JP2019097216A - Communication route control system - Google Patents

Abstract

To provide a communication route control system which can switch to an alternate route, when the deterioration of network communication performance is detected.SOLUTION: The communication route control system includes: a communication performance evaluation unit which evaluates the communication performance of a network on the basis of the number of SYN packets transmitted from first communication equipment to second communication equipment; and a route control unit which, on detection of deteriorated communication performance of the second communication equipment, changes a communication route of the first communication equipment from the second communication equipment to third communication equipment.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a communication route control system in a communication network system configured by mutually connecting a plurality of autonomous systems (ASs).

  A network is generally configured by mutually connecting ASs, which are a collection of common policies and communication devices operated under the same environment. Identification numbers (AS numbers) are assigned to the ASs connected to one another. Also, BGP (Border Gateway Protocol) is used as a route control protocol used between multiple ASs.

  A communication device that communicates by means of BGP establishes a one-to-one connection using TCP when starting communication. The transmission source communication device transmits a SYN packet, and after receiving the SYN / ACK packet from the transmission destination communication device, transmits an ACK packet to establish a TCP connection.

  When the TCP connection is established, the source communication device and the destination communication device exchange basic information (OPEN message) of BGP with each other. At this point, a BGP session is established. After the BGP session is established, the source communication device and the destination communication device exchange routing tables with each other. After that, the communication device of the transmission source transmits a KEEPALIVE message, and confirms the existence of the communication device of the transmission destination.

  As a method to cope with the occurrence of communication failure in the network, a method of transmitting traffic by forming an alternative path has been proposed. Patent Document 1 discloses a method of adding an autonomous system dedicated to a backup route as an additional network to make it redundant, and transmitting packets of an existing network using the additional network.

JP, 2009-147735, A

  In the method for coping with the occurrence of a communication failure described in Patent Document 1, the number of communication devices increases because an autonomous system dedicated to the spare route is added as an additional network. Further, if the communication function of the communication device is completely stopped, it is possible to switch to the spare route as described above. However, no measure is taken against the temporary deterioration of communication performance such as when the communication function of the communication device is not completely stopped.

  Even when the communication function of the communication device is not completely stopped, packets continue to be transmitted to the communication device as usual. As a result, there arises a problem that the communication device discards the packet or breaks the packet.

  Therefore, it is an object of the present invention to provide a communication path control system capable of switching to a detour path when a failure in communication performance or a deterioration in communication performance of a communication device is detected.

  A communication path control system according to an embodiment of the present invention includes a communication performance evaluation unit that evaluates the communication performance of a network based on the number of SYN packets transmitted by a first communication device to a second communication device; And a path control unit for changing the communication path of the first communication device from the second communication device to the third communication device when the deterioration of the communication performance of the second communication device is detected.

  In the above communication path control system, the communication performance evaluation unit may further include a measurement unit that measures the number of SYN packets.

  In the communication path control system, the communication performance evaluation unit may further include a calculation unit that calculates a rate of change based on the number of SYN packets.

  In the communication path control system, the communication performance evaluation unit may further include a determination unit that determines whether the rate of change exceeds a predetermined threshold.

  The communication path control system may include a path attribute change unit that changes the path attribute of the third communication device.

  In the above communication path control system, the path attribute may be a WEIGHT attribute.

  The communication path control system may further include a performance deterioration determination unit that evaluates whether the deterioration of communication performance is permanent or temporary.

  In the communication path control system, after changing the communication path of the first communication device from the second communication device to the third communication device, the communication performance evaluation unit determines that the deterioration of the communication performance has been recovered. The communication path of the first communication device may be changed from the third communication device to the second communication device.

  A communication path control system according to an embodiment of the present invention comprises: a communication performance evaluation unit that evaluates communication performance of a network based on a ratio of a SYN packet to a second communication device of a first communication device; And a path control unit that changes the communication path of the first communication device from the second communication device to the third communication device.

  In the above communication path control system, the ratio of the SYN packet is the ratio of the SYN packet transmitted from the first communication device to the second communication device and the SYN / ACK packet transmitted from the second communication device to the first communication device. It may be.

  In the communication path control system, the path control unit may have a path attribute change unit that changes the path attribute of the third communication device.

