JP3110583B2 - Router device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a router for interconnecting a plurality of computer networks, and more particularly to a router for distributing a load among a plurality of relay routes, detecting a faulty route, and bypassing the route.

[0002]

2. Description of the Related Art A computer network connects terminals such as computers with optical fibers or electric cables to realize functions such as transmission and reception of data between the terminals and sharing of output devices and storage devices. . One of devices for interconnecting computer networks is a router device. In a computer network interconnected by the router device, terminals on different computer networks can communicate with each other.

When a certain terminal sends data to another terminal, the source terminal adds the address of the source terminal and the address of the destination terminal to the data and transmits the data. In this manner, data obtained by adding the source and destination addresses to the data and other information necessary for relaying is called a packet. An address is an identifier for uniquely identifying a certain terminal in an interconnected computer network.

FIG. 15 shows, for example, Japanese Patent Application Laid-Open No. 3-234140.
FIG. 1 is a block diagram showing a configuration of a conventional router device as disclosed in Japanese Unexamined Patent Publication (Kokai) Publication. The conventional router 97 shown in FIG.
Has a router function 98 for performing relay processing, a routing table 99 for storing relay processing information, and local interfaces 5a to 5d for connecting the router device to a computer network. The local interfaces 5a to 5d are connected to a computer network via cables 8a to 8d.

FIG. 16 is an explanatory diagram for explaining the operation of a conventional router device. As shown in the figure, the computer networks 6a to 6h are connected to routers 97a to 97g via cables 8a to 8p, and are interconnected via the routers. Note that reference numeral 7a,
7b is a terminal on the computer network.

[0006] The router device interconnects two or more computer networks and relays packets. For this reason, it has a table called a routing table in which the relay route is recorded. FIG. 19 shows the contents of the routing table 99 of the router device 95a of FIG. In FIG. 19, each row (hereinafter, referred to as an entry) configuring the routing table 99 indicates information on a certain relay route. The item in the first column of the routing table 99 is a destination network, which is a computer network that can be finally reached. Second
The item in the column is a transfer destination router device, and is a router device to which a packet is to be transferred next in order to reach the destination network of this entry. The third column is the number of hops,
This is the number of routers, including the router itself, that pass through to reach the destination network of this entry. The fourth column shows the priority between entries having the same destination network. The smaller the number, the higher the priority. The fifth column is the update time, and indicates the time at which the content of this entry was updated recently.

FIG. 17 is a flowchart showing the operation of the relay device 97 shown in FIG. Now, FIG.
It is assumed that the terminal 7a has transmitted the packet 9 addressed to the terminal 7b. The operation of the router device 97a at this time is shown in FIG.
It is explained along. First, the local interface 5a
Receives the packet 9 (step (hereinafter referred to as S) 100), the router function 98 in FIG. 15 determines the final destination network from the destination address of the packet 9 (S101). Here, since the destination terminal is the terminal 7b, it is determined that the computer network 6b to which the terminal 7b is connected is the destination network.

Next, to search the routing table 99, 1 is set as the priority of the search target (S1).
02). Then, an entry having the same priority as the destination network and the search target is searched (S103), and it is determined whether or not there is a matching entry (S104). If there is no matching entry (NO), the received packet is discarded (S1
05) End. Here, the destination network is the computer network 6b, and the priority of the search target is 1. Then, it matches the second entry (S104:
YES). If there is a matching entry, it is determined whether the hop number of the entry is 1 (S106).
If the number of hops is 1 (YES), the data is transmitted directly to the destination terminal (S107), and the process ends (S111). Here, the hop number of the second entry is 2 (S10
6: NO), the router 97b that is the transfer destination router
(Step S108). Next, it is determined whether or not the transmission has been completed normally (S109). If it is determined that the transmission has been normally performed (YES), the process is terminated (S11)
1).

The router device 97b that has received the packet 9
Examines the destination of the packet 9, determines that the final destination is the computer network 6b, searches the routing table 99 of its own, and determines that the computer network 6b is the computer network to which it is directly connected. Since it is understood, the packet 9 is transmitted directly to the terminal 7b.

If the transmission from the router 97a to the router 97b is impossible due to, for example, a failure in the computer network 6h in the above example, it is determined that the transmission has not been completed normally (S109). : N
O), the priority of the search target is reduced by 1 to 2 (S11)
0). Then, when the routing table 99 is searched (S103), it matches the third entry (S10).
4). Since the hop number of the third entry is 3, (S10
6: NO), the router 97d that is the transfer destination router
(Step S108). Here, assuming that the transmission was successful (S109), the process ends (S1).
11).

One of the methods by which the router device dynamically learns the routing table is RIP (Routing).
Information Protocol). The operation of RIP is described in, for example, Kyoritsu Shuppan Co., Ltd., "Network Construction Vol.
(Issued December 5, 991) on pages 201-206.

Hereinafter, a method for the routers to exchange information on the relay route will be described with reference to FIG. In FIG. 16, reference numerals 28a to 28c denote relay route information periodic notifications, and the router device 97
This is a packet for notifying the other routers 97 connected to the router 97 of the contents of the routing table of each.
The relay route information periodic notification stores a set of destination networks and information on how many hops can be reached for all destination networks reachable from the source router transmission 97.

FIG. 18 is a flow chart showing the operation when the router 97 receives the periodic notification of the relay route information. Now, the router device 97b transmits the relay route information periodic notification 28.
b, the operation of the router device 97a when transmitting
This will be described with reference to the flowchart of FIG. The local interface 5a of FIG.
When the router function 98 receives (a) (S112), the router function 98 specifies the source router device from the source address of the relay route information periodic notification 28a (S113). Here, it is determined that the transmission source router device is the router device 97b. Next, each entry of the relay route reception periodic notification is examined in order (S114). Next, it is determined whether or not there is an entry (S115). If there is no entry (NO), the process ends (S116).

