Business operator terminal device and information exchange method
By using automatic discovery protocols to exchange port information between carrier and customer communication devices, the complexity and cost of L1VPN systems are reduced by eliminating the need for GMPLS functions in customer communication devices.
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- NT T INC
- Filing Date
- 2024-11-26
- Publication Date
- 2026-06-04
AI Technical Summary
Conventional L1VPN systems require customer communication devices to operate multiple complex GMPLS functions, leading to increased costs and operational complexity due to the need for high-resource devices.
Implementing an automatic discovery protocol between carrier termination devices and customer communication devices to exchange port information, eliminating the need for GMPLS functions in customer communication devices by using IP-based protocols for port information exchange and signaling.
Reduces device and network operation costs by simplifying the customer communication devices' requirements, allowing them to operate without GMPLS-compliant signaling functions.
Smart Images
Figure JP2024041825_04062026_PF_FP_ABST
Abstract
Description
Business operator terminal device, and information exchange method
[0001] The present invention relates to a business operator terminal device and an information exchange method.
[0002] VPN (Virtual Private Network), which connects remote user bases via a business operator network and constitutes a virtual closed network for each user, has become widespread. As a virtual network technology provided by business operators, L1VPN (Layer 1 VPN), which relays customer communications via a business operator network using a large-capacity Layer 1 (optical network), has been proposed.
[0003] For example, Non-Patent Document 1 describes a Peer Model technique for constructing L1VPN. The Peer Model of Non-Patent Document 1 is a method that accepts a path setting request as signaling of GMPLS (Generalized Multiprotocol Label Switching), which is a Control interface.
[0004] D. Fedyk, Ed. et al., "Layer 1 VPN Basic Mode", [online], [searched on November 12, 2024], Internet <URL: https: / / datatracker.ietf.org / doc / html / rfc5251>
[0005] However, in the conventional L1VPN of Non-Patent Document 1, it is necessary to operate many functions simultaneously in a customer communication device (CE: Customer Edge) installed within a user base. Therefore, a device with a large number of resources such as CPU, memory, and storage is required, increasing the burden on the customer side. The burden on the customer side is, for example, the burden that requires device costs and the burden that makes network operation complicated. Hereinafter, details will be described with reference to FIG. 7.
[0006] Figure 7 is a diagram of the configuration of the virtual network system 100Z. The virtual network system 100Z forms an L1VPN by connecting geographically separated locations of the same user (VPN#1) using the carrier's optical network. The local location (VPN#1 location on the left in Figure 7) is equipped with customer communication equipment CE1 for connecting to the carrier's network. The opposing location (VPN#1 location on the right in Figure 7) is equipped with customer communication equipment CE2 for connecting to the carrier's network. The carrier's network consists of optical network transmission equipment (hereinafter referred to as "carrier equipment"), including carrier termination equipment PE1, which is a provider edge (PE) connected to customer communication equipment CE1, carrier termination equipment PE2, which is connected to customer communication equipment CE2, and carrier relay equipment P1 to P8, which are not connected to any customer communication equipment.
[0007] 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 PE1 → Carrier relay device P5 → Carrier relay device P6 → Carrier relay device P7 → Carrier relay device P8 → Carrier termination device PE2 → Customer communication device CE2
[0008] 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 PE2 prepare a Port Information Table (PIT) in advance. A "port" as defined in the PIT 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. In the PIT, the information of the physical port on the customer communication device CE1 side is defined as the CPI (Customer Port Identifier), and the information of the physical port on the carrier termination device PE1 side is defined as the PPI (Provider Port Identifier), and the correspondence information between CPI and PPI is defined for each VPN. This separates the address space for each VPN user, thereby preventing connections between different VPN users.
[0009] Customer communication device CE1 and carrier termination device PE1 exchange port information (CPI and PPI) using port information exchange procedure LL1. Similarly, customer communication device CE2 and carrier termination device PE2 exchange port information using port information exchange procedure LL2. Furthermore, carrier termination devices PE1 and PE2 exchange port information using routing protocols such as OSPF (Open Shortest Path First) and BGP (Border Gateway Protocol). Based on the exchanged port information, carrier termination devices PE1 and PE2 construct their own PIT (Port Information Terminal).
