JP2006067040A - Interface converting device and protection system - Google Patents

Abstract

【Task】
In a network using an interface converter that encapsulates synchronous transmission signals such as TDM or STM with a packet transmission protocol and performs circuit emulation, a protection method for improving the reliability of the packet network, and its protection method. An interface conversion device is provided.
[Solution]
According to the protection method of the present invention, in an interface conversion device that converts a synchronous transfer signal into a packet signal, switching information is included in additional information that is added after multiplexing the TDM signal, and a destination header of the packet network is added. A pair of working and spare ports are provided at the packet network side port of the interface converter, and a path transmission path is constructed between the interface converters facing each other. A protection method is realized by making these path transmission lines into a duplex pair.
[Selection] Figure 1

Description

  The present invention relates to an interface conversion device and a protection method, and a protection method for an interface conversion device that encapsulates a synchronous transfer signal such as TDM (Time Division Multiplexing) or STM (Synchronous Transmission Mode) with a packet transmission protocol and performs circuit emulation, The present invention also relates to an interface conversion device used in the duplex configuration system. The packet protocol particularly relates to, but is not limited to, MAC defined by IEEE 802.3, IP defined by IETF (Internet Task Force) RFC 791, and MPLS defined by IETF RFC3031.

  IP-VPN (Virtual Private Network) based on IP has rapidly spread against the background of the demand for economical leased lines. However, in recent years, a wide area using Ethernet (registered trademark), which was a LAN technology, has been used. Ethernet (registered trademark) is also attracting attention as a dedicated line. In particular, there is a growing need to apply Ethernet (registered trademark) to carrier networks and metro systems, but when applying packet networks such as IP and Ethernet (registered trademark) to existing networks, Interworking technology that performs interface conversion is required. In addition, when applied to a carrier network, a failure management method with a view to network management by the carrier is required.

  As a first prior art in the present invention, there is the IEICE Technical Report CS 2004-35 (2004-07) (Non-patent Document 1). This prior art relates to an interface conversion apparatus that converts a synchronous transfer signal into a packet transmission signal. This prior art discloses a technique for encapsulating a TDM signal into a MAC frame and transferring it within an Ethernet (registered trademark) network. (Registered trademark) Although the same route is transferred partway through the network, user channel information with different final destinations is multiplexed into the same packet partway through, and the channels are recombined in the data network to obtain the final route. A means to transfer to the destination was presented. The encapsulation method according to the prior art multiplexes TDM signals, inserts additional information, and further adds a packet header. By this means, by performing route transfer using the label described in the header of the packet, an end-to-end path transmission path can be constructed between the two interface converters, and the TDM circuit switching apparatus can be simulated. became.

  In addition, this prior art has disclosed means for realizing a function for transferring OAM information provided in a conventional network, such as alarm transfer, network clock, and performance monitoring, as failure management means. By including management information in the additional information described above, fault management can be performed with a simple configuration.

  As a second prior art in the present invention, ITU-T Recommendation Y. 1413 (Non-Patent Document 1) exists. This prior art relates to a TDM-MPLS interworking technique for encapsulating a TDM signal with MPLS, and defines standards for requirements, mechanisms, and formats.

IEICE technical report “Development of TDM over Ethernet circuit emulation function”, CS 2004-35 (2004-07) ITU-T Recommendation Y. 1413 (03/2004), SERIES Y: GLOBAL INFORMATION INFRASTRUCTURE AND INTERNET PROTOCOL ASPECTS, TDM-MPLS network interworking-User plane interworking

  As described above, Non-Patent Document 1 discloses the failure management means for improving the maintainability of the network in the interface conversion device that converts the synchronous transfer signal into the packet transmission signal. However, the Ethernet (registered trademark) network or the like is disclosed. As a further problem when the packet network is applied to an existing carrier network, there is an improvement in network reliability. For this purpose, it is necessary to develop a redundancy technique.

  However, there is no document disclosing a technology related to a redundant configuration in a system using an interface conversion device that converts a synchronous transfer signal into a packet transmission signal.

  A problem to be solved by the present invention is a protection method for improving the reliability of a packet network in a network using an interface conversion device that encapsulates a synchronous transfer signal such as TDM or STM with a packet transmission protocol and performs circuit emulation. And an interface conversion device used in the protection scheme.

  In order to solve the above-mentioned problems, the protection method of the present invention provides a pair of working and spare ports on the packet network side and constructs a path for each in an interface conversion device that converts a synchronous transfer signal into a packet signal. . Protection is realized by making these paths into a duplex pair. The switching information is included in additional information provided by multiplexing TDM signals, or a switching control dedicated packet is used.

According to the first solving means of the present invention, an interface conversion device for converting a synchronous transfer signal into a packet signal and vice versa is connected to the synchronous transfer network and the packet network, and two units facing each other through the packet network. A protection method for setting a path for transmitting a packet signal between the interface converters, and for recovering when a failure occurs in the path, and in the packet network, the packet of each interface converter A working physical link connected to the network side connection end, a spare physical link, a working subpacket network connected to the working link, and a spare subpacket network connected to the spare link, and the working physical link and the working Working path established between the two interface converters via the subpacket network A backup path established between two interface converters via the backup physical link and the backup subpacket network, and the working path and the backup path are duplicated as a duplex pair. A protection scheme is provided which is characterized by forming a unified configuration.

  The present invention makes it possible to improve the reliability of a packet network in a network using an interface conversion apparatus that encapsulates a synchronous transfer signal such as TDM or STM with a packet transmission protocol and performs circuit emulation.

  Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is an example of a block showing a network configuration according to an embodiment of a duplexing method of the present invention. This network includes a packet network 101, interface converters 102-1 and 2 that convert the synchronous transfer signal according to the present embodiment into packets, or reverse conversion, conventional TDM networks 103-1 and 102, and TDM networks. , Terminals 104-1 and 104-2 connected to the interface, an active physical link 105-1 and a backup physical link 106-1 connected to the interface conversion apparatus 102-1, and an active physical link 105- connected to the interface conversion apparatus 102-2. 2 and the spare physical link 106-2, the working subpacket network 109 for joining the working physical links 105-1 and 105-2, the spare subpacket network 110 for joining the spare physical links 106-1 and 106-2, the working physical link 105-1 and An interface converter 1 that transmits the working subpacket network 109 and the working physical link 105-2. 2-1 is constructed between the interface converters 102-1 and 102-2 by transmitting the working path 107, the spare physical link 106-1, the spare subpacket network 110, and the spare physical link 106-2 constructed between the interface converters 102-1 and 2-2. A path 108 is provided. The packet network 101 corresponds to an L3 network such as an IP network, an L2 network such as an Ethernet (registered trademark) network, an MPLS network, or the like. In this system, the terminal device 104-1 is intended to perform end-to-end communication with the terminal device 104-2.

