Optical path setting device and optical path setting method

Abstract

A controller (130) is used in a virtual network system (100A) that makes it possible to perform communication with an optical path between an operator termination device (PE1) and an operator termination device (PE2) in an operator network through an operator relay device (P1) to an operator relay device (P4) in the operator network. The controller (130) issues, for relay paths of the operator relay device (P1) to the operator relay device (P4), which are part of the optical path, different relay path identifiers for different passage routes, advertises the relay path identifiers to the operator termination device (PE1), and causes the operator termination device (PE1) to designate the relay path identifiers, thereby causing the relay paths of the optical path to be set as source routing.

Description

Optical Path Setting Device and Optical Path Setting Method

[0001] The present invention relates to an optical path setting device and an optical path setting method.

[0002] A VPN (Virtual Private Network) that connects remote user bases via a carrier network and constitutes a virtual closed network for each user has become widespread. As a virtual network technology provided by carriers, an L1VPN (Layer 1 VPN) that relays customer communications via a carrier network using a large-capacity layer 1 (optical network) has been proposed.

[0003] For example, Non-Patent Document 1 describes a Peer Model technology for constructing an L1VPN. The Peer Model of Non-Patent Document 1 is a method of accepting a path setting request as signaling of GMPLS (Generalized Multiprotocol Label Switching), which is a Control interface. GMPLS is premised on the LMP (Link Management Protocol) described in Non-Patent Document 2, and LMP assumes that the main signal of the transmission device can also respond to IP.

[0004] On the other hand, there is also an implementation of source routing in which an input node adds a list indicating the order of passage of a path to a packet instead of signaling. For example, Non-Patent Document 3 describes a technology for implementing segment routing (SR: Segment Routing), which adds a segment packet indicating the order of passage of a path, on an IPv6 network (SRv6). In addition, Non-Patent Document 4 specifically defines the procedures and messages of a BGP (Border Gateway Protocol) service using SRv6.

[0005] D. Fedyk, Ed., et al., "Layer 1 VPN Basic Mode," [online], [Retrieved November 12, 2024], Internet <URL: https: / / datatracker.ietf.org / doc / html / rfc5251> J. Lang, Ed., "Link Management Protocol (LMP)," [online], [Retrieved November 14, 2024], Internet <URL: https: / / datatracker.ietf.org / doc / html / rfc4204> C. Filsfils, Ed., et al., "Segment Routing over IPv6 (SRv6) Network Programming," [online], [Retrieved November 14, 2024], Internet <URL: https: / / datatracker.ietf.org / doc / html / rfc8986> G. Dawra, Ed., et al., "BGP Overlay Services Based on Segment Routing over IPv6 (SRv6), [online], [Accessed November 14, 2024], Internet <URL: https: / / datatracker.ietf.org / doc / html / rfc9252>

[0006] The conventional L1VPN technology described in Non-Patent Document 1 generally assumes a Peer Model and utilizes GMPLS or equivalent signaling. Therefore, the carrier network where the signaling is configured is required to have IP connectivity. Consequently, it was not possible to create a section within the carrier network that only handles optical signals (optical transmission section), which prevented sufficient capacity and low latency. Furthermore, even if the relay device is a transmission device that transmits optical signals, the main signal communication processing via the data network is not limited to Layer 1 (physical layer) processing but requires processing including Layer 3 (network layer), making it complex. This complexity could be an obstacle to achieving high capacity and low latency.

[0007] Figure 10 is a configuration diagram of the virtual network system 100Z. The virtual network system 100Z forms an L1 VPN by connecting geographically separated locations of the same user (VPN#1) using the carrier's optical network. The carrier's network is functionally separated into a control network 110Z through which control signals 111Z pass, and a data network 120Z through which main signals pass via the inter-CE path CEP. Customer communication equipment CE1 for connecting to the carrier's network is located at the local location (VPN#1 location on the left in Figure 10). Customer communication equipment CE2 for connecting to the carrier's network is located at the opposite location (VPN#1 location on the right in Figure 10).

[0008] The data network 120Z consists of optical network transmission equipment (hereinafter referred to as "operator equipment"), including operator termination equipment PE1 and PE3, which are operator termination equipment (PE: Provider Edge) connected to customer communication equipment CE1, operator termination equipment PE2 and PE4, which are connected to customer communication equipment CE2, and operator relay equipment P1 to P4, which are not connected to any customer communication equipment.

