JP2011182241A - Transmission apparatus, and alarm transmitting method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that, in a network employing T-MPLS techniques handling the Ethernet, between a client device and an opposite-side client device, it is necessary to implement shutdown by transparently transferring a link disconnection alarm to each of relaying devices. <P>SOLUTION: Even in a network system where a client device and a T-MPLS device are linked by auto-negotiation, by defining a link maintenance field on an FDI, even when an opposite-side node receives the FDI, necessity/non-necessity of shutdown is determined. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention also relates to a transmission apparatus and an alarm transmission method, and more particularly to a transmission apparatus that encapsulates / decapsulates an Ethernet (registered trademark) signal into a T-MPLS (Transport-MPLS) signal and an alarm transmission method thereof.

  In recent years, broadband lines such as the Internet have become widespread in homes, and the line demand is increasing mainly for IP traffic. In response to this, high-speed and inexpensive Ethernet has rapidly spread in the market in place of SONET / SDH, ATM, etc., which have been the mainstream of WAN.

  The Ethernet signal is configured by data (at least 12 bytes or more) representing a no-signal state called an IFG (Inter Frame Gap) between a MAC (Media Access Control) frame and a MAC frame defined in IEEE 802.3. MAC is a protocol belonging to the second layer (layer 2) of the OSI reference model. The role of the MAC frame is to store the protocol and data of the third layer (layer 3) or higher of the OSI reference model in the data area of the MAC frame, and securely transmit the stored protocol of layer 3 or higher to the target terminal. That is. The MAC frame includes a preamble (8 bytes) indicating the head of the MAC frame, a destination address (6 bytes) indicating the MAC address of the destination terminal of the MAC frame, and a source address indicating the MAC address of the terminal transmitting the MAC frame (6 bytes), Type / Length (2 bytes) indicating the length of the MAC frame, etc., a data area (variable length), and an FCS (Frame Check Sequence) (4 bytes). FCS is also called a checksum value.

  In Ethernet, a communicable state is called a link-up state, and a communicable state is called a link-down state. When the encoded MAC frame or IFG is normally received without code violation, it is determined that the link is up. When the auto-negotiation function is ON, in addition to the above conditions, it is determined that the link-up state occurs when the auto-negotiation sequence specified in IEEE 802.3 is completed. The auto-negotiation function sends auto-negotiation frames such as NLP (Normal Link Pulse) / FLP (Fast Link Pulse) to each other, and based on the auto-negotiation sequence, the operation mode and status of the devices between the connected devices It is a function to exchange each other. The auto negotiation function is set to ON or OFF according to the specification of the transmission apparatus.

  On the other hand, in recent years, full IP (Internet Protocol) / Ethernet (registered trademark) has been developed in the backbone network of communication carriers. As a result, a backbone network based on the existing SDH / SONET technology and a backbone network based on the new IP / Ethernet technology coexist.

  In response to this situation, in order to eliminate the inefficiency of equipment and maintenance due to the coexistence of networks, studies are being made to consolidate IP / Ethernet-based backbone networks by converting SDH / SONET signals into IP / Ethernet packets. ing. Specifically, it is a T-MPLS (Transport-MPLS) technique defined in ITU-T Y.1370.1, Y.1371, Y.1381, and the like.

  The MPLS frame 500 will be described with reference to FIG. In FIG. 1, an MPLS frame 500 includes an 8-byte preamble 510, a 6-byte destination address 520, a 6-byte source address 530, a 3-byte Type / Length 540, a 4-byte shim header 550-1, 550-2, It consists of variable length data 560 and FCS (Frame Check Sequence) 570. The IFG 10 is inserted before and after the MPLS frame 500.

  Data 560 stores payload data of the SDH / SONET signal. The shim header 550 includes a 20-bit label 551, a 3-bit EXP 552, a 1-bit S553, and an 8-bit TTL 554. Two or more shim headers 550 can be stacked. In FIG. 1, two shim headers 550 are stacked.

  The contents of each field of the shim header will be described with reference to FIG. In FIG. 2, a label 551 is an MPLS label ID. Each node refers to the label and performs data transfer. EXP 552 is an Experimental Use bit. S553 is Bottom of Stack. When it is 1, it indicates the last label. On the other hand, S553 indicates that there is a next label when 0. TTL 554 is Time To Live, and is decremented by 1 every time it is transferred. The frame is discarded when TTL 554 is 0.