  The TDM signal transmitted from the terminal device 104-1 is accommodated in the interface conversion device 102-1 via the TDM network 103-1. The interface conversion apparatus 102-1 accommodates the TDM network 103-1, converts it into a packet signal such as an Ethernet frame, an IP packet, or an MPLS packet, and adds destination information corresponding to the interface conversion apparatus 102-2, A packet signal is transmitted to the packet network 101. The packet signal transmitted to the packet network 101 is transmitted to one or both of the working path 107 and the protection path 108. For example, in the case of the 1: 1 switching configuration, it is transmitted only to the working path 107, and in the case of the 1 + 1 switching configuration, it is transmitted to both the working path 107 and the protection path 108. In the working subpacket network 109 and the backup subpacket network 110, the route distribution device in the network distributes it according to the destination information by the route distribution device in the network, and forwards it to the interface conversion device 102-2. The packet signal arriving at the interface conversion apparatus 102-2 is reconstructed into a TDM signal by the interface conversion apparatus 102-2, and is transmitted to the terminal 104-2 via the TDM network 103-2. The route distribution device in the network corresponds to, for example, an L2 switch or a VLAN switch if the packet network 101 is an L2 network, an L3 switch or a router if the packet network 101 is an L3 network, and an LSR (Label Switched Router) if the MPLS network is an MPLS network. .

  In the above description, the signal flow from the terminals 104-1 to 104-2 connected to the TDM network has been described. However, the signal flow from the terminals 104-2 to 104-1 connected to the TDM network has been described. The same interface conversion is performed, and bidirectional signal transmission / reception is possible.

  FIG. 2 is an example of a block showing a network configuration according to the second embodiment of the protection method of the present invention. In addition to FIG. 1, this network includes an interface conversion device 102-3, a TDM network 103-3, a terminal 104-3 connected to the TDM network, and a working physical link 105-3 connected to the interface conversion device 102-3. A working path 107-2 which is transmitted between the interface converters 102-1 and 3 through the protection physical link 106-3, the working physical link 105-1 and the working subpacket network 109 and the working physical link 105-3, A backup path 108-2 that is transmitted between the physical link 106-1, the backup subpacket network 110, and the backup physical link 106-3 and is constructed between the interface conversion apparatuses 102-1 and 103 is provided. The purpose of this system is that the terminal device 104-1 and the terminal device 104-2 perform end-to-end communication, and the terminal device 104-1 and the terminal device 104-3 perform end-to-end communication.

  The TDM signals addressed to the terminal device 104-2 and the terminal device 104-3 transmitted from the terminal device 104-1 are accommodated in the interface conversion device 102-1 via the TDM network 103-1. The interface conversion apparatus 102-1 accommodates the TDM network 103-1, converts it into a packet signal such as an Ethernet frame, an IP packet, or an MPLS packet, and a signal addressed to the terminal apparatus 104-2 is addressed to the interface conversion apparatus 102-2. And the destination information addressed to the interface conversion device 102-3 are added to the signal addressed to the terminal device 104-3, and the packet signal is transmitted to the packet network 101. The packet signal transmitted to the packet network 101 is transmitted to one or both of the working path 107 and the protection path 108. For example, in the case of the 1: 1 switching configuration, it is transmitted only to the working path 107, and in the case of the 1 + 1 switching configuration, it is transmitted to both the working path 107 and the protection path 108. In the working subpacket network 109 and the backup subpacket network 110, the distribution is performed according to the destination information by the route distribution device in the network, and is transferred to the respective interface conversion devices 102-2 and 3 for the final purpose. Each packet signal arriving at the interface converters 102-2 and 3 is reconstructed into a TDM frame by the interface converters 102-2 and 3 respectively. 3 is sent out.

  In the above description, the signal flow from the terminals 104-1 to 104-2 connected to the TDM network and from the terminals 104-1 to 104-3 has been described. However, the terminal 104-2 connected to the TDM network is described. The same interface conversion is performed for the signal flow from the terminal 104-1 to the terminal 104-1 or the signal flow from the terminal 104-3 to the terminal 104-1, and bidirectional signal transmission / reception is possible.

  As a first embodiment of the switching control information transmission means, maintenance management information for mutually transmitting the communication state of the path is included as additional information in the packet format signal data, and the switching control information is included in the additional information. There is a method to include. FIG. 13 shows a first embodiment of the switching control information transmitting means. FIG. 13 shows a packet flow in which the main signal packet 1301-1 to which the switching additional information 1302-1 to 1302-1 is added is transmitted in the packet network 101.

  As a second embodiment of the switching control information transmitting means, a maintenance management dedicated packet including maintenance management information that mutually communicates the communication state of the path is used, and the switching control information is transmitted as the maintenance management dedicated packet. There is a method using a maintenance management dedicated packet. FIG. 14 shows a second embodiment of the switching control information transmitting means. FIG. 14 shows a packet flow in which a maintenance management dedicated packet 1312 is inserted between the main signal packet flows 1311-1 to 1311-1 to be transmitted in the packet network 101.

  The maintenance-dedicated packet shown in FIG. 14 is defined for each path to be maintained and the insertion timing is inserted at regular time intervals, and some switching event or switching state has occurred. It can be inserted at the timing.

  FIG. 3 is an example showing the contents of a PDU (Protocol Data Unit) transmitted to the packet network 101 by the interface conversion apparatus of the present invention. In the present embodiment, the maintenance control information, which is described as the first embodiment of the switching control information transmitting means, and transmits the communication state of the path to each other, is included as additional information in the packet format signal data, This is used in a method for including switching control information in the additional information.

  A PDU 441 indicates the contents of a PDU when the packet network 101 is an L2 network. The PDU 441 includes an L2 header 410, additional information 401, a multiplexed TDM signal 402, and an L2 trailer 411. As an example of the L2 header 410, a MAC header 412 and a VLAN tag 413 are illustrated. The MAC header is defined in IEEE802.3, and the VLAN tag is defined in IEEE802.1Q. As an example of the destination information, a VID (Virtual LAN Identifier) of the VLAN tag or a DA (Destination Address) of the MAC header can be used.

  A PDU 442 indicates the contents of a PDU when the packet network 101 is an L3 network. The PDU 442 includes an L3 header 420, additional information 401, a multiplexed TDM signal 402, and an L3 trailer 421. As an example of the L3 header 420, an IPv4 or IPv6 header 422 is shown. The IPv4 header is defined by IETF RFC791, and the IPv6 header is defined by IETF RFC1883. As an example of the destination information, a destination IP address in an IP header can be used.