[0009] Furthermore, the virtual network system 100Z generates an inter-CE path CEP connecting customer communication devices CE1 and CE2 as an optical path connecting user sites. Data packets (main signals) from the local site pass through the inter-CE path CEP to each device in the following order: Customer communication device CE1 → Carrier termination device PE3 → Carrier relay device P3 → Carrier relay device P4 → Carrier termination device PE4 → Customer communication device CE2

[0010] Furthermore, connections between locations of different companies (different users) should not be made using the CE-to-CE path CEP. Therefore, in order to determine which user locations should be connected using the CE-to-CE path CEP, the carrier termination devices PE1 and PE3 prepare a Port Information Table (PIT) in advance. The PIT stores port information. A "port" is the physical port (interface) into which the physical line is inserted when the customer communication device CE1 and the carrier termination device PE1 are connected by a physical line. Port information is defined for each VPN, with the information of the physical port on the customer communication device CE1 side being the CPI (Customer Port Identifier) ​​and the information of the physical port on the carrier termination device PE1 side being the PPI (Provider Port Identifier). This separates the address space for each VPN user, thereby preventing connections between different VPN users.

[0011] Here, since the L1VPN in Non-Patent Document 1 is based on GMPLS, when applying the L1VPN in Non-Patent Document 1 to the carrier network in Figure 10 to generate inter-CE path CEPs, each carrier device is required to have the following functions from the first to third stages that constitute GMPLS. [First stage: Link management] A function to acquire the link status between adjacent nodes. In GMPLS, the LMP (Link Management Protocol) operating on each carrier device sends and receives Hello packets for a certain period of time to confirm the normality of communication with other adjacent carrier devices and also exchange port information.

[0012] [Second Stage: Routing] This function advertises (floods) the link state and port information obtained in the first stage into the virtual network system 100Z. GMPLS performs routing within the carrier network using IGPs (Interior Gateway Protocols) such as OSPF (Open Shortest Path First) and IS-IS (Intermediate System to Intermediate System).

[0013] [Stage 3: Signaling] This stage defines a signaling protocol for configuring the optical path (LSP: Label Switched Path) between two nodes, which has been resolved by routing in Stage 2, as an inter-CE path (CEP). Examples of signaling protocols used include CR-LDP (Constraint-based Routing Label Distribution Protocol), RSVP (Resource Reservation Protocol), and its extension, RSVP-TE (Traffic Engineering).

[0014] Figure 11 is a configuration diagram showing a virtual network system 100B of the Peer model. The L1VPN described in Non-Patent Document 1 generally assumes a Peer model. Figure 10 describes a virtual network system 100Z having a data network 120Z that accommodates eight operator devices. Figure 11 describes a virtual network system 100B having a data network 120B that accommodates ten operator devices.

[0015] The virtual network system 100B forms domains 121, 122, and 123 within the carrier network. A PE-to-PE path PEP is established between the carrier termination device PE1 in domain 121 and the carrier termination device PE2 in domain 123. Carrier relay devices PR1 and PR2, which are directly connected to carrier termination device PE1, belong to domain 121. Carrier relay devices PR3 and PR4, which are directly connected to carrier termination device PE2, belong to domain 123. Carrier relay devices P1 to P4, which are not directly connected to any carrier termination device, belong to domain 122.

[0016] Furthermore, the virtual network system 100B has the following characteristics: • Even if the data network 120 is separated into three domains 121, 122, and 123, GMPLS or equivalent signaling (generation of inter-PE paths PEP) of the control network 110B is performed in a single domain 111 that spans domains 121 to 123. • Routing information / topology information is transparent. • Provisioning, fault recovery, and optimal path selection can be efficiently performed between the IP nodes of the control network 110B and the optical nodes of the data network 120. • GMPLS compliance is required for connections between operator equipment (IP / MPLS equipment) of the control network 110B.

[0017] As explained above, each operator device within the operator network requires IP connectivity in both the control network 110B, which transmits control signals, and the data network 120, which transmits test messages for the main signal, when the LMP, which is operated in the first stage of link management to comply with GMPLS, is activated. Therefore, it was not possible to create a section within the operator network that only handles optical signals (optical transmission section), and sufficient capacity and low latency could not be achieved.

[0018] Therefore, the main objective of the present invention is to achieve high capacity and low latency by using a method that replaces the GMPLS peer model, which is based on LMP, in the relay path configuration when realizing an L1VPN built within a carrier network, so that only optical signals can be handled in the optical transmission section.

[0019] To solve the aforementioned problems, the optical path setting device of the present invention comprises the following means. The present invention is an optical path setting device used in a virtual network system that enables communication between a first carrier termination device and a second carrier termination device in a carrier network via an optical path through a carrier relay device in the carrier network, characterized in that the optical path setting device issues a different relay path identifier for each different transit route for the relay path of the carrier relay device which is part of the optical path, advertises it to the first carrier termination device, and causes the first carrier termination device to specify the relay path identifier, thereby setting the relay path of the optical path as a source route.

[0020] According to the present invention, when realizing an L1VPN built within a carrier network, an alternative method to the GMPLS peer model which assumes LMP is used in the relay path configuration, enabling the handling of only optical signals in the optical transmission section, thereby achieving increased capacity and lower latency.

