JP4341918B2 - Loop detection method and program for bridge device, and bridge device - Google Patents

Description

  The present invention relates to a technique for detecting a loop generated in a bridge in a network provided by a bridge device (hereinafter also referred to as “bridge”), and in addition, a customer's frame particularly in a virtual LAN service provided to a customer by a provider. The present invention relates to a loop detection technique suitable for grasping the occurrence state of a loop in a delivery route.

  In a network provided by a bridge, when a plurality of frame distribution paths exist between two ports of the bridge, there is a possibility that a loop in which a frame passing through the path is repeatedly distributed occurs. When a loop occurs in the network frame delivery route provided by the bridge, especially broadcast and multicast destination frames and unicast frames flooded because the route has not been learned accumulates in the loop and wastes network resources. At the same time, the address learning information in each bridge is confused and has a fatal effect on the network.

  Therefore, in the network provided by the bridge, it is not allowed that a loop occurs in the path even in a very short time including a transient state such as a change in the topology of the network.

  The problem is that, in the network provided by the conventional bridge, STP (Spanning Tree Protocol) defined in IEEE standard 802.1D-1998, RSTP (Rapid Spanning Tree Protocol) defined in IEEE standard 802.1w-2001, The bridge port connected to any topology by LAN or communication line is blocked by MSTP (Multiple Spanning Tree Protocol) defined in IEEE standard 802.1Q-2003 and similar protocols. It is possible to solve this problem by making the path actually used for frame delivery into a tree structure that does not include a loop.

  However, these protocols have a problem that loops cannot always be found. For example, if there is an illegally implemented bridge in the network that does not support STP, RSTP, or MSTP protocols, and other bridges correctly implement STP, RSTP, or MSTP However, there is a problem that it is not possible to find a loop that passes through an illegally implemented bridge.

  Even if these protocols are implemented correctly, when a failure occurs in which the bidirectional link part becomes a unidirectional link, the blocked port in the redundant configuration is released, thereby causing a unidirectional loop. May occur, but there is a problem that this loop cannot be found or avoided.

  Further, STP has a problem of poor practicality because communication interruption occurs on the order of several minutes when the topology is changed. RSTP and MSTP are protocols that greatly improve this point, but there is a problem that the worst communication disconnection time such as a root bridge failure is on the order of several minutes, similar to STP. In addition, since STP and RSTP block the LAN and communication line, there is a problem that their use efficiency is lowered. Furthermore, since any protocol does not always deliver a frame through the shortest path, there are problems such as an increase in delay time required for frame delivery and a limit on the number of bridges that the protocol can practically support.

  Because of such problems, it is difficult to say that STP, RSTP, MSTP and similar protocols are widely used as loop prevention techniques in networks provided by bridges. For this reason, it is often the case that the topology of the network is set to a tree structure manually. In this case, a loop may easily occur in the frame delivery path due to a simple setting mistake or careless setting change.

  The problem of loops in the network provided by such a bridge is further complicated by the virtual LAN service provided by the provider to the customer. At present, the protocol that provides the virtual LAN service is not standardized, but the provider provides the customer as a MAC frame that relays the customer MAC frame in the relay network by extending the specification of IEEE standard 802.1Q-2003. A “Stacked VLAN” method is used in which a service VLAN identifier for identifying a virtual LAN to be assigned and an optional customer VLAN identifier for identifying a VLAN inside the customer are assigned.

  In addition, the customer MAC frame is encapsulated in an MPLS packet, an IP packet including a GRE, a MAC frame, or the like as a frame for relaying the customer MAC frame in the relay network, and the service VLAN identifier is set to the MPLS label, the GRE key, and the MAC frame. Techniques for assigning VLAN identifiers are also used.

  In order to prevent a loop in the virtual LAN service provided by the provider to the customer, the provider needs to make the topology of the virtual LAN provided to the customer a tree structure that does not include the loop. This can be realized by conventional STP, RSTP, MSTP, similar protocols, or a technique by manual setting.

  However, this alone is insufficient as a loop prevention technique. This is because even if the provider provides a virtual LAN without a loop to the customer, a loop may occur in the frame delivery route via the customer site. For example, if the customer site does not use STP, RSTP, MSTP, or similar protocols, a loop in the frame delivery path can easily occur due to a simple setting mistake by the customer or careless setting changes. There is.

  In addition, when STP, RSTP, MSTP and similar protocols are used on the customer site, or when these protocols are not used on the customer side but are provided for the customer on the provider side However, as described above, if there is an improperly implemented bridge that does not support these protocols in the customer site and discards these protocols, the other bridges of the customer are STP, Even if RSTP and MSTP are correctly implemented, a loop that passes through an illegally implemented bridge cannot be found.

  The impact of loops in the network provided by the bridge is even more severe with virtual LAN services provided by providers to customers. If a loop occurs in the route between customer sites, and the route of the loop goes through the relay network, it not only wastes the resources of the customer site but also wastes the resources of the relay network, and as a result normal The frame transfer capability for other customers is also reduced.

  Even if the route of the loop does not go through the relay network, if a loop occurs in the broadcast domain including the relay network, the resources of the relay network are still wasted, and other normal customers are lost. affect.

  Such a failure of one customer affecting another customer is not permitted as a service provided by the provider. However, as described above, even if the provider provides the customer with a virtual LAN of a frame delivery route without a loop and uses STP, RSTP, MSTP at the customer site, Even if these protocols are provided for the correspondence, the customer can generate a loop via the relay network.

  Therefore, the provider needs to detect the loop of the frame delivery route of the customer passing through the relay network and protect other customers without using STP, RSTP, MSTP, or similar protocols.

  In addition, as a prior art regarding such a loop, there exists a thing of the following patent documents 1-5.

JP 11-33235 A JP 2000-183943 A JP 2000-183940 A JP 2000-244546 A JP 2002-247061 A

  Patent Document 1 discloses a technique for detecting a loop path in a customer premises in a customer accommodation device using a CATV cable modem. As is clear from the description in the claim and paragraph “0001” in the specification, this technology relates to a customer accommodating device using a cable modem of CATV, and a virtual LAN service provided by a provider to a customer, There is a problem that is not related to the network provided by the realized bridge.

  Furthermore, even if the technique suggested by the technique described in Patent Document 1 is applied to a network provided by a bridge, there is a problem of erroneously detecting the occurrence of a loop even though no loop is generated. An example of erroneous detection by the loop detection technique suggested from Patent Document 1 will be described with reference to FIG.

  In FIG. 12, reference numeral 1201 denotes a bridge (1). This bridge (1) is connected to the relay network 1207 via the relay port (1) 1202, and is connected to the relay network 1207 via the customer accommodation port (1) 1203 (1). 1208. The bridge (2) 1204 is connected to the relay network 1207 via the relay port (2) 1205, and is connected to the customer site (2) 1209 via the customer accommodation port (2) 1206.

  As shown in FIG. 12, in the technique suggested in Patent Document 1, the inspection frame is transmitted from the customer accommodation port (1) 1203 of the bridge (1) 1201 to the customer site (1) 1208, and the bridge (2) 1204 is transmitted. When an inspection frame is received from the customer accommodation port (2) 1206, the occurrence of a loop is determined. Therefore, this technique may erroneously detect that a loop has occurred although no loop has occurred.

  This is because this technique assumes that the bridge (1) 1201 and the bridge (2) 1204 are always connected via the relay network 1207. Under this implicit assumption, it is possible to detect loops in this way. However, since there is a possibility that a failure may occur in the relay network 1207 in reality, this implicit assumption is not satisfied.

  For example, customer site (1) 1208 and customer site (2) 1209 use STP, and the line connecting customer site (1) 1208 and customer site 1209 is normally closed by STP. Consider a case where communication is performed via the relay network 1207. In this case, if a failure occurs in the relay network 1207 and the STP detects that the connectivity between the customer site (1) 1208 and the customer site (2) 1209 via the relay network 1207 is lost, the blocked line And change the network topology so that communication between sites is not interrupted.

  In this case, the inspection frame is transferred from the bridge (1) 1201 via the customer site (1) 1208 and the customer site (2) 1209 to the bridge (2) 1204 even though no loop has occurred. An erroneous detection in which a result loop is detected occurs.

  In loop detection using such a check frame, it is impossible to determine whether or not a loop has occurred in the transfer path of the MAC frame unless the check frame is transferred to the bridge device that generated the check frame. That is, the test frame must include an identifier (bridge identifier) that uniquely identifies the bridge device that generated the check frame. The bridge that has received the test frame detects the occurrence of a loop when the test frame generated by itself is received. When the test frame is not generated by itself, the bridge detects the test frame as a normal customer MAC frame. Similarly, it must be transferred to another bridge or discarded.

  However, paragraph “0102” of Patent Document 1 explicitly states that “the inspection frame received from the frame receiving unit is discarded and no further relaying is performed”. For this reason, the loop detection technique suggested in Patent Document 1 has a problem of erroneously detecting the occurrence of a loop even though no loop has occurred.

  Further, the loop detection technique suggested in Patent Document 1 is modified so as to be able to cope with the above problem, and an inspection frame including an identifier (bridge identifier) that uniquely identifies the bridge device that generated the inspection frame is included. The received bridge detects the occurrence of a loop when it receives a test frame generated by itself, and if it is not a test frame generated by itself, it sends the test frame to another bridge in the same way as a normal customer MAC frame. Even if it is corrected to perform the process of transferring or discarding, there is a problem that the loop cannot be accurately detected in the “virtual LAN service” provided by the provider to the customer.

  This problem will be described with reference to FIG. The bridge device 1301 is connected to the relay network 1305 via the relay port 1304, connected to the customer site (1) 1306 via the customer accommodation port (1) 1302, and via the customer accommodation port (2) 1303. To the customer site (2) 1307.

  Here, an identifier for identifying a virtual LAN provided by a provider to a customer is called a service VLAN identifier, and a service VLAN to which a customer MAC frame received from a customer site corresponds is predetermined for each customer accommodation port. And In addition, as described above, there are various protocols for providing a virtual LAN service. Regardless of the implementation method, a customer MAC frame encapsulated in the relay frame corresponds to the relay frame. It is assumed that a service VLAN identifier for identifying a virtual LAN to be included is included.

  As shown in FIG. 13, the bridge device 1301 transmits a test frame from the customer accommodation port (1) 1302 to the customer site (1) 1306, and receives a test frame from the customer accommodation port (2) 1303. Determine the occurrence of This determination technique may erroneously detect that a loop has occurred even though no loop has occurred.

  This is because, in this case, when the customer accommodation port (1) 1302 and the customer accommodation port (2) 1303 are receiving virtual LAN services corresponding to the same service VLAN identifier, a loop has occurred, but they are different. This is because a loop does not always occur when the service VLAN identifier is supported.

  When the bridge device 1301 transmits the inspection frame from the customer accommodation port corresponding to the service VLAN identifier (1) and receives it from the port corresponding to the service VLAN identifier (1), this clearly causes a loop. Yes. This is because the topology of each virtual LAN provided by a provider to a customer has a tree structure that does not include a loop, and therefore there is no path connecting between customer accommodation ports belonging to the same bridge unless a loop occurs. Because.

