JP2012089923A - Congestion prevention ip repeater and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an IP repeater which can prevent occurrence of congestion by detecting a sign of congestion beforehand.SOLUTION: The IP repeater 201 arranged in an IP network comprises a transmission/reception port 211 connected with a link and transmitting/receiving a packet, a packet transfer unit 221 which controls transfer of a packet, and a congestion prevention unit 281 which prevents congestion of the link. The congestion prevention unit 281 monitors the band use rate of the link, compares the band use rate with a detection reference for detecting a sign of congestion. When the band use rate exceeds the detection reference, the congestion prevention unit 281 searches an alternative route on search termination conditions that the band use rate goes below the detection reference, and reflects the obtained alternative route being searched on the route setting in the packet transfer unit 221.

Description

  The present invention relates to a network using an Internet protocol, and more particularly to a control technique for preventing congestion in the network.

  In an enterprise communication network or a service providing infrastructure, it is important for the network to guarantee communication performance such as throughput and delay. When congestion occurs in the network, communication performance deteriorates due to packet retransmission control. Therefore, it is necessary to prevent congestion in order to guarantee communication performance. As such background art, there are Patent Literature 1 and Patent Literature 2.

JP 2005-197971 A JP 2003-218917 A

  One way to prevent network congestion is to increase the line capacity of the entire network, but this method places a large burden on the equipment. On the other hand, Internet Protocol (IP) relay device detects congestion occurrence and establishes a detour route for congestion, thereby effectively using the network capacity in the network to prevent congestion. Is attracting attention. As a method of setting a detour route, a method of using a link bandwidth usage rate or the like as a route selection index has been proposed.

  In Patent Document 1 described above, a method is proposed in which the congestion control device collects network traffic information and sets a detour route. However, in this method, the traffic load accompanying the collection of traffic information causes the congestion control device to collect traffic information. Because it concentrates on the network, it cannot handle large-scale networks.

  Patent Document 2 proposes a method in which the IP relay device monitors the link bandwidth usage rate and changes the link cost of OSPF (Open Shortest Path Fast) when the bandwidth usage rate exceeds a threshold. As a feature of this method, since link costs can be shared with other IP relay devices through OSPF, it is possible to set a detour route without applying the proposed method to all IP relay devices in the network. However, when the link cost is increased, the bandwidth usage rate of each link after setting the detour route is not taken into consideration, and thus congestion may newly occur after the detour route setting.

  In order to solve the above problems, an object of the present invention is to provide a congestion-preventing IP relay apparatus capable of detecting a sign of congestion in a network in advance and preventing the occurrence of congestion, and a method thereof. It is in.

  In order to achieve the above object, in the present invention, a congestion prevention IP relay apparatus arranged in an IP network, which is connected to a link and transmits / receives a packet, and packet transfer for controlling packet transfer And a congestion prevention unit for preventing congestion of the link. The congestion prevention unit is a sign for comparing the link monitoring unit for monitoring the bandwidth utilization of the link and the detection standard for detecting the sign of congestion detection. A detection unit, a detour route search unit that searches for a detour route when the band use rate falls below the detection criterion when the band use rate exceeds the detection criterion, and a packet transfer unit that searches for the detour route that has been searched Provided is a congestion prevention IP relay device having a search result reflection unit for reflecting the route setting in the network.

  In order to achieve the above object, in the present invention, a congestion prevention IP relay apparatus arranged in an IP network, which is a transmission / reception port connected to a link for transmitting / receiving a packet, and a packet for controlling packet transfer It includes a forwarding unit and a congestion prevention unit that prevents link congestion. This congestion prevention unit compares the bandwidth usage rate of the link provided in the IP relay device with the detection criteria for detecting the sign of congestion, and further in the IP network. The predictive detection unit that notifies predictive detection information to the notification destination IP relay device, and when the bandwidth usage exceeds the detection standard, the bandwidth usage of the link included in the predictive detection information falls below the detection standard There is provided a congestion prevention IP relay device having a configuration that includes a detour route search unit that searches for a detour route using the above as a search end condition and reflects the detour route in the route setting of the packet transfer unit.

  Furthermore, in order to achieve the above object, according to the present invention, there is provided a congestion prevention IP relay method for an IP relay device including a transmission / reception port for transmitting / receiving a packet and a packet transfer unit for controlling packet transfer. Monitors the bandwidth usage rate of the connected link, compares the bandwidth usage rate with the detection criterion of congestion sign detection, and when the bandwidth usage rate exceeds the detection criteria, the search ends that the bandwidth usage rate falls below the detection criteria Provided is a congestion prevention IP relay method that searches for a detour route as a condition and reflects the detour route obtained by the search in the route setting of a packet transfer unit.

  According to the present invention, it is possible to provide an autonomous and distributed congestion prevention technique with excellent scale characteristics in an IP network.