  Here, since a case where Ethernet is used as a transmission medium is shown, a MAC header (a header from preamble to Type / Length) and an FCS which is a footer are added. However, the physical transmission medium may not be Ethernet. In this case, a header and a footer according to the transmission medium are added instead of the MAC header and the footer.

  In the T-MPLS network, destination IP address information is given to a label stored in a shim header. After that, only the label is seen and forwarding is repeated. When the destination is reached, the label is removed. As a result, the route of the label packet forwarded by MPLS can be treated like a single path. In the T-MPLS network, by controlling the label table of each node, it is possible to provide an explicit route to the IP network and prevent aggregation of packets to a specific route, thereby improving the link usage efficiency. Become.

  Also, in the T-MPLS technology, in order to support high-quality and stable transfer of transferred data even in the case of IP / Ethernet packets, ITU-T Y.1711 has an OAM (Operation And Maintenance) function and A maintenance operation function is provided.

  The OAM frame format will be described with reference to FIG. 3, the OAM frame 600 has a configuration in which the shim header 550-2 of the MPLS frame 500 shown in FIG. 1 is an OAM label 680 and the data 560 is a 44-byte OAM payload 660.

  That is, the OAM frame 600 includes an 8-byte preamble 610, a 6-byte destination address 620, a 6-byte source address 630, a 3-byte Type / Length 640, a 4-byte shim header 650, a 4-byte OAM label 680, and 44 bytes. OAM payload 660 and 4-byte FCS 670. The IFG 10 is inserted before and after the MPLS frame 600.

  The OAM label 680 includes a 20-bit label 681, a 3-bit EXP 682, a 1-bit S683, and an 8-bit TTL 684. The OAM label 680 reserves the label ID = 14 for the OAM frame according to ITU-T Y.1711. The values of EXP, S, and TTL are defined as EXP = 0, S = 1, and TTL = 1.

  The OAM payload 660 includes a 1-byte Function Type 661, a 20-byte LSP (Label Switch Path) TTSI (Trail Termination, Source Identifier) 663, a 2-byte BIP (Bit Interleaved Party) 665, and a 3-byte and 18-byte OAM frame, respectively. It consists of separate data areas 662 and 665. The contents of each field will be described below.

  Function type 661 is a field indicating the OAM type. The value of Function type is defined by Y.1711 (see FIG. 4). The LSP TTSI 663 includes an LSR ID and an LSP ID that specify an OAM frame transmission node. In Y.1711, the LSR ID is defined as an IPv6 address or an IPv4 address allocated to a node. The calculation range of the BIP16 665 for error correction is 42 bytes from the Function type 661 to immediately before the BIP16 field.

  With reference to FIG. 4, typical function types of OAM will be described. In FIG. 4, when Function type 661 is 0x01, OAM is CV (Connectivity Verification). When Function type 661 is 0x02, OAM is FDI (Forward Defect Indicator). When Function type 661 is 0x03, OAM is BDI (Backward Defect Indicator). When the Function type 661 is 0x07, the OAM is FFD (First Failure Detection).

  CV is a function for confirming the normality of End to End of the MPLS path. The CV is inserted from a UNI (User Network Interface) in the T-MPLS apparatus that is the transmission end point, and is terminated at the UNI in the T-MPLS apparatus that is the reception end point. The CV insertion period is fixed at 1 second. The UNI that is the CV receiving end point detects the LOCV (Loss Of CV) state when the CV non-receiving state continues for 3 seconds, and notifies the UNI that is the CV transmitting end point of LOCV detection by BDI. By detecting the LOCV, it is possible to confirm the state of the transmission line such as a transmission line break.

  The transmission directions of FDI and BDI will be described with reference to FIG. In FIG. 5, the network 700 includes three MPLS devices 200 and m user devices 300. In the MPLS device 200, an MPLS device 200-1, an MPLS device 200-3, and an MPLS device 200-2 are arranged in this order from West to East. User devices 300-1 to 300-n are connected to the MPLS device 200-1. User devices 300-n + 1 to 300-m are connected to the MPLS device 200-2.

  In FIG. 5, when a disconnection occurs in the transmission path from the MPLS device 200-1 to the MPLS device 200-3, the MPLS device 200-3 transmits FDI to the MPLS device 200-2. In addition, the MPLS device 200-3 transmits BDI to the MPLS device 200-1.

  The FDI notifies the abnormality and the cause thereof in the upstream direction (transmission direction of the MPLS device 200-1). The FDI is inserted into the detection path when a link down is detected with the user apparatus in the UNI or when a link down is detected between the T-MPLS apparatuses in the NNI (Network Node Interface). The FDI is inserted at 1-second intervals until failure detection is canceled. The FDI notifies the failure information causing the failure to the UNI that is the termination point of the path and the NNI that is the relay point of the path in the Defect type field 6622 (described later) of the payload.

