JP2006042288A - Semiconductor integrated circuit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a semiconductor integrated circuit capable of performing an SNMP (Simple Network Management Protocol) processing with less storage capacity. <P>SOLUTION: An SNMP processing circuit 15 comprises: a variable recording unit 21; a buffer memory 22; a message reception processing unit 23; a basic information extraction processing unit 24; a variable extraction processing unit 25; an answer creation processing unit 26; a message creation processing unit 27; and a message transmission processing unit 28. The basic information extraction processing unit 24 moves basic information to a first region wherein a header is stored. The variable extraction processing unit 25 interprets a plurality of variables and writes them in a second region following the first region. The answer creation processing unit 26 reads a plurality of values corresponding to the plurality of variables from the variable recording unit 21 and writes them in a final third region of the buffer. The message creation processing unit 27 creates basic information as an answer and writes it in a fourth region preceding to the third region, thereby creating an SNMP message as an answer. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a semiconductor integrated circuit for performing SNMP (Simple Network Management Protocol) processing.

  Currently, a hierarchical model of a communication protocol called TCP / IP is widely used in the Internet, LAN (Local Area Network) and the like. FIG. 6 is a diagram showing an approximate correspondence between each layer of the TCP / IP hierarchical model and each layer of the OSI (Open Systems Interconnection) reference model established by ISO (International Organization for Standardization).

SNMP (Simple Network Management Protocol) is widely used as a protocol for managing the state related to communication of devices using the TCP / IP hierarchical model. SNMP is defined in RFC (Request For Comments) 1157, 1901, 1902, and the like.
As shown in FIG. 6, SNMP is a protocol corresponding to the application layer of the TCP / IP hierarchical model, and uses UDP (User Datagram Protocol) as a lower layer (transport layer). UDP uses IP (Internet Protocol) as a lower layer (Internet layer). In addition, various IPs can be used as lower layers (network interface layers), but Ethernet (registered trademark) is widely used in general.

In SNMP, a device for managing other devices is called an SNMP manager, and a device managed by the SNMP manager is called an SNMP agent.
SNMP agents are often routers, bridges, and the like, and semiconductor integrated circuits for performing SNMP processing have come to be used in order to implement SNMP at low cost in these devices. Note that a semiconductor integrated circuit for performing such SNMP processing may also have UDP, IP, and Ethernet (registered trademark) functions.

In a semiconductor integrated circuit having an SNMP function, an Ethernet (registered trademark) frame, an IP datagram, a UDP datagram, and / or a reception buffer for receiving an SNMP message and a transmission buffer for transmitting, A work area for creating an SNMP message is required. Generally, about 512 bytes are required as a reception buffer, about 40 bytes as a work area, and about 512 bytes as a transmission buffer.
As described above, the semiconductor integrated circuit having the SNMP function requires a large amount of memory, which increases the cost.

By the way, in a device that transmits information to the partner side using a network protocol, a transmission buffer and a reception buffer are provided separately, and when the partner side requests retransmission of the previous transmission information, The retransmit information is directly reconfigured from the contents and transmitted to the partner machine. When a signal that cannot be recognized or cannot be accepted is received from the partner machine, the rejection signal is re-established in the receive buffer from the contents of the receive buffer. There is known an information observation transmission device that is configured to transmit from a reception buffer to a partner device side and retain the contents of the transmission buffer (see, for example, Patent Document 1).
However, the information observation / transmission apparatus described in Patent Document 1 reduces the RAM capacity necessary for the system, but does not relate to SNMP processing.

A system for selectively separating point-to-point protocol header information from a packet received from a network, wherein the sub-protocol receives the packet and identifies the sub-protocol used for the packet from there A detection device and a sub-protocol detection device, and based on the identification of the sub-protocol, separates at least a portion of the point-to-point protocol header information from the packet and thereby the entire packet There is known a system including a header separation device that reduces the size of (see, for example, Patent Document 2).
However, the system described in US Pat. No. 6,057,059 separates at least a portion of the point-to-point protocol header information from the packet, thereby reducing the overall size of the packet and reducing the system bus Although the effective bandwidth is widened, it is not related to SNMP processing.

JP 2001-127772 A JP 2001-60984 A

  In view of the above, an object of the present invention is to provide a semiconductor integrated circuit capable of performing SNMP processing with a small storage capacity.

