JP4069107B2 - Packet switching equipment - Google Patents

Description

  The present invention relates to a configuration method of a packet switching apparatus such as a router in an information communication network.

  An IP network that uses IP packets as an exchange unit can use various applications such as e-mail, WWW (World Wide Web), VoIP (Voice over IP), and video distribution. Compared with conventional telephone-based exchange methods In recent years, traffic has increased explosively due to advantages such as low device costs.

  In addition, various applications can be used, and in the use of a specific application, a function corresponding to the QoS (Quality of Service) problem of how to guarantee the required communication service quality is also required. It is getting to be. As a function for dealing with such QoS, there is a function of priority control (hereinafter simply referred to as “priority control”) according to QoS. For example, in order to execute a communication application that handles CD (Compact Disk) quality sound, it is necessary to secure a bandwidth sufficient for the application and to forward packets preferentially. In order to cope with such a request, it is necessary to determine a priority class and a necessary bandwidth in accordance with an application, and control to preferentially transfer a packet having a high priority class. Such packet congestion control is called priority control and is indispensable for current IP (Internet Protocol) communication.

  The router arranged at each node of the IP network determines the output line of the packet based on the IP header of the received packet. Conventional routers are mainly software routers that determine the output line of a packet by means of a CPU (Central Processing Unit) that is bus-coupled to the input / output line support unit. However, in order to cope with the explosive increase in traffic, Then, hardware routers that perform packet analysis at high speed by performing header analysis of IP packets by hardware and connecting the input / output line corresponding parts by high-speed switches are in the spotlight.

  The hardware router does not perform packet processing by the CPU, but performs packet processing using hardware dedicated to network processing. An example of such hardware dedicated to network processing is a network processor (NP). Depending on the hardware, the network processor reads information about the output line in the header of the packet, maintains routing information storage means, changes the header information, and determines the output line of the packet This function can be set.

  An example in which a router is configured using a network processor is shown in FIG. 4 (see Non-Patent Document 1). FIG. 4 shows a configuration example using a network processor in a normal router. In the configuration of FIG. 4, the input line corresponding unit 2B and the output line corresponding unit 3B before and after the switch unit 6B are implemented as hardware, aiming at high-speed switching processing.

In the conventional packet switching apparatus (see FIG. 4), the output line corresponding part of the packet is determined by referring to the routing information storage means based on the IP header information (not shown) of the packet in the input line corresponding part 2B. It is transmitted to the switch unit 6B together with the information of the output line corresponding unit. The switch unit 6B exchanges packets received from a plurality of input line corresponding units according to the information of the output line corresponding unit, and transmits the packets to the output line corresponding unit (corresponding to one of the codes 3B) to be transmitted. In the switch unit 6B, a packet from a plurality of input line corresponding units 2B is given to the packet in order to cope with packet congestion caused by biasing to a specific output line corresponding unit (corresponding to one of the reference numerals 3B). Priority control execution means (not shown) for exchanging packets according to the priority class. Here, in order to avoid having a high-function priority control execution means (not shown) in the switch unit 6B that accommodates the plurality of input line corresponding units 2B and the plurality of output line corresponding units 3B, the switch unit 6B and the input A protocol is defined between the line corresponding units 2B, and the input line corresponding unit 2B shares priority control in cooperation with the switch unit 6B. Further, the output line corresponding unit 3B is configured to have priority control execution means (not shown) in order to perform transmission according to the output line 5.
Aoki, Kurimoto, Kakishima, Urushidani, “A Consideration on the Construction Method of Economical Routers”, Proceedings of the 2004 IEICE General Conference, B6-87, B-II Volume, p. 87

  The conventional technique is roughly composed of three functional units, an input line corresponding unit, an output line corresponding unit, and a switch unit. In the configuration according to the prior art, when efficient priority control is performed, there is a problem in that the interface definition between the three function units becomes complicated in constructing each of the three function units individually.