  However, in a virtual LAN service provided by a provider to a customer, a single customer may subscribe to a plurality of virtual LAN services. In this case, the customer may simply use one virtual LAN and another virtual LAN connected at a single point. In addition, for a certain virtual LAN, a route provided to a customer by another virtual LAN may be regarded as a route inside the customer site. In any case, the bridge device transmits an inspection frame from the customer accommodation port corresponding to the service VLAN identifier (1) even though there is no loop in the path connecting the customer accommodation ports. May be received from the port corresponding to the service VLAN identifier (2). In this case, the occurrence of a loop is erroneously detected.

  The same situation also occurs when a customer MAC frame of a customer who subscribes to a certain virtual LAN service is transferred by a different customer who subscribes to a different virtual LAN service.

  Obviously, in the case of the virtual LAN service, the inspection frame transmitted from the customer accommodation port corresponding to the service VLAN identifier of a certain bridge is received from the customer accommodation port corresponding to the service VLAN identifier of the bridge. Alternatively, it cannot be determined that a loop has occurred unless it is received from the relay port as a relay frame including the service VLAN identifier. Therefore, the inspection frame must include an identifier (bridge identifier) that uniquely identifies the bridge device that generated the inspection frame, and an identifier (service VLAN identifier) that identifies the service VLAN that is to be inspected by the inspection frame. .

  The bridge that has received the inspection frame receives the inspection frame generated by a bridge other than itself from the customer accommodation port or the relay port, and receives the inspection frame generated by itself from the customer accommodation port, and is included in the inspection frame. When the service VLAN identifier corresponding to the customer accommodation port is different from the service VLAN identifier to be received, and when the inspection frame generated by itself is received from the relay port, the service VLAN identifier included in the inspection frame and the service VLAN included in the relay frame are received. If the identifiers are different, the inspection frame must be transferred to another bridge or discarded in the same manner as a normal customer MAC frame.

  However, Patent Document 1 does not suggest any information regarding the service VLAN identifier as information included in the inspection frame, or any loop detection technique based on the service VLAN identifier.

  Patent Document 2 discloses a technique for detecting a loop path in a customer premises in a customer accommodation device using a cable modem of CATV. As is clear from the description in the claim and paragraph “0001” in the specification, this technology relates to a customer accommodating device using a cable modem of CATV, and a virtual LAN service provided by a provider to a customer, There is a problem that is not related to the network provided by the realized bridge.

  Also, in the paragraph “0056”, “the loop detection unit 77 constantly monitors the destination MAC address of the packet supplied from the customer home LAN side, and detects the unicast MAC address determined for loop detection. Then, the transmission / discard switch unit 76 is instructed to stop relaying the packet because a loop is detected. ”, And the paragraph“ 0062 ”has a similar description.

  For this reason, even if the loop detection technique suggested by the technique described in Patent Document 2 is applied to a network provided by a bridge, whether or not it is a bridge that has generated a test frame at the time of loop detection determination is completely considered. In addition, since no information on the service VLAN identifier is taken into consideration, a problem of erroneously detecting the occurrence of a loop occurs even though no loop occurs as in Patent Document 1.

  Patent Document 3 discloses a technique for detecting a loop in a bridge device. As apparent from the description of the claims, this technique detects a loop by assigning an identifier that uniquely identifies a bridge device instead of a service VLAN identifier of a relay frame when relaying a received frame. It is.

  As described above, the current protocol for providing a “virtual LAN service” is a method of encapsulating a customer MAC frame into a relay frame together with a service VLAN identifier. Therefore, in this technique, since it is impossible to transmit a loop detection frame including a bridge identifier to a customer site, there is a problem that it cannot be applied to loop detection of a customer's frame delivery route. .

  Patent Document 4 and Patent Document 5 disclose a technique for detecting a loop in the IEEE 1394 bus and a technique for displaying an alarm when a loop is detected. The IEEE 1394 bus is an input that connects a computer device and a terminal device. The technology related to the output bus is different from the technology related to the network defined in a series of IEEE 802 standards in terms of technical content and scope of application. No technology related to the present invention is suggested.

  As described above, the customer's MAC in the “virtual LAN service” in which the provider provides the customer with the conventional loop detection technology that does not use STP, RSTP, MSTP and similar protocols in the network provided by the bridge. When used as a technology to detect a loop in the frame delivery route, it does not identify the bridge device that generated the test frame, so it is not forwarded to the bridge where the test frame was generated, and it is erroneous even though there is no loop. In the virtual LAN service provided by the provider to the customer, the first problem that is detected as the occurrence of a loop and the conventional loop detection technology do not recognize the service VLAN corresponding to the customer accommodating port that transmitted the inspection frame. Also, no loop has occurred Warazu had a second problem will be detected as occurrence of a loop accidentally.

  A technique aimed at solving such a problem in the prior art and making it possible to efficiently detect a loop of a customer's frame delivery path in a “virtual LAN service” provided by a provider to a customer is, for example, This is described in Japanese Patent Application Nos. 2004-43717 and 2004-244792 by the inventors of the present invention, which are described in detail in the “Best Mode for Carrying Out the Invention” section below.

  However, each of the techniques described in Japanese Patent Application Nos. 2004-43717 and 2004-244792 only detects the occurrence of a loop, and detects in which service VLAN the loop is occurring. You can, but determine the status of the loop, such as whether the loop occurs only at the customer site and does not include a provider bridge, or whether the loop includes a provider bridge I can't. In addition, when a customer VLAN identifier is changed by connecting a customer VLAN with a different customer using the tag VLAN in the customer site, the loop is erroneously generated even though the loop does not occur. It may be detected. Further, when a loop detection OAM frame is transmitted in the same manner, the customer may erroneously detect the occurrence of a loop by receiving it.

  In the conventional technology, the problem to be solved is that the loop generated in the service VLAN occurs only in the customer site and does not include the provider bridge, or the provider bridge is included in the loop. When the customer VLAN identifier is changed by connecting a different customer VLAN within the customer site, the customer using the tag VLAN cannot determine the status of the loop such as being included. Even if a loop has not occurred, it is erroneously detected as the occurrence of a loop. Also, when a loop detection OAM frame is transmitted in the same manner in the customer, the occurrence of a loop is erroneously detected. It is a point.

  An object of the present invention is to solve these problems of the prior art, and to more accurately detect and grasp a loop situation of a customer's frame delivery route in a virtual LAN service provided by a provider to a customer, for example. It is in.

  In order to achieve the above object, in the present invention, the loop detection OAM identifier, the bridge identifier of the bridge device, the service VLAN identifier corresponding to the customer accommodating port, whether or not the loop detection OAM frame is tagged when transmitted Customer VLAN identifier when tagged with information (customer VLAN is a subset of the topology of the network composed of provider virtual LAN and customer site, identified by customer VLAN identifier), source port The MAC frame encapsulating the loop detection OAM including at least information for identifying the customer may be tagged with or without tagging with a customer VLAN identifier that matches the customer VLAN specification of the customer MAC frame. Sent from accommodation port When it is received, the loop status is judged by comparing the transmission source port information and the reception port information, and when the transmission source port and the reception port are different, the set of the port information is stored in the storage device. It is characterized in that it is determined whether a bidirectional loop or a unidirectional loop is obtained by searching a pair in which transmission source port information and reception port information are reversed from the stored information. Further, by including transmission time information and transmission event identifier information in the loop detection OAM, erroneous detection of a loop by a MAC frame encapsulating the loop detection OAM generated by the customer is avoided.

  According to the present invention, in a technique for detecting a loop of a delivery route of a customer frame in a virtual LAN service provided by a provider to a customer, there exists a portion where only a MAC frame belonging to a specific customer VLAN passes inside the customer site. However, even if the customer VLAN has been replaced and the loop of the customer's frame delivery route has passed this part, the loop can be detected without erroneous detection. Thus, even if the customer VLAN value is converted inside the customer site, it is possible to detect the loop, and whether the loop occurs only in the customer site and the provider's bridge is not included. Does the loop contain a provider's bridge, plus If the bridge provider is included, it can be exactly determined whether bidirectional loop or unidirectional loop to protect other customers. Furthermore, when the customer uses the same loop detection means, erroneous detection of a loop by a MAC frame encapsulating the loop detection OAM generated by the customer is avoided.

  The best embodiment of the present invention will be described below with reference to the drawings.

  First, it is possible to solve the problems in the prior art described in Patent Documents 1 to 5 described above, and to efficiently detect a loop of a customer's frame delivery path in a virtual LAN service provided by the provider to the customer, for example. The technology described in Japanese Patent Application Nos. 2004-43717 and 2004-244792 by the inventors of the present application will be described.

  First, in the technology described in Japanese Patent Application No. 2004-43717, in order to detect a loop of a customer's frame delivery path in a virtual LAN service provided by a provider to a customer, a bridge device uses a loop detection OAM identifier, A MAC frame encapsulating a loop detection OAM including at least a bridge identifier of a bridge device and a service VLAN identifier corresponding to the customer accommodation port is generated, transmitted from the customer accommodation port, and received from the customer accommodation port. When the loop detection OAM is encapsulated in the MAC frame, the bridge identifier included in the MAC frame is compared with the bridge identifier of the own bridge device, and the service VLAN identifier included in the MAC frame The service VLAN identifier corresponding to the customer accommodation port is compared, and if both the bridge identifier and the service VLAN identifier match, the MAC frame is discarded, the occurrence of a loop is detected, and in other cases, The MAC frame is transferred to the MAC relay unit.

  When a relay frame is received from a relay port and the MAC frame encapsulating the loop detection OAM is included in the relay frame, the bridge identifier included in the MAC frame and the bridge identifier of the own bridge device And the service VLAN identifier included in the MAC frame is compared with the service VLAN identifier corresponding to the MAC frame. If both the bridge identifier and the service VLAN identifier match, the relay frame is discarded. The occurrence of a loop is detected, and in other cases, the relay frame is transferred to the MAC relay unit.

  Thereby, in the detection of the loop of the delivery route of the customer's MAC frame in the virtual LAN service provided to the customer by the provider, it is possible to avoid erroneously detecting the occurrence of the loop even though no loop has occurred.

  Thus, the loop of the frame delivery path in the network provided by the bridge device is a state in which a plurality of MAC frame delivery paths exist between the two ports of the bridge. In addition, a virtual LAN service provided by a provider to a customer connects customer sites via a customer accommodation port by a virtual LAN of a tree-structured path. Therefore, the loop of the MAC frame delivery route in the virtual LAN service provided to the customer by the provider means that the customer site provides a route connecting between the customer accommodation ports corresponding to a certain virtual LAN, and between the customer accommodation ports. Is a state in which there is no failure in the path of the virtual LAN connecting the.

  A bridge device that provides a virtual LAN service to a customer has a customer accommodating port that transmits and receives MAC frames from the customer site, and a relay port that transmits and receives relay frames from the relay network. The provider identifies each virtual LAN provided to the customer by a service VLAN identifier. There are various formats for the relay frame transmitted and received from the relay port, and all are in a format in which a MAC frame and a service VLAN identifier corresponding to the MAC frame are encapsulated.

  The relationship between the MAC frame received from the customer accommodation port and the service VLAN identifier corresponding to the MAC frame is that a single service VLAN identifier value is predetermined for the customer accommodation port, and the VLAN identifier value corresponding to the MAC frame is The relationship is uniquely determined by the port that received the MAC frame.