  The FDI payload 660A will be described with reference to FIG. In FIG. 6, the FDI payload 660A is configured by allocating Reserved 6621 and Defect type 6622 in the OAM-specific data area 662 of the OAM payload 660, and Defect location 6641 and Pad all0 6642 in the OAM-specific data area 664 of the OAM payload 660. The BDI payload has the same configuration.

  The BDI is a function for notifying an abnormality and its cause in the downstream direction (direction opposite to the transmission direction) shown in FIG. The BDI inserts failure occurrence information for notification to the UNI that is the end point for the path that has received the FDI and the path that has detected the LOCV. BDI is inserted at 1 second intervals while receiving FDI. Like the FDI, the BDI notifies the failure occurrence information to the UNI that is the termination point of the opposite path and the NNI that is the relay point of the path by using the defect type 6622 of the payload.

  The FFD is a function for confirming the normality of End to End of the MPLS path in the same manner as the CV. The FFD is inserted from the UNI that is the transmission end point. The FFD is terminated at a UNI that is a reception end point. The CV insertion period is fixed at 1 second, while the FFD insertion period can be variably set at 10 ms, 20 ms, 50 ms, 100 ms, 200 ms, and 500 ms. The FFD is mainly used for switching from the active system to the standby system when a transmission line break occurs. For this reason, FFD needs to change an insertion period by permissible switching time.

  In general, a transmission apparatus is required to transmit a transmission signal transparently from the viewpoint of maintenance operation. This transparent transmission will be described with reference to FIG. In FIG. 7, a network 710 is composed of a station 10-1 and a station 10-2 connected by two optical fibers 20. The two office buildings 10 are each configured by a user device 300 and a transmission device 200 connected by two optical fibers 20. The transmission apparatus 200 includes a UNI 210, a SW (switch) 230, and an NNI 240, respectively. The UNI 210 connects the user device 300. The NNI 240-1 is connected to the NNI 240-2. The SW 230 exchanges an electrical signal from the UNI 210 and transmits it to the NNI 240. In addition, the SW 230 exchanges the electrical signal from the NNI 240 and transmits it to the UNI 210. The UNI 210 and the NNI 240 include an O / E conversion unit 30 and an E / O conversion unit 40, respectively. The O / E converter 30 converts an optical signal into an electrical signal. The E / O converter 40 converts an electrical signal into an optical signal.

  In FIG. 7, the solid line connecting each device is a physical wiring (optical fiber or electric cable). A broken line indicates a logical connection. In the physical wiring on the paper surface, a signal is transmitted in the direction (West → East) from the user device 300-A to the user device 300-B. On the other hand, in the physical wiring below the paper surface, a signal is transmitted in the direction (East → West) from the user device 300-B to the user device 300-A.

  Transparent transmission is physically performed between the user apparatus 300-A installed in the station 10-1 and the user apparatus 300-B installed in the station 10-2 in the network 710. Although A and the transmission apparatus 200-B are interposed, it is logically equivalent to a state in which the user apparatus 300-A and the user apparatus 300-B are directly connected. Specifically, it refers to transmission that is output to the user apparatus 300-B as it is without changing the format or data content of the signal output from the user apparatus 300-A. In such a transparent transmission device, it is necessary to notify the user device 300-B of an alarm caused by a failure between the user device 300-A and the transmission device as it is.

  A T-MPLS apparatus that handles Ethernet signals is also required to be such a transparent transmission apparatus. The T-MPLS device needs to notify the user device 300-B of the detected link down alarm by transferring the alarm within the T-MPLS network.

  Conventionally, establishment of a data link between terminals has been monitored, and a failure can be detected by disconnecting the link at the opposite terminal regardless of where the failure occurs between the terminals. Furthermore, when the opposite terminal performs control for disconnecting the link with respect to the transmission side terminal, the transmission side terminal is in a link disconnection state and can recognize the failure. Even if there is a relay device between the terminals, the operation does not change if the relay device transfers the data from the terminal transparently without any processing.

  However, when data from a terminal is once terminated and encapsulated by a technique such as GFP (Generic Framing Procedure) to transfer a relay section, data link control between terminals cannot be performed. For this reason, there has been a problem that a failure occurring in the relay section cannot be detected by the opposite terminal. As a reason for encapsulating the relay section with GFP or the like, specifically, when a plurality of Ethernet signals are multiplexed and transmitted, it is necessary to identify which Ethernet signal each packet was included in. This is because the identification information is put in the header.