Here, it is assumed that an entry having information that the destination network is the computer network 6b and the number of hops is 1 is included first. Therefore, since there is an entry (S115: YES), the destination network is extracted from the entry of the relay route information periodic notification 28a (S117). Here, it is the computer network 6b. Then, the routing table 99 is searched for an entry in which the destination network is the computer network 6b and the transfer destination router is the router 97b (S118). Next, it is determined whether there is a matching entry (S119). Here, 2
(S119: YE
S), the router function 98 rewrites the hop number of the second entry to a value obtained by adding one to the hop number in the entry of the relay route information periodic notification 28a (S121), and rewrites the update time to the current time (S122). If there is no matching entry in the routing table 99 (S119: N
O) makes a new entry in the routing table 99 (S120), and proceeds to S121. Next, it is determined whether the number of hops has changed before and after rewriting (S
123). Here, since the number of hops has not changed before and after rewriting (S123: NO), the process moves to the next entry of the relay route information periodic notification 28a (S125). If the number of hops has changed before and after rewriting (S123: YES), the priority is recalculated for all entries of the same destination network (S124).
Proceed to S125. After S125, the process returns to S115, where the same processing is performed, the processing is performed up to the last entry, and the entire processing ends (S116).

Similarly, the router device 97a receives the relay route information periodic notification 28b and the relay route information periodic notification 28c from the router device 97d and the router device 97g. Update the contents of the sixth and eighth entries.

Each of the routers 97 normally transmits a relay route information periodic notification 28 to other routers every 30 seconds. If the router device 97 breaks down or the computer network 6 has a fault, the relay network cannot reach the destination network. In such a case, since the relay route information periodic notification 28 also does not arrive, the router device 97
Normally does not receive the relay route information periodic notification 28 for 180 seconds, determines that the relay route cannot be used, and stores the entry in the routing table 99.
Remove from.

[0017]

In the conventional router described above, the relay route having the highest priority is always used even when a plurality of relay routes exist, and the load concentrates on this relay route. There was a problem. For this reason, even though the routers 97c to 97g have room, packets exceeding the processing capacity of the router 97b are relayed to the router 97b, and the router 97b cannot process all the packets. There was a point.

Also, as described above, since it waits 180 seconds before it is determined that the relay route is unusable, even if the high-priority relay route becomes unusable, it is not known and the priority route is not determined. There has been a problem that the relay is continued with a high degree, and the transmission delay time increases.

In Japanese Patent Application Laid-Open No. 1-303832, detour type information indicating the importance of a packet is added to a packet, and when the number of transmission waits is equal to or more than a predetermined value, a packet having a low level of detour type information is detoured. A technique for selecting and transmitting a packet transfer path is disclosed. However, even with this technique, the path is always selected in the order of the highest priority, so that the load concentrates on a specific path.

Japanese Patent Laid-Open Publication No. Hei 2-203637 discloses a technique in which the priorities for selecting and using a line route at the time of calling within a terminal are determined, and connection to the line is tried sequentially in this priority order. . However, in this technology, when each terminal sets the priority in order of the transmission delay time,
After all, the load concentrates on a specific route. In order to avoid this, if the priority is arranged differently for each terminal,
In a terminal in which a route with a large transmission delay time has a higher priority, all packets are transmitted on a route selected in accordance with this priority, so that there is a problem that a transmission delay time increases even for important packets. .

The present invention has been made in view of the above problems, and a first object of the present invention is to concentrate a load on a specific relay path without increasing the transmission delay time of important packets. An object of the present invention is to provide a router device that can prevent such a problem.

It is a second object of the present invention to provide a router device which can change the priority of a relay route according to the status of the relay route.

[0023]

In order to achieve the above-mentioned object, a router according to the first aspect of the present invention interconnects a plurality of computer networks connecting a plurality of terminals, and connects the terminals to each other. In relaying a packet for communication, a routing table storing a plurality of relay routes between a source terminal and a destination terminal together with their priorities, and according to a type of a packet to be relayed, Packet priority determining means for determining the priority of the packet corresponding to the priority of the relay route to be selected; and priority of the relay route stored in the routing table and priority of the packet determined by the packet priority determining means. Packet transmission means for selecting one relay route from a plurality of relay routes based on the degree and transmitting a packet. .

Further, according to the second aspect of the present invention, there is provided the router apparatus according to the first aspect, wherein the content of the routing table is periodically transmitted to another router apparatus as the relay path information periodic notification. Means, dynamic learning means for receiving the periodic notification of the relay route information from another router device to update the contents of the routing table, and lastly receiving the periodic notification of the relay route information from the other router device. Elapsed time measuring means for measuring the elapsed time, and when the elapsed time measured by the elapsed time measuring means exceeds a predetermined elapsed time determination threshold value, the priority of the relay route via the corresponding router device is set. Priority changing means for lowering the priority.

According to a third aspect of the present invention, in the second aspect of the present invention, when the elapsed time measured by the elapsed time measuring means does not exceed the elapsed time determination threshold value, the corresponding router device is set. If the priority of the transit route has already been lowered, raise the priority.
Priority change means.

According to a fourth aspect of the present invention, there is provided a router device according to the second or third aspect, wherein the packet processing number measuring means for measuring the number of packet processing per unit time, and the packet processing number measuring means. And a notification suspending means for suspending transmission of the periodic notification of the relay route information when the number of processed packets exceeds a predetermined packet processing number determination threshold value.

According to a fifth aspect of the present invention, there is provided a router device according to the first aspect, wherein a relay route information periodic notifying means for periodically transmitting the contents of the routing table to another router device as a relay route information periodic notification. Dynamic learning means for receiving the periodic notification of the relay route information from the other router device and updating the contents of the routing table, and the time elapsed since the last reception of the periodic notification of the relay route information from the other router device Elapsed time measurement means for measuring the elapsed time measurement means, and when the elapsed time measured by the elapsed time measurement means exceeds the elapsed time determination threshold value, use of a relay path for prohibiting use of a relay path passing through the corresponding router device Prohibition means.

