JP5334912B2 - Network relay device, network system, and link trace method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make it possible to search for precise communication path information and identify a precise section where communication failure has occurred through the use of a link trace function even if the management endpoint of a source and that of a destination are located in networks with distinct communication standards. <P>SOLUTION: Switches 4 and 6 of a start end MEP are arranged in an IEEE802.1ad network 1. An edge switch 8, a core switch 10, and a core switch 12 of a terminal MEP are arranged in a IEEE802.1ah network 2. Upon the reception and encapsulation of an LTM frame 14 transmitted from the start end MEP (switch 4), the edge switch 8 references TYPE and OpCode in order to determine whether or not the LTM frame is an LTM (Link Trace Message). Similar to the edge switch 8, the core switches 10 and 12 also reference TYPE and OpCode of an LTM frame 18 to be encapsulated in order to determine whether or not it is an LTM. <P>COPYRIGHT: (C)2012,JPO&amp;INPIT

Description

  The present invention relates to a network relay device, a network system, and a link trace method that support a link trace function for operating, maintaining, and managing a network.

  Conventionally, OAM (Operations Administration and Maintenance) for network operation, maintenance and management defined by the international recommendation “Y.1731” of the ITU-T (International Telecommunication Union Telecommunication Standardization Sector) and the IEEE802.1ag communication standard. The LT (Link Trace) function is generally known.

  With regard to the link trace function of the OAM, an LTM (Link Trace Message) frame is generated at the management end point that is the starting point in the network, and information on the communication device through which this LTM frame has reached the destination management end point is retrieved. Prior art is known (see, for example, Patent Document 1). The international recommendation “Y.1731” and the IEEE802.1ag communication standard stipulate that a multicast address is set in a destination MAC address (DA MAC) of a MAC (Media Access Control) header portion of the LTM frame configuration. However, in the above prior art (Patent Document 1), when the LTM frame is generated at the management end point as the starting point, the target MAC address area included in the TLV (Type, Length, and Value) portion is referred to. Thus, the same address as the MAC address set there is set as the destination MAC address of the MAC header portion.

  According to the above prior art, even when a network relay device that does not implement OAM is interposed in the network, when the network relay device receives the LTM frame, the network relay device transmits the LTM frame to the unicast based on the destination MAC address. Can be transferred. Therefore, an LTM frame can be transferred to a destination management endpoint without broadcasting an LTM frame by a network relay device that does not have OAM installed. For network relay devices that implement OAM, when receiving an LTM frame, an LTR (Link Trace Reply) frame is generated based on the international recommendation “Y.1731” or the IEEE802.1ag communication standard, respectively. The LTR frame can be transmitted to the starting management endpoint. As a result, the management endpoint of the starting point receives the LTR frames in the order in which they are transmitted, thereby clarifying the substance of the communication path on the way from the MAC address of the network relay device through which the frame has passed before reaching the destination management endpoint. It is thought that it can be made.

JP 2008-167331 A

  However, in the above-mentioned prior art, the following problems occur when the network is arranged between the management endpoint of the starting point and the management endpoint of the destination via a network different from the network where the management endpoint of the starting point is arranged. Produce.

  For example, when the management endpoint of the starting point is arranged in a network configured in conformity with IEEE 802.1ad and the management endpoint of the destination is arranged in a network configured based on IEEE 802.1ah, If the management endpoint is located in another IEEE 802.1ad-based network connected via an IEEE 802.1ah based network, the edge in the IEEE 802.1ah compliant network When the switch receives the LTM frame, it encapsulates the frame. At this time, according to the technique of the prior art, header information (destination MAC address and VLAN TAG) in the LTM frame is reflected in the destination MAC address (DA B-MAC) in the MAC-in-MAC header.

  However, since the LTM frame itself is encapsulated in the IEEE 802.1ah network, each core switch in the network is not identified as an LTM frame, and is transferred as a normal user frame. LTR cannot be returned. Therefore, there is a problem that link trace cannot be executed from the management end point in IEEE802.1ad via IEEE802.1ah.

  In view of this, the present invention provides a link trace function between a management endpoint that is a starting point and a management endpoint that is a destination even if the management endpoint that is the starting point is routed through a different network. The issue is to provide a technology that can be used effectively.

  A first invention for achieving the above object is the second invention which is arranged in the first network conforming to the first communication standard and conforms to the second communication standard different from the first communication standard. A network relay device that, when connected to the network, receives a MAC frame transmitted from the second network and encapsulates the received MAC frame based on the first communication standard and transfers the MAC frame to the first network. is there.

  In particular, the network relay device according to the first aspect of the invention includes an encapsulation unit that generates an encapsulated frame in a format in which encapsulation header information based on the first communication standard is added to the received MAC frame at the time of the encapsulation. Of the header information included in the received MAC frame, identification means for identifying whether or not management identification information is set in the type area, and management identification information is set in the type area by the identification means If it is determined that the identification information indicating the link trace message defined in the link trace rule is set in the operation code area of the data area included in the received MAC frame Means.

  The first invention described above preferably operates as an edge switch disposed in this network in a network configured according to a communication standard such as IEEE802.1ah or EoE (Ethernet over Ethernet ("Ethernet" is a registered trademark)), for example. That is, when the network relay device according to the first aspect of the invention receives a MAC frame transferred from a network configured according to another communication standard such as IEEE802.1ad or IEEE802.1Q as an edge switch, Whether it is a normal user frame or a frame for management purposes including a link trace message based on a specific communication standard such as ITU-T international recommendation “Y.1731” or IEEE802.1ag. As a result, when the received MAC frame is a user frame, it is encapsulated and transferred, while when the received MAC frame is a management-purpose frame, it is used as an edge switch at the time of transfer. Processing based on communication standards such as “Y.1731” and IEEE802.1ag can be reliably performed.

  According to a second invention, in the configuration of the first invention, an FDB in which the C-MAC address and the B-MAC address are registered in association with each other, and identification information indicating a link trace message is set in the operation code area by the determination means. That the same value as the target MAC address set in the target MAC address area of the data area included in the received MAC frame is registered as the C-MAC address in the FDB. As a condition, a frame process for setting a B-MAC address registered in the FDB in association with this C-MAC address in a destination B-MAC address area included in the encapsulation header information and generating an encapsulated frame Linked to the operation code area When it is determined that identification information indicating a source message is set, an LTR frame including a link trace reply as a response to the link trace message in the data area is generated, and the LTR frame is transmitted to the second network. Response processing means.

  According to the second invention, in addition to the first invention, when it is determined that the link trace message is included in the MAC frame received as the edge switch, the same value as the target MAC address is in the FDB. An encapsulated frame can be generated only when it is registered as a C-MAC address. Originally in the IEEE 802.1ah communication standard, the edge switch searches whether the destination MAC address set in the received MAC frame is registered in the FDB, and if the above destination MAC address is registered in the FDB, this edge switch A B-MAC address registered in the FDB in association with the destination MAC address is set in the destination B-MAC address area when the MAC frame is encapsulated. On the other hand, in the second invention, the edge switch searches whether the target MAC address set in the received MAC frame is registered in the FDB, and if the target MAC address is registered in the FDB, the edge switch The B-MAC address registered in the FDB in association with the target MAC address is set in the destination B-MAC address area when encapsulating. As a result, even if the MAC frame is encapsulated, it can be reliably transferred within the first network, and the link trace message can be transferred to the destination management endpoint.

  As a third aspect of the invention, the frame processing means has the target MAC address registered in the FDB even when the judgment means determines that identification information indicating a link trace message is set in the operation code area. If not, the received MAC frame is discarded without generating an encapsulated frame.

  According to the third invention, in addition to the action of the second invention, the process is executed only when the target MAC address is registered in the FDB, thereby preventing the frame from being broadcast. doing. In the IEEE802.1ah communication standard, if the same value as the destination MAC address is not registered as the C-MAC address in the FDB as in the case of the user frame, this MAC frame is broadcast, and every network relay that receives this MAC frame The link trace reply is further transmitted from the device, and the link trace itself does not function. However, in the third invention, when the target MAC address is not registered in the FDB, the problem caused by the broadcast is solved by discarding the MAC frame, and the link from the management end point which is the starting point to which switch It is possible to accurately grasp whether the trace is executed effectively.

  According to a fourth aspect of the present invention, the MAC transmitted from the second network conforming to the second communication standard different from the first communication standard is arranged in the first network conforming to the first communication standard. The network relay device transfers an encapsulated frame in a format in which a frame is encapsulated by adding encapsulation header information based on a first communication standard within the first network. In particular, the network relay device according to the fourth invention is an identification for identifying whether or not management identification information is set in the type area of the header information included in the MAC frame encapsulated as an encapsulated frame. When the identification information for management is set in the type area by the means and the identification means, it is defined by the link trace rule in the operation code area of the data area included in the encapsulated MAC frame Determination means for determining whether or not identification information indicating a link trace message is set.

