JP2008054070A - Packet switching apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a packet switching apparatus which provides improved packet processing reliability by avoiding discarding a control packet with a high processing priority. <P>SOLUTION: In the packet switching apparatus 200, each of a transfer control part 101 and an apparatus control part 102 holds a packet priority table 1200 for judging a packet processing priority. By updating the packet priority table 1200 in accordance with a packet arrival frequency, a processing priority or the like, the transfer frequency of packets addressed to the apparatus control part to the apparatus control part 102. A packet transfer part 303 transfers the packets to the apparatus control part 102 in accordance with the priority judged by the transfer control part 101. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a packet switching apparatus constituting a computer network, and more particularly to a packet switching apparatus that performs priority processing of control packets.

  The application range of a network constituted by data link technology such as Ethernet (R) has been expanded, and wide area Ethernet (R) service and the like have also become common. Ethernet (R) used there is a standard data transfer speed such as Gigabit Ethernet (R), 10 Gigabit Ethernet (R), etc., and packet switching devices such as switches and routers that accommodate these line interfaces. However, improvement of packet processing capability is demanded.

  In the packet switching apparatus, the transfer of packets from line to line is the first function, and the processing capacity has been demanded to be increased. However, on the other hand, the processing for packets addressed to the device itself is also accelerated, such as the communication of the device itself, the communication that generates a packet to be discarded within the packet switching device, or the communication that uses a packet that cannot be transferred by hardware autonomous processing alone. Is starting to be demanded. In other words, higher speed is required for packet processing in the device control unit that processes packets addressed to the device itself.

  Thus, packet processing of the packet switching apparatus will be described. Non-patent document 1 describes packet processing in general network communication. Hereinafter, the internal processing of the packet switching apparatus in the processing above the second layer (hereinafter referred to as the second layer) in the OSI (Open System Interconnection) reference model (see Non-Patent Document 1) will be described.

  In general, a packet may represent a unit of data handled in the third layer (hereinafter referred to as the third layer) in the OSI reference model, or may represent data in general handled in network communication configured by a packet switching device. . On the other hand, the unit of data handled in the second layer is called a frame.

  As can be seen from the OSI reference model, frames and packets are names based on hierarchical distinction of communication data in a nested structure. Therefore, the packet switching device here is also called a packet switching device together with a device that performs frame transfer processing. Further, hereinafter, data processed in the packet switching apparatus is referred to as a packet, and particularly referred to as a frame when the processing of the second layer is described.

  The frame received from the input line analyzes the layer 2 header information and transmits it to the output line to which the destination device indicated by the layer 2 header information belongs as a frame transfer process, or from the layer 2 header information to the own device. In some cases, the packet is transferred as a router.

  Also when operating as a router, the third layer header information is analyzed and, as a packet transfer process, the second layer header information is added to the destination indicated by the third layer header information and transmitted to the destination output line. There are cases where the third layer header information is a packet addressed to the own apparatus.

When the destination MAC (Media Access Control) address, which is a part of the second layer header information of the input frame, specifies the own device defined by the protocol, the frame is referred to as the own destination frame. The destination frame of the self-addressed frame includes a case where the destination MAC address matches the MAC address set in the self-device, and a case where the MAC address is determined by a protocol so that all devices on the network can receive. Further, when the destination IP address that is a part of the third layer header information of the packet designates the own device defined by the protocol, it is called a self-addressed packet. The packet switching device processes the self-addressed frame and the self-addressed packet by the device control unit. (See Non-Patent Document 2.)
The self-addressed frame and the self-addressed packet processed by the device control unit include a control frame and a control packet for performing control communication with other devices on the network. The control frame is determined from the second layer header information and the like. The control packet is discriminated from the third layer or higher header information or packet data. Control frames, control packets, and the like are subjected to packet processing at the device control unit.
Andrew S. Tannenbaum, “Computer Network”, pp 50-61, Nikkei Business Publications, 2003. W. Stevens, “TCP / IP Illustrated, Volume1: The Protocols”, pp112, Addison-Wesley, 1994.