[0028]

According to the first aspect of the present invention, the priority of the packet corresponding to the priority of the relay route to be selected is determined by the packet priority determining means in accordance with the type of the packet to be relayed. Based on the priority of the relay route and the priority of the relay route stored in the routing table, one relay route is selected from the plurality of relay routes by the packet transmitting unit, and the packet is transmitted.

According to the second aspect of the invention, the elapsed time measuring means measures the elapsed time since the last reception of the relay route information periodic notification from another router device, and the elapsed time is a predetermined elapsed time. If the threshold value is exceeded, the priority changing means lowers the priority of the relay route passing through the corresponding router device.

According to the third aspect of the present invention, when the elapsed time measured by the elapsed time measuring means does not exceed the elapsed time determination threshold, the priority of the relay route passing through the corresponding router device is already reduced. In this case, the priority is raised by the second priority changing means.

According to the fourth aspect of the present invention, the number of packet processings per unit time is measured by the packet processing number measuring means, and when the number of packet processings exceeds a predetermined packet processing number determination threshold value, a notification is issued. By means of interruption,
The transmission of the relay route information periodic notification is interrupted.

According to the fifth aspect of the present invention, when the elapsed time measured by the elapsed time measuring means exceeds the elapsed time determination threshold value, the relay route use prohibiting means causes the relay route to be routed through the corresponding router device. The use of is prohibited.

[0033]

Embodiments of the present invention will be described below in detail. 1 to 5 relate to a first embodiment of the present invention.

FIG. 1 is a block diagram showing the configuration of the router device of this embodiment. The router device 1 of the present embodiment includes a router function 2 for performing a relay process, a routing table 3 for storing relay process information, and a packet priority determination table 4.
And local interfaces 5a to 5d for connecting the router device to a computer network. Local interface 5a-5d is cable 8a
Through 8d to a computer network. Routing table 3, packet priority determination table 4, and local interface 5
a to 5d are connected to the router function 2. The router function 2 includes a computer, a storage device for storing programs to be executed by the computer, necessary data, and the like, and has functions of a packet priority determination unit and a packet transmission unit.

FIG. 2 is an explanatory diagram for explaining the operation of the router device of this embodiment. In this figure, reference numerals 1a to 1a
1g is the router device of the present embodiment, and the other configuration is the same as that of FIG.

In the following description, it is assumed that a sufficient time has elapsed since the operation of the routers 1a to 1g started. FIG. 4 shows the contents of the routing table 3 of the router device 1a in this state. In FIG. 4, each row constituting the routing table 3 (hereinafter, referred to as an entry).
Indicates information on a certain relay route. In this embodiment, the routing table 3 has ten entries. The meaning of each column of the routing table 3 is as follows:
Since it is the same as FIG. 19, the description is omitted.

In this embodiment, the priority of the packet is
A packet whose type is called telnet has the highest priority, a priority of 1, a next priority is 2 for a packet called FTP, a priority 3 for a packet called ICMP, and a priority 4 for others. FIG. 5 shows the contents of the packet priority determination table 4 under this condition. In FIG. 5, each row (hereinafter, referred to as an entry) constituting the packet priority determination table indicates a certain packet type and its priority. Packet priority determination table 4
The first column of a packet type, the second column indicates the priority of the packet type, a higher priority smaller number.

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

In the router 1, when the local interface receives the packet (S10), the router function 2 determines the type of the packet (S11), and searches the packet priority determination table 4 (S12). Then, it is determined whether there is a matching entry in the packet priority determination table 4 (S13). If there is (YES), the priority of the received packet is set as the priority of the matching entry (S1).
4) If not (S13: NO), the priority of the received packet is set to a value obtained by adding 1 to the number of entries in the packet priority determination table (S15).

Next, the destination network is determined from the destination address of the received packet (S16), and the routing table 3 is searched in the destination network (S17). Then, it is determined whether or not there is a matching entry in the routing table 3 (S18). If not (NO), the received packet is discarded (S19), and the process ends. If there is a matching entry (S18: YES), it is determined whether there is an entry having a priority that matches the priority of the received packet (S20). If there is (YES), the entry is selected (S21), otherwise (S20: NO)
In step S22, an entry having the highest priority is selected from entries having a higher priority than the priority of the received packet. Next, it is determined whether the hop number of the entry selected in S21 or S22 is 1 (S23),
If the number of hops is 1 (YES), the data is transmitted directly to the destination terminal (S24), and the process ends (S26). If the number of hops is not 1 (S23: NO), the data is transmitted to the transfer destination router. (S25) The process ends (S26).

Next, the terminal 7a sends telne to the terminal 7b.
The operation of the router device 1a when transmitting the packet of t will be specifically described. In this case, when the local interface 5a receives the packet 9 (S10), the router function 2 checks the type of the packet 9 and determines that the packet is a telnet packet (S11). Next, telnet is searched in the packet priority determination table 4 (S1).
2) Match in the first entry. Since there is a matching entry (S13: YES), it is determined that the priority of the packet 9 is the priority of the first entry, that is, 1 (S14).

Next, the router function 2 determines from the destination address of the packet 9 that the final destination is the computer network 6b (S16), and searches the routing table 3 for the computer network 6b as the destination network (S17). . Then, the destination network 6b matches the second to fourth entries. Since there is a matching entry (S18: YES), packet 9
Search for an entry having the same priority as the priority of (S20)
Since the priority of the packet 9 is 1, the second entry of the routing table 3 is selected (S21). Since the hop number of the second entry is 2, the packet 9 is transmitted to the router device 1b which is the transfer destination router device (S2).
5) The process ends (S26).

The router 1b receiving the packet 9
The destination of the packet 9 is checked to determine that it is the final destination computer network 6b, and its own routing table 3 is searched to find that the computer network 6b is the computer network to which it is directly connected. 9 is transmitted directly to the terminal 7b.

