JPH10243016A - Network controller - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the network controller that ensures sure transmission performance and high carrying performance by sending a packet through multi-paths depending on priority within each line capacity even on the occurrence of congestion or a fault in the transmission lines. SOLUTION: The controller is made up of a transmission node, a relay node and a destination node, and the transmission node sends a packet. In this case, a flag denoting transmission priority is set to the packet, and the transmission node is provided with a routing table that stores a plurality of transmission paths between the transmission node and the destination node corresponding to the transmission priority. Then in the case of sending the packet, a required number of copies is made from the packet and they are sent to the paths corresponding to the priority.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a multipath transmission network control for duplicating and transmitting the same packet to a plurality of transmission paths between a source node and a destination node.

[0002]

2. Description of the Related Art In a conventional multi-path transmission apparatus, n transmission paths with priorities described in a routing table are selected in advance, and the same number m of redundant transmission paths is set at each node. Among the n transmission paths, m transmission paths on which no failure or congestion has occurred are selected in the order described in the routing table. At this time, if there is only one available route, m identical packets are copied and transmitted for one route. That is, m times of traffic is generated. Thus, during congestion or the like, as the number of available transmission paths decreases, packets for the redundant transmission paths concentrate on the transmission paths, and the load on the transmission paths increases. On the other hand, if the network is designed in consideration of such congestion, the line capacity between each node becomes enormous and equipment cost increases, and when used in a normal network form, the line use efficiency becomes extremely high. Deteriorate.

The above-mentioned state will be specifically described with reference to a configuration diagram of a network and a routing table. FIG.
FIG. 4 is a diagram showing the concept of a transmission path selection operation in a conventional multipath transmission device. In this figure, the originating node 101
It indicates that two transmission paths 130 and 131 are set between the destination node 102 and the destination node 102. Node 1
03 and node 104 represent relay nodes in this case, and 11
0 and 111 indicate data terminal devices that transmit and receive packets. For example, the originating node 101 includes the routing table of FIG. 15, sets the number of redundant transmission paths to m (in FIG. 14, it is “2”), and sets two transmission paths 130 and 131. Select a transmission path. In the normal state, the packet is copied and sent to both the transmission paths 130 and 131. However, when congestion occurs between the relay node 103 and the receiving node 102, the transmission path 132 is selected instead of the transmission path 130 based on the path No. described in the routing table, and multipath transmission is performed. When the relay node 103 fails, only the transmission path 131 is enabled, and redundant transmission of two copies is performed on the transmission path 131. However, when this is done, between the originating node 101 and the relay node 103, the relay node 10
4 and the destination node 102 have twice the normal traffic.

[0004] An increase in traffic when congestion occurs will be described on another network. In a normal network configuration as shown in FIG. 16, when the network configuration changes as shown in FIG.
It can be seen from FIG. 1 that for the destination node 203, the node section AB takes three times as much traffic as the conventional one.

According to Japanese Patent Application Laid-Open No. 6-334687, an apparatus is disclosed in which a packet priority is determined, registered in a table, and a route corresponding to the priority is selected in order to prevent load concentration on a specific relay route. ing. However, the configuration of the publication shown in FIG. 18 does not disclose the idea of transmission of a packet through the redundant path by the same copy.

[0006]

SUMMARY OF THE INVENTION Conventional routing
In a network control device that selects a transmission route based on a redundant transmission route registered in a table, there is a problem that when a congestion state or the like occurs, traffic concentrates between certain nodes and exceeds the load limit of the transmission line. . In order to avoid this, if a network design with a reduced line load is performed, the required line capacity becomes enormous, the line use efficiency during normal use is low, and the equipment cost increases. In the conventional multipath transmission apparatus, the number of redundant transmission paths is fixedly set, and packets are copied based on the number. Therefore, packets concentrate on available transmission paths, and the load on nodes and transmission paths increases. In addition, since all packets are handled with the same importance, there is a problem that the transmission delay time is equally increased even for packets with high importance.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problem, and ensures transmission quality by ensuring a transmission delay and a delivery rate of a certain value or more even when the network configuration in multipath transmission changes. It is another object of the present invention to obtain a network control device capable of distributing a load between each node and a transmission path.