  The loop detection OAM in the loop detection technique described in Japanese Patent Application No. 2004-43717 is a service that identifies a bridge identifier that identifies a bridge device that has generated the loop detection, and a virtual LAN that the loop detection OAM is an object of inspection. It includes a VLAN identifier and is transmitted from the corresponding customer accommodation port. In order to detect a state in which the customer site provides a route connecting the customer accommodation ports corresponding to the provider's virtual LAN and there is no failure in the route of the virtual LAN connecting the customer accommodation ports, loop detection The OAM is transferred to the bridge device that generated it, and the value of the service VLAN identifier to which the loop detection OAM corresponds (when received from the relay port, the value of the service VLAN identifier included in the relay frame, from the customer accommodation port If it is received, the occurrence of a loop is determined when the service VLAN identifier value (corresponding to the customer accommodation port) matches the service VLAN identifier for identifying the virtual LAN to be inspected. If these values are different, the bridge device transfers or discards the loop detection OAM in the same way as a normal customer MAC frame.

  Accordingly, in the loop detection technique described in the above Japanese Patent Application No. 2004-43717, the provider uses a conventional loop detection technique that does not use STP, RSTP, MSTP and similar protocols in the network provided by the bridge. When used as a technology for detecting a loop in the delivery route of a customer's MAC frame in a virtual LAN service provided to a customer, the bridge device that generated the test frame is not identified, so it is not transferred to the bridge that generated the test frame. The first problem of erroneously detecting the occurrence of a loop despite the absence of a loop and the conventional loop detection technology do not recognize the service VLAN corresponding to the customer accommodation port that transmitted the inspection frame Therefore, the provision provided by the provider to the customer In LAN service, despite the loop does not occur, it is possible to solve the second problem that results in detecting the occurrence of a loop accidentally.

  However, in the loop detection technique described in the above Japanese Patent Application No. 2004-43717 (a technique for detecting a loop of a delivery route of a customer frame in a virtual LAN service provided by a provider to a customer), the MAC received from the customer accommodation port The relationship between the frame and the service VLAN identifier corresponding to the frame is that a single service VLAN identifier value is predetermined for the customer accommodation port, and the VLAN identifier value corresponding to the MAC frame is determined by the port that received the MAC frame. If the relationship is uniquely determined, the loop detection OAM does not include the customer VLAN identifier. The customer VLAN is a subset of the topology of the network composed of the virtual LAN of the provider and the customer site, and is identified by the customer VLAN identifier.

  Therefore, in the loop detection technique described in the above Japanese Patent Application No. 2004-43717, there is a portion where only a MAC frame belonging to a specific customer VLAN passes inside the customer site, and the loop of the delivery route of the customer frame is this. When passing through this portion, the loop detection OAM does not pass through this portion, so there is a third problem that the loop is not detected.

  The above Japanese Patent Application No. 2004 is a technique for solving such a third problem and detecting a loop of a delivery route of a customer frame in a virtual LAN service provided by a provider to a customer, for example. There is a loop detection technique described in US Pat.

  In this technique, the bridge device transmits or receives information about whether or not a MAC frame not including a customer VLAN identifier has been transmitted or received from a customer accommodating port, and transmission or reception of a MAC frame including a customer VLAN identifier. If so, information including the value of the customer VLAN identifier is acquired and stored in the storage device. And a MAC frame encapsulating the loop detection OAM and including the customer VLAN identifier, including at least a loop detection OAM identifier, a bridge identifier of the bridge device, and a service VLAN identifier corresponding to the customer accommodating port. Is transmitted or received from the customer accommodation port, a MAC frame tagged with the customer VLAN identifier is generated, and a MAC frame not including the customer VLAN identifier is transmitted or received from the customer accommodation port. If so, a MAC frame that is not tagged with the customer VLAN identifier is generated and transmitted from the customer accommodation port.

  As described above, the loop detection technique described in Japanese Patent Application No. 2004-244792 is based on information regarding whether or not a MAC frame not including a customer VLAN identifier has been transmitted or received from the customer accommodation port, and the customer VLAN. When a MAC frame including an identifier is transmitted or received, information including the value of the customer VLAN identifier is acquired and stored in the storage device, so that the bridge device is used inside the customer site for each customer accommodation port. The customer VLAN is present inside the customer site by obtaining information about the customer VLAN identifier and tagging the MAC frame encapsulating the loop detection OAM with the customer VLAN identifier based on the information. Even if you want to It is a technique for detecting flop solves the third problem. However, when the customer VLAN identifier is changed inside the customer site, the fourth problem of erroneously detecting the occurrence of the loop occurs despite the absence of the loop.

  An example of erroneous detection by the loop detection technique suggested by the technique described in Japanese Patent Application No. 2004-244792 will be described with reference to FIG.

  The bridge device 1401 is connected to the relay network 1405 via the relay port 1404, connected to the customer site (1) 1406 via the customer accommodation port (1) 1402, and via the customer accommodation port (2) 1403. To the customer site (2) 1407.

  Here, it is assumed that the service VLAN to which the customer MAC frame received from the customer site corresponds is predetermined for each customer accommodation port. Similarly to the above, there are various protocols for providing a virtual LAN service, and any implementation method corresponds to a customer MAC frame encapsulated in the relay frame. It is assumed that a service VLAN identifier for identifying a virtual LAN is included.

  As shown in FIG. 14, the bridge device 1401 learns the value of the customer VLAN identifier when there is the customer VLAN identifier and the customer VLAN identifier from the MAC frame sent from the customer accommodation port (1) 1402. If there is a customer VLAN identifier, a loop detection OAM frame is tagged with the learned customer VLAN identifier, transmitted to the customer site (1) 1406, and a loop detection OAM frame is received from the customer accommodation port (2) 1403 When the value of the service VLAN identifier corresponding to the customer accommodation port matches the service VLAN identifier included in the loop detection OAM frame, the occurrence of the loop is determined.

  However, this determination technique may erroneously detect that a loop has occurred even though no loop has occurred. This is because, in this case, the customer accommodation port (1) 1402 and the customer accommodation port (2) 1403 receive the virtual LAN service corresponding to the same service VLAN identifier, and the customer VLAN identifier of the customer site (1) 1406 This is because a loop occurs when the customer VLAN identifiers of the customer site (2) 1407 are the same, but a loop does not always occur when the customer site (2) 1407 corresponds to a different customer VLAN identifier.

  When the bridge device 1401 transmits the loop detection OAM frame tagged with the customer VLAN identifier (1) from the customer accommodation port (1) 1402, and passes through the customer site (1) 1406 and the customer site (2) 1407, Even if the customer VLAN identifier is converted and the customer VLAN identifier (1) of the loop detection OAM frame is rewritten to the customer VLAN identifier (2), the bridge device 1401 does not change the bridge included in the loop detection OAM. The identifier and the self-bridge identifier are compared, and the service VLAN identifier included in the loop detection OAM is compared with the service VLAN identifier corresponding to the received customer accommodation port. End up.

  A loop detection OAM frame connected to customer accommodation port (1) 1402 and tagged with customer VLAN identifier (1) of customer site (1) 1406 passes through customer site (1) 1406 and customer site (2) 1407. Then, when the customer VLAN is tagged with the customer VLAN identifier (2) and returns to the customer accommodation port (2) 1403, since the service VLAN identifier is the same, it is sent again from the customer accommodation port (1) 1402. However, at the customer site (1) 1406, since the loop detection OAM frame is tagged with the customer VLAN identifier (2), it does not follow the same path as the frame tagged with the customer VLAN identifier (1). That is, the virtual LAN is identified by the customer VLAN in the same manner as the virtual LAN is identified by the service VLAN.

  As is clear from the above, in order to perform loop detection by transmitting a loop detection OAM frame tagged with a customer VLAN identifier, an identifier for uniquely identifying the bridge device that generated the loop detection OAM frame, and loop detection The OAM frame must contain the service VLAN identifier and customer VLAN identifier to be examined.

  The bridge that has received the loop detection OAM frame receives the loop detection OAM frame generated by a bridge other than itself from the customer accommodation port or the relay port, and receives the loop detection OAM frame generated by itself from the customer accommodation port. When the service VLAN identifier included in the loop detection OAM frame is different from the service VLAN identifier corresponding to the customer accommodation port, and when the loop detection OAM frame generated by itself is received from the relay port, the service included in the inspection frame When the VLAN identifier and the service VLAN identifier included in the relay frame are different, or the customer VLAN identifier information included in the payload of the loop detection OAM frame and the customer VL included in the header of the loop detection OAM frame If the N identifiers are different, it must be performed a process of discarding or transfer the loop detection OAM frame to the normal customer MAC frame and other bridges as well.

  However, Japanese Patent Application No. 2004-244792 describes that customer VLAN identifier information is learned and tagged with the customer VLAN identifier and a loop detection OAM frame is transmitted. However, information included in the loop detection OAM frame is described. No information about the customer VLAN identifier is included, and no loop detection / determination technique based on the customer VLAN identifier is suggested.

  In addition, in the techniques described in Japanese Patent Application Nos. 2004-43717 and 2004-244792, only the occurrence of a loop is detected, and in which service VLAN the loop is occurring is detected. However, it is not possible to determine whether the loop occurs only within the customer site and does not include the provider's bridge, or whether the loop includes the provider's bridge, etc. There were 5 problems.

  Similarly, the customer has a sixth problem that a loop is erroneously detected when a loop detection OAM frame is transmitted in the same manner.

  Hereinafter, in addition to the first to fourth problems, the fifth and sixth problems are solved, and the loop status of the customer's frame delivery route in the virtual LAN service provided to the customer by the provider is further improved. Details of the technique according to the present invention that enables accurate detection and grasping will be described with reference to FIGS. 1 to 11D.

  FIG. 1 is a block diagram showing a configuration example of a network using a bridge device for executing the processing procedure of the loop detection method according to the present invention, and FIG. 2 is a block diagram showing a configuration example of the bridge device according to the present invention. 3 is an explanatory diagram showing a first configuration example of a MAC frame transmitted / received between the customer accommodation port of the bridge device and the customer site in FIG. 1, and FIG. 4 is a customer accommodation port and customer of the bridge device in FIG. FIG. 5 is a diagram illustrating a second configuration example of a MAC frame transmitted / received between sites, and FIG. 5 is a diagram illustrating a first configuration example of a MAC frame transmitted / received between the relay port of the bridge device and the relay network in FIG. FIG. 6 and FIG. 6 show MAC frames encapsulating the loop detection OAM transmitted and received between the customer accommodation port of the bridge device in FIG. 1 and the customer site. FIG. 7 is an explanatory diagram showing a first configuration example of a network, and FIG. 7 is a second configuration example of a MAC frame encapsulating a loop detection OAM transmitted and received between the customer accommodation port of the bridge device and the customer site in FIG. FIG. 8 is an explanatory diagram showing an example of the configuration of a MAC frame encapsulating a loop detection OAM transmitted and received between the relay port and the relay network of the bridge device in FIG. 1, and FIG. 9 is a diagram of the bridge device in FIG. FIG. 10 is a diagram illustrating a second configuration example of the MAC frame transmitted / received between the relay port and the relay network, and FIG. 10 illustrates a third example of the MAC frame transmitted / received between the relay port of the bridge device and the relay network in FIG. FIG. 11A is a flowchart showing a first processing procedure example of the loop detection method by the bridge device according to the present invention, and FIG. FIG. 11C is a flowchart showing a third processing procedure example of the loop detection method by the bridge device according to the present invention, and FIG. 11D is a flowchart showing the third processing procedure example of the loop detection method by the bridge device according to the present invention. It is a flowchart which shows the 4th example of a process sequence of the loop detection method by the bridge apparatus concerned.