  In the above communication path control system, the path attribute may be a WEIGHT attribute.

  In the above communication path control system, even after changing the communication path of the first communication device from the second communication device to the third communication device, even if the ratio of the SYN packet to the second communication device of the first communication device is observed Good.

  In the communication path control system, after changing the communication path of the first communication device from the second communication device to the third communication device, the communication performance evaluation unit determines that the deterioration of the communication performance has been recovered. The communication path of the first communication device may be changed from the third communication device to the second communication device.

  The present invention can provide a communication route control system capable of switching to a bypass route when a failure in communication performance or a deterioration in communication performance of a communication device is detected in a network.

It is a figure which shows the structural example of the network which concerns on 1st Embodiment. It is a block diagram which shows the communication path control system which concerns on 1st Embodiment. It is a graph showing the fluctuation | variation of the number of SYN packets in each time. It is a flowchart which shows the process of the communication path control system which concerns on 1st Embodiment. It is a block diagram which shows the communication path control system which concerns on 2nd Embodiment. It is a figure which shows the structural example of the network which concerns on 3rd Embodiment. It is a flow chart which shows processing of a communication path control system concerning a 3rd embodiment. It is a block diagram of the communication path control system concerning a 3rd embodiment.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings and the like. However, the present invention can be implemented in many different modes, and is not construed as being limited to the description of the embodiments exemplified below. The drawings may be schematically represented for the sake of clarity of the description, but are merely examples and do not limit the interpretation of the present invention. Also, the letters appended with “first” and “second” for each element are convenient indicators used to distinguish each element, and have more meaning unless otherwise noted. Absent. In the drawings referred to in this embodiment, the same portions or portions having similar functions may be denoted by the same reference numerals or similar reference numerals, and repeated description thereof may be omitted. In addition, part of the configuration may be omitted from the drawings. In addition, when it can be recognized by a person having ordinary knowledge in the field to which the present invention belongs, special description shall not be made.

First Embodiment
A communication path control system according to the present embodiment will be described with reference to FIGS. 1 to 4.

  FIG. 1 is a block diagram showing an exemplary configuration of a network 100 according to the present embodiment. A network 100 according to the present embodiment is configured by autonomous systems AS1 to AS5. The respective autonomous systems AS1 to AS5 constituting the network are mutually connected by communication devices corresponding to the entrance and exit. In this embodiment, a path through which the communication device 111a of the autonomous system AS1 communicates with the communication device 115a of the autonomous system AS5 via the communication device 113a and the communication device 113b of the autonomous system AS3 is taken as a first communication path. Also, a case will be described where a path through which the communication device 111a of the autonomous system AS1 communicates with the communication device 115a of the autonomous system AS5 via the communication device 114a and the communication device 114b of the autonomous system AS is a second communication path. .

The communication devices 111a, 111b, 113a to 113d, 115a, and 115b included in the autonomous systems AS1 to AS5 respectively have the BGP communication function. In BGP, BGP used between different autonomous systems AS is called eBGP (external BGP), and BGP used in the autonomous system AS is distinguished by calling it iBGP (internal BGP).
For example, eBGP is used for the communication device 111a of the autonomous system AS1 and the communication device 113a of the autonomous system AS3, and iBGP is used for the communication device 113a of the autonomous system AS3 and the communication device 113b.

  In BGP, when starting communication, a one-to-one session using TCP is established. For example, the communication device 111a of the transmission source transmits a SYN packet, receives an SYN / ACK packet from the communication device 113a of the transmission destination, and transmits an ACK packet to establish a session.

  The SYN packet used for TCP is always present in a series of data communication in the normal state of the network. For example, when the communication performance with the communication device 113a transmitted from the communication device 111a is deteriorated, the number of SYN packets per unit time tends to increase rapidly. In the present specification and the like, deterioration in communication performance includes not only a failure in communication but also a decrease in communication speed.

  Therefore, in the communication path control system according to the present embodiment, the communication performance of the network is evaluated based on the number of SYN packets that the first communication device transmits to the second communication device, and the communication performance evaluation unit When the deterioration of the communication performance of the second communication device is detected, the communication path of the first communication device is changed from the second communication device to the third communication device. That is, in the communication device 111a, processing is performed to make the priority of the second communication route via the communication device 114a higher than that of the first communication route via the communication device 113a. Hereinafter, the first communication device, the second communication device, and the third communication device will be described as the communication device 111a, the communication device 113a, and the communication device 114a shown in FIG.