[0021] This is a configuration diagram of the virtual network system according to this embodiment. This is a configuration diagram showing the Overlay model virtual network system according to this embodiment. This is a configuration diagram showing the virtual network system with two optical paths configured according to this embodiment. This is a configuration diagram of the virtual network system according to this embodiment. This is a flowchart showing the processing of the virtual network system according to this embodiment. This is an explanatory diagram showing the data format exchanged by BGP between carrier termination devices according to this embodiment. This is an explanatory diagram showing the data format exchanged by BGP between carrier termination devices following the data format in Figure 6 according to this embodiment. This is a table showing the PIT generated in the carrier termination device based on the exchanged port information according to this embodiment. This is a hardware configuration diagram of each device in the virtual network system according to this embodiment. This is a configuration diagram of the virtual network system. This is a configuration diagram showing the Peer model virtual network system.

[0022] One embodiment of the present invention will be described in detail below with reference to the drawings.

[0023] Figure 1 is a configuration diagram of the virtual network system 100A. The virtual network system 100A connects the carrier termination device PE1 within the carrier network, which is composed of the control network 110 and the data network 120A, with the customer communication device CE1 outside the carrier network via a communication line at their connection ports. In other words, a connection port is a physical port (interface) into which the physical line connecting the carrier termination device PE1 and the customer communication device CE1 is inserted. Furthermore, the virtual network system 100A enables communication between the carrier termination device (first carrier termination device) PE1 and the carrier termination device (second carrier termination device) PE2 within the carrier network via an optical path through carrier relay devices P1 to P4 within the carrier network.

[0024] The virtual network system 100A has a controller (optical path setting device) 130 that is communicably connected to the data network 120A via the control network 110. The controller 130 has a path design unit 11, a routing processing unit 12, and a device setting unit 13. The routing processing unit 12 mediates the exchange of information between each carrier termination device PE1, PE2, PE3, and PE4 using BGP or the like. For example, the routing processing unit 12 exchanges the following information: - Link state information exchanged between each carrier device using BGP-LS (Link State). Note that the link state is path information collected and calculated by OSPF or IS-IS. - Information on connection ports (CPI, PPI, etc.). - Information on behavioral operations (SRv6 network programming) associated with SID (Segment IDentifier) ​​in source routing using SR.

[0025] In this manner, the controller 130 mediates between the carrier termination device PE1 and the carrier termination device PE2, by transmitting information about the connection ports of the customer communication device CE1, which are associated with the connection ports of PE1. This unifies the information exchange protocol to BGP, reducing the processing load on each device compared to a system where separate protocols are used for each piece of information to be exchanged. However, the routing processing unit 12 does not prevent the use or substitution of PCEP (Path Computation Element Protocol) for notifying route calculation results in the manner described in the implementation method.

[0026] Furthermore, it is possible to use BFD (Bidirectional Forwarding Detection) to quickly detect faults in the BGP connection between the routing processing unit 12 of the controller 130 and the carrier termination devices PE1 to PE4 of the data network 120A.

[0027] Furthermore, the routing processing unit 12 includes the functionality of a BGP RR (Route Reflector) or a BGP RS (Route Server). In addition, the routing processing unit 12 may also include the functionality of BGP-LS, which forwards data from other protocols (such as OSPF or IS-IS Link State). The information subject to this information exchange may be forwarded by the routing processing unit 12 through mediation (forwarding) between the carrier termination devices PE1 and PE2, or the information may be exchanged directly between the carrier termination devices PE1 and PE2 without going through the routing processing unit 12.

[0028] Furthermore, regarding the establishment of communication between carrier termination devices PE1 and PE2, each carrier device is automatically assigned an IPv6 Link Local address, and the adjacency relationship is automatically discovered by the NDP operated by each carrier device. Therefore, a BGP peer connection is established between carrier termination devices PE1 and PE2 according to RFC (Request for Comments) 5549 / RFC8950. Note that when LMP was used to confirm the adjacency relationship, IPv4 or IPv6 multicast was required within the LMP processing. On the other hand, in the method of this embodiment, BGP can be established if the adjacency relationship, which is a prerequisite for IPv6 connection, can be established by NDP, thus relaxing the requirements.

[0029] The path design unit 11 generates optical path information to be set for carrier equipment (mainly carrier relay devices P1 to P4) within the data network 120A, based on the information exchanged by the routing processing unit 12. Optical path information is, for example, information about the section to which an optical path is set for carrier equipment. Specifically, the path design unit 11 issues a different relay path identifier (SID) for each different transit route for the relay paths of carrier relay devices P1 to P4, which are part of the optical path (PE-to-PE path PEP). Carrier relay devices P1 to P4 are transmission devices that do not perform processing at Layer 2 or higher in the main signal. The SID is, for example, an MPLS label in the case of SR-MPLS, or an IPv6 address using SRH (Segment Routing Header) in the case of SRv6.