Next, the terminal 7a sends telne to the terminal 7b.
The operation of the router 1a when a packet other than t, FTP, and ICPM is transmitted will be specifically described. Here, it is assumed that a packet called TFTP is transmitted as an example. In this case, the local interface 5a
Receives the packet 9 (S10), the router function 2 checks the type of the packet 9 and determines that the packet is a TFTP packet (S11). Next, the TFTP is searched in the packet priority determination table 4 (S12), and a match is found in the fourth entry. Since there is a matching entry (S13: YE
S), it is determined that the priority of the packet 9 is the priority of the fourth entry, that is, 4 (S14).

Next, the router function 2 determines from the destination address of the packet 9 that the final destination is the computer network 6b (S16), and searches the routing table 3 for the computer network 6b as the destination network (S17). . Then, the destination network 6b matches the second to fourth entries. Since there is a matching entry (S18: YES), packet 9
Search for an entry having the same priority as the priority of (S20)
Since there is no entry that matches (NO), an entry with the lowest priority and higher priority than priority 4 is searched, and an entry with priority 3 is found. Since this entry is the fourth entry in the routing table 3, the fourth entry is selected (S22). Since the number of hops of the fourth entry is 4, the router device 1 which is the transfer destination router device
The packet 9 is transmitted to g (S25), and the process ends (S26).

The router 1g receiving the packet 9
The packet 9 is transmitted to the router 1f according to the same procedure, and the router 1f transmits the packet to the router 1e according to the same procedure.
The packet 9 is transmitted to The router device 1e receives the packet 9
Is checked to determine that it is the final destination computer network 6b, and its own routing table 3
And finds that the computer network 6b is the computer network to which it is directly connected, and transmits the packet 9 directly to the terminal 7b.

As described above, according to the present embodiment, the priority of a packet is determined by the packet priority determination table 4 according to the type of the packet to be relayed, and the priority of the relay route stored in the routing table 3 is determined. Since it is determined to which relay path the packet is to be transmitted in accordance with the degree, the load is distributed and the concentration of the load on a specific relay path can be prevented.

Since the priority of the packet is determined according to the type of the packet, the transmission delay of the important packet can be reduced by setting the priority of the important packet higher.

FIGS. 6 to 8 relate to a second embodiment of the present invention. In this embodiment, when the periodic notification of the relay route information from another router device is delayed, the priority of the relay route passing through the router device is lowered.

FIG. 6 is a block diagram showing the configuration of the router device of this embodiment. The router device 1 according to the present embodiment includes an elapsed time measuring device 27 that is connected to the router function 2 and measures an elapsed time after receiving a relay route information periodic notification from another router device. Further, in addition to the function in the first embodiment, the router function 2 includes a relay route information periodic notification unit,
It has the functions of dynamic learning means and priority changing means. Other configurations are the same as in the first embodiment.

FIG. 7 is an explanatory diagram for explaining an operation of transmitting and receiving the periodic notification of the relay route information of the router device of this embodiment. In this figure, reference numeral 28 denotes a relay route information periodic notification transmitted from the router 1b to the router 1a. Other configurations are the same as those in FIG.

In the following description, it is assumed that a sufficient time has elapsed since the operation of the routers 1a to 1g started. It is assumed that the contents of the routing table 3 of the router 1a in this state are as shown in FIG. In this embodiment, for example, it is assumed that a time of 40 seconds is set as the elapsed time determination threshold. Also, the router device 1 transmits the relay route information periodic notification 28 to other router devices 1 every 30 seconds.

Now, the router 1b is
Assume that 41 seconds have elapsed since the relay route information periodic notification was transmitted to a at 10: 51: 5. In FIG. 4, the update time of the second entry of the routing table 3 is the time when the router 1a received the previous relay route information periodic notification 28 from the router 1b, 10: 51: 5.

FIG. 8 is a flowchart showing the operation of the router function 2 relating to the change of the priority in this embodiment.

The router function 2 periodically checks the contents of the routing table 3. Here, it is assumed that the check is performed, for example, every one second. Router function 2 is 1
The routing table 3 is scrutinized in order from the third entry (S29). Next, it is determined whether or not there is an entry (S30). If there is no entry (NO), the process ends (S30).
31). If there is an entry (S30: YES), it is determined whether the hop number of the entry is greater than 1 (S32). If the number of hops is not greater than 1 (NO)
Shifts the processing to the next entry (S40), and returns to S30. When the hop number is larger than 1 (S32: YES)
Calculates the elapsed time by subtracting the update time of the entry from the current time (S33).

Next, it is determined whether or not the elapsed time exceeds the elapsed time determination threshold (S34). If not exceeded (NO), the process moves to the next entry (S40).
If it exceeds (S34: YES), the priority of the entry is lowered by 1 (S35). Next, an entry having the same priority in the same destination network as the corresponding entry is searched (S36). Next, it is determined whether or not there is an entry (S37). If there is an entry (YES), the priority of the matching entry is raised by 1 (S38). If not (S37: NO), the priority of the corresponding entry in S30 is changed. 1 increase (S3
9) Move to the next entry (S40).

Here, when the routing table 3 has the contents shown in FIG. 4, the operation of the router function 2 will be specifically described with reference to FIG. The router function 2 examines the routing table 3 sequentially from the first entry (S29). First, since there is the first entry (S30: YES), looking at the first hop count (S3
2) Since the number of hops is 1, there is no need to check (N
O), the process is moved to the next entry (S40).

Next, the router function 2 checks the second entry. Since the number of hops in the second entry is 2 and greater than 1 (S32: YES), the router function 2 uses the elapsed time measuring device 27 to calculate the elapsed time since the previous relay route information periodic notification 28 was received. Calculate (S3
3). The current time is 10:51:46 and the update time is 1
Since the time is 0: 51: 5, the elapsed time is 41 seconds. When this elapsed time is compared with the elapsed time determination threshold value (S3
4), the elapsed time determination threshold is 40 seconds, and the elapsed time exceeds the elapsed time determination threshold (YES). Therefore, the router function 2 performs a process of lowering the priority of the second entry as described below.

