JPWO2006082652A1 - Transmission apparatus and transmission method - Google Patents

Abstract

When transmitting a frame from the terminal 43 connected to the transmission apparatus 1000 to the terminal 63 connected to the transmission apparatus 3000, the transmission apparatus 1000 displays a label indicating that the source is the transmission apparatus 1000 and the destination is the transmission apparatus 3000. Attached to the frame and transmitted to the ring network. The transmitted frame is relayed under bandwidth control according to the assigned label, and the label is deleted and transferred to the terminal 63 when it arrives at the transmission device 3000. In addition, the ring network is made redundant, the status is monitored using a hello frame, and when a failure occurs in the active ring, the ring is switched to the standby ring.

Description

  The present invention relates to a transmission apparatus and transmission method in a ring network using Ethernet (registered trademark), and more particularly to a transmission apparatus and transmission method having a function of controlling a band between transmission apparatuses in addition to a ring redundancy function. It is.

  Conventionally, when a high-speed wide area network such as MAN (Metropolitan Area Network) is constructed, a ring network called SONET (Synchronous Optical Network) is often employed. SONET has a powerful ring redundancy function that can continue the operation of the network even if a part of the transmission apparatus constituting the ring fails. In addition, it is possible to secure a bandwidth for each path connecting between transmission devices, so that even if the traffic of a specific path increases and congestion occurs, the communication of other paths is maintained in a stable communication state. It has become.

  A network using SONET has high reliability and stability, but has a drawback of high installation cost because equipment such as a transmission device necessary for construction is expensive. Therefore, in recent years, wide area networks are often constructed using Ethernet (registered trademark) that can use relatively inexpensive devices.

  When building a wide area network using Ethernet (registered trademark), which is often used in a relatively small network such as a LAN (Local Area Network), first, reliability becomes a problem. This reliability problem can be solved by using, for example, EAPS (Ethernet Automatic Protection Switching) shown in Non-Patent Document 1.

  In EAPS, one of the transmission apparatuses constituting the Ethernet (registered trademark) ring network is set as a master, and one of the two ports provided in the master is set as a primary and the other is set as a secondary. In the initial state, the secondary is blocked to prevent a frame loop, and when a failure is detected, the failure is avoided by performing transfer from the secondary. By using this technology, it is possible to ensure reliability equivalent to SONET in a wide area network using Ethernet (registered trademark).

S. Shah, M. Yip, Extreme Networks, "Extreme Networks' Ethernet Automatic Protection Switching (EAPS) Version 1", [online], October 2003, retrieved from the Internet: <URL: http://www.ietf.org /rfc/rfc3619.txt>

  However, even if the technique shown in Non-Patent Document 1 is used, it is not possible to realize a function for securing a band between transmission apparatuses as provided in SONET. For this reason, when the amount of communication between specific transmission apparatuses increases and becomes congested, the communication between other transmission apparatuses is also affected and the frame is discarded.

  The present invention has been made in view of the above, and in a ring network constructed using Ethernet (registered trademark), in addition to a ring redundancy function, a transmission having a function of controlling a band between transmission apparatuses An object is to provide an apparatus and a transmission method.

  In order to solve the above-described problems and achieve the object, the present invention is a transmission apparatus that constitutes a ring network using Ethernet (registered trademark), and shows a transmission path in a frame received from outside the ring network. A label attaching unit for attaching a label, a label attached by the label attaching unit, and band control information held in a storage unit are collated, and the frame is transmitted to a ring network within a pre-registered band range. And a band control means.

  According to the present invention, when a frame received from the outside of the ring is transmitted to the ring network, a label indicating the transmission path of the frame is attached, and the band is controlled based on this label and then transmitted. For example, a band between the source transmission apparatus and the destination transmission apparatus can be determined in advance, and a frame can be transmitted within the range of the band.

  Further, in the present invention, in the above invention, when the bandwidth control means relays a frame flowing through the ring network, the bandwidth control means collates the label given to the frame with the bandwidth control information held in the storage means, The frame is relayed within a pre-registered bandwidth range.

  According to the present invention, when a frame is relayed, the bandwidth is controlled based on the label attached to the frame and then relayed. Therefore, for example, the bandwidth between the source transmission device and the destination transmission device Can be determined in advance and frames can be relayed within the range of the bandwidth.

