Patent Publication Number: US-2023132674-A1

Title: Optical communication network system, optical network unit, and optical communication method

Description:
TECHNICAL FIELD 
     The disclosure relates to an optical communication network system (passive optical network (PON) system) and an optical communication method. 
     BACKGROUND ART 
     For users using network services by connecting to a network through an optical transmission line, a technology to connect optical network units in customer premises to the network via an optical line terminal (OLT) has been proposed (see, for example, Non-Patent Literature 1). 
     In Non-Patent Literature 2, an OLT uses a logical link ID (LLID) to identify the logical path of each ONU. In Non-Patent Literature 3, each ONU has one media access control (MAC) address, and an OLT allocates one LLID to each ONU based on the MAC address possessed by each ONU. The ONU performs authentication based on the LLID and generates a logical path. In this connection, a technology has been proposed that allows a single ONU to construct a plurality of logical paths by allocating a plurality of LLIDs and MAC addresses to the single ONU (see, for example, Patent Literature 1). 
     However, to allocate LLIDs, the MAC addresses, corresponding to the number of logical paths to be generated for an ONU, need to be set in advance, which makes it difficult to increase the number of logical paths as desired. Specifically, in a conventional LLID distribution technology, logical path generation is performed based on the MAC address previously allocated to an ONU. Accordingly, when a plurality of MAC addresses are not allocated to the ONU, a plurality of logical paths cannot be generated. Moreover, the number of logical paths that can be generated is limited to the number of MAC addresses previously set to the ONU. Accordingly, a system can be considered in which an ONU acquires unique identity information from a connected terminal device, and the LLID generates logical path to the OLT based on the acquired ID information. 
     CITATION LIST 
     Patent Literature 
     
         
         Patent Literature 1: Japanese Patent Laid-Open No. 2007-74256 
       
    
     Non-Patent Literature 
     
         
         Non-Patent Literature 1: “gijutsu kiso kouza [GE-PON Gijutsu] dai 4 kai, GE-PON no shisutemuka kinou” (“Technical Basic Course [GE-PON technology] 4th, GE-PON Systematized Functions”) NTT Technical Review, pp. 59-61, November 2005 
         Non-Patent Literature 2: IEEE802.3-2018, clause 64 
         Non-Patent Literature 3: IEEE1904.1 SIEPON 
       