  According to the fourth invention, for example, in a network configured by a communication standard such as IEEE802.1ah or EoE, it effectively functions as a core switch arranged in this network. That is, when the core switch receives an encapsulated frame (for example, a MAC-in-MAC frame or an EoE frame) transferred from the edge switch, whether the frame is a user frame or the ITU-T international recommendation “Y .1731 "or IEEE802.1ag or the like, it is possible to accurately determine whether the frame is a management purpose frame including a link trace message. As a result, processing based on communication standards such as ITU-T international recommendation “Y.1731” and IEEE802.1ag can also be reliably performed in the core switch.

  5th invention WHEREIN: The header information contained in the encapsulated MAC frame, when it determines with the identification means which shows a link trace message being set to the operation code area | region by the determination means in the structure of 4th invention A frame processing means for performing a process of transferring the encapsulated frame on condition that the same value as the MAC address set in the destination B-MAC address area is registered as the B-MAC address in the FDB; When the determination means determines that the identification information indicating the link trace message is set in the operation code area, the data area includes a link trace reply as a response to the link trace message included in the encapsulated frame, and Source B-MA of encapsulated frame Further comprising a response processing means for generating an encapsulated LTR frame address as a destination B-MAC address and transmits the encapsulated LTR frames within the first network.

  According to the fifth invention, in addition to the operation of the fourth invention, when it is determined that the link trace message is included in the encapsulated frame received by the core switch, and the destination B-MAC The encapsulated frame can be relayed only when the same value as the MAC address set in is registered as the B-MAC address in the FDB. In addition, it is possible to transmit a frame including a link trace reply to the management end point of the starting point after reliably determining that it is a link trace message. As a result, it is possible to accurately collect the route information on which the frame is transferred at the management end point of the starting point.

  A sixth invention is the case where, in the configuration of the fifth invention, the determination means determines that the identification information indicating the link trace message is set in the operation code area, and the encapsulation included in the encapsulated frame In the header information, when it is confirmed that the MAC address set in the destination B-MAC address area is the same as its own unique MAC address, it further includes a frame processing means for terminating the transfer of the encapsulated frame.

  According to the sixth aspect of the invention, in addition to the action of the fifth aspect, when the core switch is designated as the destination management end point, the link trace reply is reliably started after accurately determining that fact. It is possible to transmit to the management end point. For example, in the communication standard of IEEE802.1ah, in order to prevent a frame from looping in the network, the received encapsulated frame is a user frame, and its own MAC is set in the destination B-MAC address area of the encapsulated frame. When an address is set, it is stipulated that this encapsulated frame be discarded. In addition, according to the sixth aspect of the invention, it is possible to reliably identify the link trace message without discarding the frame even if the MAC address of the destination is the own MAC address while reliably identifying whether or not it is a link trace message. A trace reply can be generated.

  In a seventh aspect based on the fifth aspect and the sixth aspect, the response processing means includes a source B-MAC address area and a source C-of the encapsulation header information included in the encapsulated LTR frame. Set a unique MAC address for each of the MAC address areas, set the source B-MAC address of the encapsulated frame in the destination B-MAC address area, and encapsulate in the destination C-MAC address area The MAC address set in the original MAC address area included in the frame is set.

  According to the seventh invention, in addition to the operations of the fifth invention and the sixth invention, in the process of generating the link trace reply, the encapsulated frame of the header information in the destination C-MAC address area is included. The MAC address of the starting management endpoint set in the original MAC address area can be set, and the MAC address of the edge switch can be set for the destination B-MAC address area. For this reason, the encapsulated LTR frame generated by the core switch is transferred to the edge switch based on the MAC address of the edge switch set in the destination B-MAC address area in the IEEE 802.1ah network, for example. When the frame decapsulated by the edge switch is transferred within the IEEE 802.1ad network, the frame is transferred based on the MAC address of the management endpoint at the start point set in the destination C-MAC address area. Is called. As a result, even if the starting management endpoint is arranged in a network based on a communication standard different from the destination management endpoint, the link trace reply can be sent reliably.

  An eighth invention is a network in which at least one second network compliant with a second communication standard different from the first communication standard is connected to at least one first network compliant with the first communication standard. In the system, when the first network receives the MAC frame transmitted from the second network, the first network forms an encapsulated frame in which the received MAC frame is encapsulated based on the first communication standard. An edge switch that forwards to the network, and a core switch that relays the encapsulated frame forwarded by the edge switch within the first network. The second network includes a plurality of switches that relay MAC frames, a plurality of switches Management identification in the type area included in the MAC frame header information of the switch Information and set the identification information indicating the link trace message specified in the link trace specification in the operation code area of the data area, and target any core switch located in the first network Either an LTM frame set to the MAC address, or a plurality of second networks connected to the first network and arranged in another second network connected via the first network The edge switch and the core switch included in the first network include the management end point that transmits the LTM frame in which the switch is set as the target MAC address, and the type of header information included in the MAC frame transmitted from the management end point Identifies whether management identification information is set in the area Identification information indicating that a link trace message is set in the operation code area of the data area included in the received MAC frame. Determination means for determining whether or not it has been performed.

  According to the eighth aspect of the invention, when the link trace is executed, the starting management endpoint and the destination management endpoint are arranged in networks based on different communication standards of IEEE 802.1ad and 802.1ah, respectively. In addition, it is possible to reliably determine that the edge switch that has received the link trace message is the link trace message within the network (IEEE 802.1ah) in which the destination management endpoint is located.

  According to a ninth aspect, in the eighth aspect, when the determination means determines that identification information indicating a link trace message is set in the operation code area, the data area included in the MAC frame transmitted from the management end point B, which is registered in the FDB in association with this C-MAC address on condition that the same value as the target MAC address set in the target MAC address area is registered as the C-MAC address in the FDB. -The MAC address is set in the destination B-MAC address area included in the encapsulation header information and the process of generating the encapsulated frame is performed, while the same value as the target MAC address is registered as the C-MAC address in the FDB. If not, receive without generating encapsulated frame If the identification information indicating the link trace message is set in the operation code area by the frame processing means for discarding the MAC frame and the determination means, the link trace reply as a response to the link trace message is included in the data area. Response processing means for generating an LTR frame and transmitting the LTR frame to the second network, and the core switch included in the first network sends a link trace message to the operation code area by the judging means. When it is determined that the identification information indicating is set, the MAC address set in the destination B-MAC address area of the encapsulation header information included in the encapsulated frame is the same as its own unique MAC address Make sure In this case, the frame processing means for terminating the transfer of the encapsulated frame and the link trace message included in the encapsulated frame when the determination means determines that the identification information indicating the link trace message is set in the operation code area. A link trace reply as a response to the data field, and generating an encapsulated LTR frame with the source B-MAC address of the encapsulated frame as the destination B-MAC address, and generating the encapsulated LTR frame in the first network Response processing means for transmitting within the network.

  According to the ninth aspect of the invention, the edge switch that has received the link trace message in the network (IEEE802.1ah) in which the destination management endpoint is located reliably transmits the link trace message as an encapsulated frame to the destination management endpoint. While transferring, a link trace reply can be returned to the management end point of the starting point. That is, the B-MAC address set in the destination B-MAC address area in association with the target MAC address is registered in the FDB, and the target MAC address set in the MAC frame received by the edge switch is registered in the FDB. If the MAC frame is encapsulated, the MAC frame is correctly transferred within the first network and reliably transferred to the destination management endpoint. Further, when the target MAC address of the received MAC frame is not registered in the FDB, the edge switch can reliably prevent the above-described malfunction due to the broadcast by discarding the MAC frame.

  Furthermore, the core switch can return a link trace reply to each of the encapsulated link trace messages while relaying the encapsulated link trace message to the destination management endpoint. The core switch designated as the destination management endpoint can return a link trace reply after accurately recognizing that it is a link trace message addressed to itself. As a result, the link trace function can be easily realized even in a network system over a network using a plurality of different communication standards.

  In a tenth aspect of the present invention, in a state where at least one second network conforming to the second communication standard different from the first communication standard is connected to the first network conforming to the first communication standard, Either one of the core switches arranged in the first network is set as the destination management endpoint with respect to the management endpoint of the starting point arranged in the second network, or the first network is changed from the management endpoint to the first network. A MAC frame including a link trace message in the data area is transmitted from the management endpoint of the start point to the management endpoint of the destination as one of the switches arranged in the second network connected via the network. A link trace method for executing a link trace comprises the following steps.

[Identification process]
In this process, when the MAC frame transmitted from the management endpoint of the starting point is received by the edge switch arranged in the first network, the identification information for management is included in the type area in the header information included in the MAC frame. Identifies whether it is set.

[Judgment process]
In this process, when it is identified in the previous identification process that management identification information is set in the type area, among the data areas included in the MAC frame, identification information indicating a link trace message is displayed in the operation code area. Determine whether it is set.

[Frame processing process]
In this step, when it is determined in the previous determination step that identification information indicating a link trace message is set in the operation code area, a process of generating an encapsulated frame in a format in which the encapsulation header information is added to the MAC frame As a condition that the same value as the target MAC address set in the target MAC address area of the data area included in the MAC frame is registered as the C-MAC address in the FDB, the FDB is associated with the C-MAC address. Is set in the destination B-MAC address area included in the encapsulation header information, and the encapsulated frame is transmitted within the first network.