  FIG. 2 shows a configuration diagram of the communication path control system 200 according to the present embodiment. The communication path control system 200 according to the present embodiment can be mounted on a communication device such as a boundary edge router of an autonomous system that communicates using eBGP, for example. Further, in the present embodiment, an example in which the communication path control system 200 is installed in the communication device 111 a shown in FIG. 1 will be described. Note that the communication path control system 200 according to the present embodiment may be any communication device connected to another communication device by BGP, and therefore, the communication devices 111b, 111b, 113a to 113d, 115a, 115b shown in FIG. It can also be mounted on each. The communication device 111 a further includes an interface 203 in addition to the communication path control system 200.

  The communication route control system 200 includes at least a communication performance evaluation unit 201 and a route control unit 202. The communication route control system 200 further includes a packet control unit 204, a route control message control unit 205, and a route table 206.

  The communication performance evaluation unit 201 includes a measurement unit 211, a calculation unit 212, and a determination unit 213. The path control unit 202 also includes a path attribute change unit 221 and a path calculation unit 222.

  The interface 203 establishes a connection with an adjacent communication device, and transmits and receives packets with the adjacent communication device. Also, the packet control unit 204 performs transmission of a SYN packet, reception of a SYN / ACK packet, and transmission of an ACK packet to an adjacent communication device via the interface 203. The SYN is a flag given to the first packet requesting establishment of a TCP connection. Further, ACK is a flag for response confirmation, and is a flag assigned to all packets other than the connection request. Furthermore, SYN / ACK is one in which both the SYN flag and the ACK flag are set to 1. In normal communication, the SYN / ACK packet is transmitted only when the SYN packet is received. When the communication performance is deteriorated or failure, the SYN / ACK packet may not be transmitted from the adjacent communication device.

  The path control message control unit 205 transmits and receives path control messages to and from an adjacent communication device via the interface 203. A communication device having a BGP function exchanges capability information in the form of a message in order to establish a peer with communication devices in different autonomous systems AS. Examples of the route control message include an OPEN message, a KEEPALIVE message, and an UPDATE message.

  Here, the OPEN message is a message exchanged at the start of the BGP session. The KEEPALIVE message is a message exchanged regularly to confirm that the peer is established. The UPDATE message is a message used to exchange BGP routing information. Sent when addition or deletion of a route occurs.

  The route table 206 holds all route information such as the route acquired by the route control message or the updated route, the route changed by the route control unit 202, and the like.

  In the communication performance evaluation unit 201, the measurement unit 211 measures the number of SYN packets that the communication device 111a transmits to the communication device 113a. FIG. 3 shows a graph showing the variation of the number of SYN packets at each time. In FIG. 3, the time for measuring the number of SYN packets is from time T1 to time T5. The calculated number of SYN packets is transmitted to the calculation unit 212.

  The calculation unit 212 calculates the rate of change of the SYN packet at each time based on the measured number of SYN packets. For example, in FIG. 3, the rate of change in the number of SYN packets is calculated based on the measurement results of the SYN packets at time T1 and time T2. The calculated change rate of the SYN packet is transmitted to the determination unit 213.

  The determination unit 213 determines whether the rate of change of the SYN packet exceeds a predetermined threshold set in advance. If it is determined that the threshold is not exceeded, communication is maintained as it is, assuming that the communication performance has not deteriorated in the communication device 113a.

  If it is determined that the rate of change of the SYN packet exceeds a predetermined threshold set in advance, the path control unit 202 is notified that the communication performance of the communication device 113a has deteriorated.

  When the route control unit 202 detects the deterioration of the communication performance, the route control unit 202 performs a process of changing the first communication route to the second communication route (detour route). In the present embodiment, processing for changing the communication path of the communication device 111a from the communication device 113a to the communication device 114a is performed. That is, in the communication device 111a, processing is performed to make the priority of the second communication route via the communication device 114a higher than that of the first communication route via the communication device 113a.