  Further, according to the present invention, in the above invention, one of the clockwise flow and the counterclockwise flow of the ring network is recognized as an active system, the other flow is recognized as a standby system, and the active system is The present invention is further characterized by further comprising a working / standby selection means for switching the standby system to the working system when a failure occurs.

  According to the present invention, since one flow of the ring network is used as the active system and the other flow is operated as the standby system, and the failure occurs in the active system, the standby system is switched to the active system. Even in a ring network composed of a single line, the communication path can be made redundant.

  Further, according to the present invention, in the above invention, among the multiplexed lines constituting the ring network, a predetermined line is recognized as an active system and another line is recognized as a standby system, and a failure occurs in the active system. In this case, the present invention is further characterized by further comprising working / standby selection means for switching the standby system to the working system.

  According to the present invention, among the multiplexed lines constituting the ring network, a predetermined line is used as an active system, and other lines are operated as a standby system. When a failure occurs in the active system, the standby system is Since it is configured to switch to the active system, the communication path can be made redundant in a ring network composed of a plurality of lines.

  Further, the present invention is a transmission method in a ring network configured using Ethernet (registered trademark) in the above-described invention, and shows a transmission path for the frame in a transmission apparatus that receives the frame from the outside of the ring network. A label attaching step for assigning a label, a label given by the label attaching step, and the band control information held in the storage means are collated, and the frame is sent to the ring network within a pre-registered band range. In the frame sending step and the transmission device that relays the frame, the label given to the frame is compared with the bandwidth control information held in the storage means, and the frame is relayed within the pre-registered bandwidth range And a frame relay process.

  According to the present invention, when a frame received from the outside of the ring is transmitted to the ring network, a label indicating the transmission path of the frame is attached, the band is controlled based on the label, and the frame is transmitted. Since the band control is performed in the same way when relaying in other transmission apparatuses, for example, the band between the source transmission apparatus and the destination transmission apparatus is determined in advance, and the band is set in the entire ring. The frame can be transmitted within the range of.

  The transmission apparatus according to the present invention is configured so that when a frame received from the outside of the ring is transmitted to the ring network, a label indicating a transmission path of the frame is attached and the band is controlled based on the label and transmitted. Therefore, for example, there is an effect that a band between the transmission source device and the destination transmission device is determined in advance, and a frame can be transmitted within the range of the band.

  In addition, since the transmission apparatus according to the present invention is configured to perform the band control based on the label attached to the frame when the frame is relayed, for example, the source transmission apparatus and the destination transmission apparatus An effect is obtained that a band between the frames can be determined in advance and frames can be relayed within the range of the band.

  The transmission apparatus according to the present invention operates one flow of the ring network as the active system and the other flow as the standby system, and switches the standby system to the active system when a failure occurs in the active system. Thus, the communication path can be made redundant even in a ring network composed of a single line.

  The transmission apparatus according to the present invention operates when a predetermined line is used as a working system and other lines are used as a standby system among the multiplexed lines constituting the ring network, and a failure occurs in the working system. Since the standby system is switched to the active system, the communication path can be made redundant in a ring network composed of a plurality of lines.

  Further, the transmission method according to the present invention, when transmitting a frame received from the outside of the ring to the ring network, gives a label indicating the transmission path of the frame, transmits after performing band control based on this label, Furthermore, since the band control is performed in the same manner when this frame is relayed in another transmission apparatus, for example, the band between the source transmission apparatus and the destination transmission apparatus is determined in advance, There is an effect that transmission of a frame can be performed within the range of the band as a whole.

FIG. 1 is an explanatory diagram for explaining the principle of the transmission method according to the present embodiment. FIG. 2 is a block diagram illustrating the configuration of the transmission apparatus according to the present embodiment. FIG. 3 is a sample diagram showing an example of the configuration of the hello frame. FIG. 4 is a block diagram showing a configuration of the bandwidth control unit shown in FIG. FIG. 5 is a sample diagram showing an example of a frame without a label. FIG. 6 is a sample diagram showing an example of a frame with a label attached thereto. FIG. 7 is a sample diagram illustrating an example of a mesh-connected network. FIG. 8 is a sample diagram showing an example of a ring-connected network. FIG. 9 is a flowchart showing a processing procedure when the transmission apparatus receives a frame from the LAN side. FIG. 10 is a flowchart illustrating a processing procedure when the transmission apparatus receives a frame from the ring side. FIG. 11 is a flowchart of a process procedure of the hello frame control process shown in FIG.