1 is a diagram illustrating an example of a network configuration in Embodiment 1. FIG. It is a figure which shows an example of the link cost and bandwidth utilization factor of each link in Example 1. FIG. It is a figure which shows an example of an internal function structure of the CPIP relay apparatus in Example 1. FIG. 3 is a diagram illustrating an example of an internal hardware configuration of a CPIP relay device according to Embodiment 1. FIG. FIG. 6 is a diagram illustrating an example of a flowchart of a detour route search process according to the first embodiment. It is a figure which shows the middle course of the detour route search process in Example 1. FIG. 4B is a diagram illustrating an example of a link cost and a bandwidth usage rate in the middle of the detour route search process in FIG. 4A according to the first embodiment. FIG. It is a figure which shows the search result of a detour route in Example 1. FIG. FIG. 5B is a diagram illustrating an example of a link cost and a bandwidth usage rate as a result of searching for the detour path in FIG. 5A in the first embodiment. It is a figure which shows an example of the detailed search flowchart of the detour route search part in Example 1. FIG. 6 is a diagram illustrating an example of a network configuration in Embodiment 2. FIG. It is a figure which shows an example of the header information of the packet which passes each link in Example 2, and a bandwidth usage rate. It is a figure which shows an example of the header information of the packet which passes each link after the alternative route search in Example 2, and a bandwidth usage rate. FIG. 10 is a diagram illustrating an example of a flowchart of a detour route search process according to the second embodiment. FIG. 10 is a diagram illustrating an example of a network configuration according to a third embodiment. It is a figure which shows an example of the link cost and bandwidth utilization factor of each link in Example 3. FIG. 10 is a diagram illustrating a middle course of a detour route search process in the third embodiment. It is a figure which shows an example of the link cost in the middle of the detour route search process of FIG. It is a figure which shows the search result of a detour route in Example 3. FIG. 12B is a diagram illustrating an example of a link cost and a bandwidth usage rate as a result of searching for a detour route in FIG. 12A in the third embodiment. FIG. 10 is a diagram illustrating an example of a flowchart of a detour route search process in the third embodiment. It is a figure which shows an example of the format of the packet for notifying the sign detection information in Example 3. FIG.

  Hereinafter, various embodiments of the present invention will be described with reference to the drawings. In this specification, various programs executed by the processing unit of the computer functioning as a common control unit or the like of the IP relay device may be expressed as “function”, “means”, and “unit”. For example, the congestion prevention program is expressed as “congestion prevention function”, “congestion prevention means”, and “congestion prevention unit”. Further, in this specification, the link cost means a link cost defined by a protocol used by a network such as OSPF.

  In this embodiment, when the bandwidth usage rate of the link exceeds the detection criterion of the sign detection of congestion, the bandwidth usage is set as the search end condition of the detour route search that the bandwidth usage rate of all the links is below the detection criterion. An embodiment of an IP relay network that searches for a link cost that satisfies a condition by increasing the link cost of a link whose rate exceeds the detection criterion will be described.

  FIG. 1A is a diagram illustrating an example of the entire relay network according to the first embodiment. The network in this embodiment is a packet communication network in which devices are connected in a mesh shape, and includes a plurality of transmission source devices 151-N (N = 1 to 3) and transmission destination devices 152-N (N = 1 to 2). The space includes a route, a plurality of IP relay devices 161-N (N = 1 to 6), and a congestion prevention (Congestion Prevention: CP) IP relay device 171 according to the present embodiment. In addition, the figure shows a link 191 -N (N = 1 to 8) for connecting the IP relay device 161 -N. A number in a circle of the link 191 -N indicates a link cost of the link.

  The route between the transmission source device 151-N (N = 1 to 3) and the transmission destination device 152-N (N = 1 to 2) is a route passing through the link 191-6 and a route passing through the link 191-5. And a route passing through the link 191-2. In this case, the route passing through the link 191-5 passes through the links 191-1, 191-5, 191-7, and the costs are 1, 2, 1, respectively. Therefore, the sum of the link costs of the route passing through the link 191-5 is 1 + 2 + 1 = 4. In addition, since the route passing through the link 191-6 passes through the links 191-1, 191-6, 191-8, and the costs are 1, 1, 1, respectively, the sum of the link costs of the route passing through the link 191-6 is 1 + 1 + 1. = 3. Further, since the route passing through the link 191-2 passes through the links 191-2, 191-3, and 191-4, and the costs are 1, 3 and 1, respectively, the sum of the link costs of the route passing through the link 191-2 is 1 + 3 + 1. = 5. From the above, the sum of the link costs of the route passing through the link 191-5 is 4, the sum of the link costs of the route passing through the link 191-6 is 3, and the sum of the link costs of the route passing through the link 191-2 is 5. A route passing through the link 191-6 having the smallest sum of link costs is a packet route.

  Further, the table shown in FIG. 1B indicates whether or not the band usage rates of the links 191-5 and 191-6 are equal to or lower than the detection standard. When the bandwidth usage rate of all links falls below the detection criterion, the search for the detour route is completed, and congestion can be prevented. Similar to the tables shown in FIG. 4B, FIG. 5B, FIG. 7B, FIG. 10B, FIG. 11B, and FIG. 12B, the CPIP relay apparatus 171 has this table corresponding to its operation.

  FIG. 2A is a diagram illustrating an example of the internal functional configuration of the CPIP relay device according to the present embodiment. The CPIP relay device 201 has a transmission / reception port 211, a packet transfer unit 221, and a routing protocol processing unit 231 as functions equivalent to those of the conventional IP relay device 202. Further, the CPIP relay apparatus 201 has a congestion prevention function unit 281 including a link monitoring unit 241, a sign detection unit 251, a detour route search unit 261, and a search result reflection unit 271 which are features of the present embodiment. The routing protocol processing unit 231 and each of these functional unit blocks can be realized by computer program processing, as will be described later. In this specification, the packet transfer unit 221 and the routing protocol processing unit 231 may be collectively referred to as a packet transfer unit or a packet transfer function. In the functional configuration diagram of FIG. 2A, the switch unit, which is a hardware component of the IP relay device, is not shown.