  When the transmission speed of the line interface is low or the packet switching apparatus has a small number of lines to be accommodated, the amount of self-addressed frames and self-addressed packets processed by the device control unit may exceed the processing capacity of the device control unit. It was not a problem. However, with an increase in the transmission speed of the line interface and the increase in the number of lines to be accommodated, in the packet switching device, priority is given to packet processing in the device control unit, and it is provided inside the device such as the device control unit and packet transfer unit. The storage unit has a queue for packet processing, and priority processing is performed according to the packet type.

  In the conventional packet switching device, when the amount of packet transfer to the device control unit increases, there are cases where waiting packets for processing stay in the queue and there is no free space in the queue. At this time, if the free space in the queue falls below a certain amount, the packet destined for the apparatus control unit is discarded. When the control packet in the queue is discarded due to the discard of the packet, there is a problem that the function of the device control unit by the control packet to be processed with priority is stopped. In addition, the packets in the queue contain a mixture of packets and frames that need to be changed when the queue is input based on the processing speed and priority of the device control unit. The packet or frame that requires the above processing cannot be extracted from the queue, causing a problem that the packet is discarded.

  An object of the present invention is to provide a packet switching device that improves the reliability and security of packet processing by reducing the frequency of discarding packets and frames that require priority processing in the device control unit. To do.

  In order to achieve the above object, the present invention provides a packet switching device that transmits and receives packets, and determines a processing priority of the packet based on information included in the packet received by the packet switching device. A packet search control unit for searching for a destination of the packet based on information included in the packet received by the packet switching device, and packet processing for a packet whose destination searched by the packet search control unit is addressed to the own device. A device control unit that performs the packet control, and a packet transfer unit that transfers the packet to the device control unit in accordance with the processing priority determined by the transfer control unit. The processing priority of the packet is changed according to the device control unit, and the device control unit Employing a configuration for changing the processing priority of the packet in accordance with the sense frequency and the like.

  According to the present invention, the packet processing priority in the device control unit and the packet transfer frequency to the device control unit can be adjusted according to the arrival frequency, priority, etc. of the packet. It is possible to reduce discards and thereby increase the reliability of the packet switching device.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  First, the configuration of the network including the packet switching apparatus in this embodiment will be described. FIG. 1 shows a configuration example of a network using a packet switching apparatus. As an example, a computer such as personal computers (PCs) 201 and 202 and a file server (server) 203 transfers data via a local area network (LAN) 232. The PCs 201 and 202, the storage device 241 and the server 203 are connected by packet switching devices such as the switches 211 to 213 and the router 221, respectively. At this time, the network may include a wide area Ethernet (R) 231. The packet switching devices such as the switches 211 to 213 and the router 221 include control frames and PC 201 that communicate between the switches 211 to 213 in addition to the packets that transfer data from the PCs 201 and 202, the server 203, the storage device 241, and the like. , 202 and the control frames etc. communicated between the switches 211 to 213 are transferred. The router 221 communicates control packets such as route information with other routers not shown, the switches 211 to 213, and the like. The number of packet switching devices on the network will increase as the network becomes wider, and the number of packets received by the packet switching device will increase as the number of PCs connected to each switch and router increases and the speed of the line increases. .

  Next, the configuration of the packet switching apparatus in this embodiment will be described.

  FIG. 2 is a block diagram showing a functional block configuration example of the packet switching apparatus 200. Here, the packet switching apparatus 200 corresponds to the switches 211 to 213 and the router 221 in FIG. The packet switching device 200 includes input line interfaces 3011 and 3012 that receive packets from other devices, output line interfaces 3021 and 3022 that output packets to other devices, and a packet transfer unit that performs transfer processing on received packets. 303, a device control unit 102 that controls the entire device, a packet search control unit 304 that searches for a destination of a received packet in cooperation with the packet transfer unit, a route table 305 that stores route information, and a packet search control unit 304 And a transfer control unit 101 that performs packet processing in cooperation with each other.