  In order to solve the above problems, a semiconductor integrated circuit according to the present invention is a semiconductor integrated circuit for performing SNMP (Simple Network Management Protocol) processing, and records values of a plurality of variables which are management targets of SNMP. A variable recording unit, a buffer memory having a plurality of buffers for storing frames, packets, and / or datagrams respectively, and a frame including a first SNMP message in one of the plurality of buffers When a packet and / or datagram is written by a lower layer, a message reception processing unit for receiving a notification from the lower layer and basic information in the first SNMP message All of the area in the buffer where frames, packets and / or headers in the datagram are stored or A basic information extraction processing unit for moving and / or copying to a first area that is a part, and interpreting a plurality of variables in Variable Bindings in the first SNMP message, after the first area A variable extraction processing unit for writing to the subsequent second area and a plurality of values respectively corresponding to the plurality of variables stored in the second area are read from the variable recording unit and stored in the second area. A response creation processing unit for creating Variable Bindings as a reply to the first SNMP message in correspondence with each of the plurality of variables, and writing in a third area at the end of one buffer; The basic information as a response to the first SNMP message is created based on the basic information stored in the first information, and written to the fourth area before the third area, thereby writing the first SNMP message. Answers and A message creation processing unit for creating the second SNMP message, and a message transmission processing unit for notifying the lower layer that the second SNMP message has been created.

  In this semiconductor integrated circuit, the basic information in the first or second SNMP message may include a version, a community, a PDU (Protocol Data Unit), a request ID, an error status, and / or an error index.

  Further, the plurality of buffers may have a fixed length.

The best mode for carrying out the present invention will be described below with reference to the drawings. In addition, the same referential mark is attached | subjected to the same component and description is abbreviate | omitted.
FIG. 1 is a block diagram showing an outline of a system using an SNMP (Simple Network Management Protocol) processing circuit as an embodiment of the present invention. This system includes an SNMP manager 1 and an SNMP agent 11 connected to a network N. The SNMP manager 1 and the SNMP agent 11 are connected via a network N. In the present embodiment, the network N is assumed to be Ethernet (registered trademark).

The SNMP manager 1 includes a network controller 2, an IP (Internet Protocol) processing circuit 3, a UDP (User Datagram Protocol) processing circuit 4, and an SNMP processing circuit 5.
The SNMP agent 11 includes a network controller 12, an IP processing circuit 13, a UDP processing circuit 14, and an SNMP processing circuit 15 as an embodiment of the present invention.

FIG. 2 is a diagram showing an outline of the internal configuration of the SNMP processing circuit 15. As shown in FIG. 2, the SNMP processing circuit 15 includes a variable recording unit 21, a buffer memory 22, a message reception processing unit 23, a basic information extraction processing unit 24, a variable extraction processing unit 25, and an answer creation processing unit. 26, a message creation processing unit 27, and a message transmission processing unit 28.
The variable recording unit 21 records values of a plurality of variables that are SNMP management targets.

The buffer memory 22 is shared by the network controller 2, the IP processing circuit 3, the UDP processing circuit 4, and the SNMP processing circuit 5, and has a plurality of buffers for storing Ethernet (registered trademark) frames. In the present embodiment, the plurality of buffers are assumed to have a fixed length of, for example, several tens of bytes in order to simplify memory management. Note that the plurality of buffers may be variable length.
When the SNMP manager 1 (see FIG. 1) transmits an Ethernet (registered trademark) frame including an SNMP message to the SNMP agent 11 (see FIG. 1), the transmitted Ethernet (registered trademark) frame is sent to the buffer memory 22 by the network controller 12. Are written in one of the plurality of buffers.

FIG. 3 is a diagram showing an example of an Ethernet (registered trademark) frame format including an SNMP message. As shown in FIG. 3, the Ethernet (registered trademark) frame includes an Ethernet (registered trademark) header and an IP datagram.
The Ethernet (registered trademark) header has a total of 14 bytes including a source MAC (Media Access Control) address (6 bytes), a destination MAC address (6 bytes), and a data type (2 bytes).

The IP datagram includes an IP header and a UDP datagram.
IP header includes version (4 bits), header length (4 bits), service type (1 byte), datagram length (2 bytes), ID (2 bytes), flag (3 bits), fragment offset (13 bits) ), TTL (1 byte), protocol number (1 byte), header checksum (2 bytes), source IP address (4 bytes), and destination IP address (4 bytes). Note that the IP header can include options in units of 32 bits.

The UDP datagram includes a UDP header and an SNMP message.
The UDP header has a total of 8 bytes including a source port number (2 bytes), a destination port number (2 bytes), a length (2 bytes), and a checksum (2 bytes).