  A PDU 443 indicates the contents of the PDU when the packet network 101 is an MPLS network. The PDU 443 includes one or more MPLS labels 431-1 to 431-1, additional information 401, and a multiplexed TDM signal 402. The MPLS header is called a shim header and is defined by IETF RFC3032. As an example of the destination information, the label area of the MPLS label 431 close to the additional information can be used.

  FIG. 4 shows an example of the contents of the additional information 401. The additional information 401-1 conveys a sequence number (SN) 501 for detecting packet loss, duplication, and order change, a pointer (PTR) 502 indicating the start position of TDM information, and a physical layer alarm on the TDM multiple line. Alarm (ALM) 503, error information (ERR) 504 for transmitting line quality in the physical layer, label (LABEL) 505 indicating a multiplexing method of multiplexed TDM information, length of TDM information Length information (LEN) 506 and switching information (APS) 500 representing the length.

  FIG. 5 shows a second embodiment of the contents of the additional information 401. The additional information 401-2 detects control information 507, fragmentation information (FRG) 511 for performing frame fragmentation, length information (LEN) 512 indicating the length of TDM information, packet loss, duplication, and order change. Sequence information (SN) 513 and switching information (APS) 500, and control information 507 includes an L area 508 representing local station fault information, an R area 509 representing a remote end fault, and an M area 510 representing a fault state. Composed. Among the additional information 401-2, control information (CTR) 507, fragmentation information (FRG) 511, length information (LEN) 512, and sequence number (SN) 513 are ITU-T recommendation Y. This corresponds to the content of the common interworking indicator 1413.

  FIG. 6 shows an example of the contents of the switching information (APS) 500. The switching information (APS) 500 indicates a switching request system in the case of a switching request, and system display information (K) 601 indicating a selected system in other cases, and 0 system failure information (0) indicating a 0 system path failure status of the own station ( ALM0) 602, 1-system failure information (ALM1) 603 indicating the 1-system path failure status of the own station, switching control information (OP) 604 indicating the switching status, and enable information (EN) 605 indicating the switching operation permission or prohibition status Consists of

  As an example of the contents of the system display information (K) 601, for example, a 0 system selection state or a 0 system request state, or a 1 system selection state or a 1 system request state can be considered. An example of a code is composed of 2 bits. A method of representing a 0 system selection state or a 0 system request state when the binary code is “01” and a 1 system selection state or a 1 system request state when the binary code is “10” is conceivable.

  Examples of the contents of the 0-system failure information (ALM0) 602 include, for example, that the local station 0-system path is normal without a failure, or that the local station 0-system path is faulty. As an example of the code, it is composed of 1 bit, and indicates that the local station 0 system path is normal without any failure. When the binary code is “1”, the local station 0 system path has a fault. A method of indicating this is conceivable.

  Examples of contents of the 1-system failure information (ALM1) 603 include, for example, that the local station 1-system path is normal without a failure, or that the local station 1-system path has a failure, etc. As an example of the code, it is composed of 1 bit, and indicates that the local station 1 system path is normal without any failure. When the binary code is “1”, the local station 1 system path has a fault. A method of indicating this is conceivable.

  Examples of the contents of the switching control information (OP) 604 include, for example, an idle state notification, a switching request, a switching response, etc. Examples of codes include 2 bits, 2 bits, and a binary code ' The switch request state is indicated when 11 is indicated, the switch response state is indicated when binary code “01”, and the idle state is indicated when binary code “00” and “10” are considered. It is done.

  An example of the contents of the enable information (EN) 605 includes, for example, indicating whether the switching operation is permitted or prohibited. As an example of the code, the switching operation is performed when the code is composed of 1 bit and is “1”. It can be considered that the switching operation is prohibited when the permission is “0”.

  FIG. 15 is a second embodiment showing the contents of a PDU (Protocol Data Unit) transmitted to the packet network 101 by the interface conversion apparatus of the present invention. This embodiment shows a PDU of a maintenance management dedicated packet, and is described as the second embodiment of the switching control information transmission means, and includes a maintenance management information packet that includes maintenance management information that mutually communicates the communication state of the path. And using the maintenance management dedicated packet for transmitting the switching control information as the maintenance management dedicated packet, and adding the destination information unique to the maintenance management dedicated packet in which the destination information is different from the main signal packet. Used for formula.

  A PDU 1451 indicates the contents of a PDU of a maintenance management dedicated packet when the packet network 101 is an L2 network. The PDU 1451 includes an L2 header 410, a maintenance management payload 1401, and an L2 trailer 411. As an example of the L2 header 410, a MAC header 412 and a VLAN tag 413 are illustrated. The MAC header is defined in IEEE802.3, and the VLAN tag is defined in IEEE802.1Q. As an example of the destination information, a VID (Virtual LAN Identifier) of the VLAN tag or a DA (Destination Address) of the MAC header can be used. This destination information gives unique destination information to the maintenance management dedicated packet.

  A PDU 1452 indicates the contents of a PDU when the packet network 101 is an L3 network. The PDU 1452 includes an L3 header 420, a maintenance management payload 1401, and an L3 trailer 421. As an example of the L3 header 420, an IPv4 or IPv6 header 422 is shown. The IPv4 header is defined by IETF RFC791, and the IPv6 header is defined by IETF RFC1883. As an example of the destination information, a destination IP address in an IP header can be used. This destination information gives unique destination information to the maintenance management dedicated packet.

  A PDU 1453 indicates the contents of the PDU when the packet network 101 is an MPLS network. The PDU 1453 includes one or two or more MPLS labels 431-1 to 431-n and a maintenance management payload 1401. The MPLS header is called a shim header and is defined by IETF RFC3032. As an example of the destination information, the label area of the MPLS label 431 close to the additional information can be used. This destination information gives unique destination information to the maintenance management dedicated packet.

  FIG. 16 is a third embodiment showing the contents of a PDU (Protocol Data Unit) transmitted to the packet network 101 by the interface conversion apparatus of the present invention. This embodiment shows a PDU of a maintenance management dedicated packet, and is described as the second embodiment of the switching control information transmission means, and includes a maintenance management information packet that includes maintenance management information that mutually communicates the communication state of the path. And a method using a maintenance management dedicated packet for transmitting switching control information as the maintenance management dedicated packet, and a method in which the destination information is assigned the same value as the destination given to the path to be maintained. used.