[0030] It is assumed that the wavelength between the carrier termination devices PE1 to PE4 and the carrier relay devices P1 to P4 connected to them is selectable (tunable) by using a transceiver such as OpenZR+ at carrier termination device PE1. Therefore, since the optical paths that carrier termination device PE1 can actually use are limited, the routing processing unit 12 advertises the optical paths that can be used as route-specific SIDs. Carrier termination device PE1 then refers to these advertised route-specific SIDs and selects the wavelength of the inter-PE path PEP corresponding to the advertised route-specific SID, either through its own settings or by the controller 130's specification. Here, the advertised "route-specific SID" is equivalent to a Binding SID, but it is a SID that cannot be expanded on the router side, and expanding it on the optical device would be meaningless.

[0031] The device configuration unit 13 configures the optical path information (SID, etc.) generated by the path design unit 11 in the carrier equipment (mainly carrier relay devices P1 to P4) within the data network 120A. Network device configuration protocols such as NETCONF (Network Configuration Protocol) are used for this configuration process in the carrier equipment. Furthermore, the device configuration unit 13 advertises the SID information configured in carrier relay devices P1 to P4 within the control network 110 (carrier termination devices PE1, PE2) using BGP. As a result, carrier termination device PE1 can handle the SR optical path from the IP layer. In this way, the controller 130 issues different relay path identifiers for each different transit route for the relay paths of carrier relay devices P1 to P4, which are part of the optical path, advertises them to carrier termination device PE1, and configures the relay paths of the optical path as source routing by having carrier termination device PE1 specify the relay path identifier.

[0032] Figure 2 is a configuration diagram showing a virtual network system 100C in the Overlay model. The virtual network system 100A in Figure 1 is based on the Overlay model, similar to Figure 2. Figure 1 describes a virtual network system 100A having a data network 120A that accommodates eight carrier devices. Figure 2 describes a virtual network system 100C having a data network 120C that accommodates ten carrier devices, similar to Figure 11. In the virtual network system 100C, IP is not assumed for the carrier devices (carrier relay devices PR1 to PR4, carrier relay devices P1 to P4), so LMP and LMP-WDM (Wavelength Division Multiplexing) are not operated, and the connectivity of main signal communication using IP through their operation is not confirmed.

[0033] The data network 120B in Figure 11 and the data network 120C in Figure 2 form the same domains 121, 122, and 123. On the other hand, the virtual network system 100C in Figure 2 differs from the virtual network system 100B in Figure 11 in that the domains 121 to 123 of the data network 120C correspond to the domains 112 to 114 of the control network 110C. The carrier relay devices P1 to P4 in domain 122 are OXCs (optical cross-connects) such as ROADM devices assumed by OpenROADM (Reconfigurable Optical Add / Drop Multiplexers). In addition to the WSS (Wavelength Selective Switch) function, the ROADM device has the function of performing centralized control of NETCONF as a DCN (Data Communication Network) connection using OSC (Optical Supervisory Channel).

[0034] In the virtual network system 100C, the information exchange between carrier termination devices PE1 and PE2 and the setting of the inter-PE path PEP are replaced with a method that works in conjunction with the NMS (Network Management System), as shown below. In Figure 1, the controller 130 was located outside the control network 110, but it may be configured as the same device as the NMS inside the control network 110C in Figure 2. Also, domain 113 is not GMPLS compliant and is an optical domain managed by the Optical NMS that controls ROADM, and the NMS does not need to have IP processing functionality for the main signal. The NMS can acquire the state of the optical signal for each section between each carrier relay device P1 to P4 by collecting optical signal-related parameters such as optical input / output power level, BER (Bit Error Rate), and OSNR. Furthermore, by combining the NMS's parameter collection function with the IOAM (In Situ Operations, Administration, and Maintenance) function used in IPv6, which is the basis of SRv6, and SR-MPLS, testing in the main signal section of the IP section becomes possible, thus eliminating the need for LMP.

[0035] Furthermore, communication using optical wavelengths (L1 communication) takes place between carrier relay devices P1 to P4 and carrier relay devices PR1 to PR4 within domain 113. On the other hand, the IP addresses held by carrier relay devices PR1 to PR4 perform IP communication (L3 communication) with the IP addresses of other carrier relay devices PR1 to PR4. Within each domain 112 and 114, routing / topology information is exchanged via IGPs such as OSPF and IS-IS. However, routing / topology information is not exchanged between domains 112 and 114. Here, multiple behaviors are defined in SRv6, such as End.DX6 (Endpoint with decapsulation and IPv6 cross-connect) for realizing IPv6-L3VPN and End.DX2 (Endpoint with decapsulation and L2 cross-connect) for realizing L2VPN. Domains 112 and 114 do not require GMPLS compliance because they will be building an End.DX1 (L1VPN) similar to End.DX6 and End.DX2 in SRv6. In addition, the carrier termination device PE2 at the exit of the PE-to-PE path PEP is equipped with an SRv6 network programming (End.DX1) function and a Segment List that makes End.DX1 and PPI the same.