  The process of changing the communication path of the communication device 111a from the communication device 113a to the communication device 114a is performed by changing the BGP path attribute. In BGP, based on path attributes, all communication paths are compared to select the optimal path to be used for routing. Therefore, when there are a plurality of communication paths for the same destination, path attributes of all communication paths are compared to determine the most suitable path for forwarding traffic. In BGP, communication paths are compared in order based on the following priorities.

1. Routes that do not have an IGP route to the next hop are ignored.
2. A router with the WEIGHT attribute selects the route with the largest WEIGHT attribute. (WEIGHT attribute is a Cisco proprietary path attribute)
3. Select the route with the highest LOCAL_PREF attribute value.
4. Select the route with the shortest length of the AS_PATH attribute list.
5. Select the route with the lowest type of ORIGIN attribute.
6. When the route is acquired from the same AS and multiple routes exist, the route with the lower MULTI_EXIT_DISC attribute is preferred.
7. Prioritize the route acquired by eBGP over iBGP.
8. IGP prioritizes the closest path to the next hop.
9. Give priority to the route learned from the peer with the lowest router ID.

  Therefore, the communication route from the communication device 111a to the communication device 115a can be changed by changing the path attributes such as the WEIGHT attribute, the LOCAL_PREF attribute, the AS_PATH attribute, and the ORIGIN attribute. Here, the case of changing the WEIGHT attribute as the path attribute will be described.

  The WEIGHT attribute is a vendor-defined (Cisco proprietary) path attribute, is an attribute used only in the target communication device (communication device 111a), and is not transmitted to other communication devices. By default, a value of "32768" is assigned to the communication path to which the communication device 111a is connected, and the value of the other routes is "0". In the WEIGHT attribute, higher number paths are prioritized.

  Here, in the communication device 111a, setting is made to make the value of the WEIGHT attribute for the communication device 114a larger than the value of the WEIGHT attribute for the communication device 113a. The WEIGHT value is used only in the communication device 111a, is not attached to the UPDATE message, and is not notified to the adjacent autonomous system AS.

  When the path attribute of the BGP is changed by the path attribute changing unit 221, the path calculating unit 222 calculates the optimal path. As a result of the calculation, the communication path of the communication device 111a can be changed from the communication device 113a to the communication device 114a. That is, in the communication device 111a, processing is performed to make the priority of the second communication route via the communication device 114a higher than that of the first communication route via the communication device 113a. In this way, the changed communication path is stored in the routing table 206.

  Next, processing executed by the communication path control system 200 according to the present embodiment will be described with reference to FIGS. 2 and 4. FIG. 4 is a flowchart of processing of the communication path control system.

  First, as shown in FIG. 4, in the measuring unit 211, first, the first communication device measures the number of SYN packets to be transmitted to the second communication device (step S401). Next, the calculator 212 calculates the rate of change of the SYN packet corresponding to the time based on the measurement result of the SYN packet (step S402).

  Next, the calculated change rate of the SYN packet is transmitted to the determination unit 213 (step S403). Next, the determination unit 213 determines whether the rate of change exceeds a predetermined threshold set in advance (step S404). If the rate of change does not exceed the predetermined threshold set in advance (step S404; No), the process returns to step S401. When the rate of change exceeds a predetermined threshold set in advance (step S404; Yes), the path attribute of the first communication device to the third communication device is changed (step S405).

  By changing the path attribute, the path calculation unit 222 calculates the optimum path. As a result of the calculation, in the communication device 111a, when the priority of the second communication path via the communication device 316a is higher than the priority of the first communication path via the communication device 312a, the first communication device Can be changed from the second communication device to the third communication device. That is, in the first communication device, the first communication path passing through the second communication device can be changed to a second communication path passing through the third communication device. In this way, the changed communication path is stored in the routing table 206 (step S407).

  According to the communication path control system according to the present embodiment, the deterioration of the communication performance of the network can be detected. Thereby, when deterioration of the communication performance is detected in the first communication route from the communication device 111a to the communication device 115a via the communication device 113a, the second communication route (detour route) immediately via the communication device 114a is detected. Can be switched to Thereby, the communication performance of the network can be stabilized.