[0010] Here, since the L1VPN described in Non-Patent Document 1 is based on GMPLS, customer communication devices CE1 and CE2 are required to be GMPLS-compatible nodes. Therefore, in order to perform data communication between customer communication devices CE1 and CE2 via the inter-CE path CEP, the following functions from the first to third stages that constitute GMPLS are required. [First stage: Link management] A function to acquire the link status between adjacent nodes. In GMPLS, the LMP (Link Management Protocol) operating on customer communication device CE1 confirms the normality of communication with the carrier termination device PE1 by sending and receiving Hello packets for a certain period of time. Furthermore, the LMP executes the port information exchange procedure LL1 between customer communication device CE1 and carrier termination device PE1.
[0011] [Second Stage: Routing] This function floods (advertises) the link status obtained in the first stage into the virtual network system 100Z as link state. GMPLS performs routing using IGPs (Interior Gateway Protocols) such as OSPF and IS-IS (Intermediate System to Intermediate System).
[0012] [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).
[0013] On the other hand, customer communication equipment CE1 within user sites is often an inexpensive communication device with limited functions, such as data transfer and simple communication configuration functions. Therefore, it is difficult to operate special control protocols such as the first stage (LMP), second stage (OSPF), or third stage (RSVP) on customer communication equipment CE1.
[0014] Therefore, the main objective of this invention is to reduce costs on the user's side when constructing an L1VPN.
[0015] To solve the aforementioned problems, the carrier termination device of the present invention comprises the following means. The present invention is a carrier termination device used in a virtual network system in which a carrier termination device within a carrier network and a customer communication device outside the carrier network are connected to each other via a communication line at their connection ports, characterized in that the carrier termination device exchanges information about the connection ports in the customer communication device and information about the connection ports in the carrier termination device using an automatic discovery protocol that operates between the customer communication device and the carrier termination device, and uses the information about the connection ports in the customer communication device and the information about the connection ports in the carrier termination device to construct port information data that enables communication with other carrier termination devices via L1VPN.
[0016] According to the present invention, it is possible to reduce the costs on the user's side when constructing an L1VPN.
[0017] This is a configuration diagram of the virtual network system according to this embodiment. This is a configuration diagram showing the Peer model 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 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 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.
[0018] One embodiment of the present invention will be described in detail below with reference to the drawings.
[0019] Figure 1 is a diagram of the configuration of the virtual network system 100A. The virtual network system 100A connects the carrier termination device PE1 within the carrier network and the customer communication device CE1 outside the carrier network via a communication line to each other's 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.
[0020] The main differences between the virtual network system 100A in Figure 1 and the virtual network system 100Z in Figure 7 are as follows: [First difference] In the virtual network system 100Z in Figure 7, the CE-to-CE path CEP was generated as the optical path for the L1VPN between customer communication devices CE1 and CE2. On the other hand, the virtual network system 100A in Figure 1 generates the PE-to-PE path PEP between carrier termination devices PE1 and PE2. The PE-to-PE path PEP may be an optical path (optical wavelength path) for the L1VPN, or it may be an IP communication path.
[0021] [Second Difference] As a port information exchange procedure for generating the optical path of the L1VPN, the virtual network system 100Z in Figure 7 used LMP-based port information exchange procedures LL1 and LL2, which are required by GMPLS, on the customer communication devices CE1 and CE2. On the other hand, the virtual network system 100A in Figure 1 uses IP-based automatic discovery protocols, which are commonly provided in communication devices, as port information exchange procedures SL1 and SL2, and operates on the customer communication devices CE1 and CE2. In port information exchange procedures SL1 and SL2, the following port information (item name, size) is exchanged: ・PPI length: 1 byte ・PPI: Variable length ・CPI AFI (Address Family Identifier): 2 bytes ・CPI length: 1 byte ・CPI: Variable length
[0022] In this way, the automatic discovery protocol operating between the customer communication device CE1 and the carrier termination device PE1 exchanges information about the connection ports in the customer communication device CE1 and information about the connection ports in the carrier termination device PE1. The carrier termination device PE1 then uses the information about the connection ports in the customer communication device CE1 and the information about the connection ports in the carrier termination device PE1 to construct port information data (PIT) that enables communication with the carrier termination device PE2 via L1VPN.