First, the priority of the second entry is lowered by 1 to 1 from 2 (S35). Then, an entry having a priority of 2 is searched for in the same destination network (S36). Since the third entry matches (S3
7: YES) Increase the priority of the third entry by one,
The value is changed from 2 to 1 (S38). As a result, the second to fourth destination networks whose destination networks are the computer networks 6b
The priorities of the third three entries are changed from 1, 2, and 3 to 2, 1, and 3, respectively.

Thereafter, the process is performed for the third and subsequent entries, the last entry is examined, and the process ends (S31).

As described above, according to the present embodiment, the elapsed time since the last reception of the relay route information periodic notification is measured, and when the elapsed time exceeds the threshold, the corresponding relay Since the priority of the route has been lowered, other relay routes can be used preferentially thereafter,
An increase in transmission delay time can be prevented.

Other functions and effects are the same as those of the first embodiment.

FIGS. 9 to 11 relate to a third embodiment of the present invention. In the present embodiment, when the periodic notification of the relay route information from another router device arrives before exceeding the elapsed time determination threshold, the priority of the relay route passing through the router device has already been lowered First, the priority is raised.

The configuration of the router device of this embodiment is the same as that of the second embodiment shown in FIG. 6, except that the router function 2 has the function of the second priority changing means in addition to the function of the second embodiment. have.

In the following description, it is assumed that a sufficient time has elapsed since the router devices 1a to 1g started operating. FIG. 11 shows the contents of the routing table 3 of the router device 1a in this state. 11, the first to fifth rows are the same as those in FIG. The sixth column is a priority decrease number, and a positive number larger than 0 when the priority of this entry is lower than the original priority, and smaller than 0 when the priority of the entry is higher than the original priority. It has a negative value, and its absolute value indicates the difference from the original priority.

In this embodiment, for example, it is assumed that a value of 40 seconds is set as the elapsed time determination threshold value. Also, the router device 1 transmits the relay route information periodic notification 28 to other router devices 1 every 30 seconds.

FIG. 9 is a flowchart showing the operation when the router device 1 receives the periodic notification of the relay route information.
When the local interface receives the relay route information periodic notification 28 (S41), the router function 2 specifies the source router device from the source address of the relay route information periodic notification 28 (S42). Next, each entry of the relay route information periodic notification 28 is scrutinized sequentially (S43), and it is determined whether or not there is an entry (S44). If there is no entry (NO), the process ends (S45). If there is an entry (S44: YES), the destination network is extracted from the entry of the relay route information periodic notification 28 (S46),
The routing table 3 searches for an entry in which the destination network matches and the transfer destination router is the source router (S47), and determines whether there is a matching entry (S48). If there is a matching entry (S48: YES), the elapsed time is calculated by subtracting the update time of the entry from the current time (S49), and it is determined whether the elapsed time is equal to or less than the elapsed time determination threshold. (S
51). When the elapsed time is equal to or less than the determination threshold (YES)
Determines whether the priority decrease number of the entry is greater than 0 (S52). If greater than 0 (S51: Y
ES) raises the priority of the entry by one (S53),
The priority reduction number of the corresponding entry is reduced by 1 (S54).

Next, a search is made for an entry having the same priority in the same destination network as the corresponding entry (S5).
5) It is determined whether there is an entry (S56). If there is an entry (YES), the priority of the matching entry is reduced by one (S57), and the priority reduction number of the matching entry is reduced by one.
Increase (S58). Next, the number of hops in the routing table 3 is rewritten by the number of hops + 1 of the relay route information periodic notification 28 (S59), and the update time is rewritten to the current time (S60). Next, it is determined whether the number of hops has changed (S61). When the number of hops has changed (YE
In S), the priority is recalculated for all entries of the same destination network (S62), and the process proceeds to the next entry (S62).
63), and returns to S44. If the hop number has not changed (S61: NO), the process proceeds to the next entry as it is (S6).
3).

If there is no entry in S48 (N
O) makes a new entry (S50) and proceeds to S59. If the elapsed time is greater than the elapsed time determination threshold value in S51 (NO), if the priority decrease number of the corresponding entry is 0 or less in S52 (NO), and if there is no entry in S56 (NO), Proceed directly to S59.

FIG. 10 is a flowchart showing the operation of the router function 2 relating to the change of the priority in this embodiment.

The router function 2 periodically checks the contents of the routing table 3. Here, it is assumed that the check is performed, for example, every one second. Router function 2 is 1
The routing table 3 is scrutinized in order from the first entry (S64). Next, it is determined whether or not there is an entry (S65). If there is no entry (NO), the process ends (S65).
66). If there is an entry (S65: YES), it is determined whether the hop number of the entry is greater than 1 (S67). If the number of hops is not greater than 1 (NO)
Shifts the processing to the next entry (S78), and returns to S65. When the hop number is larger than 1 (S67: YES)
Calculates the elapsed time by subtracting the update time of the entry from the current time (S68).

Next, it is determined whether or not the elapsed time exceeds the elapsed time determination threshold value (S69). If not exceeded (NO), the process proceeds to the next entry (S78).
If it exceeds (S69: YES), the priority of the corresponding entry is reduced by one (S70), and the priority reduction number of the corresponding entry is increased by one (S71). Next, a search is made for an entry having the same priority in the same destination network as the corresponding entry (S72). Next, it is determined whether or not there is an entry (S73). If there is (YES), the priority of the matching entry is increased by 1 (S74), the number of decreasing priorities of the matching entry is reduced by 1 (S76), and the next Move to entry (S78).
If there is no entry (S73: NO), the priority of the corresponding entry in S65 is increased by 1 (S75), the priority reduction number of the corresponding entry is reduced by 1 (S77), and the process proceeds to the next entry (S78).

Here, the operation when the elapsed time exceeds the elapsed time determination threshold will be specifically described with reference to FIG.

Assume that 41 seconds have elapsed since the router apparatus 1b previously transmitted the relay path information periodic notification to the router apparatus 1a at 10: 51: 5. In FIG. 11, the update time of the second entry of the routing table 3 is the time when the router device 1a received the previous relay route information periodic notification 28 from the router device 1b, 10: 51: 5.

