JP4531660B2 - Packet relay device - Google Patents

Description

  The present invention relates to a packet relay apparatus that connects between networks and relays packets based on route information in the apparatus.

  In general, in a network, the communication capacity (bandwidth) that can be communicated is naturally determined, and the amount of transmission (bandwidth) varies depending on the contents of the packet. In the packet relay device, when a large number of packets arrive due to congestion and the total amount exceeds the network bandwidth, the packets to be relayed are randomly discarded. When such congestion discard occurs, the quality of the packet deteriorates, and for example, in the case of communication such as a moving image stream, a problem occurs that an image is disturbed.

  By the way, in the conventional packet relay device, terminals that transmit and receive packets are classified into “priority class” and “non-priority class” in advance, and packets transmitted from the priority class terminals are normally short-path networks. The packet transmitted from the non-priority class terminal is transmitted via the detour network. In addition, when a short-path network fails due to a disconnection, etc., communication is not possible, it is proposed that only priority class packets are sent via the detour network and non-priority class packets are discarded. (For example, refer to Patent Document 1).

  According to the prior art described in Patent Document 1, packet transfer priority processing is enabled according to the type of terminal, and a detour network is always used, so that a packet is transmitted only to a specific network. The centralized transmission is eliminated, and the use efficiency of the entire network can be improved. Also, even if a large number of packets arrive due to congestion, priority class packets are sent to the short-circuit network, and non-priority class packets are sent to the detour network. The advantage is that it can be avoided to a certain extent.

JP 58-151747 (page 2-3, Fig. 1)

  However, the prior art described in Patent Document 1 still has the following problems. That is, in the network system, there is a case where a bypass network is not necessarily connected to each packet relay device. In the case of Patent Document 1, since the types of terminals are classified into only “priority class” and “non-priority class”, the terminals of the priority class may occupy the majority in some cases.

  If no detour network is connected to the packet relay device, or if most of the terminals connected to the packet relay device are priority classes, a large amount of packets arrive at the packet relay device due to congestion. Sometimes, the total amount of packets exceeds the network bandwidth, and congestion discard still occurs at random. For this reason, there is a problem that an image is disturbed particularly when communication such as a moving image stream is performed.

  The present invention has been made to solve the above-described problem, and provides a packet relay device capable of reducing the number of packets affected by congestion discard as much as possible even when a large amount of packets are congested. The purpose is to provide.

In order to achieve the above object, a packet relay apparatus according to the present invention uses a route information table in which route information of a network is stored and a packet input via a terminal or a network as route information in the route information table. A packet relay unit that detects whether or not congestion congestion has occurred in the packet, an interface importance table that stores the importance of the interface through which the packet is input / output, and an interface bandwidth that holds the bandwidth of each interface If there is an update of the table and the routing information table, if it is determined that the interface that relays the packet is changed to an interface with a narrower bandwidth than the current one by referring to the interface bandwidth table, it responds accordingly. And refer to the interface importance table above. And a processing unit that performs priority lowering processing low packet of said packet relay unit is characterized in that it is intended to discard the packets with lower priority that has been processed by the processing unit preferentially.
In addition to the interface importance table, a field importance table storing the importance of a specific field of a packet is provided, and when the route information table is updated as the processing unit, the interface bandwidth table is referred to. If it is determined that the interface that relays the packet is changed to an interface with a narrower bandwidth than the current one, refer to the field importance table according to this and set the priority of the less important packet. It is good also as composition which performs processing to lower.

According to the present invention, when there is a route update due to a network failure or the like, when it is determined that the interface that relays the packet is changed to an interface with a narrower bandwidth than the current one as a result of referring to the interface bandwidth table In response to this, the interface importance level table or the interface bandwidth table is referred to, and the process of lowering the priority of the low importance packet is performed, so that only the low importance packet can be preferentially discarded. As a result, it is possible prevent a packet of all streams by a route change is discarded uniformly, it is possible to reduce as much as possible the number of packets affected by the congestion discarded. For this reason, for example, image disturbance in the case of performing communication such as a moving image stream can be significantly reduced.