  FIG. 2B is a diagram illustrating an example of a hardware configuration of the CPIP relay device according to the present embodiment. The hardware configuration of the CPIP relay device can be equivalent to the hardware configuration of the IP relay device 202, that is, the IP relay device other than the CPIP relay device shown in FIG. 2B. As is apparent from FIG. 2B, the IP relay device includes a common control unit 751, a plurality of line cards 754, and a switch unit 755. Packet transfer by the plurality of line cards 754 is controlled by the common control unit 751.

  The common control unit 751 has a normal computer configuration. In the drawing, the common control unit 751 schematically shows a calculation unit 752 that is a central processing unit (CPU) for executing various function programs, and various programs and data. A storage unit 753 that is a memory to be stored is shown. The detection criterion management unit 22, the detour path storage unit 265, and the cost storage unit 232 in FIG. 2A can be formed on the storage unit 753.

  The line card 754 controlled by the common control unit 751 includes a transmission / reception port 211 and a packet transfer unit 221 having a routing table 222. The packet transfer unit 221 of each line card 754 transmits and receives packets to and from the switch unit 755.

  The routing protocol processing unit 231 in FIG. 2A is realized by program processing of the arithmetic unit 752, except for the cost storage unit 232 configured by the storage unit 753 of the common control unit 751. The routing protocol processing unit 231 notifies the link cost stored in the cost storage unit 232 to another IP relay device 202 via the detour route search unit 261 or the packet transfer unit 221 using the cost notification packet as necessary. can do. The packet transfer unit 221 in FIG. 2A is processed for each line card 754 in FIG. 2B, but can be realized by the common control unit 751. As described above, in any case, as described above, the routing protocol processing unit 231 can constitute a part of the packet transfer unit and the packet transfer function. The congestion prevention unit 281 of the CPIP relay device according to the present embodiment is also realized by the program processing of the arithmetic unit 752 of the common control unit 751 as described in detail below.

  The link monitoring unit 241 monitors the transmission / reception port 211 and notifies the predictor detection unit 251 and the detour route search unit 261 of the band usage rate obtained as a result. Further, the link monitoring unit 241 receives a notification regarding a change in setting contents from the outside, that is, an external device or a system administrator (hereinafter, represented by the administrator) from the transmission / reception port 211, and detects the detection criterion management unit 251. The detour route search unit 261 is notified of the change of the setting contents.

  The sign detection unit 251 holds the detection standard in the detection standard management unit 252. As described above, the detection criterion management unit 252 can be formed in a predetermined area of the storage unit 753 described above. The sign detection unit 251 notifies the detour path search unit 261 that a sign of congestion has been detected when the bandwidth usage rate notified from the link monitoring unit 241 is equal to or higher than the detection criterion held. In addition to the detection reference, the sign detection unit 251 stores a predetermined threshold and a band usage rate for each time period received from the link monitoring unit 241 in the detection reference management unit 252. The sign detection unit 251 has a function of comparing the threshold and the bandwidth usage rate and changing the detection reference and the threshold when the threshold is exceeded.

  The administrator of the apparatus or the entire system sets the threshold value and the contents of the setting change when the threshold is exceeded. When the threshold is not used, the administrator sets a detection standard. The threshold value and the detection standard value include the current bandwidth usage rate, the amount of increase in bandwidth usage rate per unit time, the bandwidth usage rate for each time zone stored in the detection criteria management unit 252, Information regarding bandwidth usage other than the above may be used, and which value is used is determined by the administrator or the contents of the setting change when the threshold is exceeded.

  By using this threshold value, the detection standard can be changed according to the traffic situation, and the value of the detection standard can be set to a value suitable for detecting a sign of congestion. For example, if the threshold is set for the current bandwidth usage and the detection criterion is set for the amount of increase in bandwidth usage per unit time, the detection criterion is set when the current bandwidth usage exceeds the threshold. Change the value smaller.

  The detour route search unit 261, when notified of a congestion sign from the sign detection unit 251, sets the link cost that satisfies the search end condition as a search end condition when the bandwidth usage rate of all links is below the detection criterion. Search for time. The searched link cost is notified to the search result reflecting unit 271. The detour route search unit 261 of the present embodiment includes a functional block of a link cost search unit 262, a bandwidth usage rate prediction unit 263, a header condition search unit 264, and a detour route storage unit 265.

  The link cost search unit 262 has a function of arbitrarily changing the link cost acquired from the cost storage unit 232 of the routing protocol processing unit 231 and a function of calculating a detour route using the changed link cost. The same algorithm as the routing protocol processing unit 231 is used as the algorithm for calculating the detour route.

  The bandwidth usage rate prediction unit 263 obtains the bandwidth usage rate for each packet from the link monitoring unit 241, and uses the search result of the bypass route and the bandwidth usage rate for each packet to determine the bandwidth usage rate of each link in the bypass route. Has a function to estimate.

  When searching for a link cost that satisfies the search end condition, the detour path storage unit 265 stores the bandwidth usage rate of each link when the sign is detected and the link cost that satisfies the search end condition. Further, as examples of other information stored in the detour route storage unit 265, header conditions that satisfy the search end condition and information used for setting other detour routes may be used.

  The search result reflecting unit 271 overwrites the cost storage unit 232 in the routing protocol processing unit 231 with the link cost received from the detour route searching unit 261, and transmits the packet transfer unit through the routing protocol notification message such as the cost notification packet described above. The route table 222 of 221 and the route table of the IP relay device 202 in the network are rewritten to set a detour route. When the information received from the detour route search unit 261 is not the link cost but the header condition of the packet to be detoured, the search result reflecting unit 271 outputs the output destination of the packet that matches the header condition in the route table 222 of the packet transfer unit 221 Rewrite the link information.