[0023] The automatic discovery protocols used in the port information exchange procedure SL1 between the customer communication device CE1 and the carrier termination device PE1 include, for example, the following protocols: • ARP (Address Resolution Protocol) is a protocol that resolves MAC (Media Access Control address) addresses from IPv4 addresses. • NDP (Neighbor Discovery Protocol) is a protocol that performs neighbor discovery on the same link to resolve MAC addresses from IPv6 addresses. • LLDP (Link Layer Discovery Protocol) is a protocol used to advertise each device's information (additional port information) via the connection established between the customer communication device CE1 and the carrier termination device PE1.
[0024] In other words, the carrier termination device PE1 exchanges at least one of the following addresses as connection port information: the IPv4 address of the connection port in the customer communication device CE1 resolved by ARP, one of the automatic discovery protocols, and the IPv6 linklocal address of the connection port in the customer communication device CE1 resolved by NDP, one of the automatic discovery protocols. Furthermore, the carrier termination device PE1 may include information sent as an LLDP Port ID TLV, which is transmitted from the customer communication device CE1 via LLDP, one of the automatic discovery protocols, as connection port information.
[0025] The following describes how the functions of the first to third stages of the virtual network system 100Z in Figure 7 have been modified in the virtual network system 100A in Figure 1. [Stage 1: Link Management] In the virtual network system 100A in Figure 1, the customer communication devices CE1 and CE2 are no longer located at the endpoints of the inter-PE path PEP (first difference), so the port information exchange procedures LL1 and LL2 using LMP in the virtual network system 100Z are no longer necessary. In other words, the customer communication devices CE1 and CE2 do not need to operate LMP. On the other hand, in the virtual network system 100A, in order to perform the port assignment process described later in the second stage, the customer communication devices CE1 and CE2 execute the port information exchange procedures SL1 and SL2 using an IP-based automatic discovery protocol with the carrier termination devices PE1 and PE2 (second difference). Through these port information exchange procedures SL1 and SL2, the CPI of the customer communication device CE1 and the PPI of the carrier termination device PE1 exchange information. Furthermore, within the carrier network through which the inter-PE path PEP passes, LMP may be used to verify the existence of adjacent connections, or this may be performed by the routing protocol (OSPF or IS-IS) in the second stage.
[0026] [Stage 2: Routing] In the virtual network system 100A shown in Figure 1, since the customer communication devices CE1 and CE2 are no longer located at the endpoints of the inter-PE path PEP (first difference), the customer communication devices CE1 and CE2 do not need to operate the routing protocol in Stage 2. On the other hand, within the carrier network through which the inter-PE path PEP passes, the virtual network system 100A operates the routing protocol in the same way as the virtual network system 100Z, so that port information (CPI, PPI) is exchanged between the carrier termination devices PE1 and PE2. Note that the virtual network system 100A may use BGP (Border Gateway Protocol) between the carrier termination devices PE1 and PE2 as the routing protocol instead of OSPF or IS-IS (see Figure 4 for details).
[0027] Furthermore, in the virtual network system 100A, the carrier termination device PE1 performs the allocation process to its PIT for the physical ports it possesses that are connected to the customer communication device CE1 (i.e., ports used for VPN communication). Similarly, the carrier termination device PE2 performs the allocation process to its PIT for the physical ports it possesses that are connected to the customer communication device CE2. This port allocation process is the process by which carrier termination devices PE1 and PE2 determine the physical ports (physical ports to be incorporated into the L1VPN) for connecting to the customer communication devices CE1 and CE2 based on instructions from the user or event participant. The port allocation process uses port information (CPI, PPI) exchanged by the port information exchange procedures SL1 and SL2.