In Patent Document 1, as an alarm transfer method, in the case of GFP, a transfer method in which an alarm bit is defined in a payload header and a method in which an OAM frame is defined and transferred are listed.
However, in a network using T-MPLS at present, when link down occurs, it is prescribed in ITU-T Y.1711 that FDI is transferred. Tighten the bandwidth against.

Japanese Patent Laid-Open No. 2003-110585

  In a network using the T-MPLS technology that handles Ethernet, it is necessary to transparently transfer a link disconnection alarm to each relaying device between the local client device and the opposite client device to perform shutdown. is there.

  In ITU-T Y.1711, when a link-down is detected in the T-MPLS device due to a failure between the client device and the T-MPLS device, the failure is notified to the opposite T-MPLS device using FDI. The opposite node that received it shuts down.

  When auto-negotiation is OFF, a link disconnection occurs at the failure occurrence side node, and FDI is transmitted. When the opposite side node receives this FDI, it shuts itself down to notify the client terminal connected to the opposite side node of an alarm.

  When this method is used with auto-negotiation ON, if the opposite side node that receives the FDI shuts down the transmission port to the subordinate client device, a bidirectional shutdown phenomenon is caused.

  This phenomenon is due to the auto-negotiation sequence. When the transmission port of the opposite side node shuts down, only the one-system link between the transmission port of the opposite side client device and the reception port of the opposite side node is operating. However, if the monitoring pulses are periodically transmitted and received in the auto-negotiation sequence, the response is not returned from the opposite node to the subordinate client device because it is in a single system state. In such a state in the sequence, both systems forcibly perform link down.

  Therefore, the link-down state that has occurred between the opposite-side node and the client device connected to the opposite-side node will now transfer the FDI to the local device that originally caused the link-down, so that Forcibly shuts down the system link. Due to this spillover link down, the local system and the opposite side continue to be unable to recover.

  As a link-down transfer method that can be used when auto-negotiation is ON, a link maintenance request field for determining the presence or absence of shutdown according to the state of the T-MPLS network is defined. By sending the special information (link maintenance request field) from the local T-MPLS device (node) that has detected the link down to the opposite side node, the opposite side node determines whether or not there is a shutdown according to the numerical value of the information. The above problem can be avoided.

  The problem described above is that the client device and the opposite transmission device are connected, the first signal from the client device is encapsulated and transmitted to the opposite transmission device, and the second signal from the opposite transmission device is decapsulated to the client device. In the transmission apparatus to be transmitted, the link determination unit for determining the link auto-negotiation with the client device and the up / down, the client determination unit for determining the normality of the first signal, and the second signal are shut down. When the link determination unit detects link down, the shutdown processing unit is composed of an alarm transmission / reception unit that transmits a first alarm to the opposite transmission device and receives a second alarm from the opposite transmission device, and an alarm processing unit. The alarm processing unit turns on / off auto-negotiation, executes / non-executes shutdown, and Normal / abnormal and based on, create a first alarm to be sent to the opposing transmission device, the transmission device transmits from the alarm receiving section can be achieved.

  Also, a first step for determining whether the auto-negotiation setting is ON, a second step for determining whether a signal shutdown to the client device is being executed, and a third step for determining whether the signal from the client device is normal Based on the determination results of the first step, the second step, and the third step, an alarm transmission comprising a fourth step for creating an alarm and a fifth step for transmitting the alarm to the opposite transmission device This can be achieved by the method.

  According to the present invention, alarm transfer can be performed transparently regardless of whether auto-negotiation is set to ON or OFF.

It is a format of an MPLS data frame. It is a figure explaining the content of a shim header. It is a format of an MPLS OAM frame. It is a figure explaining the typical content of MPLS OAM. It is a block diagram of the transmission network explaining the direction of FDI and BDI. This is the format of the FDI payload. It is a block diagram explaining the structure of a transmission network. It is a block diagram explaining the structure of the transmission network at the time of auto negotiation OFF. It is a hardware block diagram of an MPLS device. It is a hardware block diagram of SDH-UNI. It is a flowchart of the OAM processing part explaining the reception processing process of FDI-BDI. It is a flowchart of the alarm process part explaining the transmission processing process of FDI-BDI. It is a sequence diagram of link down transfer at the time of auto negotiation OFF. It is a block diagram explaining the structure of the transmission network at the time of auto negotiation ON. It is the format of the payload of FDI explaining a link maintenance request field. It is a flowchart of the node explaining the transmission process of FDI and a link maintenance request field. It is a sequence diagram of link down transfer at the time of auto negotiation ON.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings using examples. Note that the same reference numerals are assigned to substantially the same portions, and the description will not be repeated.