[Response processing process]
In this step, if it is determined in the previous determination step that identification information indicating a link trace message is set in the operation code area, an LTR frame including a link trace reply as a response to the link trace message in the data area is included. Generate and transmit this LTR frame to the second network.

  According to the tenth aspect of the present invention, when link trace is executed, the starting management endpoint and the destination management endpoint are arranged in networks based on different communication standards of IEEE 802.1ad and 802.1ah, respectively. In the network where the management end point of the destination is arranged (IEEE802.1ah), the edge switch that has received the link trace message correctly determines that it is a link trace message and executes encapsulation of the MAC frame. be able to. This makes it possible to prepare for an operation based on the link trace function in the first network when relaying the encapsulated frame thereafter.

  The eleventh invention further includes the following steps executed by the core switch in the tenth invention.

[Identification process]
In this process, when the encapsulated frame transmitted from the edge switch is received by the core switch arranged in the first network, the type area of the header information included in the MAC frame encapsulated as the encapsulated frame is displayed. Whether or not management identification information is set is identified by the core switch.

[Judgment process]
In this process, if it is identified in the identification process at the core switch that management identification information is set in the type area, a link trace message is sent to the operation code area of the data area included in the encapsulated MAC frame. It is determined by the core switch whether or not the identification information to be indicated is set.

[Response processing process]
In this process, when it is determined in the determination process at the core switch that identification information indicating the link trace message is set in the operation code area, a link trace reply is sent as a response to the link trace message included in the encapsulated frame. An encapsulated LTR frame included in the data area is generated, and the encapsulated LTR frame is transmitted in the first network by the core switch.

  According to the eleventh aspect, the core switch that has received the link trace message in the first network can respond to the link trace reply to the starting management endpoint while reliably processing the link trace message. As a result, the starting management endpoint can accurately grasp whether the frame has been normally transferred to the destination management endpoint based on the link trace reply received from each.

  The twelfth invention further includes the following steps executed by the core switch in the configuration of the eleventh invention.

[Frame processing process]
In this process, when it is determined in the determination process at the core switch that identification information indicating a link trace message is set in the operation code area, of the encapsulated header information included in the encapsulated frame, When it is confirmed that the MAC address set in the destination B-MAC address area is the same as its own unique MAC address, the transfer of the encapsulated frame is terminated.

  According to the twelfth aspect, in the core switch designated as the destination management end point, it is possible to accurately recognize that the link trace message is addressed to itself and return the link trace reply. As a result, the link trace can be accurately executed from the starting management endpoint to the destination management endpoint.

  In a thirteenth aspect based on the eleventh and twelfth aspects, in each response processing step, the source B-MAC address area and the source C-MAC address area in the encapsulated header information included in the encapsulated LTR frame A unique MAC address is set for each of the packets, the source B-MAC address of the encapsulated frame is set in the destination B-MAC address area, and the encapsulated frame is included in the destination C-MAC address area The MAC address set in the original MAC address area to be set is set.

  According to the thirteenth invention, in addition to the effects of the eleventh invention and the twelfth invention, the link trace reply is generated in each core switch and the encapsulated LTR frame is transmitted. The MAC address of the starting management end point set in the original MAC address area of the encapsulated frame can be set for the C-MAC address area, and the MAC address of the edge switch can be set for the destination B-MAC address area. For this reason, the encapsulated LTR frame generated by the core switch is transferred to the edge switch based on the MAC address of the edge switch set in the destination B-MAC address area in the IEEE 802.1ah network, for example. When the frame decapsulated by the edge switch is transferred within the IEEE 802.1ad network, the frame is transferred based on the MAC address of the management endpoint at the start point set in the destination C-MAC address area. Is called. As a result, even if the starting management endpoint is arranged in a network based on a communication standard different from the destination management endpoint, the link trace reply can be sent reliably.

  As described above, according to the present invention, even if the network is arranged between the management endpoint of the starting point and the management endpoint of the destination via a network different from the network where the management endpoint serving as the starting point is arranged. The communication path between frames can be searched accurately, and the link trace function can be used effectively.

1 is a diagram schematically showing a configuration of a network system. FIG. 2 is a schematic diagram showing a comparison between an IEEE 802.1ad frame format and an IEEE 802.1ah frame format. It is a block diagram which shows roughly the functional structure of the network relay apparatus arrange | positioned in an 802.1ah network. It is a flowchart which shows the outline | summary of the link trace method applicable to a network system. It is a figure which shows the format of an LTM frame schematically. It is a figure which shows schematically the format of an encapsulated LTM frame. It is a figure which shows the format of a LTR frame roughly. It is a figure which shows schematically the format of an encapsulated LTR frame. It is a flowchart which shows the example of a procedure of the LTM determination process performed by the LT frame determination part. It is a flowchart which shows the outline | summary of the encapsulation LTM frame generation process performed in the LT frame process part of an edge switch. It is a table | surface which shows FDB of an edge switch. It is a flowchart which shows the encapsulation LTR frame production | generation process performed in the LT frame process part of the core switch used as termination | terminus MEP.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The embodiments described below are, for example, (1) a form as individual network relay devices (edge switches or core switches) arranged in a network, (2) a form as a network system composed of a plurality of networks, and (3) A form as a link trace method executed using a plurality of network relay devices and a network system is included.

[Overview of network system]
FIG. 1 is a diagram schematically showing a configuration of a network system cited as the above-described form (2). This network system is assumed to be used as a wide area network, for example. The network system for wide area can be divided into, for example, three (or four or more) networks 1, 2, and 3 depending on the difference in the communication standard to be compliant. In view of the arrangement relationship shown in FIG. 1, the pair of adjacent networks 1 and 2 and the pair of networks 2 and 3 are physically connected.

  The network system realizes higher reliability as a whole and provides a large-scale (wide area) communication network. Therefore, a frame encapsulation technique called “MAC-in-MAC” is included in a part of the network 2. The communication standard corresponding to is applied. The MAC-in-MAC encapsulation technology is standardized by, for example, IEEE802.1ah, which is one of communication standards, and for this reason, individual network relay devices (reference numerals 8, 10, 12, 13) constituting the network 2 are used. ) Conforms to the IEEE 802.1ah communication standard.

  The other networks 1 and 3 comply with IEEE802.1ad, which is another communication standard. For this reason, each of the individual network relay devices (reference numerals 4, 6, 15, and 17) constituting each of the networks 1 and 3 conforms to the IEEE 802.1ad communication standard.

  The PBB (Provider Backbone Bridging) network realized by the above IEEE802.1ah can be used as a backbone network that bundles other PB (Provider Bridging) networks conforming to the IEEE802.1ad communication standard. For this reason, in the network system of the form shown in FIG. 1, the network 2 conforming to IEEE 802.1ah is a backbone (PBB) network, and this network 2 plays a role of bundling the adjacent networks 1 and 3 as a PB network. Can do. Hereinafter, the network 2 conforming to the IEEE 802.1ah standard is referred to as “802.1ah network 2”, and the networks 1 and 3 conforming to the IEEE 802.1ad standard are also referred to as “802.1ad network 1, 3”, respectively. To do.

  In each of the networks 1, 2, 3 (802.1ad network 1, 3, 802.1ah network 2), a plurality of network relay devices are arranged as described above. FIG. It is shown as a relay device (4-17). The plurality of network relay devices are connected to each other in the respective networks 1, 2, and 3. In FIG. 1, for the sake of convenience, only a part of the network relay devices related to the description of the present embodiment is shown, and a number of other network relay devices are omitted in order to prevent the drawing from being complicated. Yes.

[802.1ad network]
For example, a switch 4 and a switch 6 are disposed in the 802.1ad network 1. Similarly, for example, a switch 17 and a switch 15 are arranged in the other 802.1ad network 3. Among them, the switches 6 and 15 relay the frame transferred from the 802.1ah network 2 in each of the 802.1ad networks 1 and 3 and switch the frame transferred in each of the 802.1ad networks 1 and 3 to 802. Or relay to 1ah network 2. The switches 4 and 17 relay the frames transferred from the switches 6 and 15 in the 802.1ad networks 1 and 3, respectively.

[802.1ah network]
In the 802.1ah network 2, for example, edge switches 8 and 13 and core switches 10 and 12 are arranged. In the 802.1ah network 2, the edge switches 8 and 15 encapsulate or decapsulate the frames in the MAC-in-MAC method when relaying frames between the other 802.1ad networks 1 and 3. The core switches 10 and 12 relay the encapsulated frames transferred from the edge switches 8 and 13, respectively, in the 802.1ah network 2.

[Difference in frame format depending on communication standard]
FIG. 2 is a schematic diagram showing a comparison between the IEEE 802.1ad frame format and the IEEE 802.1ah frame format. Note that these frame formats are well known and do not require special explanation, and therefore, reference numerals are not attached to the respective parts in the frame in FIG.

[IEEE802.1ad frame format]
In FIG. 2, (A): MAC frame in a format conforming to IEEE802.1ad is an area such as DA MAC (destination MAC address), SA MAC (source MAC address), VLAN TAG, TYPE (type), etc. in the header part. It has. The MAC frame also includes a DATA (data) area and an FCS (Frame Check Sequence) area following the header portion. In FIG. 2, the values (6B, 4B, etc.) in parentheses at each part in the frame are the byte length of each area.