Explanation of symbols

10, 20 Ring 30, 50 LAN
41, 42, 43, 44, 61, 62, 63, 64 Terminal 71, 72, 73, 74 Frame 1000, 2000, 3000, 4000 Transmission device 1100 Interface unit 1110a, 1110b Ring interface unit 1120 User interface unit 1200 Control unit 1210 Hello frame control unit 1220 Source device filter 1230 Destination device filter 1240 Current / Preliminary selection unit 1250 Timer device 1260 Band control unit 1261a, 1261b Multiplexer (MUX)
1262a, 1262b Label identification unit 1263a, 1263b, 1264a, 1264b, 1265a, 1265b, 1266a, 1266b Queue 1267a, 1267b Reading unit 1270 Switch unit 1280 Label deletion unit 1290 Label attaching unit 1300 Storage unit 1310 Band information storage unit 1320 Label information Part 1330 Route information storage part

  Embodiments of a transmission apparatus and a transmission method according to the present invention will be described below in detail with reference to the drawings. Note that the present invention is not limited to the embodiments.

  First, the principle of the transmission method according to this embodiment will be described. FIG. 1 is an explanatory diagram for explaining the principle of the transmission method according to the present embodiment. As shown in the figure, in the transmission system according to the present embodiment, a network is configured by connecting transmission apparatuses by two rings, a ring 10 and a ring 20. Each transmission apparatus is further connected to a network such as a LAN.

  Of the two rings, the ring 10 and the ring 20, one functions as an active system and the other functions as a standby system. Each transmission device sends out a frame having the same content to both the ring 10 and the ring 20, and the destination transmission device discards the frame transmitted through the standby ring and only the frame transmitted through the working ring. Transfer to the target device. When a failure occurs in the working ring, the failure is avoided by switching the standby ring to the working ring. The two rings need not be physically different lines, and may share the same line.

  Further, in the transmission method according to the present embodiment, a label for identifying a transmission device is attached when sending a frame to the ring network, and band control is performed based on this label. In a network using Ethernet (registered trademark), route control is performed by a MAC (Media Access Control) address. Since this MAC address is assigned for each vendor, the network configuration and the MAC address system There is no relationship between them.

  For this reason, in order to control the bandwidth between the transmission devices based on the MAC address, a table for identifying the source transmission device and the destination transmission device, that is, all the transmission devices and the transmission devices are connected. It is necessary to prepare a correspondence table with the MAC addresses of all existing devices in each transmission apparatus, but it is very difficult to prepare such a table in a wide area network. When sending a frame to the ring network, a label for identifying the transmission source and the destination is added, so that each transmission device can control the bandwidth between the transmission devices only by having a table covering the combinations of the transmission devices. It becomes possible to do.

  A specific example will be described. When the transmission apparatus 1000 receives the frame 71 from the terminal 43 connected to the LAN 30, the transmission apparatus 1000 refers to its own route table and transmits this frame to the terminal 63 designated as the transmission destination MAC address of the frame 71. Know that it is necessary to transfer to the transmission device 3000. Then, a frame 72 to which a label indicating that the transmission source device is the transmission device 1000 and the destination transmission device is the transmission device 3000 is sent to two rings.

  Receiving the frame 72, the transmission apparatus 2000 refers to the label in the frame, and if it knows that the destination is another transmission apparatus, it collates the contents of the label with its own band control information, and performs band control. Get information about. If there is no problem in the current bandwidth, a frame having the same content is transmitted as a frame 73 to the ring. If the currently used bandwidth has already exceeded the set value, the frame 72 is discarded. The same processing is performed in the transmission device 4000 that has received the frame 72 through the other side of the ring.

