JP2002305540A - Network routing system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a network routing system that can attain quick routing in response to a change in the state of links even when a network includes an unstable network part such as a high interruption frequency of links. SOLUTION: In the network routing system that decides a path from each node in one net to each destination in the same net or other net on the network comprising a plurality of nets, a routing table 106 specifying a cross reference between a destination address and a succeeding hope node in each node is configured with an IP routing table 106a that stores the cross reference between destination addresses and in-net final nodes and with an in-net routing table 106b that stores the cross reference between in-net final nodes and succeeding hop nodes.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network routing system, and more particularly to a network routing system suitable for routing in a network composed of a plurality of networks having different quality and stability.

[0002]

2. Description of the Related Art Route changes in the ordinary Internet are performed in response to link disappearance due to a failure such as a router failure or line disconnection, and recovery from such a failure. For example, in OSPF (Open Shortest Path First), when a failure occurs, link status information is updated and publicized, and path information excluding the lost link is recalculated. Upon recovery from the failure, the route information is updated to include the link. For this reason, the routing protocol on the Internet has a function of exchanging information with each other in accordance with the disappearance and restoration of a link. As such information, data having a relatively simple structure such as the bandwidth and delay of a link connected to the router is used. The route information obtained as a result of the route calculation is managed by a combination of the destination IP address and the next hop node.

Further, in the ordinary Internet, the entire Internet is divided into a plurality of ASs (Autonomous Systems), and protocols for exchanging routing information between ASs and within the ASs are individually defined. However,
Assuming the quality of the network itself is homogeneous,
It is assumed that route change will occur with the same probability in any AS.

[0004]

In the conventional Internet technology, a routing method optimized for a network in which the quality of a part of the network is different from that of the others has not been considered. Therefore, for example, the same routing protocol is applied to each section even if the management network includes a wireless section that is susceptible to rain attenuation and a wired section with stable quality. As a result, frequent link state fluctuations in the wireless section and the route change triggered by the change affect the wired section having a stable quality, and the frequent switching of the path significantly increases the stability and performance of the entire network. There was a technical problem that it would decrease.

[0005] Further, in the conventional routing protocol, it is difficult to promptly update the route in response to the change in the link state due to the quality change (about once every few seconds) due to the radio environment factors in the radio section. There was a technical problem.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problems of the prior art, and to quickly follow a change in link state even when a part of the network includes an unstable network such as a high frequency of link connection / disconnection. The present invention provides a network routing method in which fast and quick routing is performed.

[0007]

SUMMARY OF THE INVENTION In order to achieve the above-mentioned object, the present invention relates to a network comprising a plurality of networks, wherein each node in one network is connected to the same network or in another network. In a routing system of a network that determines a route to each destination, a routing table that defines a correspondence between a destination address and a next hop node in each node stores an IP that stores a correspondence between a destination address and a last node in the network. It is characterized by comprising a routing table and an in-network routing table for storing the correspondence between the last node in the network and the next hop node.

According to the above feature, even if the link state of the wireless section in the network that is susceptible to rain attenuation changes,
Since only the routing table in the network needs to be updated,
Routing can be quickly performed according to a change in the link state.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of a routing system in a mesh network according to the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram showing a configuration of a network including a wireless mesh network M1 to which the present invention is applied, and FIG. 2 is a diagram showing a configuration of a wireless mesh network M1.

A user sub-network Sub is connected to each of the nodes N11 to N19 of the mesh network M1. A particular node of the mesh network M1 has another mesh network M
2, M3 and the Internet are interconnected. All systems, including each node of the mesh network M1,
An IP address is assigned, and in this embodiment, routing is performed using this IP address.

FIG. 3 is a block diagram schematically showing the routing function of each node of the mesh network M1.

The link status information generation unit 101 generates and holds the link status information shown in FIG.
The link status information of the present embodiment includes (1) static configuration information, (2) wireless link band information, and (3) traffic information. Hereinafter, each information will be described.