[Frame format of IEEE802.1ah]
In FIG. 2, (B): A frame in a format conforming to IEEE802.1ah is a MAC-in-MAC frame as described above. In other words, for the MAC-in-MAC frame, DA B-MAC (destination B-MAC address), SA B-MAC (source B-MAC address), B-TAG, and I-TAG are added to the IEEE 802.1ad frame format. It is a thing. Note that there is a MAC-in-MAC frame that has only the I-TAG without the B-TAG.

[Overview of encapsulation technology]
In the wide area network system shown in FIG. 1, for example, when a MAC frame is transmitted from one 802.1ad network 1 to the other 802.1ad network 3, the frame is encapsulated. For example, a case is assumed where a MAC frame is transmitted from the switch 4 in one 802.1ad network 1 as a transmission source and the switch 17 in the other 802.1ad network 3 as a destination.

  In the above case, the MAC frame is transferred from the switch 4 to the switch 6 in the 802.1ad network 1 and further transmitted from the switch 6 to the 802.1ah network 2. The edge switch 8 of the 802.1ah network 2 encapsulates the received MAC frame, and transfers it as the MAC-in-MAC frame in the 802.1ah network 2.

  In the 802.1ah network 2, relaying (transfer) is performed based on DA B-MAC added in the edge switch 8 (see (B) in FIG. 2). As a result, the MAC-in-MAC frame is sequentially relayed by the core switches 10 and 12 and reaches the other edge switch 13. When the edge switch 13 receives the MAC-in-MAC frame, it decapsulates it. Thereby, the MAC-in-MAC frame is restored to a format as a MAC frame.

  Then, the MAC frame after being decapsulated by the edge switch 13 is received by the switch 15 of the other 802.1ad network 3 and is transmitted to the destination switch 17 as a MAC frame in the 802.1ad network 3.

  As described above, when a normal MAC frame (so-called user frame) is transferred in a network system, the encapsulation technique based on IEEE 802.1ah is particularly useful.

[Assumed cases]
On the other hand, in the above case, the following phenomenon is considered to occur when the transferred frame is intended for network management.

  For example, a frame for the purpose of network management includes an LTM frame used for a link trace test. As described above, an LTM frame (without reference numerals in the figure) is sent from a management end point (hereinafter referred to as “maintenance end point”) as a start point to a destination management end point (hereinafter referred to as “end MEP”). (Abbreviated). In this case, each relay device that relays an LTM frame on the way based on a standard requirement concerning the link trace function needs to generate an LTR frame and transmit it to the transmission source of the LTM frame.

  In the network system shown in FIG. 1, for example, the switch 4 in one 802.1ad network 1 is designated as a start MEP, and the core switch 12 in the 802.1ah network 2 is designated as a termination MEP. Under this specified condition, it is assumed that a link trace test is performed on a communication path from the switch 4 at the start MEP to the core switch 12 at the end MEP.

  The switch 4 serving as the start MEP transmits an LTM frame using the destination MAC address as the multicast address, the TARGET MAC (target MAC address) as the MAC address of the core switch 12 serving as the end MEP, and the SA MAC as its own MAC address. To do. At this time, in the TYPE area of the LTM frame, for example, an OAM identification value defined by the international recommendation “Y.1731” or the IEEE 802.1ag standard is stored.

  The LTM frame is transmitted from the switch 4 to the switch 6 in the 802.1ad network 1, and the switch 6 that receives the LTM frame transfers the LTM frame to the edge switch 8 of the 802.1ah network 2. The edge switch 8 that has received the LTM frame encapsulates the LTM frame in the above-described MAC-in-MAC format, and relays the encapsulated LTM frame into the 802.1ah network 2. At this time, since the destination MAC address of the LTM frame is a multicast address, the edge switch 8 stores the multicast value in the DA B-MAC at the time of encapsulation.

  The LTM frame encapsulated as described above is transferred from the edge switch 8 to the core switch 10 and the core switch 12. At this time, the core switch 12 that has received the encapsulated LTM frame refers to the DA B-MAC and relays or discards the frame if the value is broadcast. On the other hand, when it is confirmed that the value of DA B-MAC is its own MAC address, the core switch 12 discards the frame. The discarding of the frame in this case is based on a request of IEEE 802.1ah that the core switch 12 complies with, and is naturally a process (as per the standard).

  However, the above processing is one obstacle for the link trace test performed across the 802.1ad network 1 and the 802.1ah network 2. That is, when viewed from the core switch 10 and the core switch 12, the start end MEP (switch 4) exists in the 802.1ad network 1 compliant with another communication standard. The core switch 10 and the core switch 12 cannot be recognized as a frame. Therefore, in this case, it is understood that the link trace does not function as desired even when the switch 4 serving as the start MEP transmits the LTM frame.

  In order to make link trace function as desired in the network system shown in FIG. 1 while paying attention to the above phenomenon, the inventors of the present invention use network relay devices (edge switches 8, 13 and core switches in the 802.1ah network 2). (10, 12, etc.) was found to be effective to use the following configuration.

[Network relay device configuration]
FIG. 3 is a block diagram schematically showing a functional configuration of a network relay device arranged in the 802.1ah network 2.

  First, network relay devices (edge switches 8 and 13 and core switches 10 and 12) have, for example, a frame transfer control unit 46, an FDB (Forwarding DataBase) 52, and a software-controlled CPU (as a configuration required for general frame relay). Central Processing Unit) 50 and the like. The frame transfer control unit 46 is provided with a transmission / reception unit 46a, and the transmission / reception unit 46a has a plurality of ports (reference numerals 460a, 460b,...) To which network cables are individually connected. The FDB 52 is formed using a physical memory area such as a RAM.

  In addition, the network relay device of the present embodiment has a configuration as the LT frame relay control unit 48. The LT frame relay control unit 48 incorporates a standard frame relay function execution unit 48c based on, for example, the IEEE 802.1ah standard. That is, the frame relay function execution unit 48c is a part having a normal function for executing the MAC frame encapsulation process and the MAC-in-MAC frame transfer process based on the IEEE 802.1ah standard.

  In addition, the LT frame relay control unit 48 incorporates an LT frame determination unit 48a and an LT frame processing unit 48b as functional elements unique to the present embodiment. Among these, the LT frame determination unit 48a determines whether or not the received frame includes an LTM corresponding to the link trace function of Ethernet (registered trademark) OAM (hereinafter simply referred to as “OAM” as appropriate). It is. The LT frame processing unit 48b is a part that performs processing for rewriting the content of the frame in accordance with the content of the frame corresponding to the link trace function of the OAM and converting it to another frame content. Note that functional elements such as the LT frame processing unit 48b and the LT frame processing unit 48b can be realized by an integrated circuit such as an ASIC (Application Specific Integrated Circuit) or an FPGA (Field Programmable Gate Array).

[Internal operation by relay device]
The transmission / reception unit 46a transfers all frames received at each port to the LT frame determination unit 48a. At this time, in the LT frame control unit 48, frame encapsulation processing is performed by the frame relay function execution unit 48c (in the case of the edge switches 8 and 13), and the MAC-in-MAC frame is generated.

[LT frame determination]
The LT frame determination unit 48a refers to the content of the transmitted frame and determines whether or not the content includes an LTM (link trace message) corresponding to the link trace function of OAM. Specifically, the LT frame determination unit 48a refers to the contents of the frame from the top, confirms “I-TAG” and confirms that the frame is a MAC-in-MAC frame, and then selects “TYPE”. Reference is made to identify whether or not identification information (OAM) indicating IEEE 802.1ag is described therein.

  At this time, if “TYPE” indicates OAM, the LT frame determination unit 48a next refers to the OAM HEADER (OAM header) in “DATA”, in which the identification value of “OpCode” indicates LTM. Check if it is. If the identification value indicates LTM, the LT frame determination unit 48a determines that this frame is a “(OAM) LTM frame”. In this case, the LT frame determination unit 48a transfers the “LTM frame” to the LT frame processing unit 48b. If the core switches 10 and 12 determine that the frame is not an “LTM frame”, the LT frame determination unit 48 a returns the frame to the frame transfer control unit 46. When the edge switches 8 and 13 determine that the frame is not an “LTM frame”, the LT frame determination unit 48a transfers the frame to the frame relay function execution unit 48c. The frame relay function execution unit 48 c executes a process of encapsulating the above frame based on the IEEE 802.1ah standard, and transfers the encapsulated frame to the frame transfer processing unit 46.

[LT frame processing]
When a frame determined to be an “LTM frame” is sent to the LT frame processing unit 48b, the following processing is performed in the LT frame processing unit 48b. The processing in this case is different between the case where the network relay device is positioned as the edge switches 8 and 13 and the case where the network relay device is positioned as the core switches 10 and 12.