  First, the configuration of the link-down transfer network when auto-negotiation is OFF will be described with reference to FIG. In FIG. 8, the link-down network 800 includes two nodes 400 and a client device 300 connected to each node 400. The client apparatus 300 and the node 400 are bidirectionally connected by two optical fibers 20. Further, the node 400-A and the node 400-B are bidirectionally connected by two optical fibers 20. The arrow attached to the optical fiber 20 is the transmission direction of the optical signal.

  In FIG. 8, the link A between the client apparatus 300-A and the node 400-A and the link B between the client apparatus 300-B and the node 400-B are both set without auto-negotiation connection. . Each of the two nodes 400 is a T-MPLS device.

  The hardware configuration of the T-MPLS apparatus 400 will be described with reference to FIG. In FIG. 9, the T-MPLS apparatus 400 includes four packages of SDH-UNI 410, GbE-UNI 420, SW 430, and NNI 440. The SDH-UNI 410 performs encapsulation / decapsulation and multiplexing / demultiplexing of SONET / SDH signals and MPLS signals. The GbE-UNI 420 performs encapsulation / decapsulation and multiplexing / demultiplexing of the Ethernet signal and the MPLS signal. The SW 430 switches the transmission route. The NNI 440 transmits the multiplexed high-speed signal over a long distance to the opposite MPLS device.

The SDH-UNI 410 and the GbE-UNI 420 include a plurality of SFP (Small Form Factor Pluggable) 411 and 421 as interfaces with the client device 300. In addition, the SDH-UNI 410 and the GbE-UNI 420 include a plurality of electrical connectors 417 and 427 at the interface with the SW 430. The SW 430 includes a plurality of electrical connectors 437. The NNI 440 includes an XFP (10 Gigabit Small Form Factor Pluggable) 441 as an interface with the node 400. The NNI 440 includes a plurality of electrical connectors 447 at the interface with the SW 430.
Here, regarding the OAM signal of the maintenance operation signal, the SDH-UNI 410 and the GbE-UNI 420 execute insertion / reception processing.

  The hardware configuration of the SDH-UNI 410 will be described with reference to FIG. In FIG. 10, SDH-UNI 410 includes n SFP 411, SDH / SONET / MPLS conversion unit 412, OAM processing unit 413, alarm processing unit 414, transmission line disconnection detection device 415, auto negotiation determination circuit 416, and two units. An electrical connector 417 is used.

  First, the movement of the main signal (solid line) will be described. For the SDH / SONET signal output from the user device, the SFP 411 performs photoelectric conversion. The SDH / SONET / MPLS conversion unit 412 encapsulates the converted electric signal and outputs it to the SW 430. Conversely, for the MPLS signal input from the SW 430, the transmission path disconnection detection device 415 processes the main signal and the OAM signal separately. In the case of the main signal, the SDH / SONET / MPLS conversion unit 412 decapsulates. The SFP 411 performs electro-optical conversion on the decapsulated electric signal and sends it to the user apparatus 300. The SDH / SONET / MPLS conversion unit 412 determines whether or not the reception signal from the client device 300 is normally received. The SDH / SONET / MPLS conversion unit 412 can shut down the transmission signal to the client device 300.

  Regarding the auto-negotiation connection with the user apparatus 300, the auto-negotiation determination circuit 416 performs setting and management. The auto-negotiation determination circuit 416 recognizes the support mode on the user apparatus side by transmitting and receiving an auto-negotiation frame. As a result, a mode capable of higher speed communication is selected. The auto-negotiation sequence is normally completed, and the monitoring frame is periodically transmitted even after the link is established. The auto-negotiation determination circuit 416 manages the setting. Therefore, the auto-negotiation determination circuit 416 can confirm whether or not auto-negotiation is set.

  Note that it is obvious to those skilled in the art that the SDH-UNI 410 described with reference to FIG. 10 has the same configuration as the GbE-UNI 420. That is, if the SDH / SONET / MPLS conversion unit 412 is read as the GbE / MPLS conversion unit 422, the configuration is exactly the same.