Embodiment 1 FIG.
FIG. 1 is a configuration diagram of a network system having a packet relay apparatus according to Embodiment 1 of the present invention.

In the first embodiment, packet relay apparatuses 1a, 1b, and 1c are connected to each other via networks 7a and 7b. Each terminal 9a the packet relay device 1a, 9b, 9c, 9d are also each terminal 8a, 8b are connected to the packet relay apparatus 1c.

  Although three packet relay apparatuses 1a, 1b, and 1c are illustrated here, more packet relay apparatuses are usually arranged. Further, the number of terminals connected to each of the packet relay apparatuses 1a and 1c is not limited to the illustrated number. Furthermore, a configuration in which a terminal is connected to the packet relay device 1b may be used.

  As the networks 7a and 7b, for example, the CSMA / CD system standardized by IEEE 802.3 can be applied, and what is called a wide area network (WAN) or a local area network (LAN) is also included in the present invention. Included in the network.

  The packet structure used for communication uses, for example, a MAC frame format as shown in FIG. That is, this packet is composed of a total of six fields F0 to F5 including a preamble F0, a destination address F1, a transmission source address F2, a data type F3, transmission data F4, and a bit error detection code string F5.

  The packet relay device 1 a includes a processing unit 2 and a packet relay unit 4, and both are connected by a system bus 6. The configuration of the other packet relay apparatuses 1b and 1c is basically the same as that of the packet relay apparatus 1a.

  In the case of the first embodiment, in the packet relay device 1a, the interface units 5a, 5b, 5c, 5d, and 5e are connected to the packet relay unit 4, and the interface units 5a, 5b, 5c, and 5d are connected. , 5e are individually assigned addresses such as IP addresses. Further, terminals 9a, 9b, 9c, and 9d are connected to the interface units 5a, 5b, 5c, and 5d, respectively, and a network 7a is connected to the other interface units 5e.

  The packet relay unit 4 relays packets input from the terminals 9a to 9d and the network 7a through the interface units 5a to 5e based on route information in the route information table 3 described later, and packet congestion. The presence / absence of discarding is detected, and the low-priority packets processed by the processing unit 2 are discarded preferentially.

  The processing unit 2 performs various arithmetic control processes for the packet, and holds a route information table 3 and an interface importance degree table 10.

  The routing information table 3 associates each network 7a, 7b with the interface unit of the packet destination for each network 7a, 7b. For example, OSPF (Open Shortest Path First), RIP (Routing Information Protocol), and BGP4 It is generated and updated by a routing (route) protocol that automatically sets the shortest path between packet relay apparatuses such as (Border Gateway Protocol Version 4).

  In the interface importance degree table 10, for example, as shown in FIG. 3, the importance degree for each of the interfaces 5a to 5e is individually set in advance. In this example, the importance of the interface 5e connected to the network 7a is the highest, and the importance of the interface 5c connected to the terminal 9c is set to the lowest.

  Next, in the above configuration, attention is paid to one packet relay device 1a, and the processing operation when a packet congestion discarding state occurs in the packet relay device 1a will be described with reference to the flowchart shown in FIG. . In addition, the code | symbol S means each process step.

  Now, assuming that communication is performed between the terminals 9a, 9b, 9c, 9d and the terminal 8a in a steady state, for example, the terminals 9a, 9b, 9c, 9d → the packet relay device 1a → the network 7a → the packet relay device. Packets are sent in the order of 1b → network 7b → packet relay device 1c → terminal 8a.

  Here, when the total amount of packets addressed to the terminal 8a from each terminal 9a, 9b, 9c, 9d exceeds the bandwidth of the network 7a, the packet transmitted from each of the terminals 9a, 9b, 9c, 9d is a packet. The relay unit 4 randomly discards the congestion. At this time, when the packet relay unit 4 detects occurrence of congestion discard of the packet (S1), the packet relay unit 4 notifies the processing unit 2 that this congestion discard has occurred.