  FIG. 3 is an example of a processing flowchart in which the congestion prevention function unit 281 in the common control unit 751 of the CPIP relay apparatus 171 in FIGS. 2A and 2B performs congestion detection and setting of a detour path. 4A and 5A together with FIG. 1A are diagrams showing the progress of the link cost and the bandwidth usage rate in the course of the detour route search in order.

  When the process of the flowchart of FIG. 3 starts, the sign detection unit 251 changes the setting of the detection criterion when the administrator changes the setting or the bandwidth usage rate exceeds the threshold (steps 101 and 102). In this embodiment, it is assumed that the current value of the band usage rate is used as a detection criterion in advance (proceed to NO in step 101).

  The link monitoring unit 241 notifies the sign detection unit 251 of the bandwidth usage rate of the transmission / reception port 211 (step 103).

  The sign detection unit 251 notifies the detour route search unit 261 to search for a detour route when the bandwidth usage rate of the link 191-6 is equal to or higher than the detection criterion (proceed to YES in step 104).

  The detour route search unit 261 uses the link cost search unit 262 to increase the link cost 181-2 of the link 191-6 to estimate the bandwidth usage rate of each link (step 105), and to use the estimated bandwidth usage rate as a detection criterion. Compare (step 106).

  4A and 4B show the link cost of each link and the estimation of the bandwidth usage rate when the link cost 181-2 is increased until the packet bypasses the link 191-6. The numbers in the circles in the figure indicate the link costs set in the cost storage unit 232 when the route is determined. The numbers in the diamond marks indicate unestablished link costs that appear as candidates during the detour route search process. After the link cost is increased, the sum of the link costs of the route passing through the link 191-5 is 4, the sum of the link costs of the route passing through the link 191-6 is 5, and the sum of the link costs of the route passing through the link 191-2 is 5. Become. Since the total link cost of the route passing through the link 191-5 is the smallest, the route of the packet is changed from the route passing through the link 191-6 to the route passing through the link 191-5.

  The bandwidth usage rate prediction unit 263 predicts the bandwidth usage rate of each link after an increase in link cost. As a result, as shown in the table of FIG. 4B, it is assumed that the bandwidth usage rate of the link 191-6 is equal to or lower than the detection criterion, but the bandwidth usage rate of the link 191-5 is equal to or higher than the detection criterion. This means that when a bypass route is set using the searched link cost, congestion occurs on the link 191-5 after the bypass route is set. For this reason, the bypass route search unit 261 does not notify the search result reflection unit of the link cost, increases the link cost 181-1, and searches for a route that bypasses the link 191-5 (NO in step 106 of FIG. 3). (Step 109 also returns to Step 105 where the process proceeds to NO).

  Note that, as described above, the CPIP relay apparatus can have the table shown in FIG. 4B. For example, the detour route search unit 261 of the CPIP relay device 201 in FIG. 2A can be included in the inside based on information from the link monitoring unit 241 and the cost storage unit 232. It can also be temporarily stored in the storage unit 753 of the common control unit 751 of the CPIP relay apparatus 201 of FIG. 2B. It goes without saying that the tables after FIG. 1B and FIG. 5B are the same.

  Next, increase the link costs 181-1 and 181-2 of the links 191-5 and 191-6 whose band usage rate is equal to or higher than the detection standard to estimate the bandwidth usage rate of each link (step 105). The obtained band usage rate is compared with the detection standard (step 106).

  5A and 5B show the link cost of the bandwidth usage rate of each link and the bandwidth usage rate when the link costs 181-1 and 181-2 are increased until the packet bypasses the links 191-5 and 191-6. Represents an estimate. After the link cost is increased, the sum of the link costs of the route passing through the link 191-5 is 6, the sum of the link costs of the route passing through the link 191-6 is 6, and the sum of the link costs of the route passing through the link 191-2 is 5. Become. Since the total link cost of the route passing through the link 191-2 is the smallest, the packet route is a route passing through the link 191-2.

  The bandwidth usage rate prediction unit 263 predicts the bandwidth usage rate of each link after an increase in link cost. As a result, it is assumed that the band usage rate of the links 191-5 and 191-6 is below the detection standard. This means that when a bypass route is set using the searched link cost, congestion does not occur in the links 191-5 and 191-6 after the bypass route is set. Therefore, the detour route search unit 261 notifies the search result reflection unit 271 of the link cost and sets a detour route (proceed to YES in step 106).

  The search result reflection unit 271 overwrites the received link cost in the cost storage unit 232, rewrites the routing table 222 of the packet transfer unit 221 through the routing protocol processing unit 231, and notifies the IP relay device 202 in the network of the new cost. (Step 107). After the detour route is set, if there is no stop instruction from the administrator for the program that executes the flowchart, the setting change is confirmed and the bandwidth usage rate is monitored again (NO in step 108).

  As shown in the flowchart of FIG. 3, the CPIP relay apparatus 201 sets a detour route before congestion occurs, predicts congestion that occurs in the detour route to be set, avoids congestion, and reduces congestion. To prevent.

  For the search for the link cost that satisfies the search end condition (steps 105, 106, and 109) by the detour route search unit 261 in FIG. 3, the method as shown in FIG. 6 can be used more preferably.

  First, in the flow of FIG. 6, the detour route search unit 261 searches the detour route storage unit 265 using the bandwidth usage rate of each link as a search key (step 401). The search process of the detour route due to the increase of the link cost may increase the processing time. Therefore, when searching for the detour route that has been used once, the search time using the information stored in the detour route storage unit 265 is used. Can be shortened. As another example of the search method, the sign detection unit 251 compares a threshold value having a value smaller than the detection criterion with the bandwidth usage rate, and when the bandwidth usage rate exceeds the threshold value, the detour route search unit 261 bypasses in advance. The route is searched, the search result is stored in the bypass route storage unit 265, and the sign detection unit 251 uses the information in the bypass route storage unit 265 when the bandwidth usage rate exceeds the detection criterion. You may use the method of shortening time.