  In FIG. 1, 101 and 105 are bridge devices (1) and (2) according to the present invention, and these bridge devices 101 and 105 are a CPU (Central Processing Unit), a main memory, a display device, an input device, an external device. A computer having a storage device is installed, and after programs and data recorded on a storage medium such as a CD-ROM are installed in the external storage device via an optical disk drive device, etc., the program is read from the external storage device into the main memory and the CPU The processing procedure according to the present invention may be executed by processing, or may be configured to be executed by logic using hardware.

  The bridge device (1) 101 is connected to the relay network 109 via the relay port (11) 102. Here, the relay network 109 may be a data network such as a bridge network, an MPLS network, and an IP network, and is not limited to these examples.

  Further, the bridge device (1) 101 has a customer accommodation port (11) 103 and a customer accommodation port (12) 104, which are connected to the customer site (1) 110 and the customer site (2) 111, respectively. Here, the customer site is a device that terminates a MAC frame such as a LAN, a bridge network, a router, a terminal, or the like that is a target of a virtual LAN service provided to a customer by a provider.

  The bridge device (2) 105 includes a relay port (21) 106 and a relay port (22) 107, and is connected to the relay network 109, respectively. The bridge device (2) 105 also has a customer accommodation port (21) 108 and is connected to the customer site (3) 112.

  The provider passes through the customer accommodation port (11) 103, the customer accommodation port (12) 104, and the customer accommodation port (21) 108 by the relay network 109 that connects the bridge device (1) 101 and the bridge device (2) 105. Then, the virtual LAN service is provided to the customers of the customer site (1) 110, the customer site (2) 111, and the customer site (3) 112, respectively.

  An example of the internal configuration of the bridge devices (1) 101 and (2) 105 is shown in FIG. The configuration example shown in FIG. 2 shows an example in which each of the customer accommodation port 201 and the relay port 203 is one port. However, when the number of both ports is plural, it is the same as the configuration of FIG. In addition, each port is connected via the MAC relay unit 205 and the loop detection unit 206.

  The table 207 is stored in a storage device. As shown in the table 207, the customer accommodation port 201 is a “customer VLAN identifier” which is information regarding whether or not a MAC frame not including a customer VLAN identifier has been transmitted or received. If the MAC frame including the customer VLAN identifier is transmitted or received, information regarding “customer VLAN identifiers 1 to 3” that is information including the value of the customer VLAN identifier is acquired and recorded. The

  In the table 207 of this example, MAC frames including three types of customer VLAN identifiers are transmitted and received. The recorded information may record only the fact that transmission / reception has been performed, or may record the number of transmission / reception. In addition, acquisition of these information may be performed with respect to one of transmission and reception of a frame, or may be performed with respect to both transmission and reception, or may be performed by sampling transmitted / received frames. When generating the detected OAM, transmission / reception of a MAC frame from the customer accommodating port 201 may be waited, and information may be acquired from the transmitted / received MAC frame.

  The relay port 203 transmits and receives a relay frame from the relay network via the relay line 204. When the customer data is encapsulated in the MAC frame received from the customer accommodating port 201, the MAC relay unit 205 encapsulates the MAC frame in which the customer data is encapsulated in the relay frame received from the relay port 203. In this case, the transfer process or the discard process based on a predetermined rule is performed, and the frame format is converted as necessary.

  In addition, the MAC relay unit 205 generally has an FDB (Filtering Database) function that automatically learns the customer accommodation port 201 and the relay port 203 that are transfer destinations of the received MAC frame and relay frame.

  The loop detection unit 206 generates a MAC frame encapsulating the loop detection OAM and transmits it from the customer accommodation port 201, or encapsulates a MAC frame obtained by encapsulating the loop detection OAM in the MAC frame received from the customer accommodation port 201. If YES, loop detection determination and loop detection OAM transfer processing are performed.

  FIG. 3 shows an example of a MAC frame transmitted / received between the customer accommodation port of the bridge device and the customer site in this example. In FIG. 3, the MAC frame specified in IEEE standard 802.3-2002 is used in particular. An example in which data is encapsulated is shown.

  In FIG. 3, the destination MAC address 301 is “Destination Address”, and the source MAC address 302 is “Source Address”. The type identifier 303 is “Length / Type”. The type of “MAC Client Data” which is data encapsulated in the MAC frame is identified by this type identifier 303. For example, when this value is “0x0800”, the encapsulated customer data 304 is an IPv4 packet. Indicates. FCS 305 stands for “Frame Check Sequence”.

  FIG. 4 shows different examples of MAC frames transmitted and received between the customer accommodation port of the bridge device and the customer site in this example. FIG. 4 shows an example in which “Tag Header” defined in the IEEE standard 802.1Q-2003 is added to the MAC frame example shown in FIG.

  In FIG. 4, a type identifier 407 is “Tag Protocol Identifier”, and identifies an attribute of “Tag Header”. When this value is “0x8100”, “Tag Header” is the customer VLAN tag 403. By encapsulating the customer VLAN identifier 410 in the customer VLAN tag 403, the customer VLAN identifier is tagged to the MAC frame. This customer VLAN identifier identifies a subset of the topology of the network comprised of the provider's virtual LAN and customer site.

  The priority 408 is “User Priority”, and the CFI 409 is “Canonical Format Identifier”. The type identifier 404 identifies the type of data to be encapsulated, similar to the type identifier 303 in FIG.

  In this example, the MAC frame transmitted / received between the customer accommodation port of the bridge device and the customer site is referred to as a customer MAC frame for the sake of convenience, but hereinafter this is referred to as a MAC frame. In addition, various MAC frame formats are defined in a series of IEEE 802 standards, and the MAC frame in the present invention is not limited to the above examples.

  An example of a MAC frame encapsulating the loop detection OAM (Operation Administration and Maintenance) of the present invention is shown in FIG. FIG. 6 shows an example in which the loop detection OAM is encapsulated in the MAC frame shown in FIG.

  As an example of the destination MAC address 601 in FIG. 6, there is a reserved multicast address or a reserved unicast address. In these cases, the destination MAC address 601 may be used as a loop detection OAM identifier indicating that the loop detection OAM is encapsulated in the MAC frame. The destination MAC address 601 may be the MAC address of the customer accommodation port that transmitted the MAC frame encapsulating the loop detection OAM.

  An example of the source MAC address 602 is a bridge identifier that identifies a bridge device. In this case, the source MAC address 602 may be used as a bridge identifier. As the bridge identifier, any one of the MAC address of the customer accommodating port of the bridge, the MAC address of the relay port, or the MAC address of other management port, etc. may be used, and it is uniquely assigned to the bridge. However, a management MAC address that is not used in the port may be used. This may be used as a source port identifier.

  Further, the source MAC address 602 may be the MAC address of the customer accommodating port that transmitted the MAC frame encapsulating the loop detection OAM, and this may be used as the source port identifier. The type identifier 603 may be assigned a predetermined value indicating that the loop detection OAM is encapsulated in the MAC frame, and this value may be used as the loop detection OAM identifier.

  Reference numeral 604 denotes a bridge identifier for identifying a bridge device. Reference numeral 605 denotes a service VLAN identifier, which identifies a service VLAN to be inspected by the loop detection OAM. Reference numeral 606 denotes a source port identifier, which identifies a source port that has transmitted a MAC frame encapsulating the loop detection OAM.

  Reference numeral 607 denotes transmission time information, which represents the time at which the MAC frame encapsulating the loop detection OAM is transmitted. Note that this time only needs to be able to calculate the time from transmission to reception when the bridge device receives the MAC frame encapsulating the loop detection OAM, and may not be time information synchronized across all bridge devices. Good.

  A transmission event identifier 608 indicates that a MAC frame encapsulating the loop detection OAM has been transmitted. For example, information for identifying the frame such as a sequence number, a time stamp, or a frame ID is used. The bridge device records the transmission event identifier, records that the frame has been transmitted, and if the transmission event identifier is recorded when the loop detection OAM frame is received, the bridge device It can be confirmed that the frame has been transmitted, and the occurrence of a loop can be detected. The transmission event identifier 608 only needs to be able to identify the MAC frame encapsulating the loop detection OAM or the transmission event in combination with other loop detection OAM information, and may not be information that can be identified only by this identifier.

  In this example, an encapsulated loop detection OAM is configured by the bridge identifier 604, the service VLAN identifier 605, the transmission source port identifier 606, the transmission time information 607, and the transmission event identifier 608.

  Next, different examples of MAC frames encapsulating the loop detection OAM of the present invention are shown in FIG. FIG. 7 shows an example in which “Tag Header” defined in the IEEE standard 802.1Q-2003 is added to the MAC frame example shown in FIG. Similar to the example of the MAC frame shown in FIG. 4, the MAC frame has a format in which the customer VLAN identifier 715 is tagged with the customer VLAN tag 703.

  In this example, a MAC frame that encapsulates the loop detection OAM is referred to as an “examination frame” for convenience of explanation. However, this is hereinafter referred to as a MAC frame that encapsulates the loop detection OAM.

  The MAC frame encapsulating the loop detection OAM may include at least the loop detection OAM identifier, the bridge identifier, the service VLAN identifier, and the transmission source port identifier, and the format is not limited to the above example.

  Next, FIG. 5 shows an example of a relay frame transmitted and received between the relay port of the bridge device and the relay network in the present invention. This FIG. 5 is a “Stacked VLAN method” relay frame described in the prior art, and a service VLAN tag 503 is inserted into the MAC frame to which the “Tag Header” shown in FIG. 4 shows an example of a frame that relays the MAC frame shown in FIG.

  In FIG. 5, the customer VLAN tag 504 is an option, and the customer VLAN tag 504 does not exist when the MAC frame shown in FIG. 3 is relayed. In any case, the type identifier 508 identifies the attribute of this “Tag Header”, and if this value is “0x9100”, in many implementations the “Tag Header” will be the service VLAN tag 503 and the MAC frame will be the service VLAN. It is tagged with the identifier 511. The service VLAN identifier 511 identifies a virtual LAN provided by the provider to the customer.

  FIG. 8 shows an example in which the example of the relay frame shown in FIG. 5 includes a MAC frame encapsulating the loop detection OAM. FIG. 8 shows an example in which the MAC frame encapsulating the loop detection OAM shown in FIG. 7 is included in the relay frame of the format shown in FIG.

  As is clear from FIG. 8, in this example, a service VLAN tag 803 is inserted into a MAC frame encapsulating the loop detection OAM shown in FIG. Also in this case, the customer VLAN tag 804 is optional, and the customer VLAN tag 804 does not exist when the MAC frame encapsulating the loop detection OAM shown in FIG. 6 is included.

  Next, FIG. 9 shows different examples of relay frames transmitted and received between the relay port of the bridge device and the relay network in the present invention. FIG. 9 shows an example of a frame in which the MAC frame 905 is encapsulated and relayed by the MAC frame tagged with the service VLAN identifier 910. This relay frame is a frame based on the IEEE standard shown in FIG. However, the point that the maximum length of the frame is longer than the maximum length of the MAC frame defined in the IEEE standard and the point that the service VLAN tag is used instead of the customer VLAN tag are excluded.