[0008]

A network control device according to the present invention comprises a source node, a relay node, and a destination node. In a network for transmitting a packet from a source node, a flag indicating the priority of transmission is provided in the packet. The source node has a routing table storing a plurality of transmission paths from the source node to the destination node corresponding to the priority of transmission, so that when transmitting a packet, a required number of nodes are directed toward the path corresponding to the priority. I made a copy and sent it.

Further, the network control device of the transmission node adds a congestion degree measuring means for measuring the congestion state of each transmission line, and stores the allowable transmission capacity of the corresponding transmission line at the latest time in the routing table. Then, when the congestion state of each transmission path is detected, a plurality of transmission paths corresponding to the priority, including the number of transmission paths, are changed by referring to the routing table.

[0010] Furthermore, the network control device of the transmission node adds congestion degree measuring means for measuring the congestion state of each transmission path, puts data length information on the packet, and detects the congestion state of each transmission path. Changed the data length of the packet.

Further, the network control device of the originating node calculates whether the set transmission routes between the originating node, the relay node and the destination node partially overlap, and the frequency of the duplication is equal to or more than a predetermined value. In such a case, transmission to a predetermined transmission path is stopped.

[0012] Furthermore, a packet is provided with a source, a destination, node progress information and a sequence number, and a network control device is also provided in the relay node. When the relay node receives the packet, it adds its own packet to the received packet. If there is progress information of the relay node, the packet is discarded, and if there is no progress information, the packet is copied by the number set according to the priority and transmitted to the set adjacent node.

Further, the network control device of the relay node adds a congestion degree measuring means for measuring the congestion state of each transmission line, and when the congestion state of each transmission line is detected, a predetermined setting including the number of copies is performed. Changed adjacent node to transmit packets.

Further, the packet is made to have a packet discard permission flag, and the network control device of the relay node
A congestion degree measuring means for measuring the congestion state of each transmission path is added, and when the congestion state of each transmission path is detected, the relay transmission at the relay node is stopped by checking the discard permission flag of the received packet.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION

Embodiment 1 FIG. A plurality of transmission routes, which are the gist of the present invention, are set including their relay nodes, and the number of copies is determined in accordance with the priority of packet transmission, and the same packet is transmitted in parallel to the above-mentioned set route. The basic operation to be performed will be described. FIG. 1 is a diagram illustrating an example of a network configured by the devices according to the present embodiment. In FIG. 1, the A node 301
To E node 305, five nodes are arranged, and between each node, 306AB, 307AC,
308AD, 309AE, 310BC, 311CD, 3
Eight transmission lines of 12DE and 313EB connect the nodes.

FIG. 2 shows a basic configuration diagram of each node. User data terminal 4 for inputting user data
01, a data terminal I / F unit 402 which is an interface between the terminal and the terminal, a node management unit 403 which further manages the node device itself, a routing control unit which performs routing control at the time of multi-path transmission, packet copy / disassembly / assembly A packet disassembly / assembly unit for performing processing such as duplication identification, and a line I / F which is an interface with a transmission path between nodes;
A failure management unit 408 monitors failures between nodes and transmission paths, and a database 407 stores failure information and information such as a routing table.

The operation of the originating node to which the user data terminal, which is the originator, is connected will be described. Data transmitted from the user data terminal 401 includes:
Once passing through the data terminal I / F unit 402, it is input to the packet disassembly / assembly unit 405, packetized (disassembled), and copied by the number determined according to the priority, that is, the number of redundant transmission paths. In the packet, information of a priority flag is inserted according to the transmission priority. Thereafter, based on the information on the transmission path set by the routing control unit 404, the packet is sorted and transmitted to the corresponding line I / F unit 406. The routing control unit sets the available transmission paths in the routing table in the order in which use is desired, and performs control such that the transmission paths are numbered in the order of priority from the top. The operation of the receiving node to which the destination user data terminal is connected is as follows. Data received by the line I / F unit 406 of the destination node via the relay node and the transmission path is temporarily stored in the packet disassembly / assembly unit 405, and the header is identified, duplicated packets are discarded, packets are assembled, and so on. And via the data terminal I / F unit 402,
The data is received by the user data terminal 401 of the destination. In addition,
In any of the above-mentioned transmitting node, receiving node, and relay node, the failure management unit 408 has a function of monitoring the number of transmission queues, processing load, line quality, and the like of the line I / F unit 406. The node management unit 403 has a failure management function such as device failure management of the entire node device and failure switching. The maintenance terminal 409 performs node maintenance and node information input.