The router function 2 examines the routing table 3 sequentially from the first entry (S64).
First, since there is the first entry (S65: YE
S) Looking at the first hop number (S67), the number of hops is 1, so there is no need to check (NO), and the process moves to the next entry (S78).

Next, the router function 2 checks the second entry. Since the number of hops in the second entry is 2 and larger than 1 (S67: YES), the router function 2 uses the elapsed time measuring device 27 to calculate the elapsed time since the previous relay route information periodic notification 28 was received. Calculate (S6
8). The current time is 10:51:46 and the update time is 1
Since the time is 0: 51: 5, the elapsed time is 41 seconds. When this elapsed time is compared with the elapsed time determination threshold value (S6
9) The elapsed time determination threshold value is 40 seconds, and the elapsed time exceeds the elapsed time determination threshold value (YES). Therefore, the router function 2 performs a process of lowering the priority of the second entry as described below.

First, the priority of the second entry is lowered by 1 to 1 from 2 (S70). Then, since the priority has been reduced by one, the priority reduction number is increased by one and changed from 0 to 1 (S71). Then, an entry having a priority of 2 is searched for in the same destination network (S72). Since the third entry matches (S73: YES), the priority of the third entry is increased by 1 to 2 (S7).
4). Then, since the priority is increased by one, the priority decrease number is reduced by 1 to 0 from -1 (S76). As a result,
The priorities of the second to fourth entries whose destination network is the computer network 6b are changed from 1, 2, and 3 to 2, 1, and 3, respectively. Also, the priority reduction numbers of the respective entries are 0, 0, 0, respectively, but are +1, -1, 0.

Next, FIG. 9 shows an operation when the router 1a receives the periodic notification of the relay route information at 10:51:50 and 10:52:20 from the router 1b after the above processing. This will be described specifically with reference to FIG.

First, the router device 1b operates at 10:51:50.
The operation of the router 1a when the relay route information periodic notification 28 is transmitted every second will be described. When the local interface 5a receives the relay route information periodic notification 28 (S
41), the router function 2 specifies the source router device from the source address of the relay route information periodic notification 28 (S4).
2). Here, it is determined that the source router is the router 1b. Next, each entry of the relay route information periodic notification 28 is scrutinized sequentially (S43). Here, it is assumed that an entry having information that the destination network is the computer network 6b and the number of hops is 1 is included first.

Since there is an entry (S44: YES),
The destination network is extracted from the entry of the relay route information periodic notification 28 (S46). Here, it is the computer network 6b. Then, in the routing table 3, the destination network is the computer network 6
b, and search for an entry in which the transfer destination router is the router 1b (S47). Then, it matches the second entry. Since there is an entry (S48: YE
S), the router function 2 calculates the elapsed time by the elapsed time measuring device 27 (S49). The current time is 10: 51: 5
Since the update time is 0: 05: 05: 05 and the elapsed time is 45 seconds.

Next, when this elapsed time is compared with the elapsed time determination threshold value, the elapsed time determination threshold value is 40 seconds, and the elapsed time exceeds the elapsed time determination threshold value (S
51: NO). Therefore, the router function 2 rewrites the hop number to a value obtained by adding one to the hop number in the entry of the relay route information periodic notification 28 without changing the second entry (S59), and updates the update time to 10:51 of the current time. Rewrite to minute 50 seconds (S60). Since the number of hops has not changed before and after rewriting (S61: NO), the process proceeds to the next entry of the relay route information periodic notification 28 (S6).
3). Thereafter, the same processing is performed, and when the processing reaches the last entry, the processing ends (S45).

Subsequently, the router 1b operates at 10:52:02.
The operation of the router device 1a when the relay route information periodic notification 28 is transmitted at 0 seconds will be described. The local interface 5a receives the relay route information periodic notification 28 (S4
1) After that, the router function 2 calculates the elapsed time (S
Up to 49), it is the same as the previous reception of the relay route information periodic notification 28, and thus the description is omitted. This time, the current time is 10:52:20 and the update time is 10:51:50, so the elapsed time is 30 seconds.

Next, when this elapsed time is compared with the elapsed time determination threshold value, the elapsed time determination threshold value is 40 seconds, and the elapsed time does not exceed the elapsed time determination threshold value (S51: YES). . Then, the router function 2 checks the priority reduction number of the second entry (S52). Since +1 is included in the priority reduction number in the previous process, it is determined that the value is greater than 0 (S52: YES), and the process of increasing the priority of this entry is performed. Therefore, first, the priority of this entry is increased by 1 and rewritten from 2 to 1 (S53). Then, the priority reduction number is reduced by 1 and rewritten from +1 to 0 (S54). Then, an entry having a priority of 1 is searched for in the same destination network (S5).
5). Since the third entry matches (S56), 3
The priority of the entry is decreased by 1 and rewritten from 1 to 2 (S57). Then, the priority reduction number is increased by 1 and -1
Is rewritten to 0 (S58). As a result, the priorities of the second to fourth entries whose destination network is the computer network 6b are changed from 1, 2, and 3 to 1, 2, and 3, respectively. Also, the priority reduction number of each entry is all zero.

Then, the number of hops is rewritten to a value obtained by adding 1 to the number of hops in the entry of the relay route information periodic notification 28 (S59), and the update time is rewritten to the current time of 10:52:20 (S60). Since the number of hops has not changed before and after rewriting (S61: NO), the process proceeds to the next entry of the relay route information periodic notification 28 (S6).
3). Thereafter, the same processing is performed, and when the processing reaches the last entry, the processing ends (S45).

As described above, according to the present embodiment, when a periodic notification of relay route information regarding a relay route whose priority is already lowered is received without delay from the threshold value,
The priority can be raised and returned to the original priority.

FIGS. 12 and 13 relate to a fourth embodiment of the present invention. In the present embodiment, when the number of packets processed per unit time exceeds the packet processing number determination threshold, transmission of the relay route information notification is interrupted.