  When the detour route storage unit 265 can search for the link cost that satisfies the search end condition, the search process is ended (NO in step 402). If the search has failed (YES in step 402), the link cost is increased to estimate the bandwidth usage rate of each link (step 403). The estimated band usage rate is compared with the detection criterion, and when the search end condition is satisfied, the search process is ended (step 404). As another example of the link cost search method, when a link cost satisfying the search end condition is searched for a certain time and a plurality of link costs are searched, the link cost is selected according to the selection index set by the administrator. A method may be used. For the selection index, select the one with the smallest bandwidth usage rate for each link, the one with the smallest difference in bandwidth usage for each link, or other selection methods by comparing the bandwidth usage for each link. May be used.

  When a link cost that satisfies the search end condition is not found and a predetermined time has elapsed (YES in step 405), the bypass route search unit 261 bypasses the CPIP relay device between the transmission source device and the transmission destination device. A final check is made to see if a route exists (step 406). The final confirmation method is to calculate the detour route by increasing the link cost of all the links connected to the CPIP relay device to the maximum value, or using the current route information acquired from the route table 232 and the cost storage unit 222. You can use either of these. As the maximum value of the link cost, either the maximum value of the cost allowed by the routing protocol or a value set by the administrator may be used.

  When the detour route exists as a result of the final confirmation and the setting is made so that the detour route finally confirmed by the administrator is applied (proceed to YES in step 407), the detour route search unit 261 searches by the final confirmation. The bypass route thus set is set (step 408). Even when the final confirmation is made, there is no detour route, or when it is set not to adopt the detour route finally confirmed by the administrator (the process proceeds to NO in step 407), the detour route search unit 261 does not set the detour route. (Step 409).

  According to the first embodiment described in detail above, the CPIP relay device autonomously detects a sign of congestion, predicts the bandwidth usage rate of each link after route change, and sets a detour route. It is possible to prevent congestion. Further, according to the present embodiment, it is possible to share the detour route with the IP relay device in the network by changing the link cost and setting the detour route.

  In the second embodiment, when the bandwidth usage rate of the link exceeds the detection criterion of the sign detection of congestion, the bandwidth usage rate of all links is equal to or lower than the detection criterion, An example of an IP relay device that searches for a header condition of a packet to be detoured to a link with a low bandwidth usage rate will be described.

  FIG. 7A is a diagram illustrating the entire IP relay network according to the second embodiment. The network in this embodiment is a packet communication network formed by connecting devices in a mesh shape, and includes a plurality of transmission source devices 451-N (N = 1 to 3) and transmission destination devices 452-N (N = 1 to 2). ) Is composed of a route, an IP relay device 461-N (N = 1 to 6), and a CPIP relay device 471. The table of FIG. 7B shows the destination IP and source IP, which are header information of packets passing through the links 481-1 and 481-2 connected by the CPIP relay apparatus, and the bandwidth usage rate of the packets.

  In the present embodiment, for simplicity, only the packet source IP and destination IP, specifically the source IP address and destination IP address are considered as header conditions. When the header condition is specified and the packet is bypassed, the packet to be bypassed can be specified more finely than when the packet is bypassed by changing the link cost, so congestion can occur on the bypass destination link Can be reduced.

  Note that the configuration of the CPIP relay apparatus of this embodiment is the same as that of FIG. 2B described in the first embodiment, but the functions of some of the configurations are different in the IP relay apparatus of this embodiment.

  That is, the header condition search unit 264 of the present embodiment has a function of acquiring a packet bandwidth usage rate from the link monitoring unit 241 for each header condition using one or more arbitrary fields of the packet header as a header condition. . The header condition and the bandwidth usage rate acquired from the link monitoring unit 241 are held in a format in which the header condition can be searched using the bandwidth usage rate as a search key. The header condition search unit 264 has a function of confirming that a packet reaches a destination IP address (hereinafter referred to as a destination IP) in a detour route using the header condition and the output destination link.

  As an example of a method for confirming this arrival, a method for acquiring current route information from the routing protocol processing unit 231 and the route table 222 and confirming whether the packet reaches the destination IP, or setting from an administrator in advance. Either of the header condition that the packet reaches the destination IP and the method of registering the output destination link in the header condition search unit 264 may be used by the notification of the change. The header condition search unit 264 does not use the header condition and the output destination link where the packet does not reach the destination IP as a detour path.

  The bypass route search unit 261 notifies the search result reflection unit 271 of the header condition and the output destination link when the header condition search unit 264 searches for a bypass route.

  FIG. 9 is an example of an operation flowchart of the CPIP relay device according to this embodiment. In the operation flowchart of FIG. 9, the description of the parts having the same functions as those already described with reference to FIG. 1A is omitted.

  When the CPIP relay device 471 detects a sign of congestion on the link 481-2 (YES in step 104), the header condition search unit 264 inside the detour route search unit 261 receives the bandwidth for each header condition from the link monitoring unit 241. The usage rate is acquired, and a header condition that satisfies the search end condition is searched using the bandwidth usage rate as a search key (step 651). As an example of the search method, any one of a linear search, a tree search, and other search algorithms capable of searching for a band usage rate as a target value may be used.