  A PDU 1454 indicates the contents of a PDU of a maintenance management dedicated packet when the packet network 101 is an L2 network. The PDU 1454 includes an L2 header 410, a PDU identifier 1402, a maintenance management payload 1401, and an L2 trailer 411. As an example of the L2 header 410, a MAC header 412 and a VLAN tag 413 are illustrated. The MAC header is defined in IEEE802.3, and the VLAN tag is defined in IEEE802.1Q. As an example of the destination information, a VID (Virtual LAN Identifier) of the VLAN tag or a DA (Destination Address) of the MAC header can be used. This destination information is given the same destination information as the path to be maintained.

  A PDU 1455 indicates the contents of a PDU when the packet network 101 is an L3 network. The PDU 1455 includes an L3 header 420, a PDU identifier 1402, a maintenance management payload 1401, and an L3 trailer 421, and shows an IPv4 or IPv6 header 422 as an example of the L3 header 420. The IPv4 header is defined by IETF RFC791, and the IPv6 header is defined by IETF RFC1883. As an example of the destination information, a destination IP address in an IP header can be used. This destination information is given the same destination information as the path to be maintained.

  A PDU 1456 indicates the contents of a PDU when the packet network 101 is an MPLS network. The PDU 1456 includes one or more MPLS labels 431-1 to 431-n, a PDU identifier 1402, and a maintenance management payload 1401. The MPLS header is called a shim header and is defined by IETF RFC3032. As an example of the destination information, the label area of the MPLS label 431 close to the additional information can be used. This destination information is given the same destination information as the path to be maintained.

  FIG. 17 is a fourth embodiment showing the contents of a PDU (Protocol Data Unit) transmitted to the packet network 101 by the interface conversion apparatus of the present invention. This embodiment shows a PDU of a data signal packet other than a maintenance management dedicated packet, and the maintenance management information that mutually communicates the communication state of the path described as the second embodiment of the switching control information transmitting means. Including the maintenance management dedicated packet, using the maintenance management dedicated packet for transmitting the switching control information as the maintenance management dedicated packet, and assigning the same value as the destination given to the path to be maintained by the destination information It is used in the method to do. Further, FIG. 17 shows an embodiment in which maintenance management information other than the switching control information is embedded in the data signal packet as additional information.

  A PDU 1457 indicates the contents of a PDU of a data signal packet other than the maintenance management dedicated packet when the packet network 101 is an L2 network. The PDU 1457 includes an L2 header 410, a PDU identifier 1402, additional information 401, multiplexed TDM information 402, and an L2 trailer 411. A MAC header 412 and a VLAN tag 413 are shown as examples of the L2 header 410. The MAC header is defined in IEEE802.3, and the VLAN tag is defined in IEEE802.1Q. As an example of the destination information, a VID (Virtual LAN Identifier) of the VLAN tag or a DA (Destination Address) of the MAC header can be used.

  A PDU 1458 indicates the contents of a PDU when the packet network 101 is an L3 network. The PDU 1458 includes an L3 header 420, a PDU identifier 1402, additional information 401, multiplexed TDM information 402, and an L3 trailer 421. As an example of the L3 header 420, an IPv4 or IPv6 header 422 is illustrated. The IPv4 header is defined by IETF RFC791, and the IPv6 header is defined by IETF RFC1883. As an example of the destination information, a destination IP address in an IP header can be used.

  A PDU 1459 indicates the contents of a PDU when the packet network 101 is an MPLS network. The PDU 1459 includes one or two or more MPLS labels 431-1 to 431-n, a PDU identifier 1402, additional information 401, and multiplexed TDM information 402. The MPLS header is called a shim header and is defined by IETF RFC3032. As an example of the destination information, the label area of the MPLS label 431 close to the additional information can be used.

  The PDU identifier 1402 described in PDUs 1454, 1455, 1456, 1457, 1458, and 1459 has a purpose of distinguishing a maintenance-dedicated packet from other data signals. A unique value is assigned.

  As an example of the contents of the maintenance management payload described in PDUs 1451, 1452, 1453, 1454, 1455, and 1456, the same contents as the switching information (APS) 500 shown in FIG. 6 can be considered.

  FIG. 7 shows one embodiment of the configuration of the interface conversion apparatus of the present invention. The interface conversion apparatus according to the present invention receives a frame assembling / disassembling unit 701 that converts a TDM signal into a packet signal and performs inverse conversion, and receives one or more TDM signals 719-1 to 719-n and receives a frame assembling / disassembling unit 701. One or two or more received TDM signal physical interface units 707-1 to 707 -n and the active transmission packet signal 712 output from the frame assembling / disassembling unit 701 are received, and the active transmission physical link 105-1-is received. Active-system packet transmission physical interface unit 703 that transmits to 1 and standby-system transmission packet signal 713 that is output from frame assembling / disassembling unit 701 and receives the standby-system packet transmission that is transmitted to standby-system transmission physical link 105-2-1 The active reception packet received from the physical interface unit 704 and the active reception physical link 105-1-2. An active packet receiving physical interface unit 705 that transmits information to the frame assembling / disassembling unit 701, and a spare packet receiving physical that transmits information about the standby received packet received from the standby receiving physical link 105-2-2 to the frame assembling / disassembling unit 701. Interface unit 706, maintenance information termination unit 702 that transmits transmission maintenance information 716 to frame assembly / disassembly unit 701 and receives reception maintenance information 717 from frame assembly / disassembly unit 701, frame assembly / disassembly unit 701 and device management The device management unit 709 transmits and receives information 718.

  Furthermore, the 1st structural example of the flame | frame assembly disassembly part 701 is shown in FIG. In the present embodiment, the maintenance control information for mutually transmitting the communication state of the path described as the first embodiment of the switching control information transmitting means is included as additional information in the packet format signal data. It is suitable for use in a system in which the switching control information is included in the additional information. This embodiment is an embodiment in which the packet network 101 is an L2 network and the PDU 441 described in FIG. 3 is used. Embodiment As described with reference to FIG. 3, a VLAN tag is used as destination information of a path.

  A frame assembling / disassembling unit 701 multiplexes a plurality of TDM signals 710-1 to 710-n transmitted from the received TDM signal physical interface units 707-1 to 707-n to generate a multiplexed TDM signal 850. 801, an additional information adding unit 806 for adding the additional information to the multiplexed TDM signal 850 and outputting the multiplexed TDM signal 852 to which the additional information is added, and the MAC frame from the multiplexed TDM signal 852 to which the additional information is added. A working MAC frame assembling unit 809 and a spare MAC frame assembling unit 810.