[0036] Furthermore, in the control network 110B shown in Figure 11, GMPLS or equivalent signaling (generation of inter-PE path PEPs) using RSVP-TE or CR-LDP was performed in domain 111. On the other hand, in the control network 110C shown in Figure 2, an L1VPN is established in domain 113 (NMS) by segment routing. Specifically, the device configuration unit 13 configures paths using NETCONF for each carrier relay device P1 to P4 in domain 122, which corresponds to domain 113. Then, the routing processing unit 12 creates route-specific SID values ​​for route selection corresponding to the relay paths (partial paths of inter-PE path PEPs) configured by the device configuration unit 13 using NETCONF for the device groups in domains 112 and 114 in Figure 2, assigns a route selection identifier (Color in SR Policy) to it, and advertises it.

[0037] Figure 3 is a configuration diagram showing a virtual network system 100D with two optical paths configured. Two optical paths are configured in the data network 120D of the virtual network system 100D. The controller 130 specifies the two optical paths in the SR as intended by the administrator. The first optical path 128 is a path that passes through the carrier termination device PE1 → carrier relay device P1 → carrier relay device P2 → carrier termination device PE2, and SID=101 is set using wavelength λ1. The second optical path 129 is a path that passes through the carrier termination device PE1 → carrier relay device P1 → carrier relay device P3 → carrier relay device P4 → carrier relay device P2 → carrier termination device PE2, and SID=102 is set using wavelength λ2.

[0038] Furthermore, the following Node SIDs are assigned to each carrier termination device PE1 to PE4: • Carrier termination device PE1: SID=1 • Carrier termination device PE2: SID=2 • Carrier termination device PE3: SID=3 • Carrier termination device PE4: SID=4

[0039] When communication is made from carrier termination device PE1 to carrier termination device PE2, carrier termination device PE1, as the originating node, stacks the following SID List, which indicates the route of the inter-PE path PEP, as the main signal based on instructions from controller 130. ・When using wavelength λ1: SID=101 (wavelength λ1 = relay path), SID=2 (carrier termination device PE2 = final destination) ・When using wavelength λ2: SID=102 (wavelength λ2 = relay path), SID=2 (carrier termination device PE2 = final destination) In SR, instructions from controller 130 to the originating node are either dynamically specified using PCEP or BGP based on RFC9256 (Segment Routing Policy Architecture), or statically operated by changing the settings via NETCONF, etc.

[0040] Figure 4 is a diagram of the configuration of the virtual network system 100E. For the sake of clarity, the data network 120D of the virtual network system 100E omits the illustration of carrier equipment other than carrier termination devices PE1 and PE2. First, the routing processing unit 12 advertises the PPI and CPI (RFC5195) required for L1VPN between carrier termination devices PE1 and PE2, and advertises each PPI as a route for End.DX1 between carrier termination devices PE1 and PE2. This generates two optical paths. Although Figure 3 shows two optical paths, Figure 4 only shows one optical path 128, but in reality, a total of two optical paths are generated: path wavelength λ1 "SID=101 (0x65)" and path wavelength λ2 "SID=102 (0x66)".

[0041] Next, we list the addresses assigned to each connection port. • Port p13 on the customer communication device CE11 side within carrier termination device PE1: IPv6 address = 2001:db8:fd01:1::1 • Port p25 on the carrier termination device PE1 side within carrier termination device PE2: IPv6 address = 2001:db8:fd01:65::2 • Port p23 on the customer communication device CE21 side within carrier termination device PE2: IPv6 address = 2001:db8:fd01:2::1

[0042] Then, by establishing an L1VPN from customer communication device CE11 to customer communication device CE21, main signals 201, 202, and 203 flow through the optical path 128 from customer communication device CE11 → carrier termination device PE1 → carrier termination device PE2 → customer communication device CE21. At the point of customer communication device CE11 → carrier termination device PE1, main signal 201 is only Data (user data).

[0043] When the service provider terminal device PE1 → service provider terminal device PE2, for the main signal 202, an SRH (inner header) and an IPv6 (outer header) are added to the Data of the main signal 201. The SRH includes the following items. - Segment List[0] (exit node) = 2001:db8:fd01:2::1 - Segment List[1] = 2001:db8:fd01:65::2 The IPv6 (outer header) includes the following items. - SrcIP = Port1 of PE1 = 2001:db8:fe01:1::1 - DstIP = determined by the Segment List of the SRH

[0044] When the service provider terminal device PE2 → customer communication device CE21, for the main signal 203, the SRH (inner header) and the IPv6 (outer header) are removed from the main signal 202, and only the same Data as the main signal 201 remains. Hereinafter, the operation when the service provider terminal device PE1 uses IPv6 for PPI / CPI and SRv6 between PEs and uses the optical path of wavelength λ1 will be described.