  If no label is given to the frame 72, the transmission apparatus 2000 prepares in advance to identify the transmission apparatus corresponding to the source MAC address and the transmission apparatus corresponding to the destination MAC address. You need to refer to the table. Such a correspondence table is difficult to prepare in advance when there are a large number of devices connected to the network, but such a correspondence table is not necessary in the transmission method according to the present embodiment. ing. In FIG. 1, the band is designated as a percentage for each label, but the band may be designated as an absolute value.

  Upon receiving the frame 73 from the active ring, the transmission device 3000 refers to the label in the frame, and when it knows that the destination is itself, transfers the frame 74 from which the label has been deleted from the frame 73 to the terminal 63. The frame 74 has the same contents as the original frame 71. In this way, when a transmission device sends a frame to a ring, a label for identifying the transmission device is added, so that even in a network using Ethernet (registered trademark), bandwidth control between transmission devices can be performed. It becomes possible to do.

  Note that the content of the label attached to the frame may be changed according to the type of necessary bandwidth control. For example, when the band is controlled by the source transmission apparatus regardless of the destination transmission apparatus, information that can identify the transmission source apparatus may be set. Further, when performing band control for each combination of devices such as terminals connected to the transmission apparatus, it is necessary to set information for identifying the source device and information for specifying the destination device.

  Next, the configuration of the transmission apparatus according to the present embodiment will be described. Since all the transmission apparatuses have the same configuration, the transmission apparatus 1000 will be described as an example here. FIG. 2 is a block diagram illustrating the configuration of the transmission apparatus 1000 according to the present embodiment. As shown in the figure, the transmission apparatus 1000 includes an interface unit 1100, a control unit 1200, and a storage unit 1300.

  The interface unit 1100 is an interface unit for connecting to a network, and includes a ring interface unit 1110a, a ring interface unit 1110b, and a user interface unit 1120. The ring interface unit 1110a and the ring interface unit 1110b are interface units for connecting to a network constituting the ring, and one is connected to one of the duplicated rings and the other is connected to the other ring.

  The user interface unit 1120 is an interface unit for connecting to a network such as a LAN. In the following description, it is assumed that the user interface unit 1120 is connected to the LAN for convenience. Note that a plurality of ports may be provided in the user interface unit 1120 so that they can be connected to a plurality of networks at the same time.

  The control unit 1200 is a control unit for overall control of the transmission apparatus 1000, and includes a hello frame control unit 1210, a source device filter 1220, a destination device filter 1230, an active / preliminary selection unit 1240, and a timer device 1250. A bandwidth control unit 1260, a switch unit 1270, a label deletion unit 1280, and a label applying unit 1290.

  The hello frame control unit 1210 is a control unit that controls which of the duplicated rings is to be the active system by transmitting and receiving a control frame called a hello frame. FIG. 3 is a sample diagram showing an example of the configuration of the hello frame. As shown in the figure, in the hello frame, in addition to the TPID in which the identification number indicating that the frame is the hello frame is stored, an item called TTL (Time To Live) and the transmission apparatus of the transmission source There is an item called a transmission source device number in which an identification number is stored.

  Each transmission apparatus transmits a hello frame in which the maximum value is set in TTL to both of the duplicated rings at regular intervals. If the transmission device that has received the hello frame does not transmit the hello frame, the transmission device decrements the value of TTL by 1 and transfers it to the next transmission device. Then, the value of the TTL and the halo frame received from the same transmission device via the other ring are compared, and the ring through which the hello frame with the larger TTL has passed is used as the working ring when communicating with the transmission device. select.

  If a hello frame does not arrive from the same transmission device via the other ring even after a certain period of time has passed, it is considered that a failure has occurred in the ring on which the hello frame does not arrive, and the hello frame has arrived. Is selected as the active ring. As described above, in the transmission method according to the present embodiment, a hello frame is used to detect a failure and determine whether to switch the working / standby ring. In addition, when the hello frame received by the transmission apparatus is the one transmitted by the own apparatus, the frame is discarded.

  The source device filter 1220 confirms whether or not the frames received by the ring interface units 1110a and 1110b are transmitted from the own device, and if the frames are transmitted from the own device, discards them. Otherwise, it is a processing unit that delivers to the destination device filter 1230. Since the source device filter 1220 discards the frame transmitted by the own device, it is possible to prevent the frame from looping in the ring. The method for confirming whether or not the received frame is transmitted from the own device may be a method for judging from the source device number of the label attached to the frame, or the source MAC address It is good also as a method judged from.