  The encapsulated MAC frame 905 may be a MAC frame encapsulating the customer data shown in FIGS. 3 and 4 or a MAC frame encapsulating the loop detection OAM shown in FIGS. 6 and 7. These are identified by a type identifier 904.

  Further, as shown in FIG. 10, a plurality of service VLAN identifiers 1011 and 1015 are tagged with a plurality of service VLAN tags 1003 and 1004 to the relay frame, and a virtual LAN provided to the customer by the provider is a plurality of service VLAN identifiers. 1011 and 1015 may be identified.

  The relay frame only needs to include at least the MAC frame to be relayed and the service VLAN identifier corresponding to the MAC frame. The MAC frame is encapsulated in an IP packet including an MPLS packet or GRE, and the service VLAN identifier is set to MPLS. The label may be assigned to the label of GRE or the key of GRE, and the format is not limited to these examples.

  Next, an example of a conventional realization of a virtual LAN service provided by a provider to a customer is shown by a configuration example of a bridge device in the present invention shown in FIG.

  The customer accommodation port 201 receives the MAC frame illustrated in FIGS. 3 and 4 from the customer site. When the MAC frame is received, at the customer accommodation port, the service VLAN identifier corresponding to the MAC frame becomes a service VLAN identifier predetermined for the port.

  The relay port 203 receives the relay frame illustrated in FIGS. 5, 9, and 10 from the relay network. The relay frame includes service VLAN identifiers (511, 910, 1011 and 1015) corresponding to the MAC frame included in the relay frame.

  When the bridge device receives the MAC frame from the customer accommodating port 201, if it is determined from the MAC frame type identifier (303, 404) that the customer data is encapsulated in the MAC frame, the MAC The frame is transferred to the MAC relay unit 205.

  The MAC relay unit 205 is a customer accommodating port other than the customer accommodating port that received the MAC frame, and the first relay processing for transferring the MAC frame, the MAC frame, and the service corresponding to the MAC frame A relay frame including a VLAN identifier is generated, and either or both of the second relay processes for transferring to the relay port are performed, or the MAC frame is discarded.

  Which relay processing is performed for which customer accommodation port or relay port depends on the implementation of the bridge device. In general, the MAC relay unit automatically learns the transfer destination port of the MAC frame whose destination is unicast by FDB. For this reason, if the destination is unicast and there is a learning result, it is transferred only to that port.

  However, if the destination is an unlearned unicast MAC frame, or if the destination is multicast or broadcast, a service VLAN corresponding to the MAC frame that is a customer accommodation port other than the customer accommodation port that received the MAC frame. In some cases, the forwarding is performed only to the relay port corresponding to the service VLAN identifier corresponding to the identifier.

  If there is neither a customer accommodation port nor a relay port corresponding to the service VLAN identifier corresponding to the MAC frame, the MAC frame is discarded. The MAC relay unit may selectively discard MAC frames such as a specific destination MAC address and a source MAC address.

  When the bridge device receives the relay frame from the relay port, the MAC frame included in the relay frame is transferred to the MAC relay unit 205 from the type identifier (805, 904, 1005) of the relay frame.

  The MAC relay unit 205 performs third relay processing for transferring the MAC frame to the customer accommodating port corresponding to the service VLAN identifier corresponding to the MAC frame included in the relay frame, and the relay frame. Either or both of the fourth relay processes for transferring to a relay port other than the received relay port are performed, or the relay frame is discarded. Which relay processing is performed for which customer accommodation port or relay port is the same as when receiving from the customer accommodation port.

  Hereinafter, an implementation example of the loop detection technique according to the present invention will be described with reference to a configuration example of a bridge device according to the present invention shown in FIG.

  The trigger for the bridge device to generate and transmit the MAC frame encapsulating the loop detection OAM may be based on an instruction from the management device of the bridge device, or may be periodically transmitted using a timer included in the bridge device. good.

  In addition, when a loop occurs in the MAC frame transfer path, when the MAC frame transfer destination by FDB is automatically learned, the flapping phenomenon may be observed as an opportunity.

  In any case, the trigger for generating and transmitting a MAC frame encapsulating the loop detection OAM is not limited to the above example.

  When the transmission / reception of the MAC frame not including the customer VLAN identifier is recorded in the information acquired in the table 207, the loop detection unit 206 of the bridge device encapsulates the loop detection OAM illustrated in FIG. A frame is generated and transmitted from the customer accommodation port corresponding to the service VLAN identifier 605.

  In addition, when transmission / reception of a MAC frame including a customer VLAN identifier is recorded in the information acquired in the table 207, the loop detection OAM illustrated in FIG. 7 tagged with the customer VLAN identifier is encapsulated. A MAC frame is generated and transmitted from the customer accommodation port corresponding to the service VLAN identifier 706.

  Note that when the information acquired in the table 207 records the transmission / reception of a MAC frame that does not include the customer VLAN and the MAC frame that includes the customer VLAN, or the transmission / reception of a MAC frame that includes a different customer VLAN identifier. A MAC frame encapsulating the loop detection OAM corresponding to one of them may be generated, or a plurality of MAC frames encapsulating the loop detection OAM corresponding to each of them may be generated.

  Also, the acquisition of information in the table 207 may be performed for all transmitted / received frames, or may be performed by transmitting / receiving and sampling the frames. When the loop detection OAM is generated, the customer accommodation port 201 is acquired. It is also possible to wait for transmission / reception of a MAC frame from the mobile station and acquire information from the transmitted / received MAC frame.

  Hereinafter, loop detection processing when the bridge device receives a MAC frame from the customer accommodation port 201 will be described.

  When the bridge device receives the MAC frame from the customer accommodating port 201, as illustrated in FIG. 6 or FIG. 7, the loop detection OAM is added to the MAC frame from the type identifier (603, 704) of the MAC frame. If it is determined that the MAC frame is encapsulated, the MAC frame is transferred to the loop detection unit 206.

  The loop detection unit 206 compares the bridge identifier of the bridge device with the bridge identifiers (604, 705) of the MAC frame. Then, the service VLAN identifier corresponding to the MAC frame is compared with the service VLAN identifier (605, 706) of the MAC frame.

Further, when there is a customer VLAN identifier (707), the customer VLAN identifier (715) corresponding to the MAC frame is compared with the customer VLAN identifier (707) of the MAC frame.

  If there is no customer VLAN identifier, the occurrence of a loop is detected on condition that both the bridge identifier and the service VLAN identifier match, and the MAC frame is discarded. If there is a customer VLAN identifier, the bridge identifier On the condition that the service VLAN identifier and the customer VLAN identifier all match, and the MAC frame is discarded.

  When the occurrence of a loop is detected in this way, a difference obtained by subtracting the transmission time information given to the loop detection OAM of the MAC frame from the time information of receiving the MAC frame encapsulating the loop detection OAM is obtained. Then, based on this difference, it is determined whether the MAC frame has arrived within a predetermined time, and if the time is exceeded or the time is going back (the difference is a negative value) , Loop detection and not.

  If the transmission event identifier of the MAC frame encapsulating the loop detection OAM is present in the transmission event record information recorded in the storage device in advance, and if it is not recorded in the transmission event record information Does not detect loops.

  In the above comparison, if any of the bridge identifier, the service VLAN identifier, and the customer VLAN identifier does not match in the comparison, the loop detection unit 206 transfers the MAC frame to the MAC relay unit 205 and encapsulates the customer data. Transfer processing similar to that for frames is performed.

  Next, loop detection processing when the bridge device of the present invention receives a relay frame from the relay port 203 will be described.

  As described above, when the bridge device receives the relay frame from the relay port 203, when it is determined from the type identifier of the relay frame that the loop detection OAM is encapsulated in the MAC frame included in the relay frame. Transfers the relay frame to the loop detection unit 206.

  If the format of the relay frame is the format illustrated in FIG. 8, it can be determined from the type identifier 805 that the loop detection OAM is encapsulated. Note that the customer VLAN tag 804 may not be included.

  When the format of the relay frame is the format illustrated in FIGS. 9 and 10, it can be determined from the type identifier (904, 1005) that the loop detection OAM of FIG. 6 or 7 is encapsulated, or not From the encapsulated type identifiers (603, 704) in FIG. 6 or FIG. 7, it can be determined that the loop detection OAM is encapsulated.

  The loop detection unit 206 that has received the relay frame compares the bridge identifier of the bridge device with the bridge identifier of the MAC frame included in the relay frame. When the format of the relay frame is the format illustrated in FIG. 8, the bridge identifier of the MAC frame included in the relay frame is 806, and when the format is the format illustrated in FIGS. 9 and 10, the MAC frame of FIG. 6 or FIG. Therefore, the bridge identifier is 604 in the case of FIG. 6 and 705 in the case of FIG.

  Then, the loop detection unit 206 compares the service VLAN identifier corresponding to the MAC frame with the service VLAN identifier of the MAC frame. When the format of the relay frame is the format illustrated in FIG. 8, the service VLAN identifier corresponding to the MAC frame is 816, the service VLAN identifier of the MAC frame is 807, and when the format is illustrated in FIGS. The service VLAN identifiers are 605 and 706 in the case of FIGS. 6 and 7, respectively, and the service VLAN identifiers corresponding to the MAC frames are 910 in FIG. 9 and 1011 and 1015 in FIG. .

  Furthermore, when the received relay frame has a customer VLAN identifier, the loop detection unit 206 compares the customer VLAN identifier corresponding to the MAC frame with the customer VLAN identifier of the MAC frame. When the format of the relay frame is the format illustrated in FIG. 8, the customer VLAN identifier corresponding to the MAC frame is 820, the customer VLAN identifier of the MAC frame is 808, and when the format is the format illustrated in FIGS. The customer VLAN identifier corresponding to the MAC frame shown in FIG. 7 is 707, and the customer VLAN identifier of the MAC frame is 715.

  If the received relay frame does not have a customer VLAN identifier, the loop detection unit 206 detects the occurrence of a loop when both the bridge identifier and the service VLAN identifier match, and discards the relay frame. If there is a VLAN identifier, when all of the bridge identifier, service VLAN identifier, and customer VLAN identifier match, the occurrence of a loop is detected and the relay frame is discarded.

  When the loop detection unit 206 detects the occurrence of a loop in this way, the transmission time given to the loop detection OAM of the MAC frame from the time information when the relay frame encapsulating the loop detection OAM is received. The difference obtained by subtracting the information is taken, and based on this difference, it is determined whether the relay frame has arrived within the predetermined time, and the time has been exceeded or the time has been traced back (the difference is negative). In the case of), the loop is not detected.

  If the transmission event identifier of the MAC frame encapsulating the loop detection OAM is present in the transmission event record information recorded in the storage device in advance, and if it is not recorded in the transmission event record information Does not detect loops.

  In the above comparison, if any of the bridge identifier, the service VLAN identifier, and the customer VLAN identifier does not match in the comparison, the loop detection unit 206 transfers the relay frame to the MAC relay unit 205 and encapsulates the customer data. Transfer processing similar to that of a relay frame including a frame is performed.

  In this way, when the loop detection unit 206 detects the occurrence of a loop, all the customer accommodation ports corresponding to the matched service VLAN identifiers may be blocked, or the MAC frame encapsulating the loop detection OAM is used. If the MAC address of the customer accommodation port that transmitted this is included, the customer accommodation port may be blocked. Further, when the occurrence of a loop is detected by a MAC frame encapsulating the loop detection OAM received from the customer accommodation port, the customer accommodation port may be blocked.