[Processing by edge switch]
When the network relay device is positioned as the edge switches 8 and 13, the LT frame processing unit 48b sets “SA B-MAC” added at the time of encapsulation to the MAC address of itself (edge switches 8 and 13). . For “DA B-MAC”, the LT frame processing unit 48b searches the FDB 52 using “TARGET MAC” indicated by “LTM frame” as a key, and a B-MAC address is registered in association with this “TARGET MAC”. If so, the B-MAC address is set to “DA B-MAC”.

  The FDB 52 is a table for registering C-MAC addresses (hereinafter abbreviated as “C-MAC address field”) and a table for registering B-MAC addresses (hereinafter abbreviated as “B-MAC address field”). ) And the MAC address that is the frame transfer destination is registered in these tables. Further, the MAC address registered in the C-MAC address field and the MAC address registered in the B-MAC address field are registered in association with each other, and these are provided in the edge switches 8 and 13. Is associated with a port. In the IEEE 802.1ah standard, when the MAC frame transferred from the IEEE 802.1ad network 1 or 3 is encapsulated with the MAC-in-MAC header, the MAC address set to “DA MAC” in the MAC frame is referred to. If this MAC address is registered in the C-MAC address field, the MAC address in the corresponding B-MAC address field is set to “DA B-MAC”.

  On the other hand, in this embodiment, as described above, the MAC address set in the “TARGET MAC” indicated by the received “LTM frame” is referred to, and this MAC address is registered in the C-MAC address field. Is set to “DA B-MAC”. The above setting will be described later in detail with reference to FIGS.

  In addition, the LT frame processing unit 48b sets “SA C-MAC (source C-MAC address)” to the MAC address of itself (edge switches 8 and 13) and subtracts “TTL (Time to Live)”. Do. Note that the LT frame processing unit 48b does not change the “DA MAC” of the original frame.

[Processing by core switch]
On the other hand, when the network relay device is positioned as the core switches 10 and 12, the LT frame processing unit 48b performs only the subtraction of “TTL” and the change of “SA C-MAC”. Therefore, “SA B-MAC” and “DA B-MAC” are not set (rewritten) between the core switches 10 and 12 in the 802.1ah network 2.

[LTR processing]
Next, with respect to LTR (Link Trace Reply) processing for LTM, the received LTM “SA B-MAC” is changed to “DA B” of LTR at each network relay device (edge switches 8 and 13 and core switches 10 and 12). -MAC "and" SA B-MAC "are set to the MAC address of the transmission port of each network relay device (edge switch 8, 13, core switch 10, 12) that returns the LTR. In each network relay device (edge switches 8 and 13, core switches 10 and 12), the LTR's “DAC-MAC (destination C-MAC address)” is set to the value of “ORIGINAL MAC (original MAC address)”. , “SA C-MAC” is set to the same value as “SA B-MAC”. Note that such processing can be executed by the LT frame processing unit 48b. In addition, the process of generating an LTR frame from the edge switch 8 to the switch 4 via the switch 6 is performed in accordance with the IEEE 802.1ag standard and the IEEE 802.1ad standard.

  In addition, the network relay devices (edge switches 8 and 13 and core switches 10 and 12) each subtract “TTL”, but as an agreement within the 802.1ah network 2, nothing is performed regarding LTR transfer. I will do it.

  By arranging the network relay devices (edge switches 8 and 13 and core switches 10 and 12) incorporating the functions related to link tracing as described above in the 802.1ah network 2, the following links are provided in the network system of the present embodiment. The tracing method can be realized as an example.

[Link trace method]
FIG. 4 is a flowchart showing an outline of a link trace method applicable to the network system. FIG. 4 shows only two networks (802.1ad network 1 and 802.1ah network 2) that are necessary for explaining the link trace method in the network system.

  For example, the switch 4 arranged in the 802.1ad network 1 is set as the start MEP, and the LTM frame 14 is transmitted from the switch 4 with the core switch 12 in another 802.1ah network 2 as the end MEP. For example, a monitoring terminal such as a PC or a server (not shown) is connected to the switch 4 serving as a starting MEP, and the network administrator can transmit a LTM frame 14 by inputting a command from the monitoring terminal. At this time, the switch 6, the edge switch 8, and the core switch 10 function as a MIP (Maintenance Intermediate Point) that relays the LTM frame 14 when link tracing is performed.

The link trace method is roughly executed through the following steps.
(1) An LTM frame 14 targeting the core switch 12 in the 802.1ah network 2 is transmitted from the switch 4 in the 802.1ad network 1.
(2) The switch 6 in the 802.1ad network 1 relays the LTM frame 14 and transmits the LTM frame 14 to the edge switch 8 in the 802.1ah network 2. At the same time, the LTR frame 16 is transmitted from the switch 6.
(3) At the time of encapsulation by the edge switch 8, the LTM frame 14 is determined and processed. Based on the determination result, the LTR frame 16 is transmitted from the edge switch 8.
(4) The encapsulated LTM frame 18 is transmitted from the edge switch 8 within the 802.1ah network 2.
(5) When the encapsulated LTM frame 18 is relayed by the core switch 10 in the 802.1ah network 2, the encapsulated LTM frame 18 is determined and processed. Based on the determination result, the encapsulated LTR frame 20 is transmitted from the core switch 10.
(6) The encapsulated LTM frame 18 is relayed in the 802.1ah network 2, and the encapsulated LTM frame 18 reaches the target core switch 12.
(7) The core switch 12 determines and processes the encapsulated LTM frame 18, determines that it is addressed to itself, and transmits the encapsulated LTR frame 20.
(8) The encapsulated LTR frame 20 transmitted from the core switches 10 and 12 is decapsulated by the edge switch 8 in the 802.1ah network 2 and relayed to the 802.1ad network 1 as the LTR frame 16.
(9) Each LTR frame 16 is received by the switch 4 of the start MEP, and the result of the link trace is determined from the contents of each LTR frame 16.

  The above is a schematic flow of the link trace method shown in FIG. 4, and will be described in more detail below by giving examples of formats of various frames used in the link trace method.

[LTM frame format]
FIG. 5 is a diagram schematically showing the format of the LTM frame 14. As described above, the LTM frame 14 transmitted from the start MEP switch 4 has the DA MAC 22a as the multicast address and the TARGET MAC 24e as the MAC address of the core switch 12 as the end MEP. The SA MAC 22b and the ORIGINAL MAC 24d store their own (switch 4) MAC addresses.

  In the LTM frame 14, TYPE 22d of the MAC header portion 22 stores identification information indicating that it is an OAM frame. Further, the above-mentioned OpCode (operation code) 240a is stored as a part of the header information in the OAM HEADER 24a of the data section 24, and this OpCode 240a has identification information indicating that the content of the DATA area is LTM. Stored. The TID 24b is information indicating an LTM process number, and this process number is used when an LTR is generated by each network relay device.

  The TTL 24c is a value to be subtracted when each network relay device receives the LTM frame 14 as described above. In addition, as described above, the MAC address of the switch 4 (starting MEP) that is the transmission source of the LTM frame 14 is registered in the ORIGINAL MAC 24d. In the TARGET MAC 24e, the MAC address of the core switch 12 serving as the terminal MEP is registered. Note that END 24 e is a value indicating the end of the data portion 24.

[LTM frame transmission process]
The LTM frame 14 transmitted from the switch 4 is relayed through the 802.1ad network 1 based on the DA MAC 22a and transferred from the switch 6 to the edge switch 8 of the 802.1ah network 2. Although the start MEP is the switch 4 here, the start MEP may be the switch 6 and the LTM frame 14 may be transmitted from the switch 6 to the edge switch 8 of the 802.1ah network 2.

[Identification process]
The edge switch 8 adds MAC-in-MAC header information to the received LTM frame 14 to perform encapsulation, and transfers the encapsulated LTM frame 18 to the core switch 10. At this time, the edge switch 8 refers to the TYPE 22d in the LTM frame 14 in the process of encapsulating the LTM frame 14, and confirms whether or not the value indicates OAM. This confirmation can be executed using the function of the LT frame determination unit 48a in the edge switch 8 as described above.

[Judgment process]
If TYPE 22d indicates OAM, the edge switch 8 further refers to the OpCode 240a to determine whether or not the value indicates LTM. This determination can also be executed using the function of the LT frame determination unit 48a in the edge switch 8. When the LTM frame 14 is received, the edge switch 8 performs the following setting for the encapsulated LTM frame 18.

[Encapsulated LTM frame]
FIG. 6 is a diagram schematically showing the format of the encapsulated LTM frame 18. In the process of encapsulating the LTM frame 14, the edge switch 8 basically sets the MAC address of the core switch 12 serving as the termination MEP in the DA B-MAC 34a. That is, as described above, the LT frame processing unit 48b of the edge switch 8 searches its FDB 52 using the value of the TARGET MAC 24e shown in FIG. 5 as a key, and obtains the obtained B-MAC address (that is, the MAC of the core switch 12). Address) is set to DA B-MAC 34a.

  Further, the edge switch 8 sets the MAC address of the main body in the SA B-MAC 34b, and sets the MAC address of the transmission port (port connected to the core switch 10) in the SA C-MAC 34f. One TTL 36c is also subtracted in the edge switch 8.