Second Embodiment
In the first embodiment, when the deterioration of the communication performance is detected in the first communication path of the communication device 113a, the process of switching to the second communication path, which is the bypass path, has been described immediately. In this embodiment, when the deterioration of the communication performance of the communication device 113a is temporary, after changing to the second communication route which is a bypass route passing through the communication device 114a, the first communication route which is the original communication route The case of returning to will be described with reference to FIGS. 1 and 5.

  The communication path control system according to the present embodiment includes a performance deterioration determination unit 214 in addition to the measurement unit 211, the calculation unit 212, and the determination unit 213 in the communication performance evaluation unit 201.

  The performance degradation determination unit 214 determines whether the degradation of the communication performance of the communication device 113 a determined by the determination unit 213 is temporary or permanent. The performance degradation determination unit 214 transmits the determined degradation of the communication performance to the path control unit 202.

  Here, the determination of deterioration in communication performance of the communication device 113a in the performance deterioration determination unit 214 may be performed, for example, after the number of times the rate of change of the SYN packet exceeds a predetermined threshold continues a predetermined number of times in the calculation unit 212. If it falls below a predetermined threshold, it is determined that the communication performance is temporarily degraded. Alternatively, in the calculation unit 212, when the number of times the rate of change of the SYN packet exceeds the predetermined threshold continues more than the predetermined number, it is determined as the permanent deterioration of the communication performance. Alternatively, when the change rate of the SYN packet explosively increases in the calculation unit 212, it is determined that the communication performance is not permanently deteriorated, for example, as a result of a Dos attack, instead of the temporary communication deterioration.

  The path control unit 202 changes the method of changing the communication path according to the result of the determination of the deterioration of the communication performance of the communication device 113a. If the change rate of the SYN packet exceeds a predetermined threshold, the communication device 111a changes the path attribute for the communication device 113a and the path attribute for the communication device 114a. For example, the WEIGHT value described in the first embodiment is set higher for the communication device 114a than for the communication device 113a. Thereafter, the route calculation unit 222 calculates the optimum route. As a result of the calculation, the communication path of the communication device 111a can be changed from the communication device 113a to the communication device 114a. That is, in the communication device 111a, the first communication path via the communication device 113a can be changed to the second communication path via the communication device 114a. Thus, the changed communication path is stored in the routing table 206.

  Thereafter, if the rate of change of the SYN packet continues to fall below the predetermined threshold after the predetermined number of times the number of times the predetermined threshold has been exceeded continues a predetermined number of times, the performance deterioration determination unit 214 determines that the communication performance is temporarily degraded. The determination result is transmitted to the route control unit 202. The path control unit 202 changes the path attribute for the communication device 113a and the path attribute for the communication device 114a again. For example, the values of the WEIGHT attribute for the communication device 113a of the communication device 111a and the WEIGHT attribute for the communication device 114a are returned to the values before the bypass route change. As a result, it is possible to return from the bypass route passing through the communication device 114a to the communication route passing through the communication device 113a. Also, when the communication path is restored, it is stored in the path table 206. The path attribute to be changed is not limited to the WEIGHT attribute, and other path attributes may be changed.

  In the communication path control system shown in the present embodiment, it is determined whether deterioration of communication performance is temporary or permanent. If the deterioration of the communication performance is temporary, it is possible to use the detour path, and return to the original communication path after the deterioration of the communication performance is recovered. Thereby, the communication performance of the network can be stabilized.

Third Embodiment
In this embodiment, a communication path control system different from that of the previous embodiment will be described with reference to FIGS. 6 to 8. In the present embodiment, a method of changing to the second communication path, which is a bypass path, will be described immediately if deterioration or failure of communication performance occurs on the first communication path but the failure occurrence point can not be identified. A method of returning from the second communication path to the original first communication path when the deterioration of the communication performance on the first communication path is eliminated will be described.

  FIG. 6 is a view showing a configuration example of the network 300 according to the present embodiment. FIG. 7 is a flowchart of the communication path control system according to the present embodiment. FIG. 8 is a block diagram of a communication path control system according to the present embodiment.

  As shown in FIG. 6, a network 300 according to the present embodiment is configured by autonomous systems AS11 to AS18. In FIG. 6, the communication path control system 200 according to the present invention is mounted on the communication device 311 of the autonomous system AS11.