  The destination device filter 1230 checks whether or not the delivered frame is addressed to a device connected to the local device via a LAN, and if it is addressed to a device connected to the local device via the LAN, This is a processing unit that is handed over to the preliminary selection unit 1240 and is handed over to the bandwidth control unit 1260 otherwise. The method for confirming whether or not the frame is addressed to the device connected to the local area network via LAN may be determined from the destination device number of the label attached to the frame, or the destination MAC address. It is good also as a method judged from.

  The working / standby selection unit 1240 checks whether or not the delivered frame is from the working ring, and if it is from the working ring, delivers it to the switch unit 1270, otherwise discards it. Is a processing unit. The frame delivered to the switch unit 1250 is determined by the switch unit 1270 to determine the transmission path to the destination device, the label is deleted by the label deletion unit 1280, and is transmitted to the target device via the user interface unit 1120. .

  Which of the two rings the active / preliminary selection unit 1240 considers to be the active system is based on the determination of the hello frame control unit 1210. When receiving a notification from the hello frame control unit 1210 that it is necessary to switch the ring between the active system and the standby system due to a failure or the like, the active / backup selection unit 1240 may Discard the ring frame, and then perform the switching process. Thus, by performing the switching process after discarding both frames for a certain period of time, it is possible to avoid receiving the same frame repeatedly.

  The timer device 1250 is a timer device for the hello frame control unit 1210 and the current / preliminary selection unit 1240 to measure time.

  The bandwidth control unit 1260 performs bandwidth control based on the bandwidth control information stored in the bandwidth information storage unit 1310 of the storage unit 1300 and transmits the delivered frame to the ring network via the ring interface unit 1110a or 1110b. Part. FIG. 4 is a block diagram showing a configuration of band control unit 1260 shown in FIG. As shown in the figure, the band control unit 1260 has a band control mechanism corresponding to the ring interface unit 1110a and a band control mechanism corresponding to 1110b independently.

  The bandwidth control unit 1260 receives frames from the two processing units of the destination device filter 1230 and the label assignment unit 1290. The frame delivered from the destination device filter 1230 is a mechanism corresponding to the ring on the side that received the frame. Processed by. On the other hand, the frame delivered from the label attaching unit 1290 is processed by both mechanisms.

  Since both mechanisms have the same configuration, a mechanism corresponding to the ring interface unit 1110a will be described here. The mechanism includes a multiplexer (MUX) 1261a, a label identification unit 1262a, queues 1263a to 1266a, and a reading unit 1267a. The multiplexer 1261 a is a device for joining the frame sent from the destination device filter 1230 and the frame sent from the label attaching unit 1290.

  The level identifying unit 1262a is a processing unit that identifies a label attached to a frame and stores the frame in a queue corresponding to the label. The queues 1263a to 1266a are first-in first-out buffers for storing frames distributed for each label. The reading unit 1267a is a processing unit that reads frames from the queues 1263a to 1266a so as to satisfy the conditions of the band control information stored in the band information storage unit 1310, and sends the frames to the ring network via the ring interface unit 1110a.

  The received frame is stored in a queue for each label, and a frame is read out from the queue according to a pre-registered bandwidth condition and transferred, thereby increasing communication traffic corresponding to any label. Even when the network is congested, communication corresponding to other labels can be kept stable.

  Note that the bandwidth control may be performed based on a combination of the label and another item in the same frame, instead of performing the bandwidth control based only on the label. For example, when constructing a VPN (Virtual Private Network), an item for identifying a user is added to a frame. By performing bandwidth control based on a combination of this item and a label, a dedicated line and a ring network are formed. Similar lines can be created virtually.

  Returning to the description of FIG. 2, the switch unit 1270 is a processing unit that determines the transmission path of the delivered frame with reference to the path information stored in the path information storage unit 1330 of the storage unit 1300. The switch unit 1270 determines the path of both the frame transmitted from the device connected to the transmission apparatus 1000 via the LAN to the ring network and, conversely, the frame transmitted from the ring network to the device connected to the transmission apparatus 1000 via the LAN. Do it.