  Next, the movement of the OAM signal (broken line) will be described. For the OAM signal, the OAM processing unit 413 performs transmission and reception processing. This reception process will be described with reference to FIG. In FIG. 11, the OAM processing unit 413 determines whether FDI is detected (S11). In the case of YES, the OAM processing unit 413 notifies the alarm processing unit 414 of FDI reception (S13) and ends. When NO in step 11, the OAM processing unit 413 determines whether BDI has been detected (S15). If YES, the OAM processing unit 413 notifies the alarm processing unit 414 of BDI reception (S17), and ends. If NO in step 11, the OAM processing unit 413 discards the frame as a non-standard frame (S19) and ends.

  The transmission process of the OAM processing unit 413 will be described with reference to FIG. The SDH / SONET / MPLS conversion unit 412 and the transmission line disconnection detection device 415 notify the alarm processing unit 414 when a failure is detected. The alarm processing unit 414 notifies the OAM processing unit 413 of the alarm to be notified to the opposite device according to the type of failure. In FIG. 12, the OAM processing unit 413 determines whether a packet is not flowing through the MPLS transmission line (idle) (S21). If YES, the OAM processing unit 413 sends FDI or BDI (S23) and ends. If NO at step 21, the process transitions to step 21 again.

  The operation of the OAM processing unit 413 of the SDH-UNI 410 described with reference to FIGS. 11 and 12 is exactly the same as the operation of the OAM processing unit 423 (not shown) of the GbE-UNI 420.

  With reference to FIG. 13, a link down transfer sequence at the time of auto negotiation OFF will be described. In FIG. 13, in the initial state, a link is established between the client 300-A and the node 400-A. A link is established between the client 300-B and the node 400-B. As a result, the client 300-A, the node 400-A, the client 300-B, and the node 400-B are all in a link-up state.

  From this state, a failure occurs in the transmission path from the client device 300-A to the node 400-A. The node 400-A detects link down (S31). The node 400-A transmits FDI to the node 400-B (S32). The node 400-B shuts down the output to the client device 300-B (S33). The client device 300-B detects a link down (S34). Note that the node 400-A periodically transmits the FDI to the node 400-B. As a result, the node 400-B continues to shut down the output to the client device 300-B.

  Here, the failure is recovered in the transmission path from the client apparatus 300-A to the node 400-A. As a result, the node 400-A is linked up (S37). The node 400-A cancels the FDI periodic transmission to the node 400-B (S38). The node 400-B that has not received the FDI cancels the shut down (S39). The client apparatus 300-B performs link up (recovers link down) (S41).

  Note that the client device 300-A is always in a link-up state because auto-negotiation with the node 400-A is OFF. The node 400-B is also always in a link-up state because the auto-negotiation with the client device 300-B is OFF. Therefore, the node 400-B does not transmit the FDI to the opposite node 400-A even if the output to the client device 300-B is shut down (see # 2 in Table 1 described later).

  With reference to FIG. 14, the configuration of the network when auto-negotiation is ON will be described. In FIG. 14, the configuration of the network 800A is the same as that of the network 800 of FIG. However, the link A between the client apparatus 300-A and the node 400-A and the link B between the client apparatus 300-B and the node 400-B are both set with auto-negotiation connection.

  In this embodiment, a link maintenance request field is defined on the FDI in order to avoid the spread of the node 400-A shut down due to the link down at the time of auto negotiation ON, and the opposite T-MPLS node sets the link maintenance request field. By reading, the presence / absence of shutdown is flexibly determined based on the presence / absence of auto-negotiation setting, the signal input state, and the signal output state.

  With reference to FIG. 15, the assignment of a link maintenance request field to the reserve byte in the FDI will be described. In FIG. 15, the FDI payload 660B is composed of a Function 661, a link maintenance request field 6621A, a Defect type 6622, an LSP TTSI 1663, a Defect location 6641, a Pad all0 6642, and a BIP 16 665. As is clear from comparison with FIG. 6, the link maintenance request field 6621A in FIG. 15 is allocated to the Reserved 6621 in FIG. The link maintenance request field 6621A may be assigned to another field, but by being assigned to the Reserved 6621, the communication band related to alarm transfer can be realized with the minimum necessary amount.

  With reference to FIG. 16, FDI transmission processing after detection of link-down will be described. In FIG. 16, when detecting a link down, the node 400 determines whether or not auto-negotiation is set between the current links (S51). As described above, the presence / absence of the setting is recorded in the auto-negotiation determination circuit 416, so that the determination of the presence / absence of the auto-negotiation function can be confirmed.