  On the other hand, when the TARGET MAC 24 e shown in FIG. 5 is not registered in its own FDB 52, the edge switch 8 discards the LTM frame 14. In this case, the encapsulated LTM frame 18 is not generated. This can prevent the encapsulated LTM frame 18 from being broadcast because it is not registered in the FDB 52. Therefore, the encapsulated LTR frame 20 is not generated by another network relay device (a core switch other than the core switches 10 and 12) through which a frame does not originally pass.

  The DA C-MAC 34e and the SA C-MAC 34f are formats corresponding to the DA MAC 22a and the SA MAC 22b in the LTM frame 14, respectively. When the edge switch 8 encapsulates the LTM frame 14, the LTM frame encapsulates information set in the DA MAC 22a, SA MAC 22b, VLAN TAG 22c, and TYPE 22d in the LTM frame 14 based on the IEEE 802.1ah communication standard. 18 to the corresponding format. Also, in the B-TAG 34c and the I-TAG 34d, predetermined information is set based on the IEEE 802.1ah communication standard in the same manner as the above-described formats.

  The data portion 36 of the encapsulated LTM frame 18 also stores information indicating LTM data compliant with IEEE802.1ag, like the data portion 24 in the LTM frame 14. In the OAM HEADER 36a, the ORIGINAL MAC 36d, and the TARGET MAC 36e in the DATA 35b, the same information as the OAM HEADER 22a, the ORIGINAL MAC 22d, and the TARGET MAC 22e in the LTM frame 14 is set, respectively. Information based on the IEEE 802.1ag communication standard is registered in the TID 36b, TTL 36c, and END 36e. The TYPE 35a is a format corresponding to the TYPE 22d of the LTM frame 14 shown in FIG. 5, and a value indicating OAM is set.

[Transmission of LTR frame]
Similarly to the switch 6, when receiving the LTM frame 14, the edge switch 8 generates an LTR frame 16 and transmits it to the switch 4 of the starting MEP. The LTR frame 16 transmitted from the edge switch 8 is relayed by the switch 6 of the 802.1ad network 1 and received by the switch 4.

[LTR frame]
FIG. 7 is a diagram schematically showing the format of the LTR frame 16. The switch 6 and the edge switch 8 set the DA MAC 28a of the LTR frame 16 to the ORIGINAL MAC 24d of the LTM frame 14, and set the SA MAC 28b to the MAC address of its own transmission port. In the other VLAN TAG 28c and TYPE 28d, identification information similar to the VLAN TAG 22c and TYPE 22d of the LTM frame 14 is set.

  The data section 30 stores LTR data compliant with IEEE802.1ag, and the data section 30 includes an OAM HEADER 30a, a TID 30b, a Reply TTL 30c, a Relay Act 30d, an Additional TLV (Type Length Value) 30e, and an END 30f.

  Like the LTM frame 14, the OAM HEADER 30a has an OpCode 300a in a part thereof. In this OpCode 300a, identification information indicating that the content of the data part 30 is LTR data is stored.

  Information based on the IEEE 802.1ag communication standard is set in each of the TID 30b, the Reply TTL 30c, the Relay Act 30d, the Additional TLV 30e, and the END 30f. Further, the switch 6 and the edge switch 8 subtract the TTL 24c of the received LTM frame 14, respectively, and set the value to the Reply TTL 30c.

[Relay of encapsulated LTM frame]
The encapsulated LTM frame 18 transmitted from the edge switch 8 is relayed in the 802.1ah network 2 based on the DA B-MAC 34 a and reaches the next core switch 10.

[Determination of encapsulated LTM frame]
The core switch 10 receives the encapsulated LTM frame 18 at the transmission / reception unit 46a shown in FIG. The transmission / reception unit 46a of the core switch 10 sends the encapsulated LTM frame 18 to the LT frame determination unit 48a as described above. The LT frame determination unit 48a refers to the contents of the encapsulated LTM frame 18 and determines that the encapsulated LTM frame 18 is an OAM LTM from the values set in the TYPE 35a and the OpCode 360a. In this case, the LT frame determination unit 48a sends the encapsulated LTM frame 18 to the LT frame processing unit 48b.

[Processing of encapsulated LTM frame]
The LT frame processing unit 48b of the core switch 10 subtracts the TTL 36c and changes the SAC-MAC 34f to the MAC address of the transmission port (port connected to the core switch 12). Then, the core switch 10 transfers the encapsulated LTM frame 18 to the core switch 12 based on the DA B-MAC 34a.

[Transmission of encapsulated LTR frame]
As shown in FIG. 4, the core switch 10 relays the encapsulated LTM frame 18, while generating the encapsulated LTR frame 20 and transmits it to the edge switch 8. When the edge switch 8 receives the encapsulated LTR frame 20, it performs decapsulation and transfers it to the switch 6 as the LTR frame 16. The switch 6 that has received the LTR frame 16 transfers the LTR frame 16 to the switch 4 that is the starting MEP in the same manner as the transfer process of the LTR frame 16 described above.

[Encapsulated LTR frame]
FIG. 8 is a diagram schematically showing a format of the encapsulated LTR frame 20. The encapsulated LTR frame 20 is roughly composed of a MAC-in-MAC header part 40, a data part 42, and an FCS 44. Among these, the MAC-in-MAC header section 40 includes DA B-MAC 40a, SA B-MAC 40b, B-TAG 40c, I-TAG 40d, DAC-MAC 40e, and transmission source C-MAC 40f.

  The core switch 10 that has received the encapsulated LTM frame 18 sets the SA B-MAC 34b to the DA B-MAC 40a of the encapsulated LTR frame 20, and sets the MAC address of the transmission port to the SA B-MAC 40b. The core switch 10 sets the DAC-MAC 40e to the value of the original MAC 36d, and sets the SA C-MAC 40f to the same value as the SA B-MAC 40b.

  In the other B-TAG 40c and I-TAG 40d, setting based on the IEEE 802.1ah communication standard is executed, and information for relaying the encapsulated LTR frame 20 in the 802.1ah network 2 is stored.

  Similar to the data unit 30 in the LTR frame 16, the data unit 42 stores information indicating LTR data compliant with IEEE802.1ag in the DATA 41b. That is, the same information as the information registered in the OAM HEADER 30a, the ORIGINAL MAC 30d, and the TARGET MAC 30e in the LTR frame 16 is set in the OAM HEADER 42a, the ORIGINAL MAC 42d, and the TARGET MAC 42e in the DATA 41b. The TYPE 41a is a format corresponding to the TYPE 28d included in the MAC header portion 28 in the LTR frame 16.

  Information based on the IEEE 802.1ag communication standard is set in the TID 42b, TTL 42c, and END 42e in the DATA 41b. The TTL 42c stores a result obtained by subtracting the TTL 36c of the encapsulated LTM frame 18 received by the core switch 10.

[Decapsulation / Relay of Encapsulated LTR Frame]
When the encapsulated LTR frame 20 is decapsulated, the edge switch 8 converts the encapsulated LTR frame 20 into an LTR frame 16 based on the DA MAC 28a and relays it to the 802.1ad network 1. Thereafter, the LTR frame 16 is relayed by the switch 6 and reaches the switch 4.

  On the other hand, the encapsulated LTM frame 18 is relayed in the 802.1ah network 2 based on the DA B-MAC 34a, and reaches the core switch 12 which is the terminal MEP.

[Encapsulated LTM frame determination process]
The core switch 12 also receives the encapsulated LTM frame 18 at the transmission / reception unit 46a. The transmission / reception unit 46a of the core switch 12 sends the received encapsulated LTM frame 18 to the LT frame determination unit 48a. The LT frame determination unit 48a refers to the contents of the encapsulated LTM frame 18, and determines that the encapsulated LTM frame 18 is an OAM LTM from the values set in the TYPE 34h and the OpCode 360a. In this case, the LT frame determination unit 48a sends the encapsulated LTM frame 18 to the LT frame processing unit 48b.

  At this time, the LT frame determination unit 48a determines from the contents of the DA B-MAC 34a that the received encapsulated LTM frame 18 is a frame addressed to itself. Normally, in the IEEE802.1ah communication standard, the core switch in the network is determined to discard the frame when the DA B-MAC is destined for itself. In addition, in this embodiment, even if DA B-MAC 34a designates itself as a destination, it is determined that it is an OAM LTM frame (encapsulated LTM frame 18) addressed to itself. In this case, the following processing is continued without discarding this.

[Processing of encapsulated LTM frame]
The LT frame processing unit 48b of the core switch 12, which is the terminal MEP, performs the following setting in order to transmit the encapsulated LTR frame 20 toward the edge switch 8. That is, the LT frame processing unit 48b sets the DA B-MAC 40a of the encapsulated LTR frame 20 to the same value by using the value of the SA B-MAC 34b of the received encapsulated LTM frame 18, and the transmission port of the core switch 12 The MAC address of (the port connected to the core switch 10) is set to SA B-MAC 40b and SA C-MAC 40f.