  A frame for a device connected to the LAN is delivered from the active / preliminary selection unit 1240, the port of the user interface unit 1120 to be sent is determined by the switch unit 1270, and delivered to the label deletion unit 1280. . The frame for the ring network is delivered from the user interface unit 1120, the transmission unit to be transmitted is determined by the switch unit 1270, and delivered to the label attaching unit 1290.

  The label deletion unit 1280 is a processing unit that deletes a label from a frame received from the ring network, and the label addition unit 1290 is a processing unit that adds a label to a frame transmitted to the ring network. Here, an example of a frame without a label and a frame with a label are shown.

  FIG. 5 is a sample diagram showing an example of a frame without a label. As shown in the figure, a frame without a label is called a VLAN (Virtual Local Area Network) tag in addition to items such as a destination MAC address (MAC DA) and a source MAC address (MAC SA). Items can be included. The VLAN tag is added to construct a virtual network on an Ethernet (registered trademark) network, and is useful for dividing a wide area network into groups for each base or realizing a VPN.

  FIG. 6 is a sample diagram showing an example of a frame with a label attached thereto. As shown in the figure, the label is composed of a TPID for storing an identification number indicating that the area is a label and a ring management number. The ring management number is information used as a reference for bandwidth control. In the example of this figure, the destination device number for identifying the destination transmission device and the source device number for identifying the transmission device of the source are shown. It consists of a combination. The contents of the ring management number do not have to be as shown in this figure, and may be changed according to the type of necessary bandwidth control.

  The storage unit 1300 is a storage unit that stores various types of information, and includes a band information storage unit 1310, a label information storage unit 1320, and a route information storage unit 1330. The bandwidth information storage unit 1310 is a storage unit that stores information related to bandwidth control. The label information storage unit 1320 is setting information to be referred to when the label attaching unit 1290 attaches a label to the frame. For example, a correspondence table between a device number for identifying each transmission device and a MAC address of the transmission device is used. Remember. The path information storage unit 1330 is a storage unit that stores information related to frame path control.

  In this way, by providing a transmission device that constitutes a ring based on Ethernet (registered trademark) with a function of performing bandwidth control and redundancy, the network can have the same stability as when each transmission device is mesh-connected. . As can be seen by comparing the mesh connection example shown in FIG. 7 with the ring connection example shown in FIG. 8, the number of physical network facilities is small and the cost is low in the case of ring connection. The transmission method according to the present embodiment can be said to be very useful technology because it can obtain the same stability as mesh connection by a low-cost ring connection network.

  Next, a processing procedure of the transmission apparatus 1000 illustrated in FIG. 2 will be described. FIG. 9 is a flowchart illustrating a processing procedure when the transmission apparatus 1000 receives a frame from the LAN side. When the user interface unit 1120 receives a ring-oriented frame from the LAN, the user interface unit 1120 delivers the frame to the switch unit 1270 (step S101). The switch unit 1270 refers to the route information in the route information storage unit 1330 to determine which transmission device the frame should be transmitted to (step S102), and the label attaching unit 1290 labels the frame according to the determination result. To the bandwidth control unit 1260 (step S103). The bandwidth control unit 1260 performs bandwidth control with reference to the label attached to the frame (step S104), and sends the frame to the ring network via the ring interface units 1110a and 1110b (step S105).

  FIG. 10 is a flowchart illustrating a processing procedure when the transmission apparatus 1000 receives a frame from the ring side. When the ring interface units 1110a and 1110b receive a frame from the ring network (step S201), the ring interface units 1110a and 1110b check whether the frame is a hello frame. If the received frame is a hello frame (Yes at step S202), the frame is transferred to the hello frame control unit 1210 to perform a hello frame control process (step S203).

  If the received frame is not a hello frame (No at step S202), the frame is delivered to the transmission device filter 1220 to determine whether the frame is from the own device. If the frame originates from the own device (Yes at step S204), the source device filter 1220 discards the frame (step S205).

  If the frame is not originated from the own device (No at step S204), the frame is delivered to the destination device filter 1230 to determine whether the frame is addressed to the device connected to the own device via the LAN. Here, if the frame is not addressed to the device connected to the local area network (No in step S206), the frame is handed over to the bandwidth control unit 1260 for bandwidth control (step S207), and the bandwidth-controlled frame is transferred to the ring. Transfer to the next transmission apparatus (step S208).