FIG. 12 is a block diagram showing the configuration of the router device of this embodiment. As shown in the figure, the present embodiment includes a packet processing number measuring device 79 for measuring the number of packet processing per unit time. This packet processing number measuring device 79 is connected to the router function 2 and the local interfaces 5a to 5d. Further, the router function 2 in the present embodiment has a function of a notification suspending unit in addition to the function in the second embodiment or the third embodiment. Other configurations are the same as those of the second or third embodiment shown in FIG.

In the present embodiment, for example, it is assumed that a value of 100 packets / second is set as the threshold value for the number of processed packets.

FIG. 13 is a flowchart showing the operation when the router function 2 transmits a relay route information periodic notification. In this operation, first, the router function 2 creates a transmission relay route information periodic notification 28 (S80). Next, the output of the packet processing number measuring device 79 is referred to (S81).
Next, it is determined whether the number of processed packets exceeds the number of processed packets determination threshold relay (S82). If not exceeded (NO), the router function 2 transmits the relay route information periodic notification 28 as it is (S83), and ends the processing. If it has exceeded (S82: YES), the router function 2 stops transmitting the relay route information periodic notification 28 (S8).
4), end the process.

As an example, when the router 1b tries to transmit the relay route information periodic notification 28 to the router 1a, the output of the packet processing number measuring device 79 is 50 packets /
If it is seconds, this is 1
00 packets / sec (S82: N
O), the router function 2 keeps the relay route information periodic notification 2
8 is transmitted to the router 1a (S83).

If the output of the packet processing number measuring device 79 is 110 packets / sec when the router 1b attempts to transmit the relay route information periodic notification 28 to the router 1a, this is the case where the packet processing number is determined. Threshold of 100
Since the packet rate exceeds packets / second (S82: YES), the router function 2 sends the relay device
The transmission to "a" is stopped (S84).

The router 1b sends the relay route information periodic notification 2
When the transmission of No. 8 is stopped, the priority of the relay route passing through the router 1b is reduced in the router 1a.

As described above, according to the present embodiment, when the load on the router device increases, transmission of the relay route information periodic notification is interrupted, and the load can be reduced.

Other functions and effects are the same as those of the second or third embodiment.

Next, a fifth embodiment of the present invention will be described. In the present embodiment, when the periodic notification of the relay route information from another router device is delayed, the relay route passing through the router device is disabled.

The configuration of the router device of the present embodiment is the same as that of FIG. 6, except that the router function 2 of the present embodiment has a relay route information And a function of relay route use prohibiting means. Other configurations are the same as those of the second embodiment.

In the following description, it is assumed that a sufficient time has elapsed since the router devices 1a to 1g started operating. It is assumed that the contents of the routing table 3 of the router 1a in this state are as shown in FIG. In this embodiment, the elapsed time determination threshold is set to a value of 40 seconds, and the router device 1 transmits the relay route information periodic notification 28 to the other router devices 1 every 30 seconds. .

FIG. 14 is a flowchart showing the operation of the router function 2 in this embodiment. The router function 2 periodically checks the contents of the routing table 3. As shown in FIG. 14, the router function 2 examines the routing table 3 sequentially from the first entry (S85). Then, it is determined whether or not there is an entry (S86), and if not (NO), the process ends (S8).
7). If there is an entry (S86: YES), it is determined whether the hop number of the entry is greater than 1 (S8).
8) If not large (NO), the process moves to the next entry (S96) and returns to S86. If the hop number of the entry is greater than 1 (S88: YES), the elapsed time is calculated by subtracting the update time of the entry from the current time (S89).

Next, it is determined whether or not the elapsed time exceeds the elapsed time determination threshold value (S90). If not (NO), the process proceeds to the next entry (S96). If it exceeds (S90: YES), an entry having the same destination network as the corresponding entry is searched (S91).
Next, it is determined whether or not there is an entry (S92). If there is (YES), the priority of the matching entry is increased by one (S92).
93), the process proceeds to the next entry (S94), and returns to S92. If there is no matching entry in S92 (NO), S8
6 is deleted from the routing table 3 (S95), and the process moves to the next entry (S96).

Here, when 41 seconds have elapsed since the router device 1b previously transmitted the relay route information periodic notification 28 to the router device 1a at 10: 51: 5, the router device 1a
The operation of the router function 2 will be specifically described.

The router function 2 examines the routing table 3 in order from the first entry (S8).
5). First, since there is the first entry (S86: Y
ES) Looking at the hop count of the first entry (S8)
8) Since the number of hops is 1, there is no need to check, and the process moves to the next entry (S96).

Next, the router function 2 checks the second entry. Since the number of hops in the second entry is 2 and larger than 1 (S88: YES), the router function 2 uses the elapsed time measuring device 27 to calculate the elapsed time since the previous relay route information periodic notification 28 was received. Calculate (S8
9). The current time is 10:51:46 and the update time is 1
Since the time is 0: 51: 5, the elapsed time is 41 seconds. When this elapsed time is compared with the elapsed time determination threshold value (S9
0), the elapsed time determination threshold is 40 seconds, and the elapsed time exceeds the elapsed time determination threshold. Therefore, the router function 2 performs the operation of deleting the second entry.

First, an entry having the same destination network is searched (S91). Since the third entry matches first (S92: YES), the priority of the third entry is increased by 1 to 2 (S93). When the processing is shifted to the next entry (S94), the fourth entry also matches (S92: YES), so the priority of the fourth entry is increased by 1 to 3 (S93). Further, the next entry is processed (S94), but there is no other matching entry (S92), so the first entry corresponding to the second entry is deleted from the routing table 3, and
The processing for the second entry ends.

After that, the third and subsequent entries are processed, and the entire processing is completed (S87). As a result of this process,
There are only the second and third entries whose destination network is the computer network 6b, and their priorities are respectively changed from 2, 3 to 1, 2.

As described above, according to the present embodiment, when a periodic notification of relay route information is received later than the threshold value, the corresponding relay route is disabled so that the router device with a higher load can be used. Can be relayed.