  In this embodiment, there are two communication paths from the autonomous system AS11 to the target autonomous system AS15. Further, among the two communication paths, a path from the autonomous system AS11 to the target autonomous system AS15 via the autonomous system AS12, the autonomous system AS13, and the autonomous system AS14 is taken as a first communication path. Also, a route from the autonomous system AS11 to the target autonomous system AS15 via the autonomous system AS16, the autonomous system AS13, and the autonomous system AS14 is taken as a second communication route.

  In the first communication path, when there is a communication device whose function has completely stopped, the UPDATE message is updated for the new path. Therefore, there is no deterioration or failure in communication performance. However, when there is a half-broken communication device in the first communication path, although the KEEPALIVE message and the UPDATE message can be exchanged, the communication performance may be deteriorated or failure. This is because even if a packet is sent to a half-broken communication device, it will be discarded or broken, and it will not be possible to communicate normally.

  The communication device in a half-broken state exchanges communication control messages such as a KEEPALIVE message and an UPDATE message, so that it is difficult to identify the location where the failure occurs. Also, when specifying the location where the failure occurred, you can specify the location where the failure occurred by sending a ping command to the communication device, but depending on the communication device, it is configured not to respond to ping. In some cases. In such a case, since it is not possible to identify the location where the failure has occurred, it may take time to solve the failure. Therefore, stable communication can not be provided.

  Therefore, in the present embodiment, a method of performing processing for rapidly changing to a bypass route will be described even if it is not possible to identify the failure occurrence point in the communication route. A process of returning to the original communication path when the failure in the communication path is resolved will be described.

  The processing executed by the communication path control system 200 according to the present embodiment will be described with reference to the flowchart shown in FIG. In the following description, it is assumed that the normal communication path uses the first communication path.

  In the communication path control system 200 according to the present embodiment, the ratio of SYN packets in the first communication path is observed (step S401). Here, the ratio of the SYN packet is the ratio of the SYN packet transmitted from the first communication device to the second communication device and the SYN / ACK packet transmitted from the second communication device to the first communication device. To calculate the ratio of SYN packets by measuring the number of SYN packets and the number of SYN / ACK packets is called observation of the ratio of SYN packets. In the first communication path, the ratio of the SYN packet to the SYN / ACK packet is 1 in a normal case without deterioration or failure of communication performance.

  If there is a half-broken communication device in the first communication path, the ratio of SYN packets changes in the first communication path (step S402). If the ratio between the SYN packet and the SYN / ACK packet exceeds 1, for example, there is a communication device in a half-broken state in the first communication path.

  Next, when a change in the ratio between the SYN packet and the SYN / ACK packet is detected, processing is performed to change the first communication path to the second communication path, which is a bypass path (step S403). The change of the communication path is performed by changing the path attribute for the communication device 316a of the communication device 311, instead of specifying the autonomous system through which the autonomous system AS11 reaches the target autonomous system AS15. In the change of the path attribute, for example, in the communication device 311, processing to increase the WEIGHT attribute for the communication device 316a is performed. When the priority of the second communication route passing through the communication device 316a becomes higher than the priority of the first communication route passing through the communication device 312a by performing the process of increasing the WEIGHT attribute, the first communication route To the second communication path.

  Next, the failure occurrence point in the first communication path is specified (step S404). In the autonomous system AS12, the autonomous system AS13 and the autonomous system AS14 in the first route, it is specified which communication device has an abnormality. By issuing a ping command to each communication device on the first communication path where a failure occurs in the communication performance, it is possible to identify the failure occurrence point. If an echo request can be transmitted to each communication device on the first communication path and an echo response can be received, it means that the ping command is successful. On the other hand, when the echo response can not be received, it is known that there is an abnormality in the communication device, so that the failure occurrence point can be identified.

  On the other hand, if there is a communication device that does not respond to ping on the first communication path or if there is a communication device in a half-broken state, the failure occurrence point can not be identified. In such a case (step S404; NO), the process proceeds to step S405.

  In the present embodiment, when detecting a failure in communication performance or a deterioration in communication performance and changing from the first communication path to the second communication path, the change of the WEIGHT attribute for the communication device 316 a of the communication device 311 It is carried out. The WEIGHT attribute is a value emphasized in the process of determining a communication path, but is a value for raising the priority of path selection, and is not a value for designating and communicating with an autonomous system to be passed. Therefore, it is not possible to specify an autonomous system to go through and communicate.