  Also, the frame assembly / disassembly unit 701 receives the working system received packet information 714, terminates the MAC frame, and outputs a working system MAC frame terminating unit 811 that outputs the working system multiplexed TDM signal 853 to which additional information is added; A standby system MAC frame terminator 812 that receives the standby system received packet information 715, terminates the MAC frame, and outputs a standby system multiplexed TDM signal 854 with additional information added thereto, and an active system multiplexing with additional information added. The active TDM signal 853 terminates the additional information and outputs the active multiplexed TDM signal 857 and the active path termination information 855, and the standby additional TDM signal 854 to which the additional information is added. The additional information is terminated from the standby system, and the redundant system TDM signal 858 and the standby system path termination information 856 are output. End selector 808 and a system selector that selects one of active multiplexed TDM signal 857 and standby multiplexed TDM signal 858 respectively output from active additional information termination section 807 and standby additional information termination section 808 815, a multiplexed TDM signal demultiplexing unit 802 that separates TDM information from the multiplexed TDM signal 859 selected by the system selector 815 and outputs it to one or more of the transmission TDM signal physical interfaces 708-1 to n. A maintenance information interface 813 for transmitting / receiving the transmission maintenance information 716 and the reception maintenance information 717 to / from the maintenance information termination unit 702, a device management interface 814 for transmitting / receiving the device management information 718 to / from the device management unit 709, A duplex information management unit 803 that manages duplex information is configured.

  The working MAC frame assembling unit 809 and the backup MAC frame assembling unit 810 have a path destination assigning unit 816. The active MAC frame termination unit 811 and the backup MAC frame termination unit 812 have a path destination termination unit 817. These path destinations correspond to the path destination information, and in the present embodiment, indicate the VLAN tag. The destination information may be a destination IP address when the packet network 101 is an L3 network, a label value when the packet network 101 is an MPLS network, and the like.

  The maintenance information interface 813 receives the active system path termination information 855 output from the active system additional information termination unit 807 and the standby system path termination information 856 output from the standby system additional information termination unit 808, and receives the received maintenance information 717. It is transmitted to the maintenance information termination unit 702. As examples of the contents of the active path termination information 855 and the backup path termination information 856, additional information terminated in units of paths, path failure information, and the like can be considered, and the reception maintenance information 717 includes these contents.

  In addition, the maintenance information interface 813 receives the transmission maintenance information 716 from the maintenance information termination unit 702 and transmits the duplex control information 861 to the duplex information management unit 803. As an example of the duplex control information 861, system selection information in units of switching pairs and APS additional information can be considered.

  The duplex information management unit 803 outputs the system selection information 860 to the system selector 815 and the APS additional information 851 to the additional information adding unit 806 based on the duplex control information 861. Additional information adding section 806 adds APS additional information 851 as additional information to multiplexed TDM signal 850.

  FIG. 9 shows a first embodiment of the configuration of the duplex information management unit 803. The duplex information management unit 803 reads the duplex information management table 901 storing the duplex control information 861 and the APS control information 904 for each switching pair, generates APS additional information, and outputs it as APS additional information 851. The APS additional information management unit 804 that performs this processing, and the selection system management unit 805 that reads the system selection information 905 for each path and outputs it as system selection information 860.

  FIG. 20 shows an example of the contents of the duplex information management table 901. The duplex information management table 901 is a table in which APS control information and system selection information are stored in units of switching pairs. APS, K, ALM0, ALM1, OP, and EN have the same contents as those in the embodiment of the switching information (APS) 500 described with reference to FIG. The selection system indicates the selection system of the pair.

  FIG. 10 shows an example of the configuration of the maintenance information termination unit 702. The maintenance information termination unit 702 includes a maintenance information interface 1001, a transmission APS information termination unit 1002, a reception APS information termination unit 1003, a state transition unit 1004, and a device management interface 1006.

  The reception APS information termination unit 1003 generates event information 1010 based on the reception maintenance signal 1008 and provides it to the state transition unit 1004. The state transition unit 1004 uses the event information 1010 as event information to manage internal state transitions. Based on the above, a transition state 1009 is generated and given to the transmission side APS information termination unit 1002. The transmission side APS information termination unit 1002 generates transmission maintenance information 1007 based on the transition state 1009 and gives it to the maintenance information interface 1001. The device management unit 709 gives device management information to the device management interface 1006.

  As an example of the reception maintenance signal 1008, additional information in units of paths, path failure information, and the like can be considered. As the transmission maintenance information 1007, system selection information and APS control information for each switching pair can be considered. Examples of the device management information include working path, backup path registration information, switching prohibition, switching permission, and the like. As an example of the transition state 1009, as an example of the transition state, the 0 system selection idle state, the 0 system selection switching request state, the 0 system selection switching response state, the 0 system selection switching prohibition state, the 1 system selection idle state, the 1 system A selection switching request state, a 1 system selection switching response state, a 1 system selection switching prohibition state, and the like are possible.

  FIG. 21 shows an example of the correspondence between the transition state 1009 and the transmission maintenance information 1007 when the transmission side APS information termination unit 1002 generates the transmission maintenance information 1007 based on the transition state 1009. The correspondence table 2101 shows the correspondence relationship, and associates APS control information and selection system information with each state of the transition state 1009. K, ALM0, ALM1, OP, and EN indicate APS additional information, which has the same contents as the embodiment of the switching information (APS) 500 described with reference to FIG.

  FIG. 18 shows a second configuration example of the frame assembly / disassembly unit 701. The present embodiment uses the maintenance management dedicated packet including the maintenance management information which is described as the second embodiment of the switching control information transmitting means and which communicates the communication state of the path with each other. It is suitable for use in a system that uses a maintenance management dedicated packet for transmitting switching control information. This embodiment is an embodiment in which the packet network 101 is an L2 network and the PDU 441 described in FIG. 3 is used. Embodiment As described with reference to FIG. 3, a VLAN tag is used as destination information of a path.

  The feature of FIG. 18 is that the duplex information management unit 803 outputs the APS packet information 1502, and the APS packet insertion unit 1501 provides the multiplexed TDM signal to which the additional information output by the additional information adding unit 806 is added. In 852, the switching control packet information 1502 is inserted. The additional information adding unit 806 is used when providing maintenance management information other than the switching control information.

  FIG. 19 shows a second embodiment of the configuration of the duplex information management unit 803. The feature of FIG. 19 is that it has an APS packet management unit 1601 that reads APS control information 904 in units of paths, generates an APS packet, and outputs it as APS packet information 1502. As an example of the contents of the duplex information management table 901 at this time, a table in which system selection information and APS control information described in the payload of the APS packet are stored in units of paths can be considered.