[0045] Figure 5 is a flowchart showing the processing of the virtual network systems 100A, 100C to 100E. First, as S11 to S13, each procedure performed by the service provider terminal devices PE1 and PE2 as preprocessing for setting the PE-to-PE path PEP in the service provider network will be described. The device setting unit 13 of the controller 130 assigns SIDs for path setting to each service provider relay device P1 to P4 in the domain 122 by NETCONF, as described in FIGS. 1 and 2 (S11). Alternatively, in S11, each service provider relay device P1 to P4 may directly receive the input of the SID from the user via an input device such as a keyboard. The service provider terminal device PE1 collects the port information (CPI) of the customer communication device CE11 at its own site by means of LMP or an automatic discovery protocol (such as NDP) and associates it with its own port information (PPI) (S12).

[0046] The carrier termination device PE1 exchanges port information (CPI, PPI) with the carrier termination device PE2 at the opposite site (S13). Therefore, similar to S12, the carrier termination device PE2 also collects the port information (CPI) of the customer communication device CE21 at the opposite site and associates it with its own port information (PPI). For this port information exchange process in S13, a BGP peer directly connected between carrier termination devices PE1 and PE2 may be used (in accordance with RFC5251, RFC5195), or the port information received from carrier termination device PE1 may be forwarded to carrier termination device PE2 via the routing processing unit 12.

[0047] Figure 6 is an explanatory diagram showing the data format exchanged via BGP between carrier termination devices PE1 and PE2 in S13. This data format 302 diagram is a 32-bit packet format horizontally, with numerical values ​​indicating bits 0 through 31 also shown at the top. The "SRv6 Service TLVs" shown in Figure 6 are defined in RFC9252 and are assigned as follows from BGP Prefix-SID TLV (Type-Length-Value) Types: • TLV Type (8 bits). "5" for SRv6 L3 service TLVs, "6" for SRv6 L2 service TLVs, and unassigned for SRv6 L1 service TLVs requiring new assignment. • TLV Length (16 bits) • RESERVED (8 bits) • SRv6 Service Sub-TLVs (variable length; in the diagram, the rightmost edge is indicated by a wavy line to show the variable length)

[0048] Fig. 7 is an explanatory diagram showing the data format exchanged between carrier edge devices PE1 and PE2 by BGP following the data format of Fig. 6. The data format 303 of Fig. 7 that appears after the data format 302 of Fig. 6 stores the following "SRv6 SID Information Sub-TLV" as a BGP message. - SRv6 Service Sub-TLV Type = 1: This field is set to 1 to represent the SRv6 SID information Sub-TLV. - SRv6 Service Sub-TLV Length - RESERVED1 - SRv6 SID Value (16 octets): This field encodes the SRv6 SID as defined in RFC8986. - SRv6 SID Flags: This field encodes the SRv6 service SID flag, but since it is not currently defined, "0" is stored. - SRv6 Endpoint Behavior: Encodes the SRv6 endpoint operation code point value associated with the SRv6 SID. - RESERVED2 - SRv6 Service Data Sub-Sub-TLVs

[0049] Figure 8 shows Table 301, which represents the PIT generated within the carrier termination device PE1 based on the port information exchanged in S13. The carrier termination device PE1 exchanges its own connection port information, which is associated with the connection port information of the customer communication device CE1, with the connection port information of the carrier termination device PE2, thereby constructing the exchanged connection port information as port information data (PIT). Table 301 associates the advertiser, port information (PPI, CPI), and RT (Route Target) = VPNID. For example, the first row of Table 301 stores the following port information of the customer communication device CE11, with the carrier termination device PE1 as the advertiser: - The IPv6 address of port p13 on the carrier termination device PE1 side in Figure 4 is the PPI. - The IPv6 address of port p11 on the customer communication device CE11 side is the CPI. - The VPNID of the VPN to which the customer communication device CE11 belongs. This VPNID may be collected by the carrier termination device PE1 in S12 or exchanged in S13, or it may be input by the user via an input device separately from those processes.

[0050] Furthermore, as information exchanged in S13, the carrier termination device PE1 receives, in the data format of Figures 6 and 7, that the address of carrier termination device PE2 (such as the address of port p23 on the customer communication device CE21 side) is End.DX1 as specified in SRv6 Endpoint Behaviors in Figure 7 (applying RFC9252). In this way, the controller 130 (or carrier termination device PE1), along with the process of exchanging connection port information in S13, instructs the receiving carrier termination device PE2 to specify the receiving processing content as End.DX1 for the main signal transmitted from carrier termination device PE1 along the optical path via source routing. As a result, carrier termination device PE2, which is the exit node (Endpoint) of the inter-PE path PEP, is configured to execute a special post-processing (SRv6 Endpoint Behavior) prepared in advance as End.DX1 for the main signal received via the inter-PE path PEP.