  An object of the present invention is to solve these problems of the prior art, simplify the interface definition between functional units, and increase independence.

In order to solve the above-mentioned problems, the present invention accommodates at least one input line, accommodates an input line corresponding unit for exchanging packets from the input line, accommodates at least one output line, and outputs the output line. A plurality of output line corresponding parts for exchanging packets to each other, and a transfer path for packets sent from the input line corresponding part to the output line corresponding part. In the packet switching apparatus for exchanging packets so as to be output from a predetermined output line, the input line corresponding unit includes a header reading unit that reads header information of the packet, a routing information storage unit that stores the routing information, Based on the header information, the routing information storage means is referred to and a packet is output from the plurality of output line corresponding units. Output line corresponding unit determining means for determining a predetermined output line corresponding unit for sending a packet, priority control executing means for performing priority control of a packet in accordance with a priority class assigned to the packet, and the determined output line corresponding unit wherein a packet sending means for sending a packet to be exchanged through the transfer path, said output line corresponding unit, a packet receiving unit receiving a packet sent through the transfer path, header reading means for reading the header information of the packet And priority control execution means for performing priority control of the packet independently of the priority control execution means of the input line corresponding unit according to the priority class assigned to the packet, and the transfer path is a mesh type network Composed.

  According to this configuration, the input line corresponding unit determines the predetermined output line corresponding unit by referring to the routing table for the packet input from the input line based on the packet header information, and the output determined through the transfer path. Sends the packet to the line corresponding part. As a result, the output line accommodated in the output line corresponding unit outputs the transmitted packet. In this configuration, when a priority class is set for a packet, priority control according to the priority class is executed by priority control execution means provided in the input line corresponding unit and the output line corresponding unit. Further, according to this configuration, packets can be exchanged from an arbitrary input line corresponding unit to an arbitrary output line corresponding unit.

  According to the present invention, it is possible to simplify the interface definition between the input line corresponding unit and the output line corresponding unit, and to increase the independence of the input line corresponding unit and the output line corresponding unit.

Hereinafter, the best embodiment of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a block diagram showing a packet switching apparatus according to an embodiment of the present invention. In FIG. 1, a packet switching device 1 includes an output line corresponding unit from a plurality of input line corresponding units 2 (2X, 2Y), a plurality of output line corresponding units 3 (3X, 3Y), and an input line corresponding unit 2 (2X, 2Y). 3 (3X, 3Y) including a mesh-type network 7 as a transfer path for packets sent to 3 (3X, 3Y).

[Input line support section]
Each input line corresponding unit 2 accommodates at least one or more input lines 4, and interfaces 23a and 23b that are directly connected to the header reading unit 21, the output line corresponding unit determining unit 22, and all the output line corresponding units 3X and 3Y. , The routing information storage means 24 and the priority control execution means 25. The header reading means 21 reads header information of a packet input from the input line 4. Then, the output line corresponding unit determining unit 22 determines the output line corresponding unit 3 to which the packet is to be sent by referring to the routing information storage unit 24 based on the header information. Then, the priority control execution means 25 determines the status of the interface 23a connected to the output line corresponding unit 3X, the interface 31a of the output line corresponding unit 3X described later, and the line bandwidth of the mesh type network 7, and the packet The priority is controlled according to the priority class based on the header information. Here, the interface 23 (23a, 23b) corresponds to the packet transmission means in the claims. The transfer capacity of the interface 23 may be large or small, but if the transfer capacity is small, congestion may occur due to this. By the way, the interface 23a of the input line corresponding unit 2X is connected to the interface 31a of the output line corresponding unit 3X, and the interface 23b of the input line corresponding unit 2X is connected to the interface 31c of the output line corresponding unit 3Y via the mesh type network 7. Yes. Since the interfaces 23c and 23d are the same as the interfaces 23a and 23b, description thereof is omitted. In addition, the input line corresponding unit 2Y has the same configuration as the input line corresponding unit 2X, and the description thereof will be omitted.