  If the frame is addressed to the device connected to the local area network via LAN (Yes at step S206), the frame is transferred to the active / preliminary selection unit 1240 to determine whether the frame is from the active ring. If the frame is not from the active ring (No at Step S209), the current / preliminary selection unit 1240 discards the frame (Step S210).

  If the frame is from the active ring (Yes at Step S209), the label deletion unit 1280 deletes the label after being route-controlled by the switch unit 1270 (Step S211), and passes through the user interface unit 1120. Transfer to the LAN (step S212).

  FIG. 11 is a flowchart of a process procedure of the hello frame control process shown in FIG. Upon receiving the hello frame, the hello frame control unit 1210 determines whether the hello frame is a frame originating from the own device. Here, if the hello frame is a frame originating from the own apparatus (Yes at step S301), the hello frame is discarded (step S302).

  If the hello frame is not a frame originating from the own device (No at Step S301), the TTL value is decremented by -1 (Step S303), and the frame is transferred to the next transmission device on the ring (Step S304). It waits for a hello frame from the same device to arrive (step 305). Here, if the hello frame does not arrive even after a predetermined time has elapsed (Yes at step S306), the ring on the side where the hello frame has arrived is selected as the active system (step S307).

  When a hello frame originating from the same device arrives from the other ring (No at step S306), the TTL value of the received hello frame is decremented by -1 (step S308), and the frame is sent to the next transmission device on the ring. Transfer (step S309). The TTL values of two hello frames received from the same transmission apparatus are compared, and the ring on the side where the frame with the larger value arrives is selected as the active system (step S310).

  If the working ring is selected in step S307 or step S310, the working / reserve selection unit 1240 is notified of the ring selected as the working system (step S311). Upon receiving the notification, the working / standby selection unit 1240 determines whether or not switching between the working system and the standby system is necessary. If switching is necessary (Yes in step S312), a frame received from the working system and the standby system is determined. Discard for a certain period of time (step S313), and then switch between the active and standby rings (step S314).

  As described above, the transmission apparatus and the transmission method according to the present invention are useful in a ring network using Ethernet (registered trademark). In particular, in addition to the ring redundancy function, the transmission apparatus and the transmission method have a function of controlling the bandwidth between the transmission apparatuses. Suitable when necessary.

Claims (6)

A transmission device that constitutes a ring network using Ethernet (registered trademark),
Label attaching means for attaching a label indicating a transmission path to a frame received from outside the ring network;
Band control means for collating the label given by the label giving means with the band control information held in the storage means and sending the frame to the ring network within the pre-registered bandwidth range. A characteristic transmission device.   When relaying a frame flowing through the ring network, the bandwidth control means collates the label given to the frame with the bandwidth control information held in the storage means, and the frame is within a pre-registered bandwidth range. The transmission apparatus according to claim 1, wherein the transmission apparatus relays the data.   If one of the clockwise and counterclockwise flows of the ring network is recognized as the active system, the other flow is recognized as the standby system, and if there is a failure in the active system, the standby system is used 3. The transmission apparatus according to claim 2, further comprising working / preliminary selection means for switching to a system.   Of the multiplexed lines that make up the ring network, recognize a given line as the active system, recognize another line as the standby system, and switch to the active system when a failure occurs in the active system The transmission apparatus according to claim 2, further comprising a current / preliminary selection unit.   The transmission apparatus according to claim 3 or 4, wherein the working / standby selecting means discards a frame addressed to the own apparatus for a predetermined time before switching the standby system to the working system. A transmission method in a ring network configured using Ethernet (registered trademark),
A labeling step of giving a label indicating a transmission path to the frame in a transmission device that has received the frame from outside the ring network;
A frame sending step for collating the label given by the label giving step with the bandwidth control information held in the storage means, and sending the frame to a ring network within a pre-registered bandwidth range;
In the transmission apparatus for relaying the frame, a frame relay step of collating the label given to the frame with the band control information held in the storage means and relaying the frame within a pre-registered band range; A transmission method characterized by including.

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