    
     SUMMARY OF THE INVENTION 
     Technical Problem 
     As a typical method for obtaining information about a terminal device, it can be considered to acquire information included in an address resolution protocol (ARP) request from the terminal device and using a MAC address or the like of the terminal device as an information ID. However, in this case, the method is applied only to the terminal device that is directly connected to an ONU, and cannot be applied to environments where terminal devices of a plurality of users are connected to the ONU via a router device (NAPT device) such as Home Gateway. For this reason, a system is required which enables the ONU to acquire ID information of the terminal devices that are connected through a network device such as a router. 
     Accordingly, an object of the present disclosure is to enable an ONU to acquire ID information of terminal devices even when a network device is connected between the ONU and the terminal devices, and to thereby enable generation of a logical path between the ONU and the OLT. 
     Means for Solving the Problem 
     An optical communication network system of the present disclosure is a passive optical network (PON) system configured to connect a plurality of terminal devices to an optical network unit (ONU) via a network device. In the system, the network device and the ONU are provided with an L 2  tunnel function to make the ONU function as a same local network under a router, and the ONU is provided with a function (ID acquisition unit) to acquire terminal IDs of the terminal devices and thereby acquires the ID information directly from the terminal devices. As a result, the system is configured to generate logical path generation addresses from the acquired ID information, and perform generation and management of the logical path for each of the terminal devices. 
     Here, the network device of the present disclosure is an optional device that can connect one or more terminal devices to an ONU, the optional device including Home Gateway and other router devices (Network address port translation (NAPT)/IP masquerade/Port Address Translation devices). 
     The optical communication network system according to the present disclosure is an optical communication network system configured to connect terminal devices and a passive optical network (PON) system via a network device. The PON system includes an optical line terminal and an optical network unit connected using an optical transmission line. The optical network unit is configured to construct a tunnel to the network device, acquire ID information of the terminal devices connected to the network device from the terminal devices via the tunnel, and generate a logical path to the optical line terminal on the optical transmission line using the acquired ID information. 
     An optical network unit according to the present disclosure is an optical network unit connected to an optical line terminal using an optical transmission line and connected to terminal devices via a network device. The optical network unit is configured to construct a tunnel to the network device, acquire ID information of the terminal devices connected to the network device from the terminal devices via the tunnel, and generate a logical path to the optical line terminal on the optical transmission line using the acquired ID information. 
     An optical communication method according to the present disclosure is an optical communication method executed by an optical network unit connected to an optical line terminal using an optical transmission line and connected to terminal devices via a network device. The optical communication method includes: constructing a tunnel to the network device; acquiring ID information of the terminal devices connected to the network device via the tunnel; and generating a logical path to the optical line terminal on the optical transmission line using the acquired ID information. 
     Effects of the Invention 
     According to the present disclosure, even when communication between an ONU and a terminal device is via a network device in the situation where a logical path between the ONU and an OLT is not generated, the ID information of the terminal device can be acquired and used to generate the logical path between the OLT and the ONU. As a result, logical path allocation can be performed for each terminal device, and different bandwidth allocation and priority control can be performed for each terminal device even when each terminal device is under the same ONU. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    shows an example of the schematic configuration of a system according to the present disclosure. 
         FIG.  2    shows an example of the overall configuration of the system of the present disclosure. 
         FIG.  3    shows an example of a functional block diagram of the system of the present disclosure. 
         FIG.  4    shows a basic flow at the time of connecting a router and an ONU. 
         FIG.  5    shows an example of a basic flow at the time of connecting a terminal device and the router. 
         FIG.  6    shows a sequence diagram at the time of connecting the terminal device and the router. 
         FIG.  7    shows an example of a method of generating a virtual MAC address. 
         FIG.  8    shows examples of a logical path for each terminal device. 
         FIG.  9    shows examples of a logical path for each service. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     An embodiment of the present disclosure will be described hereinafter in detail with reference to the drawings. The present disclosure is not limited to the embodiment stated below. The embodiment is merely exemplary, and the present disclosure can be carried out in modes changed and modified in various manners based on the knowledge of those skilled in the art. Note that component members similar to each other are designated by similar signs in the present description and drawings. 
     (Outline of Present Disclosure) 
     Hereinafter, the outline of the present disclosure will be described with reference to  FIG.  1   . In the present disclosure, a router  96 , such as Home Gateway, and an ONU  92  are provided with an L 2  tunnel function based on an open system interconnection (OSI) reference model, so that the ONU  92  is used as the same local network under the router  96 . The ONU  92  is further provided with a function (ID acquisition unit) to acquire ID information of terminal devices  94  and thereby acquires the ID information directly from the terminal devices  94 . Accordingly, the optical communication network system according to the present disclosure can generate addresses used to generate logical paths from the ID information obtained from the terminal devices  94 , and generate and manage the logical paths for the respective terminal devices  94 . The route  96  is an example of the network device of the present disclosure. In the embodiment described below, the network device is the router  96 . 
     [Overall Configuration] 
       FIG.  2    shows an example of the system configuration of the present disclosure. The optical communication network system of the present disclosure includes the terminal devices  94  for users, the router  96 , a PON system  90 , and a network  95 . The PON system  90  includes the ONU  92 , an optical transmission line  93  in a PON segment, and an OLT  91 . 
     The terminal devices  94  are connected to the router  96  via a wired or wireless medium. The router  96  is connected to the ONU  92  via a wired or wireless medium. The ONU  94  is connected for communication to the OLT  91  via the optical transmission line  93  in the PON segment. The router  96  is a device that connects the terminal devices  94  to the ONU  92 , the router  96  including network address port translation (NAPT)/IP masquerade/Port address translation devices, and Home Gateway. 
     Typically, it is considered to acquire information included in an ARP request from the terminal device  94  and use the MAC address or the like of the terminal device  94  as the identification information. However, in this case, the method can be applied only to the terminal device  94  directly connected, and is not applicable to the environment where two or more terminal devices  94  are connected via the router  96 . For this reason, a system is required which enables the ONU  92  to acquire ID information of the terminal devices  94  that are connected through the router  96 . The ONU  92  usually inspect only the packets addressed to itself. 
     (Function Block Diagram) 
       FIG.  3    shows an example of a functional block diagram of the optical communication network system of the present disclosure. 
     The OLT  91  includes an optical signal processing unit  11 , a control unit  12  and a network connection unit  13 . 
     The ONU  92  includes a terminal connection unit  25 , a signal processing unit  23 , a control unit  24 , connection identification units  22  (#1, #2, . . . , #N (where N is an integer greater than or equal to 2), an optical signal processing unit  21 , an ID acquisition unit  26 , a virtual LAN interface  31 , and an L 2  tunnel connection unit  32 . In the drawings, the interface may be expressed as IF (interface). 
     The router  96  includes an ONU connection unit  61 , a virtual WAN interface unit  64 , a NAPT function unit  65 , a virtual LAN interface unit  63 , an L 2  tunnel connection unit  62 , and a dynamic host configuration protocol (DHCP) server function unit  66 . 
     [Configuration of ONU] 
     The terminal connection unit  25  is connected for communication to the router  96  via a wired or wireless medium. The terminal connection unit  25  is also connected to the signal processing unit  23 .
 