  Further, when the loop detection unit 206 detects the occurrence of a loop, the priority of frames transmitted from all customer accommodating ports corresponding to the matched service VLAN identifier may be reduced, or the bandwidth may be reduced. When the MAC address of the customer accommodating port that transmitted the MAC frame encapsulating the detected OAM is included, the priority of the frame transmitted from the customer accommodating port may be lowered or the band may be lowered. Further, when the occurrence of a loop is detected by a MAC frame encapsulating the loop detection OAM received from the customer accommodation port, the priority of the frame transmitted from the customer accommodation port may be reduced, or the bandwidth may be reduced.

  Further, when the loop detection unit 206 detects the occurrence of a loop, an alarm for the occurrence of the loop and the state of the occurrence of the loop may be displayed on the management device of the bridge device. The management device can be realized by a terminal device that inputs a command line to the bridge device, a management device based on SNMP, a management device based on CMIS, or a management device based on the web, and is not limited to these examples.

  Further, when the loop detection unit 206 detects the occurrence of the loop, the fact of the occurrence of the loop and the state of the occurrence of the loop may be notified to the customer at the customer site corresponding to the customer accommodating port corresponding to the matched service VLAN identifier. good. As a method of notifying the fact of the occurrence of the loop and the state of the occurrence of the loop, the fact of the occurrence of the loop and the state of the occurrence of the loop may be displayed directly on the customer's network management device. The fact of the occurrence of the loop and the state of the occurrence of the loop may be indirectly notified by telegram, telex, FAX, e-mail, mobile phone, PHS, etc., and is not limited to these examples.

  Note that the standards and recommendations referred to in this specification refer to the latest one at the time of filing, but the description of the specification can be traced back to devices conforming to previous versions of these standards and recommendations. It is obvious that it applies, and if these standards and recommendations are revised in the future, they will be applied to drafts of these standards and recommendations and devices based on methods similar to the contents of standards and recommendations. It is obvious.

  Next, a loop detection processing procedure executed by the bridge device having the configuration shown in FIG. 2 will be described with reference to FIGS.

  As shown in FIG. 11A, the bridge device of this example, when transmitting / receiving from a customer accommodating port (step S1101), according to whether or not transmission or reception of a MAC frame not including a customer VLAN identifier has been performed (step S1101). S1102), information related thereto is registered in the storage device (table 207) (steps S1103 and S1104). When a MAC frame including a customer VLAN identifier is transmitted or received, information including the value of the customer VLAN identifier is acquired and stored in the storage device (table 207) (step S1105).

  Then, as shown in FIG. 11B, when transmitting the MAC frame (step S1106), the contents recorded in the storage device (table 207) in the process of FIG. 11A are referred to (step S1107), the loop detection OAM identifier, its bridge A MAC frame in which a loop detection OAM including at least a service VLAN identifier and a transmission source port identifier corresponding to a bridge identifier of a device and a customer accommodating port is encapsulated, and a MAC frame including the customer VLAN identifier is transmitted from the customer accommodating port. If it has been transmitted or received (step S1108), a MAC frame tagged with the customer VLAN identifier is generated and transmitted from the customer accommodating port (step S1109), and M does not include the customer VLAN identifier. If you were sent or received from the customer accommodating port C frame (step S1108), it generates a MAC frame which has not been tagged with the customer VLAN identifier, and transmits from the customer receiving port (step S1110).

  FIG. 11C shows a processing procedure operation at the time of receiving a MAC frame. First, it is determined whether or not loop detection OAM information is encapsulated in the received MAC frame (step S1111).

  If it is encapsulated, the bridge identifier included in the MAC frame is compared with the bridge identifier of the own bridge device to determine a match (step S1112), and then the service VLAN identifier included in the MAC frame is The service VLAN identifier corresponding to the customer accommodation port (when receiving from the customer accommodation port) or the service VLAN identifier included in the relay frame (when receiving from the relay port) is compared to determine the match (step S1113). . Further, it is determined whether or not the customer VLAN identifier is included in the MAC frame (step S1114).

  When the customer VLAN identifier is included in the MAC frame, the customer VLAN identifier corresponding to the MAC frame is compared with the customer VLAN identifier included in the frame to determine a match (step S1115). Alternatively, if the customer VLAN identifier is not included in the MAC frame in the determination in step S1114, the difference between the reception time and the transmission time of the MAC frame is not negative and is within a predetermined specified time ( If transmission event information given to the MAC frame is recorded (step S1116), the occurrence of a loop is detected and the MAC frame is discarded (step S1118).

  At this time, if there is no customer VLAN identifier, a loop is generated only when both the bridge identifier and the service VLAN identifier match, that is, when both of the processes in steps S1112 and S1113 are Y. The MAC frame is detected and discarded, and if there is a customer VLAN identifier, only when the bridge identifier, the service VLAN identifier, and the customer VLAN identifier all match, that is, in steps S1112, S1113, and S1115. When all of the processes are Y, the occurrence of a loop is detected and the MAC frame is discarded (step S1118). In other cases, that is, when any of the processes in steps S1112, S1113, and S1115 is N, or when any of the processes in steps S1116 and S1117 is N, the MAC frame is transferred to the MAC relay unit. (Step S1119).

  If the occurrence of a loop is detected in the process of step S1118, the loop state is determined according to the procedure shown in detail in FIG. 11D (step S1120). That is, as shown in FIG. 11D, first, the source port identifier included in the MAC frame is compared with the identifier of the reception port that has received the MAC frame (step S1121). It is determined that the port is not included and the port is not included in the loop (step S1122).

  When the transmission source port identifier and the reception port identifier are different, the bridge is included in the loop, and it is detected that there is a loop passing through the customer site from the transmission source port to the reception port (step S1123). . Further, it is determined whether or not both identifiers belong to the customer accommodation port (step S1124). If both identifiers belong to the customer accommodation port, the customer including the service VLAN identifier and the presence / absence of the customer VLAN identifier is determined. The set of the VLAN identifier information and both identifiers is stored in the storage device as a table entry (step S1125), and the identifier of the port that received the MAC frame and the service VLAN identifier is the same as the customer VLAN identifier information. And a pair of table entries having the identifier of the transmission port included in the MAC frame as the identifier of the reception port is searched (step S1126).

  If the table entry exists, it is determined that the detected loop is a bidirectional loop passing through the transmission port and the reception port of the bridge (step S1127). If there is no table entry, the detected loop is the bridge. Is determined to be a one-way loop transferred from the source port to the receiving port of the bridge via the network (step S1128).

  Also, if both the identifiers do not belong to the customer accommodation port as a result of the determination process in step S1124, it is determined whether or not the reception port is a relay port (step S1129), and the reception port is a relay port. For example, a set of customer VLAN identifier information including the presence or absence of a service VLAN identifier and a customer VLAN identifier, a reception port identifier, and a relay source bridge identifier is stored in a storage device as a table entry (step S1130), and is stored in the relay source bridge. A table entry having the same service VLAN identifier and customer VLAN identifier information and having the bridge identifier of the own bridge as a relay source is searched (step S1131). If there is the table entry, the detected loop is the transmission port of the bridge. And the relay If there is no table entry, the detected loop is transmitted from the transmission source port of the bridge via the customer site to the relay source bridge. It is determined that the one-way loop is transferred in the direction (step S1133).

  The determination results in steps S1122, S1127, S1128, S1132, and S1133 are notified to, for example, the management device (step S1134).

  Although the present invention has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the scope of the invention. Of course there is. For example, it may be a processing procedure that omits the processing in step S1116 and step S1117 in FIG. 11C.

  As described above with reference to FIGS. 1 to 11D, in this example, as loop detection OAM information, the loop detection OAM identifier, the bridge identifier of the bridge device, the service VLAN identifier corresponding to the customer accommodation port, and Including at least information indicating whether or not the loop detection OAM frame has been tagged at the time of transmission (customer VLAN identifier in the case of tagging) and information for identifying the source port, and encapsulating such loop detection OAM When the received MAC frame is tagged with a customer VLAN identifier that matches the customer VLAN specification of the customer MAC frame or is not tagged, the source is sent. The loop status is judged by comparing the port information and the information of the receiving port. In addition, when the transmission source port and the reception port are different, a set of service VLAN identifier and customer VLAN identifier information and its port information is obtained. When the reception port is a relay port, service VLAN identifier, customer VLAN identifier information and transmission are provided. The source port and the relay source bridge identifier are stored in the storage device, and from the stored information, the service VLAN identifier and the customer VLAN identifier information are the same and the source port information and the reception port information are reversed. Is searched for a pair in which the relay source bridge identifier information is paired to determine whether it is a bidirectional loop or a unidirectional loop.

  Specifically, the bridge device (101, 105) of the present example has a relay frame between the customer accommodating port (201) for transmitting and receiving the MAC frame to and from the customer line (202) and the relay network (204). A relay port (203) for transmitting and receiving the MAC and a MAC relay unit (205) for performing a transfer process and a discard process for the MAC frame and the relay frame, and predetermining a single service VLAN identifier in association with the customer accommodation port The MAC frame received at the customer accommodation port is associated with the service VLAN identifier corresponding to the customer accommodation port, the relay frame includes at least the MAC frame and the service VLAN identifier corresponding to the MAC frame, and the MAC received at the customer accommodation port Customer data in the frame If it is a cell of, the MAC frame, also if it contains a MAC frame that encapsulates the customer data to the relay frame received by the relay port and forwards the relay frame to the MAC relay portion.

  In this MAC relay unit, for a MAC frame transferred from a customer accommodation port, the MAC frame is a service other than the customer accommodation port that received the MAC frame and associated with the MAC frame. A first relay process for transferring to one or a plurality of customer accommodation ports corresponding to the VLAN identifier, and a relay frame including the MAC frame and the service VLAN identifier associated with the MAC frame to the one or a plurality of relay ports Either one or both of the second relay processing or the MAC frame is discarded, and the relay frame received from the relay port is received for the relay frame transferred from the relay port. One or more than the relay port One or both of a third relay process for transferring to the port and a fourth relay process for transferring the MAC frame to one or a plurality of customer accommodating ports corresponding to the service VLAN identifier associated with the MAC frame This process is performed or the relay frame is discarded.

  And it is characterized by including the following 1st-7th procedures as a loop detection processing procedure by a bridge device.

  First procedure: Loop detection OAM information is encapsulated in a MAC frame received from a customer accommodation port, and the MAC frame payload includes a one-to-one or one-to-many correspondence with the service VLAN identifier in the customer accommodation port. The customer VLAN identifier included in the MAC header of the MAC frame is compared with the customer VLAN identifier included in the MAC payload of the MAC frame, and the MAC frame The bridge identifier and the bridge identifier of the own bridge device are compared, and the service VLAN identifier included in the MAC frame is compared with the service VLAN identifier corresponding to the customer accommodating port. Only when all of Besshi and customer VLAN identifiers match, the procedure detects the occurrence of a loop, and discards the MAC frame, the otherwise, forwarding the MAC frame to the MAC relay portion.