[0051] The following is an example of End.DX1 code. S01. Remove the outer IPv6 header with all its extension headers S02. Forward to the OIF I Note that "S01" and "S02" indicate the line numbers of the code, with line S01 decapsulating the SRv6 encapsulation and line S02 forwarding to a specific interface. In addition, the carrier termination device PE2 distinguishes between main signals to which this End.DX1 code applies and main signals to which it does not apply by referring to the SID of the main signal. Therefore, the carrier termination device PE2 exchanges the SID to which the End.DX1 code applies (the SID indicating that it is the main signal of the inter-PE path PEP) in advance using the routing protocol.

[0052] For reference, the following code shows the upper-layer header processing operation of End.DX2 as described in RFC8986. S01. If (Upper-Layer header type == 143(Ethernet) ) { S02. Remove the outer IPv6 header with all its extension headers S03. Forward the Ethernet frame to the OIF I S04.} Else { S05. Process as per Section 4.1.1 S06.} In this End.DX2, the process to check whether the upper-layer header is Ethernet (registered trademark) is described in line S01. On the other hand, End.DX1 removes the IPv6 header and extension headers from the upper-layer header regardless of its contents and forwards it to the specified OIF (Output Interface).

[0053] Next, steps S14 to S16 describe the procedure for setting up the inter-PE path PEP from carrier termination device PE1 to carrier termination device PE2, and for transmitting the main signal through this inter-PE path PEP. Carrier termination device PE1 receives data for the main signal that is to be transmitted from its own customer communication device CE11 to the opposite customer communication device CE21 (S14). Carrier termination device PE1, which is the entry node of the inter-PE path PEP, uses the opposite carrier termination device PE2, which is heading toward the opposite customer communication device CE21, as the exit interface of the exit node (S15). For example, carrier termination device PE1 sets the IPv6 address of port p23 on the customer communication device CE21 side within carrier termination device PE2 (=2001:db8:fd01:2::1) as the Segment List[0] (exit node) of the main signal SRH.

[0054] Therefore, the operator termination device PE1 searches for the RT (e.g., 64500:1) assigned to its own (advertiser = PE1) input interface (PPI = 2001:db8:fd01:1::1) from the information managed in table 301 (PIT) in Figure 8. Then, the operator termination device PE1 retrieves the other (advertiser = PE2) input interface (PPI = 2001:db8:fd01:2::1) to which the same RT (e.g., 64500:1) as the retrieved RT is assigned.

[0055] Furthermore, the carrier termination device PE1 sets the intermediate relay paths of the optical path to the SRH of the main signal as appropriate, and then transmits the main signal data to the optical path (PE-to-PE path PEP) (S16). In S16, the carrier termination device PE1 may specify the intermediate relay paths (paths of carrier relay devices P1 to P4) of the main signal path using the Binding SID equivalent, which is the "path-specific SID" advertised by the controller 130. Here, since different optical paths have different relay paths, different optical wavelengths are assigned as relay path identifiers (SIDs). Therefore, the carrier termination device PE1 can indirectly specify (change) the paths of carrier relay devices P1 to P4 by specifying the optical wavelength corresponding to the desired relay path.

[0056] The above describes the communication process in which the carrier termination device PE1 refers to port information data (PIT) and sets the path for the main signal passing through one of the carrier relay devices P1 to P4 to the carrier termination device PE2 as source routing. In other words, the carrier termination device PE1 performs the communication processing of the main signal on the data plane from the carrier termination device PE1 to the carrier termination device PE2 in accordance with instructions from the controller 130 (NMS). The communication processing of the main signal from the carrier termination device PE2 to the carrier termination device PE1 is similar.

[0057] Furthermore, if the port information (PPI, CPI) is IPv4, since the PPI is an IPv4 address, the IPv6 address used as the exit node for the SRv6 output interface should have its lower 32 bits set to an IPv4 address. As a result, the carrier termination device PE1 establishes an L1VPN from customer communication device CE1 to customer communication device CE2, using IPv4 for PPI / CPI, SRv6 between PEs, and wavelength λ1 for the optical path. Also, if the connection between carrier termination devices PE1 and PE2 is SR-MPLS, the SID will be an MPLS label regardless of whether the PPI is IPv4 or IPv6, so the example IPv6 address should be replaced with the MPLS label.