  Therefore, even when the process of increasing the priority of the second communication path via the communication device 316a is performed, the same autonomous system as the first communication path may be used. For example, as shown in FIG. 6, in the first communication path, the target AS 15 is reached from the autonomous system AS 11 via the autonomous system AS 12, the autonomous system AS 13 and the autonomous system AS 14. In addition, in the second communication path, the target AS is reached from the autonomous system AS11 via the autonomous system AS16, the autonomous system AS13, and the autonomous system AS14. Therefore, the target AS 15 is reached via the same autonomous system AS 13 and the autonomous system AS 14 in the first communication path and the second communication path.

  Therefore, even after changing the path from the first communication path to the second communication path, the ratio between the SYN packet and the SYN / ACK packet in the first communication path is continuously observed (step S405).

  If the ratio between the SYN packet and the SYN / ACK packet in the first communication path is continuously observed, and normal SYN packet and SYN / ACK packet can be observed for a certain period, the process proceeds to step S407. The observation of a normal SYN packet is a state in which the ratio between the SYN packet and the SYN / ACK packet is 1. Immediately after changing from the first communication path to the second communication path, the number of SYN packets in the first communication path is significantly reduced. Therefore, the accuracy of determining whether a failure occurs in the first communication path is reduced. In addition, even if the second communication path is returned to the first communication path, if an abnormality is immediately detected in the first communication path, it is necessary to change to the second communication path again. Therefore, in the first communication path, it is necessary to confirm that the ratio of the SYN packet to the SYN / ACK packet is 1 for a certain period. Here, the fixed time is about 1 hour to 2 hours.

  Next, in the first communication path, it is confirmed that occurrence of a peer down, identification of a failure of a communication device, and that there is no report on Internet failure from the outside (step S407). The occurrence of peer-down, identification of a failure of a communication device, and the failure of the Internet from outside are confirmed by a route control message (UPDATE message).

  Finally, in the first communication path, when it is confirmed that there is no report about the occurrence of peer down, etc., processing for returning from the second communication path to the first communication path is performed (step S408). The processing for returning from the second communication path to the first communication path is processing for restoring the changed path attribute. For example, when the value of the WEIGHT attribute is changed, the value of the WEGHT attribute is restored.

  After that, observation of the ratio between the SYN packet and the SYN / ACK packet in the first communication path is continued (step S401).

  Again, when a change in the ratio between the SYN packet and the SYN / ACK packet is detected in the first communication path (step S402), the processing from step S403 to step S408 is performed.

  If the failure occurrence point can be specified in the first communication path in step S404 (step S404; YES), then recovery of the failure occurrence point is confirmed (step S409). Recovery of the failure point can be confirmed by the UPDATE message. Thereafter, processing for returning from the first communication path to the second communication path is performed (step S408).

  If the ratio between the SYN packet and the SYN / ACK packet can not be observed in step S405, the process waits for a fixed period (step S410). The fixed period is, for example, about 1 hour to 2 hours. After a certain period of time, the process proceeds to step S407. Thereafter, if there is no report on the occurrence of peer down, etc., it is determined that there is a temporary failure, and processing for returning from the second communication path to the first communication path is performed (step S408).

  Thereafter, the ratio between the SYN packet and the SYN / ACK packet is observed again for a predetermined period (step S401), and if the ratio of the SYN packet is within 1, communication on the first communication path is continued.

  According to the above process, when the communication device 311 detects deterioration of the communication performance in the first communication path, it can be immediately changed to the second communication path which is the bypass path. In addition, in the first communication path, when the deterioration of the communication performance is eliminated, it is possible to return from the second communication path which is the detour path to the original first communication path. Stable communication can be provided by performing the above processing.

  Next, a block diagram of the communication path control system 200 according to the present embodiment will be described with reference to FIG. A case where the communication path control system 200 according to the present embodiment is installed in the communication device 311 will be described.

  The communication performance evaluation unit 201 includes a measurement unit 211, a calculation unit 212, and a determination unit 213.

  In the present embodiment, in the communication performance evaluation unit 201, the measurement unit 211 measures the number of SYN packets to be transmitted from the communication device 311 to the communication device 312a. Further, the number of SYN / ACK packets to be transmitted from the communication device 312a to the communication device 311 is measured.