When there is no corresponding entry in the routing table 3 upon receiving the relay route information periodic notification, a new entry is created in the same manner as in S50 in FIG.

Further, similarly to the fourth embodiment, when the number of packets processed per unit time exceeds the threshold, transmission of the relay route information periodic notification may be interrupted.

[0108]

As described above, according to the first aspect of the present invention, one relay route is provided from a plurality of relay routes based on the priority of the packet according to the type of the packet and the priority of the relay route. Is selected, it is possible to prevent concentration of load on a specific relay path without increasing the transmission delay time of important packets.

According to the second aspect of the present invention, when the time elapsed since the last reception of the periodic notification of the relay route information from another router has exceeded the threshold value, the corresponding router , The priority of the relay route passing through is reduced, so that the priority of the relay route is changed according to the status of the relay route to prevent the transmission delay time from increasing. There is an effect that can be.

According to the third aspect of the present invention, when the elapsed time since the last reception of the periodic notification of the relay route information from another router does not exceed the threshold value, the corresponding router In the case where the priority of the relay route passing through is already lowered, the priority is increased. Therefore, in addition to the effect of the invention according to claim 2, the priority of the normal relay route is changed to the original priority. There is an effect that can be returned.

According to the fourth aspect of the present invention, when the number of processed packets exceeds the threshold value, the transmission of the periodic notification of the relay route information is interrupted. In addition to the effects described above, when the load on the router device increases, the transmission of the periodic notification of the relay route information is interrupted, and the load can be reduced.

According to the fifth aspect of the present invention, when the time elapsed since the last reception of the periodic notification of the relay route information from another router has exceeded the threshold value, the corresponding router The use of a relay route passing through a router is prohibited, and in addition to the effect of the invention described in claim 1, there is an effect that it is possible to avoid relaying to a router device having a high load or a relay route having an abnormality.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a router device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an operation of the router device according to the first embodiment of the present invention.

FIG. 3 is a flowchart showing an operation of a router function in the first embodiment of the present invention.

FIG. 4 is an explanatory diagram showing the contents of a routing table in the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing the contents of a packet priority determination table according to the first embodiment of the present invention.

FIG. 6 is a block diagram illustrating a configuration of a router device according to a second embodiment of the present invention.

FIG. 7 is an explanatory diagram for explaining the operation of the router device according to the second embodiment of the present invention.

FIG. 8 is a flowchart showing the operation of the router function according to the second embodiment of the present invention.

FIG. 9 is a flowchart illustrating an operation when the router according to the third embodiment of the present invention receives a periodic notification of relay route information.

FIG. 10 is a flowchart showing an operation of a router function according to the third embodiment of the present invention.

FIG. 11 is an explanatory diagram showing the contents of a routing table in the third embodiment of the present invention.

FIG. 12 is a block diagram illustrating a configuration of a router device according to a fourth embodiment of the present invention.

FIG. 13 is a flowchart showing the operation of the router function in the fourth embodiment of the present invention.

FIG. 14 is a flowchart showing the operation of the router function according to the fifth embodiment of the present invention.

FIG. 15 is a block diagram showing a configuration of a conventional router device.

FIG. 16 is an explanatory diagram showing an example of the operation of a conventional router device.

FIG. 17 is a flowchart showing an operation of a router function in a conventional router device.

FIG. 18 is a flowchart showing an operation of a router function in a conventional router device.

FIG. 19 is an explanatory diagram showing the contents of a routing table in a conventional router device.

[Explanation of symbols]

 1 router device 2 router function 3 routing table 4 packet priority judgment table

Continuation of the front page (56) References JP-A-5-191455 (JP, A) JP-A-5-68049 (JP, A) Ei Yamaguchi, "Route control mechanism (3)", Unix Magazine, (1993. 03.01), Vol 8, No. 3, p. 25-39 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/56

Claims (5)

(57) [Claims] 1. A router device for interconnecting a plurality of computer networks connecting a plurality of terminals and relaying a packet for communication between the terminals, comprising: a plurality of relay routes between a source terminal and a destination terminal; A routing table stored with the priority of the relay route, a packet priority determining means for determining the priority of the packet corresponding to the priority of the relay route to be selected according to the type of the packet to be relayed, Selecting one of the plurality of relay routes based on the priority of the relay route stored in the routing table and the priority of the packet determined by the packet priority determination unit, and transmitting the packet; A router device comprising: a packet transmitting unit. 2. A relay route information periodic notification unit for periodically transmitting the contents of a routing table to another router device as a relay route information periodic notification, and receiving a relay route information periodic notification from another router device for routing. Dynamic learning means for updating the contents of the table; elapsed time measuring means for measuring the elapsed time since the last reception of the periodic notification of the relay route information from another router; and elapsed time measuring means for measuring the elapsed time. 2. A priority changing means for lowering the priority of a relay route passing through a corresponding router device when the elapsed time exceeds a predetermined elapsed time determination threshold value. Router equipment. 3. When the elapsed time measured by the elapsed time measuring means does not exceed the elapsed time determination threshold,
3. The router device according to claim 2, further comprising second priority changing means for increasing the priority when the priority of the relay route passing through the corresponding router device has already been lowered. 4. A packet processing number measuring means for measuring the number of packet processings per unit time, and when the packet processing number measured by the packet processing number measuring means exceeds a predetermined packet processing number determination threshold value. 4. The router device according to claim 2, further comprising: a notification suspending unit that suspends transmission of the relay route information periodic notification. 5. A relay route information periodic notification means for periodically transmitting the contents of a routing table to other routers as a relay route information periodic notification, and receiving a relay route information periodic notification from another router to perform routing. Dynamic learning means for updating the contents of the table; elapsed time measuring means for measuring the elapsed time since the last reception of the periodic notification of the relay route information from another router; and elapsed time measuring means for measuring the elapsed time. 2. A relay route use prohibition unit for prohibiting use of a relay route passing through a corresponding router device when the elapsed time exceeds an elapsed time determination threshold value. Router device.