  FIG. 11 shows an embodiment of the switching sequence by the protection method according to the present invention. A duplex system is constructed between the interface converter (A) 102-1 and the interface converter (B) 102-2. Interface conversion apparatus (A) 102-1 state 1103 (hereinafter referred to as state A), interface conversion apparatus (A) 102-1 selection system 1101 (hereinafter referred to as system A), interface conversion apparatus (B) 102 -2 state 1104 (hereinafter referred to as state B) and the selection system 1102 (hereinafter referred to as system B) of the interface conversion apparatus (B) 102-2 will be described below.

  In the initial state, state A is “0 system selection, no failure, idle state”, system A is 0 system, while state B is “0 system selection, no failure, idle state”, system B is 0 It is a system. In this state, the switching information (APS) 500 (hereinafter referred to as output A) of the interface conversion apparatus (A) 102-1 is “system 0 idle state” 1111 and the switching of the interface conversion apparatus (B) 102-2. Information (APS) 500 (hereinafter referred to as output B) is “0-system idle state” 1112.

  When a failure 1113 occurs in the 0-system path of the interface conversion apparatus (A) 102-1, the state A is “1 system selection state, 0 system failure, switching request state”, the system A is 1 system, and the output A is “ 1 system switching request "1114. The interface conversion apparatus (B) 102-2 that has received the “1 system switching request” 1114 has the state B “1 system selection state, no failure, switching response state”, the system B becomes the 1 system, and the output B is “1”. System switching response "1115. The interface conversion apparatus (A) 102-1 that has received the “1 system switching response” 1115 has the state A of “1 system selection state, 0 system failure, idle state”, the system A maintains the 1 system, and the output A is “1 system idle state” 1116 is entered. The interface conversion apparatus (B) 102-2 that has received the “1 system idle state” 1116 maintains that the state B is “1 system selection state, no failure, idle state”, the system B maintains the 1 system, and the output B is “ 1 system idle state "1117. Thereafter, when the 0-system path failure of the interface conversion apparatus (A) 102-1 is recovered 1118, the state A is “1 system selection state, no failure, idle state”, and the system A and the output A maintain the current state.

  The sequence of FIG. 11 does not perform failback, but a sequence for failback is also possible. In addition, when a failure 1113 occurs in the 0-system path of the interface conversion apparatus (A) 102-1, the system A is switched to the 1-system, but at the timing when the output B receives the "1-system switching response" 1115 A may be switched to the first system. 11 shows the case where a failure 1113 occurs in the 0-system path of the interface conversion apparatus (A) 102-1, but a failure occurs in the 0-system path of the interface conversion apparatus (B) 102-2. In this case, the switching sequence is similarly performed.

  FIG. 12 shows an embodiment of a protection type switching trigger according to the present invention. Switching triggers are classified as main signal failure and performance degradation. As a first example of the switching trigger due to the main signal failure, when the connection failure of the working path of the interface converter is detected, the switching operation to the protection path is performed. As an example of a connection failure detection method, when the arrival interval of packets that continuously arrive via a path is equal to or longer than a threshold time, it is determined that the connection failure of the corresponding path.

  As a second embodiment of the switching trigger due to the main signal failure, switching to the backup path when a physical failure is detected at the packet network side connection end to which the working physical link is connected at the packet network side connection end of the interface converter. Perform the action.

  As a first embodiment of a switching trigger due to performance degradation, a missing, duplicated, or reordered packet arriving via the path is detected, and the missing, duplicated, or reordered packet occurring per unit time is detected. When the occurrence frequency of the event exceeds a certain threshold value, the switching operation to the protection path is performed.

  According to the present invention, it is possible to improve the reliability of a packet network in a network using an interface conversion apparatus that encapsulates a synchronous transfer signal such as TDM or STM with a packet transmission protocol and performs circuit emulation.

It is one Example of the block which shows the structure of the network by embodiment of the duplexing method of this invention. It is one Example of the block which shows the structure of the network by embodiment of the duplexing method of this invention. It is a 1st Example of the format of the Ethernet (trademark) frame, IP packet, or MPLS packet which passes an Ethernet (trademark) network, an IP packet network, or an MPLS network. It is one Example of the content of the additional information added by each layer. It is one Example of the content of the additional information added by each layer. It is one Example of the content of the APS information contained in the additional information added by each layer. It is one Example of the structure of the interface converter of this invention. It is a 1st Example of the structure of the flame | frame assembly / disassembly part contained in the interface converter of this invention. It is a 1st Example of the structure of the duplication information management part contained in the flame | frame assembly / disassembly part of this invention. It is one Example of the structure of the maintenance information termination | terminus part contained in the interface converter of this invention. It is one Example of the switching sequence of the duplexing method of this invention. It is one Example of the switching trigger of the duplexing method of this invention. It is a 1st Example of the transmission means of switching control information. It is a 2nd Example of the transmission means of switching control information. It is a 2nd Example of the format of the Ethernet (trademark) frame, IP packet, or MPLS packet which passes an Ethernet (trademark) network, an IP packet network, or an MPLS network. It is a 3rd Example of the format of the Ethernet (trademark) frame, IP packet, or MPLS packet which passes an Ethernet (trademark) network, an IP packet network, or an MPLS network. It is a 3rd Example of the format of the Ethernet (trademark) frame, IP packet, or MPLS packet which passes an Ethernet (trademark) network, an IP packet network, or an MPLS network. It is a 2nd Example of the structure of the flame | frame assembly / disassembly part contained in the interface converter of this invention. It is a 2nd Example of the structure of the duplex information management part contained in the flame | frame assembly / disassembly part of this invention. It is one Example of the content of the duplex information management table 901. FIG. This is an example of the correspondence between the transition state 1009 and the transmission maintenance information 1007.