FIG. 3A shows a route number that is desirably used from the A node 301 to the C node 303, and the route is stored in the routing 407 stored in the database 407.
FIG. 3B is a diagram showing the number of redundant transmission paths for each priority of the routing table. FIG. 4 shows a packet format to be transmitted and received. The order of the use routes in FIG. 3A is set, and FIG.
The routing table in which the redundancy numbers corresponding to the priorities are determined can be set in advance from the maintenance terminal 409 to each node. In each node, the routing table is referred to by the routing control unit 404, so that line connection information,
The redundant transmission path information is exchanged with the packet disassembly / assembly unit 405 to realize multi-path transmission. Normally, the routing table describes the order of the used routes in ascending order of the number of elapsed nodes. For example, when the transmission route with the priority of “urgent” level is the number of redundant transmission routes, that is, the number of copies is 3, the routes of the route numbers 1 to 3 in FIG. 3A are selected. Further, for example, when a failure occurs in the B node 302, the path numbers 1, 3, and 4 are selected as the transmission paths. As for the priority, the number of redundant routes is naturally determined in consideration of the amount of traffic. In addition, packets having a high degree of importance are set as much as possible in consideration of the above-mentioned traffic amount so that transmission quality such as immediacy and certainty of transmission arrival can be guaranteed. As described above, according to the present embodiment, a higher priority packet is given more routes in an advantageous route order than a packet having no priority, so that there is an effect that transmission can be performed quickly and reliably in any situation. . In other words, a network that aims to ensure multi-path transmission of packets without exceeding the line capacity even when the network configuration changes due to transmission path congestion or failures, device failures, etc., and to ensure reachability and resistance. This is a control method.

Embodiment 2 In the first embodiment, the transmission route is selected in accordance with the routing table set in advance from the maintenance terminal 409. However, in actual operation, node failures and line congestion occur at various places, so that the fixed routing route is set. Optimal route selection may not be possible with route selection according to the table. Therefore, while constantly monitoring the transmission queue and line quality in each transmission path,
If the transmission path is in a good line condition within the range of the preset line capacity (that is, the transmission queue is small,
It is effective to have a function of selecting the number of copies in order from the one with the least retransmission). FIG.
1 shows a maximum line capacity table of each node section in FIG. 1, which is also stored in, for example, a database and a routing table.

The operation of the apparatus according to the present embodiment which is added to the previous embodiment is as follows. Fault management unit 408
Has a mechanism (congestion degree measuring means) for measuring and monitoring the congestion state of the transmission path, that is, the transmission waiting queue and the line quality.
The information is notified to the routing control unit 404. The routing control unit 404 always reflects the information on a new routing table. That is, the traffic amount in each section is calculated based on the number of redundant transmission paths for each priority shown in FIG. 3B, and it is checked whether or not the upper limit of the maximum line capacity shown in FIG. 5 is exceeded. The transmission paths are reduced from those with lower priority. That is, when the traffic increases, the number of copies of the packet is reduced, and the load on the node is reduced. Thus, the transmission control is performed by updating the optimal transmission path order and the number of redundant transmission paths, and the information is stored in the database 409. According to the apparatus of the present embodiment, transmission of a high-priority packet is guaranteed even in a congested state, and further, there is an effect that a load on a node is suppressed.