  The input line interfaces 3011 and 3012 and the output line interfaces 3021 and 3022 include input band control units 3013 and 3016 and output band control units 3023 and 3026, respectively. However, it may be configured to include either the input bandwidth control units 3013 and 3016 or the output bandwidth control units 3023 and 3026. The input bandwidth control units 3013 and 3016 record the arrival time of received packets, monitor the bandwidth of the input line from the interval of packet arrival times, and notify the transfer control unit 101 of packet types that exceed the set bandwidth of the input line be able to. The output bandwidth control units 3023 and 3026 can manage the transmission time of packets to be transmitted, control the bandwidth of the output line, and notify the transfer control unit 101 of packet types that exceed the set bandwidth of the output line.

  Here, the input line interfaces 3011 and 3012 and the output line interfaces 3021 and 3022 are often mounted on the same board, but here, in order to simplify the packet processing flow, they are shown functionally divided. . Further, the packet transfer unit 303, the packet search control unit 304, the route table 305, the transfer control unit 101, and the like may be configured in one integrated circuit.

  FIG. 3 is a block diagram illustrating a configuration example of the device control unit 102 and the transfer control unit 101 of the packet switching device 200. The device control unit 102 includes a storage unit 1022 for storing a program such as an operating system, a control CPU 1021 for executing the program, and a packet priority table 1200 for determining the priority of control packets transferred to the device control unit. It consists of. The transfer control unit 101 also includes a priority control unit 1011 that determines the priority for each packet type, a transfer bandwidth control unit 1012 that measures the arrival frequency for each packet type, and updates the packet priority table 1200. And a packet priority table 1200. The device control unit 102 and the transfer control unit 101 each have the same packet priority table 1200, and when each updates the table, synchronization is achieved by transmitting the packet priority table 1200 to each other. Details of the packet priority table 1200 will be described later with reference to FIG. Here, the packet priority table 1200 is configured to be held by the device control unit 102 and the transfer control unit 101, but may be configured to have one packet priority table shared by the device control unit 102 and the transfer control unit 101. Good.

  FIG. 4 shows an example of a packet structure used by the packet switching apparatus 200 for communication. The packet is composed of layered header information and data 44 corresponding to the protocol of each layer of the OSI reference model. Specifically, the header information includes a second layer header 41, a third layer header 42, a fourth layer header data 43, and the like. Protocols such as Ethernet (R), ATM (Asynchronous Transfer Mode), MPLS (Multi-Protocol Label Switching), etc. can be used as the second layer protocol. Protocols such as Internet Protocol version 4 (IPv4) and Internet Protocol version 6 (IPv6) can be used as the third layer protocol. Protocols such as TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) can be used as the fourth layer protocol.

  FIG. 5 shows a header field of an Ethernet (R) version 2 (v2) frame as an example of the second layer header 41 (FIG. 4). The Ethernet (R) v2 frame header includes, as fields, a preamble / SFD 51 indicating the start of the frame, a destination MAC address 52 that is the MAC (Media Access Control) address of the destination terminal in the second layer, and transmission in the second layer. The source MAC address 53, which is the MAC address of the original terminal, the type 54 indicating the third layer protocol, and the like are defined as header fields.

  FIG. 6 shows a header field of an IPv4 datagram as an example of the third layer header 42 (FIG. 4). The IPv4 header includes, as fields, ToS 61 indicating the packet transfer quality, protocol 62 indicating the protocol of the fourth layer, source IP address 63 indicating the IP address of the source terminal, and destination IP address indicating the IP address of the destination terminal. 64 etc. are defined as header fields.

  FIG. 7 shows a header field of an IPv6 datagram as an example of the third layer header 42 (FIG. 4). The IPv6 header includes, as fields, a class 71 indicating packet transfer quality, a next header number 72 indicating the next header type stored hierarchically by the header, a source IP address 73 indicating the IP address of the source terminal, A destination IP address 74 indicating the IP address of the destination terminal is defined as a header field.