In response to this, the processing unit 2 searches and searches for all interfaces on which congestion is discarded (S2). After that, the processing unit 2 refers to the interface importance level table 10 to check the importance levels of the interface units 5a, 5b, 5c, and 5d for which the congestion discard is performed,
Among them, the interface having the lowest importance is selected (S3), and the priority of the packet received at the selected interface is temporarily changed to be the lowest (S4).

  For example, in the case of the interface importance degree table 10 shown in FIG. 3, the interface part 5c has the lowest importance among the interface parts 5a, 5b, 5c, and 5d. Make the degree the lowest. Then, this information is transmitted from the processing unit 2 to the packet relay unit 4. In response to this, the packet relay unit 4 preferentially discards the low priority packet transmitted from the terminal 9c and received by the interface 5c.

  If congestion discarding continues even after this processing is performed (S5), the processing unit 2 searches for the remaining interfaces (here, 5a, 5b, 5d) where congestion discarding occurs ( S6) When there are a plurality of remaining interfaces (S7), the interface importance degree table 10 is checked again for the next lowest priority interface, and the lowest priority is assigned in order. Further, the priority of the received packet is lowered. This process is performed until there is no congestion discard. Then, when congestion discard is settled or when the remaining interface is one even when it is not settled, the processing for reducing the influence of this packet discard is ended (S8).

  As a result, only packets transmitted from a specific terminal having a low priority are discarded from a state where packets transmitted from each of the terminals 9a, 9b, 9c, and 9d are randomly discarded. Therefore, it becomes possible to stably communicate with other terminals having high priority.

  As described above, in the first embodiment, the importance of the interfaces 5a to 5d to which packets are input is classified into the class even when the packets are congested from the terminals 9a to 9d to the packet relay apparatus 1a. In other words, only the packets input from the less important interface are preferentially discarded, so that the number of packets affected by congestion discard can be minimized. For this reason, for example, in the case of communication such as a moving image stream, it is possible to greatly reduce image disturbance.

Embodiment 2. FIG.
FIG. 5 is a configuration diagram of a network system having a packet relay apparatus according to the second embodiment of the present invention. Components corresponding to those in the first embodiment shown in FIG.

  In the network system of the second embodiment, in the packet relay device 1a, the packet relay device 1d is further connected to the end of the interface unit 5a connected to the packet relay unit 4, and terminals 9a and 9b are connected to the packet relay device 1d. It is connected. Terminals 9c and 9d are connected to the interfaces 5c and 5d. On the other hand, the processing unit 2 is provided with a field importance level table 11 that weights the importance level according to a specific field in the received packet, instead of the interface importance level table.

  That is, the field importance table 11 has the highest importance when the destination address (field F1) is the terminal 8a and the data type (field F3) is image information, as shown in FIG. When the destination address (field F1) is the terminal 8b and the data type (field F3) is character information, the importance is set to the lowest.

  The configuration of the other packet relay apparatuses 1b and 1a is basically the same as that of the packet relay apparatus 1a, and a detailed description thereof is omitted here.

  In the packet relay apparatus 1a, when the importance is assigned in units of physical ports of the interfaces 5a to 5e to determine whether or not relaying is possible, a plurality of interfaces are placed ahead of one interface 5a as in the configuration of the second embodiment. When a plurality of packets arrive at this interface 5a, the priorities of both packets are prioritized using the interface importance degree table 10 as shown in FIG. Is difficult.

  Therefore, in the second embodiment, the processing unit 2 of the packet relay device 1a refers to the field importance degree table 11 for the packets input from the terminals 9a to 9d, and the specific fields F1 and F2 in each packet. , F3, etc., and a process of lowering the priority of a packet having a low importance field is performed. The processing in this case is basically the same as the flowchart shown in FIG. 4 except that the field importance level table 11 is used instead of using the interface importance level table 10, and detailed description thereof is omitted here. To do.