  Second procedure: When the loop detection OAM information is encapsulated in the MAC frame received from the customer accommodating port and the customer VLAN identifier is not included in the payload of the MAC frame, the MAC frame is included in the MAC frame. The bridge identifier and the bridge identifier of the own bridge device are compared, and the service VLAN identifier included in the MAC frame is compared with the service VLAN identifier corresponding to the customer accommodating port, and both the bridge identifier and the service VLAN identifier match. A procedure for detecting the occurrence of a loop only when discarding the MAC frame and discarding the MAC frame; otherwise, transferring the MAC frame to the MAC relay unit.

  Third procedure: When a relay frame received from a relay port includes a MAC frame in which loop detection OAM information is encapsulated and a payload of the MAC frame includes a customer VLAN identifier, A comparison between the customer VLAN identifier included in the MAC header of the MAC frame and the customer VLAN identifier included in the MAC payload of the MAC frame; a comparison between the bridge identifier included in the MAC frame and the bridge identifier of the own bridge device; and The service VLAN identifier included in the MAC frame is compared with the service VLAN identifier corresponding to the MAC frame, and the occurrence of a loop is detected only when all of the bridge identifier, the service VLAN identifier, and the customer VLAN identifier match. Te, and discards the MAC frame, and otherwise forwards the relay frame to the MAC relay portion procedures.

  Fourth procedure: When a MAC frame in which loop detection OAM information is encapsulated is included in the relay frame received from the relay port, and the customer VLAN identifier is not included in the payload of the MAC frame, the bridge A procedure for detecting the occurrence of a loop only when both the identifier and the service VLAN identifier match, discarding the MAC frame, and transferring the relay frame to the MAC relay unit in other cases.

  Fifth procedure: information on whether or not a MAC frame including a customer VLAN identifier or a MAC frame not including a customer VLAN identifier has been transmitted / received at a customer accommodating port, and a MAC frame including a customer VLAN identifier is transmitted and received. And the information including the value of the customer VLAN identifier in the case of being received and stored in the storage device.

  Sixth procedure: When a MAC frame encapsulating loop detection OAM is transmitted from a customer accommodation port, a MAC frame including a customer VLAN identifier is transmitted to and received from the storage device in the fifth procedure for the customer accommodation port. When information is stored, a procedure for generating a MAC frame including the customer VLAN identifier in the payload and tagged with the customer VLAN identifier and transmitting the MAC frame from the customer accommodating port.

  Seventh procedure: When a MAC frame encapsulating the loop detection OAM is transmitted from the customer accommodation port, a MAC frame not including the customer VLAN identifier is transmitted to and received from the storage device in the fifth procedure with respect to the customer accommodation port. If the stored information is stored, a procedure for generating a MAC frame that is not tagged with the customer VLAN identifier and transmitting it from the customer accommodating port.

  Further, in the bridge device of this example, the MAC frame encapsulating the loop detection OAM information including the service VLAN identifier previously associated with the bridge identifier of the own bridge device and the customer accommodating port regardless of whether or not the customer frame is transmitted / received. Is generated and transmitted from the customer accommodation port.

  In the bridge device of this example, the loop detection OAM information includes transmission port identifier information of the transmission source bridge. When a loop is detected based on the loop detection OAM information, the identifier of the port that received the MAC frame and the MAC If the identifiers of the transmission ports included in the frame are compared, and both identifiers are the same, it is determined that a loop that does not include the bridge is generated, and if both identifiers are different, a loop that includes the bridge is generated. It has the procedure to judge.

  In the bridge device of this example, the loop detection OAM information includes transmission port identifier information of the transmission source bridge. When a loop is detected based on the loop detection OAM information, the identifier of the port that received the MAC frame and the MAC The identifiers of the transmission ports included in the frame are compared, and if both identifiers are the same, it is determined that a loop that does not include the bridge is generated, and if both identifiers are different, the detected loop is It is determined that the loop is transferred from the transmission source port of the bridge to the reception port of the bridge via the network.

  In the bridge device of this example, the loop detection OAM information includes transmission port identifier information of the transmission source bridge. When a loop is detected based on the loop detection OAM information, the identifier of the port that received the MAC frame and the MAC When the identifiers of the transmission ports included in the frame are compared, and both identifiers are the same, it is determined that a loop not including the bridge has occurred, both identifiers are different, and both identifiers are customer accommodation ports. , The service VLAN identifier, the customer VLAN identifier information including the presence or absence of the customer VLAN identifier, and the combination of both identifiers are stored in the storage device as table entries, and the service VLAN identifier and the customer VLAN identifier information are stored in the storage device. Same for the identifier of the port that received the MAC frame A pair of table entries having a transmission port identifier included in the MAC frame as a reception port identifier is searched, and if there is the table entry, the detected loop is the transmission port of the bridge. If there is no table entry, the detected loop is transferred from the transmission source port of the bridge to the reception port of the bridge via the network. Judged as a one-way loop. If both identifiers are different and the reception port is a relay port, a set of customer VLAN identifier information including presence / absence of service VLAN identifier and customer VLAN identifier, reception port identifier, and relay source bridge identifier is entered in the table. Is stored in the storage device, and a table entry having the same service VLAN identifier and customer VLAN identifier information in the relay source bridge and having the bridge identifier of the own bridge as the relay source is searched, and if there is such a table entry, it is detected. It is determined that the loop is a bidirectional loop passing through the transmission port of the bridge and the port of the relay source bridge, and if there is no table entry, the detected loop sends the customer site from the transmission port of the bridge. Via the relay bridge It is determined that the one-way loop to be transferred to the direction.

  In the bridge device of this example, the loop detection OAM information includes the transmission time information of the MAC frame, and when the MAC frame is received and the loop is detected, the loop detection OAM information is included in the MAC frame from the reception time of the MAC frame. A difference obtained by subtracting the transmission time information is obtained, and if the obtained difference is a negative value or exceeds a predetermined time, it is not determined that a loop has been detected.

  Further, in the bridge device of this example, the loop detection OAM information represents that the MAC frame encapsulating the loop detection OAM information is transmitted. For example, the loop detection OAM information identifies the frame such as a sequence number, a time stamp, and a frame ID. When transmitting a MAC frame that includes transmission event identification information for encapsulating the loop detection OAM information and storing the event identification information in a storage device and receiving the MAC frame to detect a loop Whether or not the transmission event identification information included in the MAC frame is stored in the storage device is searched. If it is not stored, it is not determined that the loop has been detected.

  Further, the bridge device of this example periodically generates and transmits a MAC frame encapsulating the loop detection OAM information.

  Further, in the bridge device of this example, when the occurrence of a loop is detected, a part or all of the customer accommodation ports corresponding to the matched service VLAN identifier, or one of the customer accommodation ports corresponding to the matched service VLAN identifier. The priority or bandwidth of the MAC frame transmitted from a part or all of the part is reduced. Further, when the occurrence of a loop is detected, the loop occurrence warning information is notified to the management device of the own bridge device or to the customer at the customer site corresponding to the customer accommodating port associated with the matched service VLAN identifier. .

  In this way, in the loop detection technology of the bridge device of this example, in the technology for detecting the loop of the delivery route of the customer's frame in the virtual LAN service provided by the provider to the customer, a specific customer is installed inside the customer site. Even if there is a part that passes only the MAC frame belonging to the VLAN, the customer VLAN has been replaced, and the loop of the delivery route of the customer frame has passed this part, false detection The loop can be detected without doing so.

  As a result, in the virtual LAN service provided by the provider to the customer, it is possible to correctly detect the loop of the frame delivery route of the customer passing through the relay network and protect other customers. Furthermore, when the customer uses the same loop detection means, it is possible to avoid erroneous loop detection due to the MAC frame encapsulating the loop detection OAM generated by the customer.

It is a block diagram which shows the structural example of the network using the bridge | bridging apparatus which performs the process sequence of the loop detection method concerning this invention. It is a block diagram which shows the structural example of the bridge | bridging apparatus concerning this invention. It is explanatory drawing which shows the 1st structural example of the MAC frame transmitted / received between the customer accommodation port of the bridge | bridging apparatus in FIG. 1, and a customer site. It is explanatory drawing which shows the 2nd structural example of the MAC frame transmitted / received between the customer accommodation port of the bridge | bridging apparatus in FIG. 1, and a customer site. It is explanatory drawing which shows the 1st structural example of the MAC frame transmitted / received between the relay port of the bridge apparatus in FIG. 1, and a relay network. FIG. 2 is an explanatory diagram illustrating a first configuration example of a MAC frame encapsulating a loop detection OAM transmitted and received between the customer accommodation port of the bridge device and the customer site in FIG. 1. It is explanatory drawing which shows the 2nd structural example of the MAC frame which encapsulated the loop detection OAM transmitted / received between the customer accommodation port of the bridge | bridging apparatus in FIG. 1, and a customer site. FIG. 2 is an explanatory diagram illustrating a configuration example of a MAC frame encapsulating a loop detection OAM transmitted and received between the relay port of the bridge device in FIG. 1 and a relay network. It is explanatory drawing which shows the 2nd structural example of the MAC frame transmitted / received between the relay port of the bridge | bridging apparatus in FIG. 1, and a relay network. It is explanatory drawing which shows the 3rd structural example of the MAC frame transmitted / received between the relay port of the bridge apparatus in FIG. 1, and a relay network. It is a flowchart which shows the 1st process sequence example of the loop detection method by the bridge | bridging apparatus concerning this invention. It is a flowchart which shows the 2nd process sequence example of the loop detection method by the bridge | bridging apparatus concerning this invention. It is a flowchart which shows the 3rd process sequence example of the loop detection method by the bridge | bridging apparatus concerning this invention. It is a flowchart which shows the 4th example of a process sequence of the loop detection method by the bridge | bridging apparatus concerning this invention. It is explanatory drawing which shows the 1st misdetection example by the conventional loop detection technique. It is explanatory drawing which shows the 2nd example of a misdetection by the conventional loop detection technique. It is explanatory drawing which shows the 3rd example of a false detection by the conventional loop detection technique.

Explanation of symbols

  101, 105, 1201, 1204, 1301, 1401: Bridge device, 102, 106, 107, 203, 1202, 1205, 1304, 1404: Relay port, 103, 104, 108, 201, 1203, 1206, 1302, 1303 1402, 1403: Customer accommodation port, 109, 1207, 1305, 1405: Relay network, 110, 111, 112, 1208, 1209, 1306, 1307, 1406, 1407: Customer site, 202: Customer line, 204: Relay line, 205: MAC relay unit 206: Loop detection unit 207: Table 301, 401, 501, 601, 701, 801, 901, 1001: Destination MAC address 302, 402, 502, 602, 702, 802, 902 1002 Source MAC address, 303, 404, 407, 505, 508, 512, 603, 704, 712, 805, 813, 817, 904, 907, 1005, 1008, 1012: type identifier, 304, 405, 506: customer data 305, 406, 507, 609, 711, 812, 906, 1007: FCS, 403, 504, 703, 804: Customer VLAN tag, 408, 509, 513, 713, 814, 818, 908, 1009, 1013: Priority 409, 510, 514, 714, 815, 819, 909, 1010, 1014: CFI, 410, 515, 717, 715, 808, 820: customer VLAN identifier, 503, 803903, 1003, 1004: service VLAN tag, 511,605 806, 807, 816, 910, 1011 and 1015: Service VLAN identifier, 604, 705, 806: Bridge identifier, 606, 708, 809: Source port identifier, 607, 709, 810: Transmission time information, 608, 710, 811: Transmission event identifier, 905, 1006: MAC frame.