  The header condition search unit 264 confirms whether or not the packet reaches the destination IP on the detour path using the header condition and the output destination link (step 652). In this embodiment, it is assumed that the administrator has searched for a detour route from the header condition and the output destination link registered in advance so that the packet reaches the transmission destination IP (proceed to YES in step 652). . If another method is used to check whether or not the packet reaches the destination IP, and if the packet does not reach the destination IP, the header condition is searched again (NO in step 652). Go to).

  The table 801 in FIG. 8 shows the result of the search processing of the detour route search unit 261, as a result of each link when a part of the packet passing through the link 481-2 is detoured to the link 481-1 by specifying the header condition. Shows the relationship between bandwidth usage and detection criteria. When the packet is detoured by increasing the link cost, the packet must be detoured for each destination IP, but by specifying the header condition, only a part of the packets that match the condition can be diverted. This operation can avoid the occurrence of congestion on the detour link.

  As described above, according to the second embodiment, the CPIP relay device specifies header conditions and changes the output destination link of some packets, thereby preventing an increase in the bandwidth usage rate of the detour destination link and preventing the occurrence of congestion. It is possible to do.

  In the third embodiment, when there are multiple CPIP relay devices in the network, CPIP relay devices notify each other of predictive detection information such as bandwidth usage and detection criteria, and detect a sign of congestion. Shows an example of an IP relay network that searches for a detour route in which the bandwidth usage rate of all links to which each CPIP relay device is connected falls below the detection criterion.

  FIG. 10A is an overall view showing the IP relay network of the present embodiment. The network in this embodiment is a packet communication network formed by connecting devices in a mesh shape, and includes a transmission source device 501-N (N = 1 to 3) and a transmission destination device 502-N (N = 1 to 2). A space between the IP relay device 511-N (1-5) and the CPIP relay device 521-N (1-2). In addition, the figure shows a link 541-N (N = 1 to 8) for connecting the IP relay device 511-N. The number in the circle of the link 541-N indicates the link cost of the link. The route between the transmission source device 501-N and the transmission destination device 502-N includes a route that passes through the link 541-2, a route that passes through the link 541-5, and a route that passes through the link 541-6. In this case, since the route passing through the link 541-2 passes through the links 541-2, 541-3, and 541-4, and the costs are 2, 1, and 1, respectively, the total link cost of the route passing through the link 541-2 is 2 + 1 + 1 = 4. Further, since the route passing through the link 541-6 passes through the links 541-1, 541-6, and 541-8, and the costs are 1, 1, 1, respectively, the sum of the link costs of the route passing through the link 541-6 is 1 + 1 + 1. = 3. In addition, since the route passing through the link 541-5 passes through the links 541-1, 541-5, and 541-7, and the costs are 1, 3 and 1, respectively, the total link cost of the route passing through the link 541-5 is 1 + 3 + 1. = 5. From the above, the sum of the link costs of the route passing through the link 541-2 is 4, the sum of the link costs of the route passing through the link 541-5 is 5, and the sum of the link costs of the route passing through the link 541-6 is 3. A route that passes through the link 541-6 having the smallest sum of link costs is a packet route.

  Further, the table of FIG. 10B indicates whether or not the band usage rates of the links 541-2, 541-5, and 541-6 are below the detection standard. When the bandwidth usage rate of all links falls below the detection criterion, the search for the detour route is completed, and congestion can be prevented.

  The configuration of the CPIP relay device of this embodiment is the same as that of FIG. 2B described in the first embodiment. In the IP relay device of this embodiment, the functions of a part of the configuration are different. For example, the sign detection unit 251 according to the present embodiment has a function of notifying each other of sign detection information such as a bandwidth usage rate and a detection standard between CPIP relay apparatuses.

  That is, in FIG. 2A, the sign detection unit 251 sends the sign detection information 291 used for searching for a detour route such as a detection reference and a link bandwidth usage rate to the other CPIP relay apparatus 201 in the network. The notification is made via the transmission / reception port 211. The notification of the sign detection information 291 is performed at a predetermined time interval or when a sign is detected. Examples of a method for recognizing another CPIP relay device 201 in the network include whether the CPIP relay device 201 transmits a confirmation packet to an adjacent IP relay device, or sets an IP address of a notification destination device by an administrator, Either method may be used. When the CPIP relay apparatus 201 receives the confirmation packet, either the confirmation packet transmission source CPIP relay apparatus 201 is set as a notification destination apparatus, or the response packet is transmitted to the confirmation packet transmission source CPIP relay apparatus 201 to A CPIP relay device may be set as a notification destination device. When an IP relay device other than the CPIP relay device 201 receives the confirmation packet, the confirmation packet is discarded.

  FIG. 13 is an operation flowchart of the CPIP relay device in this embodiment. In the operation flowchart of FIG. 13, the description of the portion having the same function as the portion denoted by the same reference numeral as illustrated in FIG. 1A is omitted. 10B, FIG. 11B, and FIG. 12B sequentially show the progress of the link cost and the bandwidth usage rate in the process of searching for a detour route.

  In the flowchart of FIG. 13, the CPIP relay apparatuses 521-1 and 521-2 notify the sign detection information 291 to each other at regular time intervals (steps 751 and 752).

  FIG. 14 shows an example of a format of a packet 701 including the sign detection information 291 that the CPIP relay apparatus 521-1 that is the notification source notifies the CPIP relay apparatus 521-2 that is the notification destination IP relay apparatus. In the packet 701, the sign detection information is inserted following the normal MAC header and IP header. Examples of the content of the sign detection information 291 include detection criteria 702 and 704, link bandwidth usage rates 703 and 705, and other detour paths such as the above-described link cost and packet header conditions for changing the output destination link. Any of the information used when searching can be included. As an example of a method for notifying the sign detection information 291, a method performed when the CPIP relay apparatus 201 detects a sign of congestion may be used.