  FIG. 8 shows a header field of a TCP segment as an example of the fourth layer header 43 (FIG. 4). In the TCP header, a source port number 81, a destination port number 82 for identifying a TCP segment by an upper layer such as an application, a TCP flag 83 indicating a TCP communication state, etc. are defined as header fields. Yes.

  FIG. 9 shows details of the TCP flag 83 in FIG. The TCP flag 83 includes an emergency flag (URG) 91 that instructs the receiving terminal to urgently pass the received data to the application, an acknowledgment flag (ACK) 92 that notifies the transmitting terminal that the receiving terminal has received the data, and transmission A flag (PSH) 93 that instructs the terminal and the receiving terminal to pass data to the application without delay, a flag (RST) 94 that supports the resetting of the TCP connection, a flag (SYN) 95 that instructs the establishment of the connection, and the termination of the connection It consists of six flags of 96 (FIN) that supports

  FIG. 10 shows a header field of a UDP segment as an example of the fourth layer header 43 (FIG. 4). In the UDP header, a source port number 1001, a destination port number 1002, a message length 1003, and a checksum 1004 are defined as header fields for the upper layer such as an application to identify a UDP segment.

  FIG. 11 shows a configuration example of the packet priority table 1200 (FIG. 3). Each item of the priority control condition 1202 is composed of information of the second layer header field, the third layer header field, and the fourth layer header field of the packet. The respective items are shown in FIGS. It is possible to arbitrarily select from each field of the described packet header. In the configuration example shown in FIG. 11, the destination MAC address, type, destination IP address, protocol, Tos, source port number, destination port number, and the like are used as priority control conditions. Note that “*” set as the value of each item indicates a wild card, and the set value is not particularly limited.

  In the packet priority table 1200, the packet type 1201 is determined by the combination of the values of each item of the priority control condition 1202, and the priority 12031, the input bandwidth determination 12032, the congestion determination 12034, etc. are searched according to the packet type 1201. The result 1203 can be obtained. The priority 12031 indicates the processing priority according to the packet type, and the higher the value, the higher the priority. The input bandwidth determination 12032 indicates the arrival frequency of a packet received by the packet switching apparatus 200. The larger the value is, the higher the arrival frequency is. The congestion determination 12034 indicates the congestion state of the packet output from the packet switching device 200. The larger the value is, the higher the congestion state is.

  FIG. 12 shows a packet processing procedure in the transfer control unit 101 (FIG. 3). When receiving the packet information from the packet transfer unit 303, the transfer control unit 101 first analyzes the packet header from the packet information received by the priority control unit 1011 and extracts the packet header information (step 1401). In parallel with step 1401, the packet search control unit 304 also receives packet information from the packet transfer unit 303, and searches for destination information of the packet using the route table 305. The destination information of the packet obtained by the search is notified to the transfer control unit 101.

  Next, the transfer bandwidth control unit 1012 records the arrival time of the packet, measures the arrival frequency from the interval of the packet arrival times, and similarly measures the transmission frequency of the packet (step 1402). The arrival frequency and transmission frequency are measured for each packet type based on the packet header information acquired in step 1401. Here, although the transfer bandwidth control unit 1012 measures the arrival frequency and transmission frequency of the packet, the input bandwidth control units 3013 and 3016 and the output bandwidth control units 3023 and 3026 described in FIG. The measurement result may be notified to the transfer bandwidth control unit 1012.

  Next, the priority control unit 1011 searches the packet priority table 1200 based on the destination information of the packet notified from the packet search control unit 304 and the packet header information extracted in step 1401, so that each packet type The priority is determined, and the input bandwidth determination and the congestion determination are acquired (step 1403).

  Next, the transfer control unit 101 registers the packet in the packet processing queue in the packet storage unit of the packet transfer unit 303 (not shown) (step 1404). The queue is divided for each packet priority, and the packet is registered in a queue corresponding to the priority determined in step 1403. In the queue, since a packet with a high priority is preferentially transmitted to the device control unit 102, a packet type with a higher priority has a higher transfer frequency to the device control unit 102.