  As a result, only a specific packet set with a low priority is discarded from a state where packets transmitted from each of the terminals 9a, 9b, 9c, and 9d are randomly discarded. Communication of other high packets can be performed stably.

  As described above, in the second embodiment, the importance level of each packet is determined based on the field information in each packet such as the destination address (field F1), the transmission source address (field F2), the data type (field F3), and the like. Therefore, it is possible to permit finer communication permission, for example, protecting the communication of the terminal 9a and discarding the communication of the terminal 9b.

Embodiment 3 FIG.
FIG. 7 is a configuration diagram of a network system having a packet relay device according to the third embodiment of the present invention. Components corresponding to those in the first embodiment shown in FIG.

  In the third embodiment, the packet relay unit 4 is provided with buffers 12a to 12d that temporarily store packets input from the interfaces 5a to 5d, while the processing unit 2 includes the path information table 3 and the interface. The importance level table 10 is held, and a buffer threshold value table 13 is further provided.

  That is, in the buffer threshold value table 13, for example, as shown in FIG. 8, threshold values La to Le relating to packet usage rates in the buffers 12a to 12d are set in advance. The threshold values La to Le in this case may all be the same, but can also be set individually according to the importance of each interface 5a to 5d.

  The configuration of the other packet relay apparatuses 1b and 1c is basically the same as that of the packet relay apparatus 1a. Other configurations are the same as those in the first embodiment, and detailed description thereof is omitted here.

  Here, when packets are input from the terminals 9 a to 9 d to the packet relay unit 4 via the interfaces 5 a to 5 d, these packets are temporarily stored in the buffers 12 a to 12 d of the packet relay unit 4.

  The processing unit 2 refers to the buffer threshold table 13 and monitors whether or not the usage rates of the packets temporarily stored in the buffers 12a to 12d of the packet relay unit 4 are equal to or higher than the thresholds La to Le, respectively. When the usage rate of a certain buffer is equal to or greater than the threshold value, it is predicted that packet congestion discard will occur, and the importance level will be described with reference to the interface importance level table 10 (FIG. 3). The priority of a packet received on an interface with a low is temporarily changed to a low priority. The processing at that time is basically the same as the content of the flowchart shown in FIG.

  As described above, in the third embodiment, the processing unit 2 does not take the countermeasure after the packet relay unit 4 detects the occurrence of the congestion congestion of the packet, but before the congestion discard actually occurs, the buffer 12a Since whether or not there is a congestion state is determined based on the usage rate of ~ 12d, it is possible to take early measures such as which of the packets input from the interfaces 9a to 9d should be discarded with priority. It becomes possible to reliably prevent the packet from being discarded.

Embodiment 4 FIG.
FIG. 9 is a configuration diagram of a network system having a packet relay apparatus according to the fourth embodiment of the present invention. Components corresponding to those in the first embodiment shown in FIG.

  In the fourth embodiment, the packet relay apparatuses 1a, 1b, 1c are connected to each other via the networks 7a, 7b, and the two packet relay apparatuses 1a, 1c are connected to each other via the other network 7c. ing.

  In addition, the processing unit 2 of the packet relay apparatus 1a holds the route information table 3 and the interface importance degree table 10, and is further provided with an interface bandwidth table 14.

  In the interface bandwidth table 14, for example, as shown in FIG. 10, the bandwidths of the interfaces 5e and 5f to which the networks 7a and 7c are connected are registered in advance. In this example, one interface 5f is registered with a bandwidth of 100 Mbps, and the other interface 5e is registered with a bandwidth of 10 Mbps.

  The configuration of the other packet relay apparatuses 1b and 1c is basically the same as that of the packet relay apparatus 1a. Other configurations are the same as those in the first embodiment, and detailed description thereof is omitted here.

