from step 2 above.
If the search end flag corresponding to the received identification code is “1”, the search result identification unit 9 determines that the search is complete, and the result information generation unit 3 determines a series of search results related to the packet based on the sequence information. Send to. For example, in the case of the setting shown in FIG. 4, the search results received together with the identification codes 0, 2, 4 or the identification codes 1, 3, 5 are transmitted as a series of search results.

(S10) The result information generation unit 3 receives this search result, generates destination information, and transmits it.
As described above, according to the present embodiment, it is possible to perform a search process for a plurality of tables by using one interface unit 8, and the packet processing units 1, 2, and 3 can be mounted on one device. Cost reduction, downsizing, and power saving are possible.

  In the present embodiment, the search order setting register holds the search sequence in a rewritable manner, and the search order can be changed by updating the search sequence by software setting. For example, by rewriting the setting of FIG. 3 to the setting of FIG. 4, the IPv4 relay sequence can be changed from the IPv4 routing table → the IPv4 flow table → the IPv4 filtering table to the IPv4 routing table → the IPv4 filtering table.

In this embodiment, the priority is set in the order in which the search requests are read, that is, the order in which the destination table 4 is searched, so that it is possible to prioritize the search for a specific packet.
Further, in the present embodiment, the interface unit 8 creates an interface signal based on the interface sequence of the rewritable interface sequence setting register 13, so that the setting of the interface sequence setting register 13 is set to an external device (CAM, memory ), The user can freely select an external device.

<Other embodiments>
The present invention is not limited to the illustrated examples described above, and various modifications can be made without departing from the scope of the present invention.
For example, the same effects as those of the above-described embodiment can be obtained even with the configurations described below. These components can be combined as much as possible.

(Appendix 1)
The packet type is identified from the received packet, an identification code corresponding to the packet type is generated, and field information necessary for the search is extracted from the packet, and the search according to the field type is performed. A search identification unit for generating a key and transmitting the identification code and the search key;
A search unit that searches a plurality of tables for the search key in the order according to the identification code, and outputs the search results;
A result information generating unit that generates and outputs result information from a search result relating to the packet;
A table search apparatus in which the search identification unit, the search unit, and the result information generation unit are mounted on a single device, and performs the search for a table outside the device. (1)

(Appendix 2)
The search unit
An order determining unit that determines a search order corresponding to the identification code based on a predetermined search sequence;
A search request unit that provides search keys in the order determined by the order determination unit;
The table search device according to Supplementary Note 1, comprising: (2)

(Appendix 3)
The table search device according to appendix 2, wherein the order determination unit stores the search sequence in a rewritable manner. (3)

(Appendix 4)
The table search device according to appendix 2, wherein the search request unit includes a plurality of queues for storing the search keys, and the search unit further includes a search arbitration unit that reads a search key from each queue according to priority. . (4)

(Appendix 5)
The table search apparatus according to appendix 1, wherein the search unit includes an interface unit that searches the table based on a predetermined interface sequence for the search key.

(Appendix 6)
The table search device according to appendix 5, wherein the interface unit stores the interface sequence in a rewritable manner.

(Appendix 7)
Identifying the packet type from the received packet and generating an identification code according to the packet type;
Extracting field information necessary for the search from the packet and generating a search key according to the type of the field;
Searching a plurality of tables for the search key in the order according to the identification code, and outputting the search results;
Generating and outputting result information from a search result relating to the packet;
Table search method for performing the above in the apparatus. (5)

(Appendix 8)
In the step of performing the search,
Determining a search order corresponding to the identification code based on a predetermined search sequence;
Providing a search key in the order;
The table search method according to appendix 7, wherein:

(Appendix 9)
The table search method according to appendix 7, wherein the storage unit storing the rewritable search sequence is referred to in the step of determining the order.

(Appendix 10)
The table search method according to appendix 7, wherein a step of reading the search key according to the priority from a plurality of queues storing the search key is performed.

(Appendix 11)
The table search method according to appendix 7, including a step of searching the table based on a predetermined interface sequence for the search key.

(Appendix 12)
The table search method according to appendix 11, wherein, when the search is performed, a storage unit that stores the interface sequence in a rewritable manner is referred to.

Schematic configuration diagram of a packet processing apparatus according to the present invention The figure which shows the example of allocation of the identification code with respect to several tables Diagram showing search sequence setting example Diagram showing search sequence setting example Explanatory drawing of the table search method concerning this invention Principle explanatory diagram of the present invention Illustration of prior art

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Search identification part 2 Search part 3 Result information generation part 4 External device 5 Search request part 6 Search mediation part 7 Search control part 8 Interface part 9 Search result identification part 10 Packet processing apparatus (table search apparatus)
12 Search order setting register 13 Interface sequence setting register

Claims (5)

The packet type is identified from the received packet, an identification code corresponding to the packet type is generated, and field information necessary for the search is extracted from the packet, and the search according to the field type is performed. A search identification unit for generating a key and transmitting the identification code and the search key;
A search unit that searches a plurality of tables for the search key in an order according to the identification code, and outputs the search result;
A result information generating unit that generates and outputs result information from a search result relating to the packet;
A table search apparatus in which the search identification unit, the search unit, and the result information generation unit are mounted on a single device, and performs the search for a table outside the device. The search unit
An order determining unit that determines a search order corresponding to the identification code based on a predetermined search sequence;
A search request unit that provides search keys in the order determined by the order determination unit;
The table search device according to claim 1, comprising:   The table search device according to claim 2, wherein the order determination unit stores the search sequence in a rewritable manner.   The table search according to claim 2, further comprising: a search arbitration unit that has a plurality of queues for storing the search key in the search request unit, and reads a search key from each queue according to priority. apparatus. Identifying the packet type from the received packet and generating an identification code according to the packet type;
Extracting field information necessary for the search from the packet and generating a search key according to the type of the field;
Searching a plurality of tables for the search key in the order according to the identification code, and outputting the search results;
Generating and outputting result information from a search result relating to the packet;
Table search method for performing the above in the apparatus.

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