(1) In the static configuration information, the “connection state of the radio link between nodes”
In the example of 2, between nodes N11 and N12, nodes N11 and N1
This is information indicating that a wireless link exists between four or the like. In the wireless mesh network, since the bidirectional link band can be asymmetric and temporally fluctuate even between the same nodes,
The connection state of the wireless link is handled for each link direction.

The "address of a terminal or a sub-network accommodated in a node" is information indicating that the sub-networks Sub111, 8ub112, Sub113 and Sub114 are accommodated in the node N11 in the example of FIG.

"Address of external terminal / external subnet"
Is the address of an external terminal or subnet connected via a gateway, like other wireless mesh networks M2, M3 or an external network (Internet). In FIG. 2 as an example, this corresponds to a list of subnet addresses on the wireless mesh network M3 connected from the node N11 via the node N17, a list of subnet addresses connected from the node N13 via the Internet, and the like.

(2) In the wireless link band information, the “maximum communication band of the wireless link” fluctuates dynamically (each fixed band: discrete value) according to various radio wave environments such as fine weather and rain. Shall be.

(3) In the traffic information, “the amount of traffic transferred by a node in the wireless mesh network” indicates, in the routing in the wireless mesh network, the amount of traffic from the node where the traffic occurred to the last node in the wireless mesh network. Used when performing load balancing between multiple routes.

The last node is a node if a terminal or subnet accommodated in a node in the network is a destination, and a gateway if the destination is outside the network (in FIG. 2, nodes N11, N13, N15, N17, N18, N19).

Returning to FIG. 3, link status information exchanging section 102 notifies the other nodes in the mesh network of the link status information on the own node, and receives the link status information notified from the other nodes. Transmission and reception of each piece of link status information is performed when each piece of link status information is updated.

The topology analysis unit 103 analyzes a topology based on link status information on the own node and link status information distributed from another node in the network.

The intra-network route information generation unit 104 recalculates intra-network route information including the correspondence between the last node in the network and the next hop node based on the result of the topology analysis. IP
The route information generation unit 105 recalculates IP route information including the correspondence between the destination IP address and the last node in the network based on the result of the topology analysis.

The routing table updating unit 108 updates the routing table 106 based on the recalculated intra-network route information and IP route information.

FIG. 5 shows the routing table 106.
FIG. 4 is a diagram showing an example of the present embodiment, and the present embodiment includes the following two types of tables.

(A) IP routing table This is a table for giving the last node in the wireless mesh network to the destination IP address (including the information of the subnet mask), and is a table used in normal IP routing. In this structure, the next hop router is replaced with the last node. This IP routing table 106a is not affected by fluctuations in the bandwidth or traffic of wireless links in the network to which the own node belongs.

(B) Intra-network routing table This is a table for giving the next hop node from the own node to the last node. The intra-network routing table 106b is changed due to a change in the state of a wireless link in the wireless mesh network, a change in band, or a change in traffic volume.

Returning to FIG. 3, the routing unit 107 distributes the received packet to a predetermined route based on the route information stored in the routing table 106.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG.

In step S1, it is determined whether an update such as addition, deletion, or change has been made to the link status information of the own node. If the link status information has been updated, the link status information of the own node is notified to other nodes in the network via the link status information exchange unit 102 in step S2.

On the other hand, if the link status information of the own node has not been updated, it is determined in step S6 whether link status information has been notified from another node in the network. If the link status information has been notified, the process proceeds to step S3 because a change has occurred in the link state in the network.

That is, each node in the network changes its link status information and updates its own link status information, or each node in the network changes its link status information under the control of another node in the network. When the link status information is notified from the other node and changes, the process proceeds to step S3 to recalculate the route information.

In this embodiment, a boundary node between the own network and another network executes a routing protocol specific to each network to obtain link status information of each network, and obtains link status information of one network. Each node in the other network is notified. Therefore, when the link state of another network changes, link status information is notified from this boundary node.