Explanation of symbols

DESCRIPTION OF SYMBOLS 101 ... Packet network 102-1 ... Interface converter 102-2 ... Interface converter 102-3 ... Interface converter 103-1 ... Conventional TDM network 103-2 ... Conventional TDM network 103-3 ... Conventional TDM network 104-1 ... terminal 104-2 connected to TDM network ... terminal 104-3 connected to TDM network 104-3 ... terminal 105-1 connected to TDM network ... working physical link 105-2 ... working physical link 105 -3 ... working physical link 106-1 ... protection physical link 106-2 ... protection physical link 106-3 ... protection physical link 107 ... working path 107-1 ... working path 107-2 ... working path 108 ... protection path 108-1 ... protection path 108-2 ... protection path 109 ... working subpacket network 110 ... protection subpacket network 401 ... additional information 401-1 ... Additional information 401-2 ... Additional information 402 ... Multiplexed TDM signal 410 ... L2 header 411 ... L2 trailer 412 ... MAC header 413 ... VLAN tag 420 ... L3 header 421 ... L3 trailer 422 ... IPv4 or IPv6 header 431-1-n ... MPLS label 441 ... PDU of L2 network
442 ... PDU of L3 network
443: MPLS network PDU
500 ... switching information 501 ... sequence number (SN)
502 ... Pointer indicating the start position of TDM information 503 ... Alarm 504 ... Error information 505 ... Label indicating a multiplexing method of TDM information 506 ... Length information 507 ... Control information 508 ... L area 509 representing time-dependent failure information ... Remote end R region 510 representing failure ... M region 511 representing failure state ... Fragmentation information 512 ... Length information 513 ... Sequence number 601 ... System display information 602 ... 0 system failure information 603 ... 1 system failure information 604 ... Switching control information 605 ... Enable Information 701 ... Frame assembly / disassembly unit 702 ... Maintenance information termination unit 703 ... Active packet transmission physical interface unit 704 ... Standby packet transmission physical interface unit 705 ... Active packet reception physical interface unit 706 ... Reserve packet reception physical interface unit 707-1 ~ N ... TDM signal physical interface unit 708-1 to n ... Transmission TDM signal physical interface unit 709 ... Device management unit 710-1 to n ... Reception TDM signal 711-1 to n ... Transmission TDM signal 712 ... Active transmission packet signal 713 ... Reserve System transmission packet signal 714 ... Active system reception packet signal 715 ... Standby system reception packet signal 716 ... Transmission maintenance information 717 ... Reception maintenance information 718 ... Device management information 719-1 to n ... Reception TDM signals 720-1 to n ... Transmission TDM Signal 801 ... Multiple TDM information generation unit 802 ... Multiple TDM information separation unit 803 ... Duplex information management unit 804 ... APS additional information management unit 805 ... Selection system management unit 806 ... Additional information addition unit 807 ... Active system additional information termination unit 808 ... Standby system additional information terminal unit 809 ... Active system L2 frame assembly unit 810 ... Backup system L2 frame group Unit 811 ... active L2 frame termination unit 812 ... standby L2 frame termination unit 813 ... maintenance information interface 814 ... device management interface 815 ... system selector 816 ... path destination assignment unit 817 ... path destination termination unit 850 ... multiplexed TDM signal 851 ... APS additional information 852 ... multiplexed TDM signal 853 with additional information added ... active multiplexed TDM signal 854 with additional information added ... standby multiplexed TDM signal 855 with additional information added ... active path termination Information 856 ... Protection path termination information 857 ... Active multiplexed TDM signal 858 ... Standby multiplexed TDM signal 859 ... Multiplexed TDM signal 860 ... System selection information 861 ... Duplex control information 862 ... Active path failure information 863 ... Backup path failure information 901... Duplex information management table 904... APS control information 905. System management unit 1001 ... maintenance information interface 1002 ... transmission APS information termination unit 1003 ... reception APS information termination unit 1004 ... state transition control unit 1005 ... state transition management table 1006 ... device management interface 1007 ... transmission maintenance information 1008 ... event information 1009 ... Transition state 1010 ... Reception grant information 1011 ... State transition information 1101 ... Selection system 1102 of interface converter A ... Selection system 1103 of interface converter B ... Switch state 1104 of interface converter A ... Switch state 1111 of interface converter B 1118 ... Each step 1200 of the switching sequence ... Examples 1301-1 to 4 of the switching trigger ... Main signal packet 1302-1 to 4 ... Additional information 1311-1 to 3 ... Main signal packet 1312 ... Maintenance management dedicated packet 1401 Maintenance payload 1402 ... PDU identifier 1451 ... L2 network of the PDU of maintenance management dedicated packet
1452 ... L3 network PDU of maintenance management dedicated packet
1453 ... MPLS network PDU of maintenance management dedicated packet
1454 ... L2 network PDU of maintenance management dedicated packet
1455: L3 network PDU of maintenance management dedicated packet
1456: MPLS network PDU for maintenance management dedicated packets
1457: L2 network PDU of main signal data packet
1458: L3 network PDU of main signal data packet
1459 ... MPLS network PDU of main signal data packet
1501 ... APS packet insertion unit 1502 ... APS packet information 1601 ... APS packet management unit 2101 ... Correspondence between transition state 1009 and transmission maintenance information 1007

Claims (14)