[0028] [Stage 3: Signaling] In the virtual network system 100A shown in Figure 1, the customer communication devices CE1 and CE2 are no longer located at the endpoints of the inter-PE path PEP (first difference), so the customer communication devices CE1 and CE2 do not need to have the function of generating an optical path (LSP). On the other hand, within the carrier network through which the inter-PE path PEP passes, the virtual network system 100A generates the inter-PE path PEP by referring to the PIT prepared in Stage 2 within the carrier termination devices PE1 and PE2, by operating a signaling protocol similar to that of the virtual network system 100Z.
[0029] As explained above, the virtual network system 100A in Figure 1 eliminates the need for customer communication devices CE1 and CE2 to implement each protocol of GMPLS in the first to third stages. As a result, the virtual network system 100A can reduce costs on the user site side when constructing an L1VPN. The "carrier network" in the virtual network system 100A where the inter-PEP path PEP is generated can be functionally separated into a control plane (control network), which is a DCN (Data Communication Network) through which control signals flow, and a data plane (data network) through which data signals (main signals of VPN users) flow. There are two types of control plane models, and either model may be used in the virtual network system 100A of this embodiment. ・Peer model (explained in Figure 2). ・Overlay model (explained in Figure 3).
[0030] Figure 2 is a configuration diagram showing the Peer model virtual network system 100B. The virtual network system 100B is a model in which the carrier network of the virtual network system 100A in Figure 1 is functionally separated into a control plane control network 110A and a data plane data network 120. The virtual network system 100B forms domains 121, 122, and 123 within the data network 120. An inter-PE path PEP is set up between the carrier termination device PE1 in domain 121 and the carrier termination device PE2 in domain 123. Carrier relay devices P1 and P5, which are directly connected to carrier termination device PE1, belong to domain 121. Carrier relay devices P4 and P8, which are directly connected to carrier termination device PE2, belong to domain 123. Carrier relay devices OP2, OP3, OP6, and OP7, which are not directly connected to any carrier termination device, belong to domain 122.
[0031] 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 of the control network 110A is performed in a single domain 111 that spans domains 121 to 123. ・Routing information / topology information is transparent. ・Efficient provisioning, fault recovery, and optimal path selection can be performed between the IP nodes of the control network 110A and the optical nodes of the data network 120. ・Connection between operator equipment (IP / MPLS equipment) of the control network 110A requires GMPLS compliance or an alternative technology for path allocation that considers resources across layers equivalent to GMPLS.
[0032] Figure 3 is a configuration diagram showing the virtual network system 100C of the Overlay model. The virtual network system 100C is a model in which the carrier network of the virtual network system 100A in Figure 1 is functionally separated into a control plane control network 110B and a data plane data network 120. The configuration of each domain 121, 122, 123 of the data network 120 and the carrier equipment belonging to each domain is the same as that of the virtual network system 100B in Figure 2 and the virtual network system 100C in Figure 3.
[0033] On the other hand, while the control network 110A in Figure 2 had one domain 111, the control network 110B in Figure 3 is replaced by three domains 112 to 114. Then, each of the domains 121 to 123 of the data network 120 corresponds to each of the domains 112 to 114 of the control network 110B.
[0034] The virtual network system 100C has the following characteristics: • There are two types of domains (Optical domain and IP domain) between domain 121 of the data network 120 and domain 112 of the control network 110B. The same applies between domain 123 of the data network 120 and domain 114 of the control network 110B. • Domains 112 and 114 are GMPLS-compliant domains. • Domain 113 is an Optical NMS (Network Management System) that is not GMPLS-compliant. The NMS requests connections using the UNI (User Network Interface) interface defined by the OIF (Optical Internetworking Forum). • Routing / topology information is not exchanged between domains 112 to 114.
[0035] Figure 4 is a configuration diagram of the virtual network system 100D. The virtual network system 100D is an example of using BGP between carrier termination devices PE1 and PE2 as the second-stage routing protocol in the virtual network system 100A of Figure 1. A protocol for enabling BGP-based automatic discovery and configuration for L1VPN has been proposed as RFC5195. The virtual network system 100D further has a controller 130 connected to the control network 110A. The controller 130 has a BGP processing unit 131 for forwarding BGP messages between carrier termination devices PE1 and PE2. The BGP processing unit 131 includes the functions of a BGP RR (Route Reflector) or a BGP RS (Route Server). Furthermore, the BGP processing unit 131 may also include the function of BGP-LS for forwarding data from other protocols (such as OSPF or IS-IS Link State).