  Further, the LT frame processing unit 48b sets the value of the DAC-MAC 40e of the encapsulated LTR frame 20 to the same value using the value of the ORIGINAL MAC 36d of the received encapsulated LTM frame 18. Then, the LT frame processing unit 48b subtracts the TTL 36c of the encapsulated LTM frame 18 and sets the value to the Reply TTL 42c of the encapsulated LTR frame 20.

[Transmission of encapsulated LTR frame]
When the above processing is performed, the LT frame processing unit 48b sends the encapsulated LTR frame 20 to the transmission / reception unit 46a. The transmission / reception unit 46a transmits the encapsulated LTR frame 20 based on the DA B-MAC 40a.

[Relay of encapsulated LTR frame]
When the encapsulated LTR frame 20 is received by the core switch 10, a relay operation is performed based on the DA B-MAC 40a without any particular processing.

  Thereafter, the encapsulated LTR frame 20 is decapsulated by the edge switch 8 as described above, and relayed through the 802.1ad network 1 as the LTR frame 16. In the 802.1ad network 1, the LTR frame 16 is relayed based on the DA MAC 28a, and finally reaches the switch 4 that is the starting MEP.

  As described above, the link trace method can be realized in the network system of this embodiment by executing the processing given to each network relay device in the two networks 1 and 2. Thereby, the normality of the communication path between the switch 4 arranged in the 802.1ad network 1 and the core switch 12 arranged in the 802.1ah network 2 can be determined. In addition, it is possible to accurately grasp the MAC addresses of relay devices (switch 6, edge switch 8, core switch 10, etc.) that have passed through from the switch 4 to the core switch 12 and the intermediate communication path. .

  In order to realize the link trace method described above, in the present embodiment, network relay devices (edge switch 8, core switches 10, 12, etc.) arranged in the 802.1ah network 2 are replaced with an LT frame determination unit 48a and an LT frame processing unit. Although it has the function as 48b, the example of the control procedure for implement | achieving each function below is given, and it shall contribute to suitable implementation of invention.

[LTM judgment processing]
FIG. 9 is a flowchart illustrating an exemplary procedure of the LTM determination process executed by the LT frame determination unit 48a. In the following, the case where the LT frame determination unit 48a of the edge switch 8 determines LTM is taken as an example, but the LT frame determination unit 48a of the core switches 10 and 12 similarly applies to the received encapsulated LTM frame 18 as well. The same process is executed.

  Step S100: The LT frame determination unit 48a refers to the MAC header portion of the frame (LTM frame 14 or other user frame) sent from the transmission / reception unit 46a. Specifically, “DA MAC” to “TYPE” stored in the MAC header portion are sequentially referred to. For the core switches 10 and 12, “DA B-MAC” to “TYPE” in the MAC-in-MAC header part are sequentially referred to.

  Step S102: When it is determined that the referenced “TYPE” value is identification information indicating IEEE 802.1ag (Yes), the LT frame determination unit 48a proceeds to Step S104 and subsequent steps. On the other hand, when the value of “TYPE” is not identification information indicating IEEE802.1ag (No), the LT frame determination unit 48a transfers the received frame (other user frame) to the frame relay function execution unit 48c (step S108). This process is terminated. The frame relay function execution unit 48 executes an encapsulation process based on the IEEE802.1ah standard on the frame (other user frames), and transfers the encapsulated frame to the frame transfer control unit 46.

Step S104: Next, the LT frame determination unit 48a refers to the “data part” of the received frame.
Step S106: The LT frame determination unit 48a refers to “OpCode” of the OAM HEADER unit in the region stored in the “data unit”, and information registered therein is identification information indicating the LTM. Whether or not (determination step). As a result, when the identification information indicating the LTM is registered (Yes), the LT frame determination unit 48a proceeds to Step S110.

  Step S110: The LT frame determination unit 48a transfers the received frame to the LT frame processing unit 48b, and ends this processing. At this time, if it is the edge switch 8, the LTM frame 14 is sent to the LT frame processing unit 48b. In the case of the core switches 10 and 12, the encapsulated LTM frame 18 is sent to the LT frame processing unit 48b.

  On the other hand, when the information registered in the OpCode 240a is not identification information indicating LTM (step S106: No), the LT frame determination unit 48a transfers the received frame to the frame transfer control unit 46 (step S108). End the process. Note that such a procedure is executed when, for example, a received frame is an OAM and a function different from the link trace function is supported.

[Encapsulated LTM frame generation processing]
FIG. 10 is a flowchart showing an outline of the encapsulated LTM frame generation process executed by the LT frame processing unit 48b of the edge switch 8. FIG. 11 is a table showing the FDB 52 of the edge switch 8. The LT frame processing unit 48b of the edge switch 8 executes the following processing with the LTM frame 14 sent from the LT frame determination unit 48a as a trigger. Here, the edge switch 8 is a representative example, but other network relay devices arranged as “edge switches” in the 802.1ah network 2 also receive the LT frame processing when the LTM frame 14 is received. The same processing is performed in the unit 48b.

Step S300: The LT frame processing unit 48b refers to “TARGET MAC” set in the LTM frame 14.
Step S302: The LT frame processing unit 48b searches the FDB 52 using “TARGET MAC” as a key. That is, if the same MAC address as the “TARGET MAC” (that is, the MAC address of the core switch 12) is not registered in the C-MAC address field of the FDB 52 shown in FIG. 11 (No), the LT frame processing unit 48b The received LTM frame 14 is discarded (step S306), and this process ends.

  On the other hand, when the same MAC address as “TARGET MAC” is registered in the C-MAC address field in the FDB 52 (step S302: Yes), the LT frame processing unit 48b executes step S304 and subsequent steps.

Step S304: When generating the encapsulated LTM frame 18, the LT frame processing unit 48b, based on the MAC address of the core switch 12 registered in the C-MAC address field in the FDB 52, corresponds to the B in the FDB 52. -Set the MAC address registered in the MAC address field to DA B-MAC 34b. Note that the MAC address of the core switch 12 is registered in the B-MAC address column shown in FIG. 11, and the MAC address of the core switch 12 is set in the DA B-MAC 34b.
Step S308: The LT frame processing unit 48b sets SA B-MAC 34b and SA C-MAC 34f, respectively. The details of the values set for each are as described above.

  Step S310: The LT frame processing unit 48b sets each region of the B-TAG 34c and the I-TAG 34d based on the IEEE 802.1ah communication standard.

  Step S312: The LT frame processing unit 48b sets each area of the data unit 36 based on the IEEE 802.1ag communication standard. Specifically, identification information indicating the LTR is set for the OpCode 360a of the OAM HEADER 36a. Also, a value obtained by subtracting 1 from the value registered in the TTL 24c in the LTM frame 14 as described above is set in the TTL 36c. In the ORIGINAL MAC 36d and the TARGET MAC 36e, the same values as the ORIGINAL MAC 24d and the TARGET MAC 24e of the LTM frame 14 are set, respectively.

  Step S314: The LT frame processing unit 48b transfers the generated encapsulated LTM frame 18 to the frame transfer control unit 46, and ends this processing.

[Encapsulated LTR frame generation processing]
Next, FIG. 12 is a flowchart showing an encapsulated LTR frame generation process executed by the LT frame processing unit 48b of the core switch 12 serving as the terminal MEP. The LT frame processing unit 48 of the core switches 10 and 12 executes the following processing triggered by the fact that the encapsulated LTM frame 18 has been sent from the LT frame determination unit 48a. Here, the core switches 10 and 12 are representative examples, but other network relay devices arranged as “core switches” in the 802.1ah network 2 also receive the encapsulated LTM frame 18 respectively. Similar processing is performed by the LT frame processing unit 48b.

  Step S400: The LT frame processing unit 48b sets a value in each area of the MAC-in-MAC header unit 40 when generating the encapsulated LTR frame 20. In addition, about the setting of a specific value, it is as having already demonstrated in the example of the link trace method.

  Step S402: Next, the LT frame processing unit 48b sets a value in each area of the data unit 42. That is, the LT frame processing unit 48b refers to the TTL 36c of the received encapsulated LTM frame 18, and sets a value obtained by subtracting 1 from the value in the ReplyTTL 42c. The LT frame processing unit 48b sets identification information indicating the LTR in the OpCode 420a. In addition, values based on the IEEE 802.1ag communication standard are set in the TID 42b, the Relay Act 42d, and the Additional TLV 42e (details are omitted).

  Step S404: When the above procedure is completed, the LT frame processing unit 48b transfers the encapsulated LTR frame 20 to the frame control unit 46, and ends this processing.

  Through the above processes, the edge switch 8 and the core switches 10 and 12 in the 802.1ah network 2 refer to the “TYPE” and “OpCode” of the received frame, and confirm that the received frame is an OAM LTM. Can be determined. For this reason, a frame transmitted from an 802.1ad network 1 with a different standard is not mistaken as a user frame, or the frame is not discarded by the core switch 12 specified by the TARGET MAC. It is possible to effectively utilize the link trace function of OAM for the communication path.

  The present invention is not limited to the above-described embodiments, and can be implemented with various modifications without departing from the scope of the claims. For example, network relay devices arranged in the 802.1ad networks 1 and 3 and the 802.1ah network 2 are not limited to the IEEE802.1ag communication standard but are defined in the international standard “Y.1731” of ITU-T. The link trace function may be implemented.