  The packet input from the input line 4 is output by the output line corresponding unit determining means 22 to be transmitted by the header information of the packet and the entry of the routing table included in the routing information storage means 24. (3X, 3Y) Is transmitted to the interface 23 (23a, 23c) connected to the interface 31 (31a, 31b) of the determined output line corresponding unit 3 according to the priority control by the priority control execution means 25. At this time, a priority class packet having a high priority is preferentially transmitted to the interface 31 of the determined output line corresponding unit 3 using a preferentially reserved bandwidth, but a priority class having a low priority is used. Packets belonging to or whose priority class has not been determined may be transmitted using the remaining bandwidth and may be partially discarded. Note that any priority control method can be used for the priority control means 25, and is not limited to the priority control method in the present embodiment.

[Output line support section]
The output line corresponding unit 3 (3X, 3Y) includes interfaces (receiving units) 31 (31a, 31b), header reading unit 32, and priority control executing unit that are directly connected to all input line corresponding units 2 (2X, 2Y). 33 is connected to at least one output line 5. The priority control execution means 33 judges the physical line capacity of the output line 5 and the path capacity of layer 2 or higher such as LSP (Label Switched Path) on the output line and sends the packet according to the priority class assigned to the transfer packet. Control. The transfer capacity of the interface 31 may be large or small. However, if the transfer capacity is small, congestion may occur due to this. Note that the interfaces 31c and 31d are the same as the interfaces 31a and 31b, and a description thereof will be omitted.

  In the output line corresponding unit 3, packets arrive at the corresponding interfaces 31 (31a, 31b) from all the input line corresponding units 2 (2X, 2Y). Packets arriving at the corresponding interface 31 from a plurality of input line corresponding units 2 are controlled by the priority control execution means 33 according to the path capacity of layer 2 or higher in which each packet is accommodated, and sent to the output line 5. Note that any priority control method can be used for the priority control means 33, and the priority control method is not limited to the priority control method in the present embodiment.

[Mesh type network]
FIG. 2 is a diagram showing a configuration of the mesh type network shown in FIG. Next, the configuration of the mesh type network 7 will be described with reference to FIG.

  In FIG. 1 described above, the input line corresponding unit 2 is described with two reference numerals 2X and 2Y, and the output line corresponding unit 3 is also illustrated with two reference numerals 3X and 3Y. However, as shown in FIG. There may be any number of corresponding units 2 and output line corresponding units 3. The required number of interfaces 23 and 31 may be prepared in accordance with the number of input lines 4 and the number of output lines 5, respectively. Then, as shown in FIG. 2, if each input line corresponding unit 2A and all output line corresponding units 3A are directly connected one by one, the configured line network becomes a mesh type line network.

  When this is compared with the configuration shown in FIG. 4, it can be seen that the mesh-type network 7 has a function to replace the switch unit 6 in FIG. As can be seen from this comparison, as a result of adopting the configuration of this embodiment, the interface specification between the input line corresponding unit 2B and the switch unit 6B (see FIG. 4), the switch unit 6B, and the output, which were necessary in the configuration of FIG. There is no need to define the interface between the line corresponding unit 3B, and only the interface definition of the input line corresponding unit 2B and the output line corresponding unit 3B need be considered. This not only reduces the number of combinations of interface rules, but also simplifies the interface rules themselves.