  When auto-negotiation is OFF (NO), the node 400 sets “0x00” in the link maintenance request field in the FDI reserve byte transmitted to the opposite node (S56). Here, the link maintenance request field of “0x00” is an output shut down instruction to the opposite node. The node 400 executes a shut down (S57). The node 400 transmits the FDI (S58) and ends.

If auto-negotiation is ON in step 51, the node 400 determines whether the transmission-side port to the client is shut down (S52). When the determination is NO, the node 400 transitions to step 56. When YES in step 52, the node 400 determines whether the strength of the carrier input to the reception port is insufficient (S53). When the determination is NO, the node 400 transitions to step 56. If YES in step 53, the node 400 sets the link maintenance request field “0x01” in the FDI reserve byte (S54), and proceeds to step 58. Here, the link maintenance request field “0x0” is a link maintenance instruction to the opposite node.

Table 1 Conditions for determining link maintenance request field value -----------------------------------
# Auto Nego Link Down Shutdown No signal FDI link maintenance request
Situation Status Input status Sending field ------------------------------------
1 OFF 1 d.c. d.c. ○ 0x00
2 OFF 0 d.c. d.c. × −
3 ON 1 1 1 ○ 0x00
4 ON 1 1 0 ○ 0x01
5 ON 1 0 1 ○ 0x00
6 ON 0 1 1 × −
7 ON 1 0 0 ○ 0x00
8 ON 0 1 0 × −
9 ON 0 0 1 × −
10 ON 0 0 0 × −
-----------------------------------

  With reference to Table 1, FDI transmission in each status and setting of link maintenance request field values will be described. In Table 1, the reserve byte determination condition includes auto-negotiation, Link Down, Shutdown Status, no signal input state, FDI transmission, and link maintenance request field. Link down is 1 when link-down is detected, and 0 when link-down is not detected (in a link-up state). When the Shutdown Status is 1, the shutdown is being executed. When the Shutdown Status is 0, the signal transmission status is indicated. The signal non-input state is a state where the power intensity of the transmission carrier is insufficient when it is 1, and a state where input can be normally confirmed when it is 0. The link maintenance request field (in this embodiment, the FDI reserve byte is used) indicates that shutdown execution is performed when “0x00”, and shutdown execution is not performed when “0x01”. The facing T-MPLS device determines whether or not there is a shutdown according to these conditions. In Table 1, d.c. is don't care, meaning irrelevant.

  # 1 and # 2 are determined according to each status under the condition that the auto negotiation setting is OFF. When the own node finds that the link is down, the FDI for executing the shutdown of the link maintenance request field “0x00” is transmitted to the opposite side node (# 1). On the other hand, since # 2 is in a link-up state, FDI is not transmitted.

  # 3 to # 10 are FDI transmission and link maintenance request field setting values according to each status when the auto-negotiation setting is ON. In # 3, when a link-down is detected, the transmission port is in a shutdown state and no signal input state. This is because link between the own node and the subordinate client device is not possible, especially when the signal from the subordinate client device is not normally received because the signal is not input at the receiving port. Therefore, the FDI for executing the shutdown of the link maintenance request field “0x00” is transmitted to the opposite side node.

  In # 4, when a link down is detected, the transmission port is shut down and the signal input state is normal. In this case, FDI is transmitted to the opposite side node, but “0x01” is set in the link maintenance request field. When the node 400-B in FIG. 14 is replaced with its own node, the node 400-B receives the FDI from the node 400-A when the auto-negotiation is ON. Therefore, the node 400-B has a transmission port to the client device 300-B. Shut down. The reception port of the node 400-B normally receives a signal from the client device 300-B. In this case, it can be estimated that the cause of the link down is the own shutdown. In order to avoid the both-system shutdown state, the node 400-B sets the link maintenance request field “0x01” that does not cause the opposite T-MPLS apparatus to shut down.

  In # 5, when a link down is detected, the transmission port is not shut down, and the signal is not input. Since no signal is input to the receiving port, the signal from the subordinate client device does not reach normally. Therefore, since the link down is detected, the FDI for executing the shutdown of the link maintenance request field “0x00” is transmitted to the opposite side node.

  In # 6, the transmission port is shut down at the time of link up, and no signal is input. This is a case where link down is not detected even though the signal is not input, and does not occur during normal operation. As a measure when the link down is no longer detected due to a failure of the device itself, the setting is made so that FDI is not transmitted.

  In # 7, when a link down is detected, the transmission port is not shut down, and the signal input state is also normal. This is a situation that occurs while sending and receiving auto-negotiation frames to establish a link between the own node and subordinate client devices. Since the link down is detected, the FDI for executing the shutdown of the link maintenance request field “0x00” is transmitted to the opposite side node.