Embodiment 3 In the above-described embodiment, the selection of the transmission path according to the routing table is sequentially changed due to the deterioration of the line quality or the like. However, this change may cause the traffic to concentrate on the transmission path having the good line quality. Therefore, in the present embodiment, an embodiment will be described in which data transmission is continued and the packet data length is made variable first, even when the transmission quality is deteriorated, rather than the path change. The apparatus of the present embodiment has the configuration shown in FIG. 1, but differs in the operation of the packet disassembly / assembly unit 405b. The failure management unit 408 has a function of constantly measuring and monitoring the transmission queue and line quality, and notifies the packet disassembly / assembly unit 405 of the information. The fault management unit 408 monitors the line quality by checking the number of retransmissions and the bit error rate in transmission control between adjacent nodes.

FIG. 6 is a diagram showing an example of route monitoring data notified by the fault management unit 408 in the present embodiment.
The packet disassembly / assembly unit 405b shortens the length of the packet data to be transmitted when the information indicates the detection of the congestion state based on the information. That is, a “data length division value” is added to the packet format of FIG. 4, and the division of the packet data length is shown here. The packet disassembly / assembly unit 405b in the relay node and the destination node changes the data length of the relay or incoming packet according to the data length division value with reference to this division, and transmits or receives the packet. FIG. 7 shows the packet format.

Embodiment 4 In the above-described embodiment, the transmission path selection is treated as a different transmission path if the transmission path is different even in one section. However, in the multi-path transmission in which the transmission sections partially overlap, the delay or the like in the overlapping section is considered. Occurs, and although the flexibility and the immediacy of the multi-path transmission can be ensured, it is deviated from the purpose of ensuring the efficiency of the network and the reliability by the multi-path. Therefore, in the present embodiment, in consideration of the degree to which the sections partially overlap the entire settable transmission path between the source node and the destination node, if the paths overlap by a certain value or more, the transmission path Then, one of the transmission paths is selected and the other is removed from the transmission path, thereby reducing the load on the network. For example, in the example of FIG.
In this case, the paths 4 and 6, the paths 5 and 7, and the paths 6 and 7 have the degree of overlap of 2, and only one of these transmission paths is used. The routes 2, 5, and 7 have a degree of overlap of 3, and the route 2 is selected. According to the above-described configuration and operation, the effectiveness of multi-path transmission for securing the reliability of transmission data can be obtained, and the load on the network can be suppressed.

In the above embodiment, basically, the transmission path between the A node 301 and the C node is the routing table on the transmitting node side, and the routing table on the receiving node is also turned over. I was supposed to. That is, the transmission path of the A node 301 and the transmission path of the C node 303 are the same in the upstream and downstream. However, as there is a parent-child relationship in data transmission and reception, the amount of traffic to be transmitted and received is not always the same for uplink and downlink, and the priority of information may be different. Therefore, the routing tables may be managed completely separately on the transmitting side and the receiving side nodes, and the transmission path may be changed in priority between upstream and downstream, even for data transmission and reception in the same section. By doing so, the load on the network can be more finely controlled. That is, the above-mentioned FIG. 3 is separately managed on the transmitting node side and the receiving node side, and packet transmission in uplink and downlink is performed. However, in this case, the transmission control method is different from that of the previous embodiment, and it is necessary to confirm the delivery between the nodes. Also,
It is necessary to employ so-called end-to-end transmission control between the source node and the destination node.

Embodiment 5 FIG. In the above-described embodiment, multipath transmission is regarded as redundant transmission between a source node and a destination node, and redundant selection of the transmission path has been described. In the present and following embodiments, a device will be described that focuses not on the route between the endpoints of the source node and the destination node but on the route that the relay node itself receives for relay and the route that relays and transfers to the adjacent node. That is, multi-path transmission can be performed even if transmission of packets of a preset numerical value is continuously performed to an adjacent node and finally redundant transmission is performed to a destination node, and network traffic can be distributed with simple control. is there. The source node copies the packets by a predetermined number corresponding to the priority of the packets, selects a non-congested transmission line with good line quality from the route information table managed by each node, Send a packet to the node.