  In the configuration having the input line corresponding unit, the switch unit, and the output line corresponding unit (see FIG. 4), the interface definition between the input line corresponding unit 2B and the switch unit 6B and the interface between the switch unit 6B and the output line corresponding unit 3B. The regulation requires a fine response regarding congestion control. Otherwise, a somewhat large control delay will occur until an appropriate amount of packets arrives via the switch unit 6B and the input line corresponding unit 2B due to fluctuations in the congestion of the output line corresponding unit. There is an inconvenience that the control delay changes greatly according to the fluctuation pattern of congestion. Therefore, the interface specification must be complicated to some extent. On the other hand, even if the interface definition for performing the congestion control of the input line corresponding unit 2B and the output line corresponding unit 3B of the present embodiment is simplified, in this embodiment, the input line corresponding unit 2B and the output line corresponding unit 3B are used. Are in a direct connection relationship, the control delay can be kept within a certain range. Furthermore, if the correspondence with respect to the difference in priority class, the buffer usage status, and the like is included, the simplicity of the interface definition in this embodiment becomes more important.

  Further, in the interface regulations when the configuration in which the output line corresponding unit accommodates a plurality of output lines is considered, when the transmission restriction associated with the congestion caused by the specific output line in the output line corresponding unit is performed, the corresponding output is performed. Not only the interface regulation for restricting transmission to the line corresponding unit, but also the interface rule concerning transmission restriction for each output line accommodated by the corresponding output line corresponding unit. On the other hand, in the configuration of the present embodiment, since direct connection is made between the input line corresponding unit and the output line corresponding unit, it is good to simply specify the interface for transmission restriction for all output lines. Congestion control is possible.

  In addition, in the interface specification when considering a configuration composed of a multi-stage switch section (here, three stages), the switch section located at the center of the three multi-stage switch sections has an output side. When regulating transmissions due to congestion at the switch unit, the interface relating to transmission regulation for each output line connected to the output side switch unit as well as the interface regulation for transmission regulation to the output side switch unit Regulations are also required. On the other hand, in the configuration of the present embodiment, direct connection is made between the input line corresponding unit and the output line corresponding unit for all the lines, so that the adjacent input line corresponding unit for each output line. Convenient congestion control can be achieved only by a simple interface regulation that regulates transmission of the.

  In addition, the interface specification for processing the header information of the packet necessary for the switch unit 6B to intervene can be omitted, which also contributes to the simplification of the interface specification.

[Operation of packet switching equipment]
Next, the operation of the packet switching apparatus having the above-described configuration will be described with reference to FIG. 3 with reference to FIG. 1 and FIG. FIG. 3 is a sequence diagram showing the operation of the packet switching apparatus.

  For example, when the input line corresponding unit 2X of the packet switching apparatus 1 inputs a packet from the input line 4 accommodated therein (S21), the header reading unit 21 first reads the header of the input packet (S22). . Then, using this information, the input line corresponding unit 2X refers to the routing information storage unit 24, and determines the destination output line corresponding unit 3 by the output line corresponding unit determining unit 22 (S23). Here, it is assumed that the packet destination is the output line corresponding unit 3Y. Then, the priority class is determined based on the header information (S24). As a result, when the priority class of the packet is higher, the input line corresponding unit 2X uses the bandwidth secured by the priority control execution means 33 (S25) to accommodate the output line corresponding unit 3Y. The packet is transferred from the output line 5 to be transmitted. If the priority class of the packet is lower or the priority class is not set, the packet is transferred from the predetermined output line 5 within a range in which output is possible with the remaining bandwidth (S26). In this case, when the remaining bandwidth is insufficient, some of the packets are discarded (S26), and only the remaining packets are transferred.

  The input line corresponding unit 2X transmits the packet from the interface 23b to the interface 31c of the destination output line corresponding unit 3Y through the mesh type network 7. The output line corresponding unit 3Y receives the transmitted packet via the interface 31c. The output line corresponding unit 3Y that has received the packet reads the priority class information of the header of the packet by the header reading unit 32 (S31).

  The priority control execution means 33 performs priority control according to the priority class according to this information, and transmits a packet to the line 5 accommodated in the output line corresponding unit 3Y (S33, S34, S35). As priority control, description will be given by taking, as an example, priority control of three classes of the highest priority class, the bandwidth reservation class, and the best effort class.