  Here, for example, if communication is performed between the terminals 9a, 9b, 9c, and 9d and the terminal 8a, the terminals 9a, 9b, 9c, and 9d → the packet relay device 1a → the network 7c → the packet in a steady state. Packets are sent in the order of relay device 1c → terminal 8a.

  On the other hand, when the network 7c becomes unusable due to a failure or disconnection, the route information table 3 is updated, so that communication is performed by the terminals 9a, 9b, 9c, 9d → the packet relay device 1a → the network 7a → the packet relay. The route is shifted from the device 1b to the network 7b to the packet relay device 1c to the terminal 8a.

  When updating the route information table 3, the processing unit 2 refers to the interface bandwidth table 14 and determines whether or not the bandwidth becomes narrower than before. When it is determined that the bandwidth is reduced from 100 Mbps to 10 Mbps, the interface importance level table 10 (FIG. 3) is continuously referred to, and the priority level of the packet received at the interface with low importance level is temporarily set to low priority. Change to Since the processing at that time is basically the same as the content of the flowchart shown in FIG. 4, detailed description thereof is omitted here.

  As described above, in the fourth embodiment, when the path information table 3 is updated, it is checked whether or not the bandwidth is narrowed by referring to the interface bandwidth table 14, and when it is determined that the bandwidth is narrowed, the interface importance degree table continues. By referring to 10, it is possible to prevent the packets of all the streams due to the route change from being uniformly discarded.

Embodiment 5 FIG.
FIG. 11 is a configuration diagram of a network system having a packet relay device according to the fifth embodiment of the present invention. Components corresponding to those in the first embodiment shown in FIG.

  In the network system of the fifth embodiment, the bandwidth of the network 7b connecting the packet relay devices 1b and 1c is smaller than the network 7a connecting the packet relay devices 1a and 1b. An example of such a case is when one network 7a is used frequently and the other network 7b is used less frequently.

  In addition, the processing unit 2 of the packet relay apparatus 1a holds the route information table 3 and the interface importance degree table 10, and further includes a discard message transmission / reception unit 15.

  In this case, the importance level is set in the interface importance level table 10 in consideration of the bandwidths of the networks 7a and 7b. In addition, when the packet relay unit 4 generates a packet discard, the discard generation message transmission / reception unit 15 transmits a discard generation message to another packet relay device in response to this, A discard occurrence message is received from the packet relay device.

  The configuration of the other packet relay apparatuses 1b and 1c is basically the same as that of the packet relay apparatus 1a. Other configurations are the same as those in the first embodiment, and detailed description thereof is omitted here.

  Here, when the stream amount of packets addressed to the terminal 8a from the terminals 9a, 9b, 9c, and 9d exceeds the bandwidth of the network 7b, the packet relay apparatus 1b causes congestion discard of packets. When a packet addressed to the terminal 8 is discarded in the packet relay device 1b, the discard message transmission / reception unit (not shown) of the packet relay device 1b transmits a discard message to the packet relay device 1a located upstream. .

  When the discard message transmission / reception unit 15 provided in the processing unit 2 of the packet relay apparatus 1a receives the discard generation message via the packet relay unit 4, the processing unit 2 responds to the interface importance table. Referring to FIG. 10, the priority of the packet received on the interface with low importance is temporarily changed to low priority. Since the processing at that time is the same as the content of the flowchart shown in FIG. 4, detailed description is omitted here.

  As described above, in the fifth embodiment, when congestion discard occurs in the packet relay apparatus 1b in the middle of the communication path, the packet inflow is limited in the packet relay apparatus 1a on the upstream side from this, Packets that are discarded in the middle of the communication path can be limited by the packet relay device 1a close to the transmission source terminals 9a to 9d, and the bands of the networks 7a and 7b can be effectively used.

  In the above-described Embodiments 3 to 5, the interface importance degree table 10 (FIG. 3) is provided. When congestion discarding occurs, the importance degree is low with reference to the interface importance degree table 10. Although processing for lowering the priority of the packet is performed, a field importance level table 11 (FIG. 6) as in the second embodiment may be provided instead of the interface importance level table 10. In this case, it is possible to perform processing for lowering the priority of a packet having a low importance field with reference to the interface importance degree table 11.