[0036] The BGP processing unit 131 forwards port information notified as a BGP message from the carrier termination device PE1 to the carrier termination device PE2. The BGP processing unit 131 also forwards port information notified as a BGP message from the carrier termination device PE2 to the carrier termination device PE1. This eliminates the need for a direct connection between carrier termination devices PE1 and PE2, thus reducing the number of BGP connections. Alternatively, by providing a direct BGP connection between carrier termination devices PE1 and PE2, the controller 130 can be eliminated.
[0037] Figure 5 is a flowchart showing the processing of virtual network systems 100A to 100D. The carrier termination device PE1 obtains port information of its own site from the customer communication device CE1 using the port information exchange procedure SL1 described in Figure 1 (S11). The carrier termination device PE1, using the BGP processing unit 131 of the controller 130 described in Figure 4, notifies the carrier termination device PE2 at the opposite site via BGP of information for generating an inter-PE path PEP that includes the port information of its own site obtained in S11 (S12). Similarly, the carrier termination device PE1 at the own site receives port information of the opposite site from the carrier termination device PE2 using the BGP processing unit 131 (S13).
[0038] The information notified in S12 and S13 may include, for example, the following: [Case 1] PPI = IPv4 address of the connection port in the carrier termination device PE1. CPI = IPv4 address of the connection port in the customer communication device CE1 resolved by ARP. [Case 2] PPI = IPv6 address of the connection port in the carrier termination device PE1. CPI = IPv6 linklocal address of the connection port in the customer communication device CE1 resolved by NDP. [Case 3] PPI = Information sent as the IPv4 address of the connection port in the carrier termination device PE1 and LLDP Port ID TLV. CPI = Information received as the IPv4 address of the connection port in the customer communication device CE1 resolved by ARP and LLDP Port ID TLV. [Case 4] PPI = Information sent as the IPv6 address of the connection port in the carrier termination device PE1 and LLDP Port ID TLV. CPI = Information received as the IPv6 linklocal address of the connection port in the customer communication device CE1 resolved by NDP and LLDP Port ID TLV.
[0039] Here, the first and second cases involve the exchange of addresses only, while the third and fourth cases involve the exchange of addresses and additional port information using the LLDP Port ID TLV. Additional port information includes, for example, the identifier (VPN-ID) of the user site (VPN#1) to which the customer communication device CE1 belongs, and communication of the main signal between user sites with the same VPN-ID is performed via the PE-to-PE path PEP. In the first and third cases, the normally configured IPv6 Link Local address is exchanged. In the second and fourth cases, the IPv4 address is exchanged if an IPv4 address is configured on the connection port. The carrier termination device PE1 then generates its own PIT (Personal Information Terminal) by assigning the port information obtained in S11 and S13 to its own connection port (carrier termination device PE1) (S14).
[0040] Furthermore, the carrier termination device PE1 refers to the PIT in S14 and sets up an inter-PE path PEP with the carrier termination device PE2 (S15). Here, the communication path between carrier termination devices PE1 and PE2 in S15 is not limited to the inter-PE path PEP using the third-stage signaling protocol, but can also be established using other methods to enable VPN main signals to be used for data communication.
[0041] For example, a carrier termination device PE1 may use Segment Routing (SR) to sequentially specify the communication path within the carrier network to carrier termination device PE2. SR is implemented using protocols such as SRv6 or SR-MPLS, and these SR protocols operate through OSPF or IS-IS protocol extensions. In SR, similar to RSVP, the controller 130 uses a protocol such as PCEP (Path Computation Element Protocol) to search the carrier network for a path that meets the requirements. An SR-enabled node (carrier device) instructed by the controller 130 performs path forwarding by stacking a Segment Identifier (SID) on the main signal. In the case of SR-MPLS, the stacked SID is an MPLS label, and in the case of SRv6, the SID is an IPv6 address SRH (Segment Routing Extension Header).
[0042] Figure 6 is a hardware configuration diagram of each device in the virtual network systems 100A to 100D. Each device in the virtual network systems 100A to 100D (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 (information exchange 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 6 is a representative example of each device in the virtual network systems 100A to 100D, 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).