  Next, the transfer bandwidth limiting unit 1012 determines the priority, input bandwidth determination, and congestion determination for each packet type determined and acquired by the priority control unit 1011 in step 1403 based on the arrival frequency and transmission frequency of the packet measured in step 1402. If it is not appropriate in view, the values of the priority 12031, the input bandwidth determination 12032, and the congestion determination 12033 of the packet type included in the packet priority table 1200 are updated (step 1405). For example, when the arrival frequency of the packet measured in step 1402 is high, the value of the input bandwidth determination 12032 is increased by 1 and the value of the priority 12031 is also increased by 1, so that the processing priority of the packet type is increased. Can be high. The packet priority table 1200 may be updated in step 1403.

  Next, the transfer control unit 101 transmits the updated packet priority table 1200 to the device control unit 102 (step 1406). Upon receiving the packet priority table 1200, the device control unit 102 updates the table with the received content.

  The transfer control unit 101 appropriately updates the packet priority table 1200 according to the procedure described above, so that the transfer control unit 101 adjusts the frequency of packet transfer from the packet transfer unit 303 to the device control unit 102 for each packet type. It becomes possible.

  FIG. 13 shows a packet processing procedure in the apparatus control unit 102. First, the device control unit 102 receives a packet from a queue corresponding to the priority for each packet type in the packet storage unit of the packet transfer unit 303 (step 1501).

  Next, the device control unit 102 analyzes the packet header from the received packet and extracts packet header information (step 1502).

  Next, the apparatus control unit 102 determines the priority of the packet received in Step 1501 by the same procedure as Step 1403 in FIG. 12 (Step 1503).

  Next, processing described later is performed by the apparatus control unit according to the packet type, and the processing speed of the packet type is determined by measuring the time required for the processing. Further, the processing time of the packet is recorded, and the processing frequency of the packet type is measured from the interval of the packet processing time (step 1504).

  Next, the packet priority table 1200 is updated as necessary based on the measured processing speed and processing frequency for each packet type (step 1505). For example, if the packet type has a low processing speed and a low processing frequency, the processing priority of the packet type can be lowered by lowering the value of the priority 12031 in the packet priority table 1200.

  Next, the device control unit 102 transmits the updated packet priority table 1200 to the transfer control unit 101 (step 1506). When the transfer control unit 101 receives the packet priority table 1200, the transfer control unit 101 updates the table with the received contents.

  The device control unit 101 appropriately updates the packet priority table 1200 according to the procedure described above, so that the device control unit 101 changes from the packet transfer unit 303 to the device control unit 102 according to its own processing speed and processing frequency for the packet. Can be adjusted for each packet type.

  Note that the packet addressed to the device control unit 102 by the packet search control unit 304 is transferred to the packet processing process operating on the control CPU 1021 installed in the device control unit 102. In the control CPU 1021, an operating system or the like stored in the storage unit 1022 operates to execute a packet processing process for processing a packet transferred to the device control unit 102. The packet types transferred to the device control unit 102 include control packets such as BPDU (Bridge Protocol Data Unit), flooding packets, packets due to factors such as TTL (Time To Live) over, and the like. These packets are transferred to the device control unit 102 with different priorities depending on the packet type.

  Thus, packets addressed to the device itself are processed by the device control unit 102. According to the present embodiment, the amount of packet processing at the device control unit 102 is determined based on the processing speed and processing frequency of the device control unit 102 itself. Therefore, the frequency of discarding a packet type having a high processing priority can be reduced even when the amount of packet transfer to the apparatus control unit is increased.

  FIG. 14 shows another configuration example of the packet priority table 1200. The example of FIG. 14 is the same as the packet priority table of FIG. 11 except that the transmission mirror port 12034 is added to the search result item. When the output line (port number) is specified as the value of the transmission mirror port 12034, the packet transferred to the device control unit 102 is copied by the packet transfer unit 303, and one of the copied packets is specified It is also possible to control the packet transfer unit to output to the output line. Since an arbitrary output line can be specified for the transmission mirror port 12034 of the packet priority table 1200, the packets output to the output line are all packet types or a part of the packets transferred to the device control unit 102. Packet types can be selected. In this way, the transmission mirror port 12034 is added to the packet priority table 1200, and the packet transferred to the device control unit 102 is duplicated by the packet transfer unit to transfer and analyze the packet to a PC etc. outside the packet switching device. Processing can be performed.