Each packet is added with node progress information, a series of sequence numbers between the originating node and the destination node, and the source and destination information.
When receiving a packet, these node progress information, sequence number,
Check the destination information. It checks whether there is information indicating the progress of the corresponding node. If there is the progress information, the packet is discarded. If there is no progress information, the progress information is added and transmitted to the next node. In a received packet, if the sequence number is already received, it is similarly discarded. FIG. 8 shows a route information table according to the present embodiment. FIG. 9 shows a packet data format. The failure management unit 408 monitors the state of the line I / F unit 406, measures the line quality between adjacent nodes, and so on.
Notify the routing control unit 404b. The routing control unit 404b creates a route information table from the information, stores the information in the database 407, and notifies the packet disassembly / assembly unit 405 of the information. The packet disassembly / assembly unit 405 determines whether the corresponding line I /
The information is transmitted to the F unit 406, and the node progress information, the source, and the destination information are set. When each node receives a packet, the packet disassembly / assembly unit 405 identifies the header, checks the node progress information, checks the sequence number,
The destination information is checked, and the packet is relayed, discarded, or captured.

Embodiment 6 FIG. In the present embodiment, a case will be described in which the relay node of the previous embodiment is combined with congestion degree measuring means to perform transmission control during congestion. The network control device in each node has congestion degree control means for sequentially measuring and monitoring the traffic volume and line quality between adjacent nodes, and means for transmitting monitoring result information to the adjacent nodes. The relay node creates a traffic information table based on the above-described traffic information and line quality information, and grasps traffic information of the entire network. The originating node combines the routing table and the traffic information table, digitizes and knows the traffic state from the originating node to the destination node, and selects a transmission path based on the magnitude of the numerical value. FIG. 10 shows a line quality table.
FIG. 11 shows a traffic state table. These are combined to form a traffic information table. FIG.
In addition, routing and traffic information table
Show the table.

The fault management unit 408b measures the line state (line error rate) between adjacent nodes and the amount of traffic (the number of packets processed per unit time), and transmits the information to the routing control unit 404b and the packet disassembly / assembly unit 405. Send to The routing control unit 404b updates the routing table of FIG. 12 stored in the database 407 and the traffic information tables of FIGS. 10 and 11. The packet disassembly / assembly unit 405 transmits the traffic information table to an adjacent node other than the own node. The traffic information table received from another node
Once transmitted to the routing control unit 404b via the packet disassembly / assembly unit 405, the table of the database 407 is updated. At the time of route selection, this table is referred to and an optimal transmission route is selected adaptively.

Embodiment 7 If the relay node finds out that the line is congested at the time of sending out the packet, the packet may be temporarily discarded based on the packet discarding permission flag given only to the copy packet to avoid network congestion. explain. FIG. 13 shows a packet data format in the present embodiment. Each node constantly measures and monitors the number of transmission queue waits on the transmission path between adjacent nodes, and when the number of waits exceeds a preset threshold, regarding packets to be transmitted thereafter, is a copy packet, and Packets for which the packet discarding permission flag is on are discarded until the transmission wait queue falls below a threshold. This requires complicated control such as temporarily discarding the copy packets staying in the network due to the adoption of multipath transmission, checking the priority, and reducing the number of transmission paths whose transmission paths have been changed. Without recovering the network from the congestion state.

[0030]

As described above, according to the present invention, priority is set and multiple transmission paths are selected, so that high-priority packets are more immediate and more reliable than other packets. There is an effect that can be transmitted. There is also an effect of suppressing the construction cost of multipath transmission.

Furthermore, since the transmission route and the redundancy are changed while monitoring the congestion state and the like, there is an effect that the optimum route is selected and the load on the entire network is suppressed.

Further, since the packet data length is changed by monitoring the congestion state and the like, the possibility that transmission is concentrated on a transmission line having good line quality is reduced, and there is an effect of alleviating the load distribution of the network.

Further, in selecting the multiple transmission paths, the degree of overlap of transmission sections is taken into consideration, so that there is an effect that the load on the network can be suppressed.

Further, in the relay node, packets of the number of copies are distributed and transmitted to the adjacent nodes.
Although the traffic volume is slightly increased, there is an effect that the load of the network can be distributed.

Further, since the relay node detects the congestion state and temporarily discards the packet based on the packet discard permission flag, multi-path transmission cannot be realized, but the congestion state of the network can be solved in a short time. There is.

[Brief description of the drawings]

FIG. 1 is a diagram of a network configuration in a normal state according to Embodiment 1 of the present invention.