[0058] Figure 9 is a hardware configuration diagram of each device in the virtual network systems 100A, 100C to 100E. Each device in the virtual network systems 100A, 100C to 100E (the carrier relay device P, the carrier termination devices PE1 and PE2, the controller 130, and the customer communication devices CE1 and CE2) is configured as a computer 900 having a CPU 901, RAM 902, ROM 903, HDD 904, communication I / F 905, input / output I / F 906, and media I / F 907, respectively. The communication I / F 905 is connected to an external communication device 915. The input / output I / F 906 is connected to an input / output device 916. The media I / F 907 reads and writes data to the recording medium 917. Furthermore, the CPU 901 controls each processing unit by executing a program (optical path setting program) loaded into the RAM 902. Furthermore, this program (also called an application, or simply an app) can be distributed via a communication line or by recording it on a recording medium 917 such as a USB memory stick and distributing it that way. Note that the computer 900 in Figure 9 is a representative example of the virtual network systems 100A, 100C to 100E, but in some cases, some of the processing performed on the CPU 901 may be replaced by dedicated semiconductors such as ASICs (application-specific integrated circuits).

[0059] The virtual network systems 100A, 100C to 100E described above mainly have the following features: - Since the inter-PE path PEP is not configured on the customer communication devices CE1 and CE2, the customer communication devices CE1 and CE2 do not require the various functions of GMPLS (such as LMP) on which L1VPN is based. - Since the SID of the SR is assigned to the carrier relay devices P1 to P4, the transmission devices (carrier relay devices P1 to P4) also do not require the various functions of GMPLS (such as LMP). - The path design unit 11 and the routing processing unit 12 of the controller 130 exchange path information between carrier termination devices PE1 and PE2 using BGP.

[0060] [Effect] The present invention relates to a controller 130 used in a virtual network system 100 that enables communication between carrier termination equipment PE1 and carrier termination equipment PE2 within a carrier network via carrier relay equipment P1 to P4 within a carrier network using an optical path, characterized in that the controller 130 issues different relay path identifiers for each different transit route for the relay paths of carrier relay equipment P1 to P4, which are part of the optical path, advertises them to carrier termination equipment PE1, and causes carrier termination equipment PE1 to specify the relay path identifier, thereby setting the relay path of the optical path as source routing.

[0061] As a result, the virtual network system 100A can construct an L1VPN without using GMPLS for the transmission section between carrier relay devices P1 to P4 using source routing. Therefore, the virtual network system 100A can eliminate the need for IP processing in the main signal connection for this transmission section, and in the relay path configuration when realizing an L1VPN built within a carrier network, it can use a method that replaces the GMPLS peer model which assumes LMP, allowing only optical signals to be handled in the optical transmission section, thereby achieving increased capacity and lower latency.

[0062] The present invention is characterized in that a carrier termination device PE1 and a carrier termination device PE2 are each connected to a customer communication device CE1 outside the carrier network via a communication line and connection port, and a controller 130 mediates between the carrier termination device PE2 and the carrier termination device PE1, which associates the connection port information of the customer communication device CE1 with the connection port information of the carrier termination device PE1.

[0063] As a result, the virtual network system 100A does not need to prepare BGP peers between carrier termination devices PE1 and PE2 for each combination of carrier termination devices, thus simplifying network management.

[0064] The present invention is characterized in that, in conjunction with the process of exchanging information about the connection port, the controller 130 instructs the receiving carrier termination device PE2 on the processing content for the main signal transmitted along the optical path by source routing.

[0065] As a result, the virtual network system 100A can process the main signal faster than conventional protocol-specific main signal receiving-side processing by designating the carrier termination device PE2 to process the main signal transmitted via L1VPN.

[0066] 11 Path Design Unit 12 Route Processing Unit 13 Device Setting Unit 100A-100E Virtual Network System 130 Controller (Optical Path Setting Device) CE1, CE2 Customer Communication Devices PE1, PE2 Carrier Termination Device PEP Inter-PE Path 301 Table

Claims

1. An optical path setting device used in a virtual network system that enables communication between a first carrier termination device and a second carrier termination device within a carrier network via a carrier relay device within the carrier network, wherein the optical path setting device issues different relay path identifiers for each different transit route for the relay paths of the carrier relay device which are part of the optical path, advertises these identifiers to the first carrier termination device, and causes the first carrier termination device to specify the relay path identifiers, thereby setting the relay paths of the optical path as source routing.

2. The optical path setting device according to claim 1, wherein the first carrier termination device and the second carrier termination device are each connected to a customer communication device outside the carrier network via a communication line through a connection port, and the optical path setting device mediates between the second carrier termination device and the connection port information of the first carrier termination device, which is associated with the connection port information of the customer communication device.

3. The optical path setting device according to claim 2, characterized in that, in conjunction with the process of exchanging information of connection ports, it instructs the receiving second carrier termination device on the content of the receiving side's processing targeting the main signal transmitted along the optical path by source routing.

4. An optical path setting method performed by an optical path setting device used in a virtual network system that enables communication between a first carrier termination device and a second carrier termination device within a carrier network via a carrier relay device within the carrier network, wherein the optical path setting device issues different relay path identifiers for each different transit route for the relay paths of the carrier relay device which are part of the optical path, advertises these identifiers to the first carrier termination device, and causes the first carrier termination device to specify the relay path identifiers, thereby setting the relay paths of the optical path as source routing.

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