  In the packet switching apparatus according to the present embodiment, it becomes possible to adjust the packet processing priority in the device control unit and the packet transfer frequency to the device control unit according to the arrival frequency and priority of the control packet, and the priority is low. It is possible to limit the processing frequency of packets addressed to the device control unit, and to reduce the discard of control packets with high priority, thereby improving the reliability of the packet switching device.

1 shows an example of a network configuration including a packet switching apparatus according to an embodiment of the present invention. A block diagram of the packet switching apparatus 200 is shown. 2 shows a block configuration diagram of the device control unit 102 and the transfer control unit 101 of the packet switching device 200. FIG. 3 is a diagram illustrating an example of a packet structure used for communication by the packet switching apparatus 200. FIG. FIG. 5 shows a header field configuration diagram of an Ethernet (R) v2 frame which is an example of a second layer header in the packet shown in FIG. 4. FIG. 5 shows a header field configuration diagram of an IPv4 datagram which is an example of a third layer header in the packet shown in FIG. 4. FIG. 5 shows a header field configuration diagram of an IPv6 datagram which is an example of a third layer header in the packet shown in FIG. 4. FIG. 5 shows a header field configuration diagram of a TCP segment which is an example of a fourth layer header in the packet shown in FIG. 4. FIG. 9 shows a field configuration diagram of a TCP flag in the TCP header field shown in FIG. 8. FIG. 5 shows a header field configuration diagram of a UDP segment, which is an example of a fourth layer header in the packet shown in FIG. 4. 5 is a diagram illustrating a configuration example of a packet priority table 1200. FIG. 4 is a flowchart illustrating an example of a packet processing procedure in a transfer control unit 101. 4 is a flowchart illustrating an example of a packet processing procedure in the apparatus control unit 102. 6 is a diagram illustrating another configuration example of a packet priority table 1200. FIG.

Explanation of symbols

101: transfer control unit, 102: device control unit, 200: packet switching device, 303: packet transfer unit, 304: packet route control unit, 305: route table, 1011: priority control unit, 1012: transfer bandwidth control unit, 1200 : Packet priority table, 3011, 3012: Input line interface, 3021, 3022: Output line interface

Claims (6)

A packet switching device for transmitting and receiving packets,
A transfer control unit that determines processing priority of the packet based on information included in the packet received by the packet switching device;
A packet search control unit for searching for a destination of the packet based on information included in the packet received by the packet switching device;
A device control unit that performs packet processing on a packet whose destination searched by the packet search control unit is addressed to its own device;
A packet transfer unit that transfers the packet to the device control unit according to the processing priority determined by the transfer control unit;
The packet transfer apparatus, wherein the transfer control unit changes a processing priority of the packet according to a packet arrival frequency or a transmission frequency. The packet switching apparatus according to claim 1, wherein
The device control unit changes the processing priority of the packet according to a packet processing speed, a packet processing frequency, or the like of the device control unit itself. The packet switching device according to claim 2, wherein
The packet switching device holds a packet priority table that stores a packet and a processing priority of the packet in association with each other,
The packet switching device, wherein the transfer control unit and the device control unit change the processing priority of the packet by updating the packet priority table. The packet switching device according to claim 3, wherein
The packet switching device, wherein the transfer control unit and the device control unit determine the processing priority of the packet for each packet type. The packet switching device according to claim 4, wherein
The packet transfer unit, wherein the packet transfer unit duplicates a received packet and transfers the duplicated packet to an arbitrary output line connected to the packet exchange device. The packet switching device according to claim 5, wherein
The packet forwarding unit duplicates an arbitrary packet among the packets forwarded to the device control unit, and forwards the duplicated packet to the output line connected to the packet switching device. apparatus.

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