FIG. 2 is a configuration block diagram of a node according to the first embodiment of the present invention.

FIG. 3 is a diagram of a routing table according to the first embodiment.

FIG. 4 is a diagram showing a packet format according to the first embodiment.

FIG. 5 is a table showing a maximum line capacity table according to Embodiment 2 of the present invention.

FIG. 6 is a diagram of a routing table according to the third embodiment of the present invention.

FIG. 7 is a diagram showing a packet format according to the third embodiment.

FIG. 8 is a diagram showing a route information table according to the fifth embodiment of the present invention.

FIG. 9 is a diagram showing a packet format according to the fifth embodiment.

FIG. 10 shows a line quality table according to Embodiment 6 of the present invention.

FIG. 11 is a diagram of a traffic state table according to the sixth embodiment.

FIG. 12 is a diagram of a traffic information table according to the sixth embodiment.

FIG. 13 is a diagram showing a packet format according to the seventh embodiment of the present invention.

FIG. 14 is a conceptual diagram of a multipath transmission system.

FIG. 15 is a diagram of a routing table in a conventional multipath transmission system.

FIG. 16 is a diagram illustrating a network configuration in a normal state for explaining a multipath transmission system.

FIG. 17 is a diagram illustrating a network configuration at the time of an abnormality illustrating a multi-path transmission system.

FIG. 18 is a diagram of a priority determination table in another conventional example.

[Explanation of symbols]

101 sending node, 102 receiving node, 103, 1
04 relay node, 110, 111 data terminal, 13
0, 131, 132 transmission path, 201, 202, 20
3,204,205,301,302,303,30
4,305 nodes, 306AB, 307AC, 308
AD, 309AE, 310BC, 311CD, 312D
E, 313 EB Transmission path, 404, 404b Routing control unit, 405, 405b Packet disassembly / assembly unit, 408, 408b Fault management unit.

Claims (7)

[Claims] 1. A network comprising a source node, a relay node, and a destination node and transmitting a packet from the source node, wherein the packet is provided with a flag indicating transmission priority, and the source node corresponds to the priority. A routing table storing a plurality of transmission routes from the originating node to the destination node, and transmitting a required number of copies toward a route corresponding to the priority when transmitting a packet and transmitting the packet. Network controller. 2. The network control device of the transmitting node,
A congestion degree measuring means for measuring the congestion state of each transmission line is added, the permissible transmission capacity of the corresponding transmission line at the latest time is stored in the routing table, and when the congestion state of each transmission line is detected, the above routing is performed.・
2. The network control device according to claim 1, wherein a plurality of priority-based transmission paths are changed, including the number of transmission paths, with reference to the table. 3. The transmitting node's network control device comprises:
Congestion degree measuring means for measuring the congestion state of each transmission line is added, data length information is added to the packet, and when the congestion state of each transmission line is detected, the data length of the packet is changed. The network control device according to claim 1, wherein 4. The network control device of the transmitting node,
Calculate whether the transmission paths set between the source node, the relay node, and the destination node partially overlap, and if the frequency of the duplication is equal to or more than a predetermined value, stop transmitting to the predetermined transmission path. 2. The network control device according to claim 1, wherein: 5. A packet includes a source, a destination, node progress information, and a sequence number. A network control device is also provided in the relay node. When the relay node receives the packet, the relay node relays the packet to the received packet. 2. The apparatus according to claim 1, wherein the packet is discarded when the progress information of the node is present, and the packet is transmitted by copying the set number according to the priority when there is no progress information to the set adjacent node. The network control device according to claim 1. 6. The network control device of the relay node,
A congestion degree measuring means for measuring the congestion state of each transmission line is added, and when the congestion state of each transmission line is detected, a predetermined set adjacent node including the number of copies is changed to transmit a packet. The network control device according to claim 5, wherein: 7. A packet discarding permission flag is given to a packet, and the network control device of the relay node adds a congestion degree measuring means for measuring a congestion state of each transmission line, and when detecting a congestion state of each transmission line, 6. The network control device according to claim 5, wherein the relay transmission is stopped at the relay node based on the discard permission flag of the received packet.