The SNMP message includes basic information and Variable Bindings.
The basic information includes version, community, PDU (Protocol Data Unit), request ID, error status, and error index.
In SNMP, a combination of an object ID and an instance, or a combination of an object ID, an instance, and a value is called Variable Binding, and a set of Variable Bindings is called Variable Bindings.
Basic information and Variable Bindings are variable length.

  The Ethernet (registered trademark) header is used by the network controller 12, the IP header is used by the IP processing circuit 13, and the UDP header is processed by the UDP processing circuit 14. . The Ethernet (registered trademark) header, the IP header, and the UDP header may be left as they are after being used, or may be deleted. Which is left to the implementation of Ethernet (registered trademark), IP, and UDP.

Referring to FIG. 2 again, the Ethernet® frame is written by the network controller 12 into one of the plurality of buffers in the buffer memory 22, and the network controller 12, the IP processing circuit 13, and the UDP processing circuit. After the processing of 14, the UDP processing circuit 14 notifies the message reception processing unit 23 to that effect.
When receiving the notification from the UDP processing circuit 14, the message reception processing unit 23 instructs the basic information extraction processing unit 24 to operate.

At this time, the Ethernet (registered trademark) header, the IP header, and the UDP header (see FIG. 3) are unnecessary, and the area in which the Ethernet (registered trademark) header, the IP header, and the UDP header are stored is It can be used as a free area.
The basic information extraction processing unit 24 converts the basic information in the SNMP message into a first area in the buffer (Ethernet (registered trademark) header, IP header, part of the area in which the UDP header was stored, or Move and / or copy all). FIG. 4A is a diagram showing a state in the buffer at this time. Note that the original basic information is unnecessary and may be left as it is or may be deleted. Further, unnecessary information in the basic information may not be moved and / or copied. Furthermore, information such as the source IP address (in the IP header), the source port number (in the UDP header), the destination port number (in the UDP header), etc. is moved and / or copied to the first area together with the basic information. It is also good.

  Next, the variable extraction processing unit 25 interprets Variable Bindings in the SNMP message, and stores each variable in the second area after the first area. FIG. 4B is a diagram showing a state in the buffer at this time. At this time, the second area can be reduced (saved) by converting each variable to indicate an entry in the OID database held in the SNMP processing circuit 15. Note that the original Variable Bindings is unnecessary and may be left as it is or may be deleted. In any case, the area in which the original variable bindings are stored can be used as a free area.

  Next, the answer creation processing unit 26 reads values corresponding to the respective variables in the second area from the variable recording unit 21, creates Variable Bindings as a response to the SNMP message received from the SNMP manager 1, Write to the third area at the end of the buffer. FIG. 5A is a diagram showing a state in the buffer at this time. Note that each variable in the second area is unnecessary and may be left as it is or may be deleted. In any case, the second area can be used as an empty area.

  Next, the message creation processing unit 27 creates basic information as a reply to the SNMP message received from the SNMP manager 1 based on the basic information in the first area, and the fourth information before the third area. The SNMP message as an answer to the SNMP message received from the SNMP manager 1 is created. FIG. 5B is a diagram showing a state in the buffer at this time. The basic information in the first area is unnecessary and may be left as it is or may be deleted. In any case, the first area can be used as an empty area.

When the SNMP message as a reply to the SNMP message received from the SNMP manager 1 is created in this way, the message transmission processing unit 28 notifies the UDP processing circuit 14.
Thereafter, the UDP processing circuit 14 writes the UDP header in the area before the basic information in FIG. 5B, the IP processing circuit 13 writes the IP header in the area before the UDP header, and the network controller 12 It is possible to create an Ethernet (registered trademark) frame by writing an Ethernet (registered trademark) header in an area in front of the IP header.

  Thus, according to the SNMP processing circuit 15, an SNMP message as a reply to the SNMP message received from the SNMP manager 1 is created in the buffer in which the Ethernet (registered trademark) frame received from the SNMP manager 1 is stored. can do. This makes it possible to perform SNMP processing with a small storage capacity. Further, since no new memory area is required other than the buffer in which the received Ethernet (registered trademark) frame is stored, when the processing load of the SNMP processing circuit 15 is large, the memory cannot be secured and the SNMP processing performance is deteriorated. There is nothing to do.

  Although this embodiment performs SNMP processing, it is possible to use the header portion of the lower protocol as a free area in other protocol processing.