  Further, the present invention is not limited to only the configuration aspects of the above-described first to fifth embodiments. For example, the configurations of the first to fifth embodiments can be appropriately combined, and depart from the spirit of the invention. Various modifications can be made within the range not to be performed.

It is a block diagram of a network system having a packet relay device in Embodiment 1 of the present invention. It is a block diagram of the packet for communication employ | adopted with this network system. It is a figure which shows an example of an interface importance table. 6 is a flowchart illustrating a processing operation of the packet relay device when a packet congestion discard state occurs in the first embodiment of the present invention. It is a block diagram of the network system which has a packet relay apparatus in Embodiment 2 of this invention. It is a figure which shows an example of a field importance table. It is a block diagram of the network system which has a packet relay apparatus in Embodiment 3 of this invention. It is a figure which shows an example of a buffer threshold value table. It is a block diagram of the network system which has a packet relay apparatus in Embodiment 4 of this invention. It is a figure which shows an example of an interface bandwidth table. It is a block diagram of the network system which has a packet relay apparatus in Embodiment 5 of this invention.

Explanation of symbols

1a, 1b, 1c, 1d packet relay device, 2 processing unit, 3 route information table,
4 packet relay unit, 5a, 5b, 5c, 5d, 5e, 5f interface unit,
7a, 7b, 7c network, 8a, 8b terminal, 9a, 9b, 9c, 9d terminal, 10 interface importance table, 11 field importance table,
12a, 12b, 12c, 12d buffer, 13 buffer threshold table,
14 Interface bandwidth table, 15 Discard message transmission / reception unit.

Claims (4)

A route information table storing network route information and a packet that relays packets input via a terminal or network based on the route information in the route information table and detects whether congestion congestion of the packet has occurred If there is an update of the relay unit, the interface importance table storing the importance of the interface through which packets are input / output, the interface bandwidth table holding the bandwidth of each interface, and the routing information table, the interface bandwidth table is If it is determined that the interface that relays the packet is changed to an interface with a narrower bandwidth than the current one , refer to the interface importance table according to this and the priority of the packet with the lower importance And a processing unit that performs processing to lower the Packet relay unit, the packet relay apparatus, characterized in that it is intended to discard the packets with lower priority that has been processed by the processing unit preferentially. A route information table storing network route information and a packet that relays packets input via a terminal or network based on the route information in the route information table and detects whether congestion congestion of the packet has occurred When there is an update of the relay unit, the field importance table storing the importance of a specific packet field, the interface bandwidth table holding the bandwidth of each interface, and the routing information table, the interface bandwidth table is referred to. Te when interface for relaying the packet is determined to band than those of the current is changed to a narrow interface lowers the priority of the packets with lower importance with reference to the field importance level table accordingly A processing unit that performs processing, and the packet relay unit Packet relay apparatus, characterized in that to discard preferentially lower packet priority that has been processed by the processing unit. If a packet discard has occurred in the packet relay unit, a discard generation message is transmitted to another packet relay device in response to this, and a discard message is received from another packet relay device An occurrence message transmission / reception unit, and when the discard occurrence message transmission / reception unit receives the discard occurrence message, the processing unit refers to the interface importance degree table according to this and prioritizes a packet with low importance The packet relay device according to claim 1, wherein the packet relay device performs processing to reduce the degree . If a packet discard has occurred in the packet relay unit, a discard generation message is transmitted to another packet relay device in response to this, and a discard message is received from another packet relay device A generation message transmission / reception unit, and when the discard generation message transmission / reception unit receives the discard generation message, the processing unit refers to the field importance table according to the priority, and prioritizes packets with low importance. The packet relay apparatus according to claim 2, wherein the packet relay apparatus performs a process of reducing the degree .

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