  The packet of the highest priority class determined as the highest priority class from the priority class information (S32) waits for packets of other classes, and the lines accommodated by the output line corresponding unit 3Y in the order of arrival between the highest priority class packets. 5 (S33). The bandwidth reservation class packet determined to be the bandwidth reservation class from the priority class information (S32), when there is no packet of the highest priority class waiting for transmission, the output line corresponding unit within the bandwidth allocated to the bandwidth reservation class It is transmitted to the line 5 accommodated by 3Y (S34). The best effort class packet determined as the best effort class from the priority class information (S32) is a bandwidth reservation for transmission within the bandwidth allocated to the bandwidth reservation class when there is no packet of the highest priority class waiting for transmission. When there is no class packet (in FIG. 3, the highest priority class and the bandwidth reservation class are expressed as higher classes), the packet is transmitted to the line 5 accommodated in the output line corresponding unit 3Y (S35). The best-effort class packet is accumulated in the buffer if there is no opportunity to be transmitted to the line 5 accommodated by the corresponding unit 3Y, and is discarded due to a buffer overflow. Only the packet transmitted from the priority control execution means 33 to the line 5 accommodated in the output line corresponding unit 3Y is output from the output line (S36).

  As described above, in the present embodiment (see FIG. 2), since the configuration in which the input line corresponding unit 2A and the output line corresponding unit 3A are directly connected by the mesh type network 7 is adopted, the input line corresponding unit 2A and the output The line-corresponding unit 3A realizes a relationship that does not require exchange of complicated information via the switch unit 6 (see FIG. 4) as in the prior art. As a result, a highly independent configuration between the input line corresponding unit 2 and the output line corresponding unit 3 is possible. This not only facilitates the design of the input line corresponding part and the output line corresponding part in the present embodiment, but also when the higher performance hardware appears for each part, It is possible to have a highly flexible configuration that can be easily updated to hardware. In the above-described embodiment, the transfer path is described as a mesh type. However, the transfer path is not limited to this, and other transfer paths, for example, a mode involving establishment of a large-capacity optical pass-through in Non-Patent Document 1. It may be like a transfer path.

It is a block diagram which shows the packet switching apparatus which concerns on embodiment of this invention. It is a figure which shows the specific example of the mesh type | mold network shown in FIG. It is a sequence diagram which shows operation | movement of the packet switching apparatus of FIG. It is a figure which shows the structural example of the conventional packet switching apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Packet switching device 2 Input line corresponding part 3 Output line corresponding part 4 Input line 5 Output line 7 Mesh type | mold network (forwarding path)
21 Header Reading Unit 22 Output Line Corresponding Portion Determining Unit 23 Interface (Packet Sending Unit)
24 routing information storage means 31 interface (packet receiving means)
32 Header reading means 33 Priority control execution means

Claims (1)

An input line corresponding unit that accommodates at least one input line and exchanges packets from the input line, and an output line correspondence unit that accommodates at least one output line and exchanges packets to the output line And a transfer path for a packet sent from the input line corresponding unit to the output line corresponding unit, and the packet is output so that a packet input from the input line is output from a predetermined output line. In the packet switching device to be exchanged,
The input line correspondence unit includes a header reading unit that reads packet header information, a routing information storage unit that stores routing information, and the routing information storage unit that refers to the plurality of outputs based on the header information of the packet. An output line corresponding part determining means for determining a predetermined output line corresponding part for sending a packet from among the line corresponding parts, a priority control executing means for performing priority control of a packet according to a priority class assigned to the packet, and a packet sending means for sending the packets exchanged through the transfer path to the determined output line corresponding unit,
The output line corresponding unit includes a packet receiving unit that receives a packet transmitted through the transfer path, a header reading unit that reads header information of the packet, and the input line corresponding unit according to a priority class assigned to the packet. Priority control execution means for performing priority control of packets independently of the priority control execution means of
The packet switching apparatus, wherein the transfer path is constituted by a mesh type network.

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