  When the CPIP relay device 521-1 detects a sign of congestion on the link 541-6 (step 104), the detour route search unit 261 of the CPIP relay device 521-1 detects the link whose bandwidth usage rate exceeds the detection criterion. The link cost 531-2 is increased (step 753), and the estimated band usage rate of each link is compared with the detection standard (step 106). In this embodiment, the detour route is searched by increasing the link cost. However, as an example of another method of searching for the detour route, the header condition of the packet for changing the output destination is used, and the bandwidth usage rate is used as the search key. A searching method may be used.

  FIG. 11B shows the link cost of each link and the estimation of the bandwidth usage rate when the link cost 531-2 is increased until the packet bypasses the link 541-6. After the link cost is increased, the sum of the link costs of the route passing through the link 541-5 is 5, the sum of the link costs of the route passing through the link 541-6 is 5, and the sum of the link costs of the route passing through the link 541-2 is 4. Become. Since the total link cost of the route passing through the link 541-2 is the smallest, the route of the packet is a route passing through the link 541-2.

  The bandwidth usage rate prediction unit 263 predicts the bandwidth usage rate of each link after an increase in link cost. As a result, it is assumed that the estimation of the band usage rate of the links 541-5 and 541-6 is below the detection criterion, but the estimation of the bandwidth usage rate of the link 541-2 is above the detection criterion. This means that if a bypass route is set using the searched link cost, congestion may occur in the link 541-2 after the bypass route is set. For this reason, the bypass route search unit 261 does not notify the search result reflection unit 271 of the link cost, increases the link cost 531-3, and searches for a route that bypasses the link 541-2 (NO in step 106). Step 109 also proceeds to NO).

  Next, the detour route search unit 261 increases the link costs 531-2 and 531-3 of the links 541-6 and 541-2 for which the estimation of the band usage rate exceeds the detection criterion (Step 753). The bandwidth usage rate is estimated and compared with the detection standard (step 106).

  FIG. 12B shows the link cost of each link and the estimation of the bandwidth usage rate when the link cost 531-2 and 531-3 are increased until the packet bypasses the links 541-2 and 541-6. After the link cost is increased, the total link cost of the route passing through the link 541-5 is 5, the total link cost of the route passing through the link 541-6 is 6, and the total link cost of the route passing through the link 541-2 is 6. Become. Since the total link cost of the route passing through the link 541-5 is the smallest, the route of the packet is a route passing through the link 541-5.

  The bandwidth usage rate prediction unit 263 predicts the bandwidth usage rate of each link after an increase in link cost. As a result, as shown in the table of FIG. 12B, it is assumed that the band usage rate estimates of the links 541-2, 541-5, and 541-6 are all equal to or lower than the detection standard. This means that when a bypass route is set using the searched link cost, congestion does not occur in the links 541-2, 541-5, and 541-6 after the bypass route is set. Therefore, the detour route search unit 261 notifies the search result reflection unit 271 of the link cost and sets a detour route (proceed to YES in step 106).

  In this embodiment, the CPIP relay device 521-1 searches for the link cost 531-3 of the CPIP relay device 521-2. However, as an example of a method for searching for another detour route, the CPIP relay device 521-1 is When the bandwidth usage rate of the links 541-5 and 541-6 falls below the detection standard, the estimated bandwidth usage rate and the link cost after the link cost increase is notified to the CPIP relay apparatus 521-2 as the sign detection information 291. Then, the link cost 531-3 may be increased by the CPIP relay apparatus 521-2 to search for a link cost that satisfies the search end condition.

  According to the third embodiment, the CPIP relay device formulates a detour route in consideration of the link state of the other CPIP relay device on the network, so that congestion including the routes possessed by other CPIP relay devices can be reduced. It is possible to select an optimal route for prevention.

  Although various embodiments of the present invention have been described above, the present invention is not limited to these embodiments, and it goes without saying that various modifications can be included. It should be noted that the above-described embodiments are described for better understanding of the present invention, and are not limited to those having all the configurations described. Further, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Needless to say, the configurations, functions, processing means, and the like of the above-described embodiments may be configured not only as software configurations but also as dedicated hardware configurations or configurations sharing them.

  The present invention is useful as a control technique for preventing congestion in a network using the Internet protocol.

151-1 Transmission source device 152-1 Destination device 161-1 IP relay device 181-1 Link cost 191-1 Link 201 CPIP relay device 211 Transmission / reception port 221 Packet transfer unit 231 Routing protocol processing unit 241 Link monitoring unit 251 Predictive detection Unit 261 Detour Route Search Unit 271 Search Result Reflection Unit 281 Congestion Prevention Unit 291 Predictive Detection Information 701 Predictive Detection Information Notification Packets 702 and 704 Detection Criteria 703 and 705 Bandwidth Utilization 751 Common Control Unit 752 Calculation Unit 753 Storage Unit 754 Line Card 755 Switch part.