  Further, the encapsulated LTM frame 18 and the encapsulated LTR frame 20 can also be applied to a frame of a format in which the B-TAG 34c and the B-TAG 40c do not exist.

1 Network (IEEE802.1ad network)
2 Network (IEEE802.1ah network)
3 Network (IEEE802.1ad network)
4 switch (starting MEP)
8 Edge switch 12 Core switch (Terminal MEP)
14 LTM frame 16 LTR frame 18 Encapsulated LTM frame 20 Encapsulated LTR frame 22d, 28d, 35a, 41a TYPE
240a, 300a, 360a, 400a OpCode

Claims (9)

The second network is arranged in the first network conforming to the first communication standard and connected to the second network conforming to the second communication standard different from the first communication standard. Receiving the MAC frame transmitted from the network relay device for encapsulating the received MAC frame based on the first communication standard and transferring the encapsulated MAC frame to the first network,
Encapsulating means for generating an encapsulated frame in a format in which encapsulation header information based on the first communication standard is added to the received MAC frame at the time of the encapsulation;
Identification means for identifying whether or not management identification information is set in the type area of the header information included in the received MAC frame;
When it is identified by the identification means that management identification information is set in the type area, a link trace defined by a link trace rule in the operation code area of the data area included in the received MAC frame Determining means for determining whether identification information indicating a message is set ;
An FDB in which a C-MAC address and a B-MAC address are registered in association with each other;
When it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, the data is included in the received MAC frame, and the target MAC address area is set. On the condition that the same value as the target MAC address is registered as the C-MAC address in the FDB, the B-MAC address registered in the FDB in association with the C-MAC address is used as the encapsulation header information. Frame processing means for setting the destination B-MAC address area included in
If it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, an LTR frame including a link trace reply as a response to the link trace message in a data area is generated. Response processing means for transmitting the LTR frame to the second network;
With
The frame processing means includes
Even if it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, if the target MAC address is not registered in the FDB, the encapsulated frame A network relay device that discards the received MAC frame without generating a message . By being arranged in the first network compliant with the first communication standard, the MAC frame transmitted from the second network compliant with the second communication standard different from the first communication standard is the first frame. A network relay device that transfers an encapsulated frame in a form encapsulated by adding encapsulated header information based on the communication standard in the first network,
Identification means for identifying whether or not management identification information is set in the type area of the header information included in the MAC frame encapsulated as the encapsulated frame;
When it is identified by the identification means that management identification information is set in the type area, a link trace is defined in the operation code area of the data area included in the encapsulated MAC frame. Determining means for determining whether or not identification information indicating a link trace message to be set is set ;
When it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, a link trace reply as a response to the link trace message included in the encapsulated frame is stored in the data area. Response processing means for generating an encapsulated LTR frame using the source B-MAC address of the encapsulated frame as a destination B-MAC address and transmitting the encapsulated LTR frame in the first network. Network relay equipment provided. The network relay device according to claim 2 ,
In the case where it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, among the encapsulated header information included in the encapsulated frame, the destination B- A network relay device characterized by further comprising a frame processing means for terminating the transfer of the encapsulated frame when it is confirmed that the MAC address set in the MAC address area is the same as its own unique MAC address . In the network relay device according to claim 2 or 3 ,
The response processing means includes
Of the encapsulated header information included in the encapsulated LTR frame, a unique MAC address is set for each of the source B-MAC address area and the source C-MAC address area, and the destination B-MAC address is set. A source B-MAC address of the encapsulated frame is set in an area, and a MAC address set in an original MAC address area included in the encapsulated frame is set in a destination C-MAC address area. Network relay device to be used. A network system in which at least one second network based on a second communication standard different from the first communication standard is connected to at least one first network based on the first communication standard,
The first network is
When receiving a MAC frame transmitted from the second network, an edge switch that transfers the received MAC frame as an encapsulated frame encapsulated based on the first communication standard into the first network;
A core switch that relays the encapsulated frame transferred by the edge switch in the first network;
The second network is
A plurality of switches that relay the MAC frame;
Among the plurality of switches, management identification information is set in the type area included in the header information of the MAC frame, and a link trace message defined by the link trace rule is shown in the operation code area of the data area With the identification information set, an LTM frame in which any one of the core switches arranged in the first network is set as a target MAC address, or a plurality of second networks are connected to the first network A management endpoint for transmitting an LTM frame in which any one of the switches arranged in another second network connected via the first network is set to a target MAC address,
The edge switch and the core switch included in the first network are:
Identification means for identifying whether management identification information is set in a type area of header information included in the MAC frame transmitted from the management endpoint;
When the identification means identifies that management identification information is set in the type area, identification information indicating the link trace message is set in the operation code area of the data area included in the received MAC frame and a judging means for judging whether it is,
The edge switch included in the first network is:
When it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, the target MAC address of the data area included in the MAC frame transmitted from the management endpoint On the condition that the same value as the target MAC address set in the area is registered as the C-MAC address in the FDB, the B-MAC address registered in the FDB in association with the C-MAC address is used as the capsule. If the same value as the target MAC address is not registered as the C-MAC address in the FDB while setting the destination B-MAC address area included in the header header information and generating the encapsulated frame, Do not generate the encapsulated frame Said MAC frame discarding frame processing unit that receives,
If it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, an LTR frame including a link trace reply as a response to the link trace message in a data area is generated. Response processing means for transmitting the LTR frame to the second network,
The core switch included in the first network is:
When it is determined by the determining means that identification information indicating the link trace message is set in the operation code area, the destination B-MAC address area of the encapsulated header information included in the encapsulated frame Frame processing means for ending the transfer of the encapsulated frame, when it is confirmed that the MAC address set to is the same as its own unique MAC address;
When it is determined by the determination means that identification information indicating the link trace message is set in the operation code area, a link trace reply as a response to the link trace message included in the encapsulated frame is stored in the data area. Response processing means for generating an encapsulated LTR frame using the source B-MAC address of the encapsulated frame as a destination B-MAC address and transmitting the encapsulated LTR frame in the first network. A network system with more . In a state where at least one second network compliant with a second communication standard different from the first communication standard is connected to the first network compliant with the first communication standard, the second network One of the core switches arranged in the first network is set as a destination management endpoint with respect to the management endpoint of the start point arranged in the network, or from the management endpoint via the first network A MAC frame including a link trace message in a data area from a management end point of the start point to the management end point of the destination as any one of the switches arranged in the second network connected to the destination A link trace method for sending and executing a link trace,
When the MAC frame transmitted from the management endpoint of the start point is received by an edge switch arranged in the first network, management identification information is included in the type area of the header information included in the MAC frame. An identification process for identifying whether it is set,
When it is identified in the identification step that management identification information is set in the type area, identification information indicating the link trace message is set in the operation code area of the data area included in the MAC frame. A determination step of determining whether or not
When it is determined in the determination step that identification information indicating the link trace message is set in the operation code area, a process of generating an encapsulated frame in a format in which encapsulation header information is added to the MAC frame; Assuming that the same value as the target MAC address set in the target MAC address area of the data area included in the MAC frame is registered as the C-MAC address in the FDB, the FDB is associated with the C-MAC address. Frame processing step of transmitting the encapsulated frame in the first network by setting the B-MAC address registered in the destination B-MAC address area included in the encapsulation header information;
s If it is determined in the determination step that identification information indicating the link trace message is set in the operation code area, an LTR frame including a link trace reply as a response to the link trace message in a data area is generated. And a response processing step of transmitting the LTR frame to the second network. The link trace method according to claim 6 ,
When the encapsulated frame transmitted from the edge switch is received by the core switch arranged in the first network, the type area of the header information included in the MAC frame encapsulated as the encapsulated frame An identification step for identifying whether or not management identification information is set in the core switch,
When it is identified in the identification step in the core switch that management identification information is set in the type area, the link trace is stored in the operation code area of the data area included in the encapsulated MAC frame. A determination step of determining whether or not identification information indicating a message is set in the core switch;
If it is determined in the determination step at the core switch that identification information indicating the link trace message is set in the operation code area, a link trace as a response to the link trace message included in the encapsulated frame And a response processing step of generating an encapsulated LTR frame including a reply in a data area and transmitting the encapsulated LTR frame in the first network by the core switch. . The link trace method according to claim 7 ,
In the determination step in the core switch, when it is determined that identification information indicating the link trace message is set in the operation code area, of the encapsulation header information included in the encapsulation frame And further comprising a frame processing step for terminating the transfer of the encapsulated frame when it is confirmed that the MAC address set in the destination B-MAC address area is the same as the MAC address unique to the destination B-MAC address area. Link trace method. In the link trace method according to claim 7 or 8 ,
In each response processing step,
Of the encapsulated header information included in the encapsulated LTR frame, a unique MAC address is set for each of the source B-MAC address area and the source C-MAC address area, and the destination B-MAC address is set. A source B-MAC address of the encapsulated frame is set in an area, and a MAC address set in an original MAC address area included in the encapsulated frame is set in a destination C-MAC address area. Link trace method to do.

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