  The Ethernet (registered trademark) header has 14 bytes, and may be different from other protocols (for example, PPP (Point to Point Protocol)) of the network interface layer. However, even when a network interface layer other than Ethernet (registered trademark) is used, it can be applied by adjusting the basic information and variable conversion method according to the size of the free area. When using a part of information of Ethernet (registered trademark) header and IP header in higher-level protocol, the header may not be deleted, but only necessary information can be extracted to reduce the header, or a fixed length buffer. It can be applied by preparing a dedicated area inside.

  The free space in the buffer (see FIGS. 3 to 5) is used for input / output among the basic information extraction processing unit 24, variable extraction processing unit 25, answer creation processing unit 26, and message creation processing unit 27. In addition, the basic information extraction processing unit 24, the variable extraction processing unit 25, the answer creation processing unit 26, and the message creation processing unit 27 can be used as work areas for internal processing.

  In FIG. 3, it is also possible to use an empty area after the received Ethernet (registered trademark) frame. However, whether or not this free area exists depends on the received Ethernet (registered trademark) frame length. When this empty area exists, the received Ethernet (registered trademark) frame length is short. That is, since the number of variables included in Variable Bindings is small, the Ethernet (registered trademark) header, IP header, and UDP header regions are sufficient. Therefore, using an empty area after the received Ethernet (registered trademark) frame is less effective than using the Ethernet (registered trademark) header, IP header, and UDP header areas.

  In addition, when the network controller 12, the IP processing circuit 13, and the UDP processing circuit 14 operate while holding unnecessary areas (areas where each header is stored) in the buffer, the received message is before the received SNMP message. Can be expected to have free space. In such a case, the buffer may have a variable length.

  In addition, when the SNMP message length as a response becomes larger than the received SNMP message length as a result of making the buffer variable, the transmission buffer may be secured separately from the reception buffer. At this time, the work area can be either a reception buffer or a transmission buffer, or can be divided and taken as both.

  The present invention can be used in a semiconductor integrated circuit for performing SNMP (Simple Network Management Protocol) processing. This circuit can be used in routers, bridges, and the like.

1 is a diagram showing a system using a semiconductor integrated circuit according to an embodiment of the present invention. The figure which shows the outline | summary of the internal structure of the SNMP process circuit 15 of FIG. The figure which shows the format of the flame | frame in the buffer memory 22 of FIG. The figure which shows the mode in the buffer memory 22 of FIG. The figure which shows the mode in the buffer memory 22 of FIG. The figure which shows the correspondence of an OSI reference model and a TCP / IP hierarchy model.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 SNMP manager, 2 Network controller, 3 IP processing circuit, 4 UDP processing circuit, 5 SNMP processing circuit, 11 SNMP agent, 12 Network controller, 13 IP processing circuit, 14 UDP processing circuit, 15 SNMP processing circuit, 21 Variable recording part , 22 buffer memory, 23 message reception processing unit, 24 basic information extraction processing unit, 25 variable extraction processing unit, 26 reply creation processing unit, 27 message creation processing unit, 28 message transmission processing unit

Claims (3)

A semiconductor integrated circuit for performing SNMP (Simple Network Management Protocol) processing,
A variable recording unit for recording values of a plurality of variables to be managed by SNMP;
A buffer memory having a plurality of buffers for respectively storing frames, packets, and / or datagrams;
To receive a notification from the lower layer when a frame, packet, and / or datagram containing the first SNMP message is written by the lower layer in one of the plurality of buffers. A message reception processing unit;
A first area in which basic information in the first SNMP message is all or part of an area in which a header in a frame, packet, and / or datagram in the one buffer is stored A basic information extraction processing unit for moving and / or copying to
A variable extraction processing unit for interpreting a plurality of variables in Variable Bindings in the first SNMP message and writing in a second area following the first area;
A plurality of values respectively corresponding to a plurality of variables stored in the second area are read from the variable recording unit, and each of the values is associated with the plurality of variables stored in the second area. An answer creation processing unit for creating Variable Bindings as a reply to one SNMP message and writing it in the third area at the end of the one buffer;
By creating basic information as a reply to the first SNMP message based on the basic information stored in the first area and writing it in the fourth area before the third area, A message creation processing unit for creating a second SNMP message as a reply to the first SNMP message;
A message transmission processing unit for notifying the lower layer that the second SNMP message has been created;
A semiconductor integrated circuit comprising:   The semiconductor integrated circuit according to claim 1, wherein the basic information in the first or second SNMP message includes a version, a community, a PDU (Protocol Data Unit), a request ID, an error status, and / or an error index.   The semiconductor integrated circuit according to claim 1, wherein the plurality of buffers have a fixed length.

Images