In step S3, the topology analysis unit 103 analyzes the topology based on the updated new link status information. In step S4, the state of each link is recalculated based on the analysis result of the topology. In step S5, the IP routing table 106a or the in-network routing table 106b of the routing table 106 is updated based on the result of the recalculation.

More specifically, in this embodiment, when the static configuration information of the link status information is changed and the correspondence between the destination address and the last node in the network is changed, the IP routing table 1
06a is updated. In this case, there is no effect on the intra-network routing table 106b.

When the radio link band information of the link status information is changed, the route to the last node is recalculated, and when the correspondence between the last node and the next hop node in the network changes, the routing in the network is changed. The table 106b is updated.

Further, when the traffic information of the link status information changes greatly, the route from the own node to the last node is recalculated, and if the correspondence between the last node in the network and the next hop node changes, the routing table in the network is changed. 106b is updated. However, in this case, a method is used in which a local optimal solution with little change is selected so as not to cause a sudden change in the traffic transfer route.

As described above, in this embodiment, each node calculates the topology of the mesh network based on the link status information, and calculates the route from the own node to the destination. Here, a node located at the boundary between the wireless mesh network and the external network interprets each routing method applied in both sections and notifies the other of the path information generated in each section.

As a result, each node in the wireless mesh network sets, as a route to the destination, path information (intra-network routing table) from its own node to the last node (boundary node) in the wireless mesh network and the route information in the wireless mesh network. It can hold the route information (IP routing table) from the last node to the destination.

Since the recalculation of the route according to the change in the link state in the wireless mesh network may be performed only on the routing table in the network, the route can be quickly followed by following the change in the link state. Become like

[0040]

According to the present invention, only the in-network routing table needs to be updated even if the link state of a radio section that is susceptible to rain attenuation fluctuates. Routing becomes possible.

[Brief description of the drawings]

FIG. 1 is a diagram showing a network configuration including a wireless mesh network M1 to which the present invention is applied.

FIG. 2 is a diagram showing a configuration of a wireless mesh network M1.

FIG. 3 is a block diagram schematically illustrating a routing function of each node.

FIG. 4 is a diagram showing an example of link status information.

FIG. 5 is a diagram illustrating an example of a routing table.

FIG. 6 is a flowchart showing the operation of the present embodiment.

[Explanation of symbols]

101: link status information generation unit, 102: link status information exchange unit, 103: topology analysis unit, 10
4 ... intra-network route information generation unit, 105 ... IP route information generation unit,
106: routing table, 107: routing unit, 108: routing table update unit

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Toshihiko Kato 2-1-1-15 Ohara, Kamifukuoka-shi, Saitama F-term in KDD Corporation (reference) 5K030 GA01 HA08 HD03 KA05 LB05 MB04 5K033 AA02 CB08 DA05 DB18

Claims (4)

[Claims] 1. A network routing system for determining a route from each node in one network to each destination in the same network or another network on a network composed of a plurality of networks. The routing table that defines the correspondence between the destination address and the next hop node, stores the IP routing table that stores the correspondence between the destination address and the last node in the network, and the correspondence between the last node in the network and the next hop node. A network routing system comprising a network routing table for storing. 2. A boundary node located at a boundary with another network in a network executes a routing protocol specific to each network, recalculates route information of each network, and calculates route information of one network. Is notified to each node in the other network, respectively. 3. Each node obtains route information based on link status information of its own node and link status information notified from other nodes in the network, and the correspondence between the last node in the network and the next hop node is determined. 3. The network routing system according to claim 1, wherein the network routing table is updated in response to the change. 4. Each node obtains route information based on its own link status information and link status information notified from another node in the network, and the correspondence between the destination address and the last node in the network changes. 4. The network routing system according to claim 1, wherein said IP routing table is updated in response thereto.