An interface converter for converting a synchronous transfer signal into a packet signal and vice versa is connected to the synchronous transfer network and the packet network,
A path for transmitting a packet signal between the two interface converters facing each other through the packet network;
A protection method that performs recovery in the event of some failure in the path,
In the packet network,
A working physical link connected to the packet network side connection end of each of the interface converters, a spare physical link, a working subpacket network connected to the working link, and a spare subpacket network connected to the spare link; ,
A working path set between the two interface converters via the working physical link and the working subpacket network;
A backup path established between the two interface converters via the backup physical link and the backup subpacket network;
A protection system characterized in that a duplex configuration is formed by using the working path and the backup path as a duplex pair. The protection method according to claim 1,
There are three or more interface converters,
When there are a plurality of paths set between any two interface conversion devices among the interface conversion devices,
In the packet network,
Each working physical link and spare physical link connected to the packet network side connection end of each interface converter;
A plurality of working paths set between any two interface conversion devices of the interface conversion devices are set via any one of the plurality of working physical links and the working subpacket network;
A plurality of protection paths set between any two interface conversion devices among the interface conversion devices are set via any one of the plurality of protection physical links and the working subpacket network,
2. The protection system according to claim 1, wherein each of the working paths forms a duplex configuration by pairing any one of the plurality of protection paths. The protection system according to claim 1, wherein the interface conversion device includes:
2. The protection system according to claim 1, wherein maintenance management information that communicates the communication state of the path with each other is included as additional information in signal data in a packet format. The protection method according to claim 3, wherein the additional information includes:
The protection method according to claim 3, further comprising switching control information. The protection system according to claim 1, wherein the interface conversion device includes:
2. The protection method according to claim 1, wherein maintenance management information for mutually communicating the communication state of the path using a maintenance management dedicated packet is included in the maintenance management dedicated packet. In the protection method according to claim 5, as the maintenance management dedicated packet,
6. The protection method according to claim 5, wherein a maintenance-dedicated packet for transmitting switching control information is used. The protection method according to claim 1,
In the interface conversion device,
A connection failure detection means for determining a connection failure of the path when arrival of packets continuously arriving via the path is interrupted;
2. The protection system according to claim 1, wherein when a connection failure in the working path is detected, a switching operation to a protection path is performed. The protection method according to claim 1,
In the interface conversion device,
Physical failure detection means for detecting a physical failure occurring at the packet network side connection end,
2. The protection system according to claim 1, wherein when a physical failure is detected at the packet network side connection end to which the working physical link is connected, the switching operation to the protection path is performed. The protection method according to claim 1,
In the interface conversion device,
Means for detecting missing, duplicated, or reordering of packets arriving via the path;
2. The protection method according to claim 1, wherein the switching operation to the protection path is performed when the frequency of occurrence of the packet loss, duplication, or reordering event per unit time exceeds a certain threshold value. . An interface conversion device that converts synchronous transfer signals into packet signals and vice versa, and embeds maintenance management additional information that mutually communicates the communication state of the transmission section as additional information inside the packet format data,
A pair of working packet transmission physical interface unit and standby packet transmission interface unit;
A pair of active packet reception physical interface unit and backup packet reception interface unit;
Multiple receive synchronous transfer signal physical interfaces;
A plurality of transmission synchronous transfer signal physical interfaces;
A maintenance information termination section for terminating maintenance information;
A device management unit that performs device management;
A frame assembly / disassembly unit that converts a synchronous transfer signal into a packet signal and vice versa;
In the frame assembly and disassembly unit,
A working active packet assembly unit and a standby active packet assembly unit;
A pair of working system packet termination unit and backup system packet termination unit,
A multiplexed synchronous transfer signal generation unit that multiplexes synchronous transfer signals received from the plurality of received synchronous transfer signal physical interfaces to generate a multiplexed synchronous transfer signal;
An additional information adding unit that adds the maintenance management additional information to the multiplexed synchronous transfer signal and outputs the same to both the active packet assembling unit and the standby packet assembling unit;
Terminating the maintenance management additional information included in the signals output from the active packet termination unit and the standby packet termination unit, respectively, and outputting the multiplexed synchronous transfer signal, respectively, and the standby system addition An information termination section;
A system selector that selects any one of the multiplexed synchronous transfer signals output from the active additional information termination unit and the standby additional information termination unit, respectively,
A multiplexed synchronous transfer signal separating unit that separates the synchronous transfer signal from the multiplexed synchronous transfer signal output from the system selector and outputs the separated synchronous transfer signal to any one or a plurality of transmission synchronous transfer signal physical interfaces;
A maintenance information interface for terminating maintenance information in the maintenance information termination unit;
It has a duplex information management unit that manages duplex information,
The maintenance information interface is:
The working path termination information and the protection path termination information output from the working additional information termination unit and the standby additional information termination unit are received, and duplex control information is sent to the duplex information management unit. Output,
The duplex information management unit
Based on the duplex control information output from the maintenance information interface, the switching information additional information is output to the additional information adding unit, the system selection information is output to the system selector,
In the additional information giving unit,
Adding the switching control additional information output by the duplex information management unit to the multiplexed synchronous transfer signal;
The system selector is
An interface conversion apparatus that performs a selection operation according to the system information output by the duplex information management unit. The interface conversion device according to claim 10, wherein the duplex information management unit includes:
A duplex information management table for storing the duplex control information;
A switching control additional information management unit that reads the switching control information from the duplex information management table, generates additional information, and outputs the additional information to the additional information adding unit;
9. The interface conversion apparatus according to claim 8, further comprising a selection system management unit that reads out system selection information from the duplex information management table and outputs the system selection information to the system selector. The interface converter according to claim 10, wherein
The maintenance information terminal is
A maintenance information interface for transmitting and receiving maintenance information to and from the frame assembly and disassembly unit;
A receiving-side switching information terminating unit that receives the maintenance information from the maintenance information interface and outputs state transition event information to the state transition control unit;
A state transition control unit that controls state transition with reference to the state transition event information;
9. The interface conversion apparatus according to claim 8, further comprising: a transmission-side switching information termination unit that generates maintenance information based on the transition state determined by the state transition control unit and outputs the maintenance information to a maintenance information interface. Converts synchronous transfer signals into packet signals and reverses them, and embeds maintenance management information indicating the communication status of the transmission section as additional information inside the packet format data, or mutually using maintenance management packets An interface converter that communicates with each other,
A pair of working packet transmission physical interface unit and standby packet transmission interface unit;
A pair of active packet reception physical interface unit and backup packet reception interface unit;
Multiple receive synchronous transfer signal physical interfaces;
A plurality of transmission synchronous transfer signal physical interfaces;
A maintenance information termination section for terminating maintenance information;
A device management unit that performs device management;
A frame assembly / disassembly unit that converts a synchronous transfer signal into a packet signal and vice versa;
In the frame assembly and disassembly unit,
A working active packet assembly unit and a standby active packet assembly unit;
A pair of working system packet termination unit and backup system packet termination unit,
A multiplexed synchronous transfer signal generation unit that multiplexes synchronous transfer signals received from the plurality of received synchronous transfer signal physical interfaces to generate a multiplexed synchronous transfer signal;
An additional information adding unit that adds the maintenance management additional information to the multiplexed synchronous transfer signal and outputs the same to both the active packet assembling unit and the standby packet assembling unit;
Terminating the maintenance management additional information included in the signals output from the active packet termination unit and the standby packet termination unit, respectively, and outputting the multiplexed synchronous transfer signal, respectively, and the standby system addition An information termination section;
A system selector that selects any one of the multiplexed synchronous transfer signals output from the active additional information termination unit and the standby additional information termination unit, respectively,
A multiplexed synchronous transfer signal separating unit that separates the synchronous transfer signal from the multiplexed synchronous transfer signal output from the system selector and outputs the separated synchronous transfer signal to any one or a plurality of transmission synchronous transfer signal physical interfaces;
A maintenance information interface for terminating maintenance information in the maintenance information termination unit;
A duplex information management unit for managing duplex information;
A switching control packet insertion unit for inserting a switching control packet;
The maintenance information interface is:
The working path termination information and the protection path termination information output from the working additional information termination unit and the standby additional information termination unit are received, and duplex control information is sent to the duplex information management unit. Output,
The duplex information management unit
Output switching control packet information based on the duplex control information output from the maintenance information interface, and output system selection information to a system selector;
The switching control packet insertion unit is
Inserting a switching control packet into the multiplexed synchronous transfer signal stream to which the multiplexed synchronous transfer signal has added the maintenance management additional information,
The system selector is
An interface conversion apparatus that performs a selection operation according to the system information output by the duplex information management unit. 14. The interface conversion device according to claim 13, wherein the duplex information management unit includes:
A duplex information management table for storing the duplex control information;
A switching control packet management unit that reads switching control information from the duplex information management table, generates a switching control packet, and outputs the switching control packet to the switching control packet insertion unit;
14. The interface conversion apparatus according to claim 13, further comprising a selection system management unit that reads system selection information from the duplex information management table and outputs the system selection information to the system selector.

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