  Also, the calculation unit 212 calculates the ratio of the measured SYN packet and the SYN / ACK packet. The calculated ratio of SYN packets is transmitted to the determination unit 213.

  The determination unit 213 detects a change in the ratio of the SYN packet. When the ratio of the SYN packet is 1, it is determined that the communication performance is not deteriorated. On the other hand, when the ratio of SYN packets exceeds 1, it is determined that the communication performance is degraded.

  If it is determined that there is a change in the ratio of the SYN packet, the path control unit 202 and the communication unit 207 are notified that the communication performance of the communication device 311 has deteriorated.

  When the route control unit 202 detects deterioration in communication performance, the route control unit 202 performs processing to change the first communication route to the second communication route, which is a bypass route. In the present embodiment, processing of changing the communication path of the communication device 311 from the communication device 312a to the communication device 316a is performed.

  In addition, when the communication unit 207 detects the deterioration of the communication performance, the communication unit 207 identifies a failure occurrence point in the communication path. As a method of identifying the failure occurrence point, a ping command is executed on all the communication devices on the communication path in which a failure has occurred in the communication performance to perform survival confirmation of the communication devices. The ping command is a command for requesting a response to a device connected via a network and confirming a response to the request using an ICMP protocol. If an echo request can be transmitted to the communication device on the communication path and an echo response can be received, it can be known that the communication device has no abnormality. However, if the echo response can not be received, it is possible to identify the failure occurrence location on the assumption that the communication device is abnormal. Here, when the failure occurrence point can not be identified, the communication performance evaluation unit 201 observes the ratio of the SYN packet in the first communication path.

  The route control message control unit 205 receives a route control message related to BGP route information in the network, such as occurrence of a peer down, identification of a communication device in which a failure has occurred on the first communication route, and an Internet failure. In the network, when there is a change in the BGP routing information, it is sent to the routing table 206.

  The route table 206 stores the communication route changed by the route control unit 202 and the route information received by the route control message (UPDATE message).

  According to the communication path control system according to the present embodiment, even if there is a communication device in the first communication path where the occurrence point of the fault is hard to identify, it is detected as deterioration or failure of the communication performance, and it is the detour path immediately. It can be changed to the second communication path. Further, after the change to the second communication path, if the deterioration or failure of the communication performance in the first communication path is resolved, the original first communication path can be returned from the second communication path. Thereby, stable communication can be provided.

  Those skilled in the art may appropriately add, delete, or change design elements or processes based on the above-described embodiments, as long as the gist of the present invention is included within the scope of the present invention.

100: network, 111a: communication device, 113a: communication device, 113b: communication device, 114a: communication device, 115a: communication device, 200: communication route control system, 201: communication performance evaluation unit, 202: route control unit, 203 : Interface, 204: packet control unit, 205: route control message control unit, 206: route table, 211: measuring unit, 212: calculating unit, 213: determining unit, 214: performance deterioration determining unit, 221: path attribute changing unit , 222: Route calculation unit

Claims (6)

A communication performance evaluation unit that evaluates the communication performance of the network based on the ratio of the SYN packet to the second communication device of the first communication device;
And a path control unit for changing the communication path of the first communication device from the second communication device to the third communication device when the communication performance evaluation unit detects a change in the ratio of the SYN packet. Communication path control system.   The ratio of the SYN packet is a ratio of a SYN packet transmitted from the first communication device to the second communication device and a SYN / ACK packet transmitted from the second communication device to the first communication device. The communication path control system according to claim 1.   The communication route control system according to claim 1, wherein the route control unit has a path attribute change unit that changes a path attribute of the third communication device.   The communication path control system according to claim 3, wherein the path attribute is a WEIGHT attribute.   The ratio of the SYN packet to the second communication device of the first communication device is observed even after the communication path of the first communication device is changed from the second communication device to the third communication device. A communication path control system according to any one of Items 1 to 4. After changing the communication path of the first communication device from the second communication device to the third communication device,
The communication performance evaluation unit changes the communication path of the first communication device from the third communication device to the second communication device when it is determined that the deterioration of the communication performance in the communication path has been eliminated. The communication path control system according to any one of claims 1 to 5.

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