In # 8, at the time of link up, the transmission port is shut down, and the signal input state is also normal. Since the link is not down, FDI is not transmitted.
In # 9, when the link is up, the transmission port is not shut down and the signal is not input. As in # 6, it is assumed that no signal is input but link-down is not detected and a failure occurs due to the failure of the device itself. In this case, FDI is not transmitted.
In # 10, the transmission port is not shut down at the time of link up, and the signal input state is also normal. Since all the set statuses are normal, the FDI is not transmitted.

  With reference to FIG. 17, the link-down transfer sequence when auto-negotiation is ON will be described. In FIG. 17, in the initial state, the link A between the client apparatus 300-A and the node 400-A and the link B between the client apparatus 300-B and the node 400-B are currently being linked up. When a failure occurs between the links A, the node 400-A detects a link down (S61). The client apparatus 300-A detects the link down due to the failure of the auto negotiation sequence (S62). The node 400-A sends FDI to the node 400-B (S63). Here, the FDI link maintenance request field 6621A is set to “0x00”. The node 400-B executes shutdown by receiving the FDI (S64). The client device 300-B detects a link down (S66).

  The node 400-B fails in the auto-negotiation sequence and detects a link down (S67). Since the node 400-B corresponds to the state of # 4 in Table 1, the FDI having the link maintenance request field 6621A of “0x01” is transmitted (S68). Even if the node 400-A receives the FDI in the link maintenance request field 6621A, the node 400-A does not perform the shutdown. Note that the node 400-A and the node 400-B continue to periodically transmit FDI.

  When the failure between the links A is recovered, the node 400-A is linked up (S71). The client device 300-A succeeds in the auto-negotiation sequence and links up (S72). The node 400-A cancels the periodic transmission of the FDI (S73). Since the node 400-B does not receive the FDI, the node 400-B cancels the shut down (S74). As a result, the client device 300-B is linked up (S76). The node 400-B succeeds in the auto-negotiation sequence and links up (S77). The node 400-B cancels the periodic transmission of the FDI (S78).

  As described above, by setting the link maintenance request field in the FDI reserve byte value, it is possible to avoid a network spillover link down when auto-negotiation is ON.

  200 ... MPLS device (node), 300 ... user device (client device), 400 ... MPLS device (node), 410 ... SDH-UNI, 420 ... GbE-UNI, 430 ... SW, 440 ... NNI, 411 ... optical module ( SFP), 412... SDH / SONET / MPLS conversion unit, 413... OAM processing unit, 414... Alarm processing unit, 415... Transmission path detection device, 416 .. auto negotiation determination circuit, 417. 421 ... SFP, 427 ... electric connector, 430 ... SW, 437 ... electric connector, 440 ... NNI, 441 ... XFP, 447 ... electric connector.

Claims (5)

Connected to a client device and a counter transmission device, encapsulates a first signal from the client device and transmits it to the counter transmission device, and decapsulates a second signal from the counter transmission device and transmits it to the client device In the transmission device
A link determination unit for determining auto-negotiation of a link with the client device and up / down, a client determination unit for determining normality of the first signal, and a shutdown processing unit for shutting down the second signal And an alarm transmission / reception unit that transmits a first alarm to the opposite transmission device and receives a second alarm from the opposite transmission device, and an alarm processing unit,
When the link determination unit detects a link down, the alarm processing unit is configured to detect the opposite based on ON / OFF of auto negotiation, execution / non-execution of shutdown, and normality / abnormality of the first signal. The transmission device, wherein the first alarm to be transmitted to the transmission device is created and transmitted from the alarm transmission / reception unit. The transmission device according to claim 1,
The alarm processing unit controls the opposite transmission apparatus not to shut down when auto-negotiation is ON, shutdown is executed, and the first signal is normal. The transmission device according to claim 1,
The alarm processing unit controls the opposite transmission apparatus to shut down when auto-negotiation is ON, shutdown is executed, and the first signal is other than normal. The transmission device according to claim 3,
When the shutdown is not executed, the shutdown processing unit shuts down the second signal. A first step for determining whether the auto negotiation setting is ON;
A second step of determining whether a signal shutdown to the client device is being executed;
A third step of determining whether the signal from the client device is normal;
A fourth step of creating an alarm based on the determination results of the first step, the second step, and the third step;
An alarm transmission method comprising: a fifth step of transmitting the alarm to an opposing transmission device.

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