Claims (17)

A congestion prevention IP relay device arranged in an IP network,
A transmission / reception port connected to the link for transmitting and receiving packets, a packet transfer unit for controlling transfer of the packet, and a congestion prevention unit for preventing congestion of the link,
The congestion prevention unit
A link monitoring unit for monitoring the bandwidth usage of the link;
A sign detection unit that compares the bandwidth usage rate with a detection standard for sign detection of congestion;
A detour route search unit that searches for a detour route with a search end condition that the band utilization rate is less than or equal to the detection criterion when the band utilization rate exceeds the detection criterion;
A search result reflecting unit that reflects the searched detour route in route setting of the packet transfer unit;
Congestion prevention IP relay device. The congestion prevention IP relay apparatus according to claim 1,
The link monitoring unit
Notifying the bandwidth usage rate to the sign detection unit and the detour search unit,
Receiving a notification of a setting change from the outside via the transmission / reception port;
Congestion prevention IP relay device. The congestion prevention IP relay apparatus according to claim 1,
The sign detection unit
In addition to the detection criteria, a threshold value is retained,
When the bandwidth usage exceeds the threshold, set the detection criteria;
When the bandwidth usage rate exceeds the detection criterion, the detour route search unit is notified that a sign of congestion has been detected.
Congestion prevention IP relay device. The congestion prevention IP relay apparatus according to claim 1,
The detour route search unit
Using the link cost of the link as a change parameter, search for a link cost that satisfies the search termination condition,
Notifying the search result reflection unit of the link cost that satisfies the search termination condition and the detour route,
Congestion prevention IP relay device. The congestion prevention IP relay apparatus according to claim 4,
The packet transfer unit includes a routing protocol processing unit including a cost storage unit,
The search result reflecting unit
Setting the detour route by writing the link cost that satisfies the search termination condition in the cost storage unit of the routing protocol processing unit,
The routing protocol processing unit
By setting the detour path of the other IP relay device by notifying the other IP relay device on the IP network the link cost that satisfies the search termination condition,
Congestion prevention IP relay device. The congestion prevention IP relay apparatus according to claim 1,
The detour route search unit
Using one or more arbitrary fields of the header of the packet as a header condition, the bandwidth usage rate for each header condition is acquired from the link monitoring unit,
Using the bandwidth usage rate as a search key, search for the header condition that satisfies the search end condition and the detour destination link of the header condition,
Notifying the search result reflection unit of the header condition that satisfies the search end condition;
Congestion prevention IP relay device. The congestion prevention IP relay device according to claim 6,
The detour route search unit
Specify whether the packet arrives by specifying the header condition and the detour link that satisfy the search termination condition;
When the header condition and the detour destination link are not specified and reached, the other than the header condition and the detour destination link is set as the detour path.
Congestion prevention IP relay device. The congestion prevention IP relay device according to claim 6,
The search result reflecting unit
Changing the output destination link of the packet that matches the header condition satisfying the search termination condition to the bypass destination link;
Congestion prevention IP relay device. A congestion prevention IP relay device arranged in an IP network,
A transmission / reception port connected to the link for transmitting / receiving packets; a packet transfer unit for controlling transfer of the packet; and a congestion prevention unit for preventing congestion of the link;
The congestion prevention unit
Compare the bandwidth usage rate of the link provided in the IP relay device and the detection criterion for detecting the sign of congestion, and the sign detection unit that notifies the sign detection information to the notification destination IP relay device arranged in the IP network;
A detour route search unit that searches for a detour route with a search end condition that the band use rate of the link included in the predictive detection information is equal to or less than the detection criterion when the band usage rate exceeds the detection criterion; And the obtained detour route is reflected in the route setting of the packet transfer unit,
Congestion prevention IP relay device. The congestion prevention IP relay device according to claim 9,
The sign detection information includes any one or a combination of the bandwidth usage rate, the detection criterion, and other information used for searching for the detour path,
Congestion prevention IP relay device. The congestion prevention IP relay device according to claim 9,
Registration of the notification destination IP relay device is performed from the outside, or by checking whether another IP relay device adjacent on the IP network is provided with the congestion prevention unit,
Congestion prevention IP relay device. A congestion prevention IP relay method of an IP relay device comprising a transmission / reception port for transmitting / receiving a packet and a packet transfer unit for controlling the transfer of the packet,
Monitor the bandwidth utilization of the link connected to the transmission / reception port,
Comparing the bandwidth usage rate with the detection criteria for predicting congestion,
When the bandwidth usage rate exceeds the detection criterion, a search is made for a detour route with a search termination condition that the bandwidth usage rate is equal to or less than the detection criterion,
Reflect the obtained detour route in the route setting of the packet transfer unit,
An IP relay method for preventing congestion. The congestion prevention IP relay method according to claim 12,
In addition to the detection criteria, a threshold value is retained,
Setting the detection criteria when the bandwidth usage exceeds the threshold;
An IP relay method for preventing congestion. The congestion prevention IP relay method according to claim 12,
Using the link cost of the link as a change parameter, search for a link cost that satisfies the search termination condition,
Reflecting the link cost that satisfies the search termination condition and the bypass route in the route setting of the packet transfer unit,
An IP relay method for preventing congestion. The congestion prevention IP relay method according to claim 12,
Using one or more arbitrary fields of the header of the packet as a header condition, obtaining the bandwidth usage rate for each header condition;
Searching for the header condition that satisfies the search end condition and the detour destination link of the header condition using the bandwidth usage rate as a search key;
An IP relay method for preventing congestion. The congestion prevention IP relay method according to claim 15,
Changing the output destination link of the packet that matches the header condition satisfying the search termination condition to the bypass destination link;
An IP relay method for preventing congestion. The congestion prevention IP relay method according to claim 12,
The notification destination IP relay device arranged in the IP network is notified of the sign detection information, and when the bandwidth usage rate exceeds the detection criterion, the bandwidth usage rate of the link included in the sign detection information is Search the detour route as a search end condition to be below the detection criterion,
Reflect the searched detour route in the route setting of the packet transfer unit,
An IP relay method for preventing congestion.

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