[0043] [Effects] The present invention relates to a carrier termination device PE1 used in a virtual network system 100A in which a carrier termination device PE1 within the carrier network and a customer communication device CE1 outside the carrier network are connected to each other via a communication line at their connection ports, characterized in that the carrier termination device PE1 exchanges information about the connection ports in the customer communication device CE1 and information about the connection ports in the carrier termination device PE1 using an automatic discovery protocol that operates between the customer communication device CE1 and the carrier termination device PE1, and uses the information about the connection ports in the customer communication device CE1 and the information about the connection ports in the carrier termination device PE1 to construct port information data that enables communication with a carrier termination device PE2 via L1VPN.
[0044] As a result, the virtual network system 100A can exclude the customer communication device CE1 outside the carrier network from the optical path communication of the L1VPN, so that the customer communication device CE1 does not need to bear the GMPLS-compliant signaling function required for the L1VPN. Therefore, the customer communication device CE1 does not need to support special control protocols such as RSVP and LMP required by GMPLS, which can reduce the device cost and the NW operation cost.
[0045] The present invention is characterized in that the carrier terminal device PE1 exchanges at least one of the IPv4 address of the connection port in the customer communication device CE1 resolved by ARP, which is one of the auto-discovery protocols, and the IPv6 linklocal address of the connection port in the customer communication device CE1 resolved by NDP, which is one of the auto-discovery protocols, as the information of the connection port.
[0046] As a result, the virtual network system 100A can collect the information of the connection port from the customer communication device CE1 by utilizing ARP and NDP, which are often originally equipped in routers as auto-discovery protocols.
[0047] The present invention is characterized in that the carrier terminal device PE1 includes the information transmitted by the LLDP Port ID TLV, which is transmitted from the customer communication device CE1 by LLDP, which is one of the auto-discovery protocols, in the information of the connection port.
[0048] As a result, the virtual network system 100A can collect additional information as well as the address of the connection port as the information of the connection port.
[0049] 100A to 100D Virtual network system 130 Controller 131 BGP processing unit CE1, CE2 Customer communication device CEP CE-to-CE path LL1, LL2 Port information exchange procedure PE1, PE2 Carrier terminal device PEP PE-to-PE path SL1, SL2 Port information exchange procedure
Claims
1. A carrier termination device used in a virtual network system in which a carrier termination device within the carrier network and a customer communication device outside the carrier network are connected to each other via a communication line at their connection ports, wherein the carrier termination device exchanges information about the connection ports within the customer communication device and information about the connection ports within the carrier termination device using an automatic discovery protocol that operates between the customer communication device and the carrier termination device, and uses the information about the connection ports within the customer communication device and the information about the connection ports within the carrier termination device to construct port information data that enables communication with other carrier termination devices via L1VPN (Layer 1 Virtual Private Network).
2. The carrier termination device according to claim 1, characterized in that it exchanges at least one of the following addresses as connection port information: the IPv4 address of the connection port in the customer communication device resolved by ARP (Address Resolution Protocol), which is one of the automatic discovery protocols, and the IPv6 linklocal address of the connection port in the customer communication device resolved by NDP (Neighbor Discovery Protocol), which is one of the automatic discovery protocols.
3. The carrier termination device according to claim 2, characterized in that the carrier termination device includes information transmitted from the customer communication device using LLDP (Link Layer Discovery Protocol), which is one of the automatic discovery protocols, as information transmitted as an LLDP Port ID TLV, in the connection port information.
4. An information exchange method performed by a carrier termination device used in a virtual network system in which a carrier termination device within the carrier network and a customer communication device outside the carrier network are connected to each other via a communication line at their connection ports, characterized in that the carrier termination device exchanges information about the connection ports within the customer communication device and information about the connection ports within the carrier termination device using an automatic discovery protocol that operates between the customer communication device and the carrier termination device, and uses the information about the connection ports within the customer communication device and the information about the connection ports within the carrier termination device to construct port information data that enables communication with other carrier termination devices via L1VPN (Layer 1 Virtual Private Network).