Claims (14)

Customer accommodating port that transmits / receives MAC frame to / from customer site, relay port that transmits / receives relay frame to / from relay network, and MAC relay means that performs transfer processing and discard processing of MAC frame and relay frame And
A single service VLAN identifier is predetermined in association with the customer accommodation port, and a service VLAN identifier corresponding to the customer accommodation port is associated with the MAC frame received at the customer accommodation port,
The relay frame includes at least a MAC frame and a service VLAN identifier corresponding to the MAC frame;
When customer data is encapsulated in the MAC frame received by the customer accommodating port, the MAC frame is transferred to the MAC relay means, and the MAC frame transferred by the MAC relay means is transferred to the MAC frame. A first relay process for transferring the frame to one or more customer accommodation ports corresponding to the service VLAN identifier associated with the MAC frame other than the customer accommodation port receiving the frame; the MAC frame and the MAC Either one or both of the second relay processing for transferring the relay frame including the service VLAN identifier associated with the frame to one or a plurality of relay ports, or discarding the MAC frame,
When the MAC frame encapsulating customer data is included in the relay frame received at the relay port, the relay frame is transferred to the MAC relay means, and the relay frame transferred by the MAC relay means A third relay process that transfers the relay frame to one or more relay ports other than the relay port that has received the relay frame, and one or more customer accommodation ports corresponding to the service VLAN identifier associated with the MAC frame A loop detection method by a bridge device that performs either one or both of the fourth relay processing for transferring the MAC frame to the network or discards the relay frame,
As a loop detection processing procedure executed by the bridge device,
In the MAC frame received from the customer accommodation port, the identification information (bridge identifier) of the bridge device that transmitted the MAC frame, the service VLAN identifier associated in advance with the customer accommodation port, and the bridge identifier and the service VLAN Loop detection OAM information including at least a loop detection OAM identifier indicating that the identifier is encapsulated in the MAC frame is encapsulated, and the service VLAN identifier in the customer accommodating port is included in the payload of the MAC frame. When the customer VLAN identifier associated with one-to-one or one-to-many is included, the customer VLAN identifier included in the MAC header of the MAC frame and the custom VLAN identifier included in the MAC payload of the MAC frame Comparison with the VLAN identifier, comparison between the bridge identifier included in the MAC frame and the bridge identifier of the own bridge device, and the service VLAN identifier included in the MAC frame and the service VLAN identifier corresponding to the customer accommodating port A comparison is made, and only when the bridge identifier, the service VLAN identifier, and the customer VLAN identifier all match, the occurrence of a loop is detected and the MAC frame is discarded. In other cases, the MAC frame is A first procedure for forwarding to the MAC relay means;
When the loop detection OAM information is encapsulated in the MAC frame received from the customer accommodating port and the customer VLAN identifier is not included in the payload of the MAC frame, the bridge identifier included in the MAC frame Is compared with the bridge identifier of the own bridge device, and the service VLAN identifier included in the MAC frame is compared with the service VLAN identifier corresponding to the customer accommodating port, and both the bridge identifier and the service VLAN identifier match. A second procedure for detecting the occurrence of a loop and discarding the MAC frame, and otherwise transferring the MAC frame to the MAC relay means only when
When the MAC frame in which the loop detection OAM information is encapsulated is included in the relay frame received from the relay port, and the customer VLAN identifier is included in the payload of the MAC frame, Comparison between the customer VLAN identifier included in the MAC header and the customer VLAN identifier included in the MAC payload of the MAC frame, comparison between the bridge identifier included in the MAC frame and the bridge identifier of the own bridge device, and the MAC frame The service VLAN identifier included in the MAC frame is compared with the service VLAN identifier corresponding to the MAC frame, and the occurrence of a loop is detected only when the bridge identifier matches the service VLAN identifier and the customer VLAN identifier. This The MAC frame is discarded, and in other cases, the third procedure for transferring the relay frame to the MAC relay means and the MAC frame in which the loop detection OAM information is encapsulated in the relay frame received from the relay port are included. If the customer VLAN identifier is not included in the payload of the MAC frame, the occurrence of the loop is detected only when both the bridge identifier and the service VLAN identifier match, and A fourth procedure for discarding the frame and otherwise forwarding the relay frame to the MAC relay means;
In addition, transmission / reception of the MAC frame including the customer VLAN identifier and information regarding whether or not the MAC frame including the customer VLAN identifier is transmitted / received at the customer accommodating port and the MAC frame including the customer VLAN identifier are performed. A fifth procedure for acquiring information including the value of the customer VLAN identifier in the case of being stored and storing it in the storage device;
When a MAC frame encapsulating the loop detection OAM is transmitted from a customer accommodation port, information regarding transmission / reception of the MAC frame including the customer VLAN identifier to the storage device in the fifth procedure is transmitted for the customer accommodation port. If so, a sixth procedure for generating a MAC frame including the customer VLAN identifier in the payload and tagged with the customer VLAN identifier and transmitting from the customer accommodating port;
When transmitting a MAC frame encapsulating the loop detection OAM from a customer accommodation port, information regarding transmission and reception of the MAC frame not including the customer VLAN identifier to the storage device in the fifth procedure for the customer accommodation port Is stored, a seventh procedure for generating a MAC frame that is not tagged with the customer VLAN identifier and transmitting the MAC frame from the customer accommodating port is provided. A loop detection method for a bridge device according to claim 1,
As a loop detection processing procedure executed by the bridge device,
Regardless of whether or not a customer frame is transmitted / received, a MAC frame is generated by encapsulating the loop detection OAM information including the service VLAN identifier previously associated with the bridge identifier of the own bridge device and the customer accommodation port, and the customer accommodation is performed. A method for detecting a loop of a bridge device, comprising a step of transmitting from a port. A loop detection method for a bridge device according to claim 1 or 2,
The loop detection OAM information includes identifier information of the transmission port of the source bridge,
When a loop is detected by receiving a MAC frame encapsulating the loop detection OAM information, the identifier of the port that received the MAC frame is compared with the identifier of the transmission port included in the MAC frame, and both identifiers are the same. A method of detecting a loop of a bridge device, comprising: a step of determining that a loop not including the bridge is generated when the identifier is different, and determining that a loop including the bridge is generated when both identifiers are different. A loop detection method for a bridge device according to claim 1 or 2,
The loop detection OAM information includes identifier information of the transmission port of the source bridge,
When a loop is detected by receiving a MAC frame encapsulating the loop detection OAM information, the identifier of the port that received the MAC frame is compared with the identifier of the transmission port included in the MAC frame, and both identifiers are the same. If it is determined that a loop that does not include the bridge has occurred, and the identifiers of both are different, the detected loop is transferred from the transmission source port of the bridge to the reception port of the bridge via the network. A method for detecting a loop of a bridge device, comprising a step of determining that the loop is a loop to be performed. A loop detection method for a bridge device according to claim 1 or 2,
The loop detection OAM information includes identifier information of the transmission port of the source bridge,
When a loop is detected by receiving a MAC frame encapsulating the loop detection OAM information, the identifier of the port that received the MAC frame is compared with the identifier of the transmission port included in the MAC frame, and both identifiers are the same. If it is, it is determined that a loop that does not include the bridge occurs,
If both identifiers are different and both identifiers belong to the customer accommodation port,
A set of service VLAN identifier and customer VLAN identifier information including presence / absence of customer VLAN identifier and both identifiers is stored in the storage device as a table entry, and
A table of sets in which the service VLAN identifier and customer VLAN identifier information are the same, have the identifier of the port that received the MAC frame as the identifier of the transmission port, and the identifier of the transmission port included in the MAC frame as the identifier of the reception port Search for entries
If the table entry is present, the detected loop is determined to be a bidirectional loop passing through the transmission port and the reception port of the bridge,
If the table entry does not exist, it is determined that the detected loop is a one-way loop transferred from the transmission source port of the bridge to the reception port direction of the bridge through the network.
If both identifiers are different and the receiving port is a relay port,
A set of customer VLAN identifier information including the presence or absence of a service VLAN identifier and a customer VLAN identifier, a receiving port identifier, and a bridge identifier of a relay source is stored in a storage device as a table entry;
Search the table entry having the same service VLAN identifier and customer VLAN identifier information in the relay source bridge and having the bridge identifier of the own bridge as the relay source,
If the table entry exists, it is determined that the detected loop is a bidirectional loop that passes through the transmission port of the bridge and the port of the relay bridge,
If there is no table entry, the detected loop includes a procedure for determining that the detected loop is a one-way loop transferred from the transmission source port of the bridge to the relay source bridge via the customer site. Device loop detection method. A method for detecting a loop of a bridge device according to any one of claims 1 to 5,
The loop detection OAM information includes transmission time information of the MAC frame,
When detecting the occurrence of a loop by receiving the MAC frame, obtain a difference obtained by subtracting the time of transmission time information included in the MAC frame from the reception time of the MAC frame, and whether the difference is a negative value, A loop detection method for a bridge device, characterized by having a procedure that does not determine that the occurrence of a loop is detected when a predetermined time is exceeded. A loop detection method for a bridge device according to any one of claims 1 to 6,
The loop detection OAM information includes transmission event identification information indicating that a MAC frame encapsulating the loop detection OAM information is transmitted, and the event identification when the MAC frame encapsulating the loop detection OAM information is transmitted. A procedure for storing information in a storage device;
When detecting the occurrence of a loop by receiving the MAC frame, it is searched whether or not the transmission event identification information included in the MAC frame is stored in the storage device. A method for detecting a loop of a bridge device, comprising: A loop detection method for a bridge device according to any one of claims 1 to 7,
As a loop detection processing procedure executed by the bridge device,
A loop detection method for a bridge device, comprising a procedure for periodically generating and transmitting a MAC frame encapsulating the loop detection OAM information. A loop detection method for a bridge device according to any one of claims 1 to 8,
As a loop detection processing procedure executed by the bridge device,
A method for detecting a loop of a bridge device, comprising: a step of blocking a part or all of a customer accommodation port corresponding to a matched service VLAN identifier when the occurrence of the loop is detected. A loop detection method for a bridge device according to any one of claims 1 to 9,
As a loop detection processing procedure executed by the bridge device,
A loop of a bridge device comprising a procedure for reducing the priority or bandwidth of a MAC frame transmitted from a part or all of a customer accommodating port corresponding to a matched service VLAN identifier when the occurrence of the loop is detected Detection method. It is a loop detection method of the bridge device according to any one of claims 1 to 10,
As a loop detection processing procedure executed by the bridge device,
A loop detection method for a bridge device, comprising: a step of outputting an alarm for the occurrence of the loop to a management device of the own bridge device when the occurrence of the loop is detected. A loop detection method for a bridge device according to any one of claims 1 to 11,
As a loop detection processing procedure executed by the bridge device,
A loop detection of a bridge device comprising a procedure for notifying a customer of a customer site corresponding to a customer accommodating port associated with a matching service VLAN identifier when the occurrence of the loop is detected Method.   The program for making a computer perform each procedure in the loop detection method of the bridge device in any one of Claims 1-12. A bridge device comprising: a customer accommodating port for transmitting / receiving a MAC frame to / from a customer site; a relay port for transmitting / receiving a relay frame to / from a relay network; There,
A storage device for storing the program according to claim 13;
13. A bridge device comprising: a central processing unit that executes each procedure in the loop detection method for a bridge device according to claim 1 using a program stored in the storage device.

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