The signal processing unit  23  is connected to the terminal connection unit  25 . The signal processing unit  23  is also connected to the optical signal processing unit  21  via N connection identification units  22  (#1 to #N) in pair with one of the N connection identification units  22 . The signal processing unit  12  is also connected for communication to the control unit  24 .
 
The control unit  24  is connected for communication to the signal processing unit  23 . The control unit  24  is also connected for communication to the N connection identification units  22  (#1 to #N), respectively.
 
The control unit  24  includes, for example, a processor such as a central processing unit (CPU).
 
     The optical signal processing unit  21  is connected for communication to the signal processing unit  23  via N connection identification units  22  (#1 to #N) in pair with one of the N connection identification units  22 . The optical signal processing unit  21  is connected for communication to the OLT  91  via the optical transmission line  93  in the PON segment. Note that the connection identification units  22  are configured to identify, for example, the terminal devices  94  and the like based on the LLID, but are not limited to this configuration. For example, the connection identification units  22  can be configured by combining a connection identification unit that identifies the terminal device based on information different from the LLID, and a connection identification unit that identifies the terminal devices based on the LLID. 
     The L 2  tunnel connection unit  32  uses an L 2  tunneling protocol such as a layer 2 tunneling protocol (L2TP) to construct an L 2  tunnel to the router  96  connected to the terminal connection unit  25 . 
     The ID acquisition unit  26  is connected for communication to the virtual LAN interface unit  31  and the control unit  24 , and notifies the control unit  24  of the ID information acquired from the virtual LAN interface unit  31 . 
     [Configuration of OLT  91 ] 
     The optical signal processing unit  11  is connected for communication to the ONU  92  via the optical transmission line  93  in the PON segment. The signal processing unit  11  is also connected for communication to the network connection unit  13 .
 
The control unit  12  includes a processor such as a CPU, for example.
 
The network connection unit  13  is connected for communication to the optical signal processing unit  11 .
 
     [Configuration of Router  96 ] 
     The ONU connection unit  61  is connected for communication to the ONU  92  via a wired or wireless medium. The ONU connection unit  61  is also connected for communication to the virtual WAN interface unit  64 . The ONU connection unit  61  is further connected for communication to the virtual LAN interface unit  63  via the L 2  tunnel connection unit.
 
The virtual LAN interface unit  63  is connected for communication to the terminal devices  94 . The NAPT function unit  65  is connected for communication to the virtual WAN interface unit  64  and the virtual LAN interface unit  63 , and performs NAPT processing between the two interfaces.
 
The DHCP server function unit  66  is connected for communication to the virtual LAN interface unit  63  and distributes an IP address to the opposite device (interfaces) that is connected for communication to the L 2  tunnel function unit  62 . For example, the DHCP server function unit  66  issues the IP address to the virtual LAN interface unit  31  of the ONU  92 .
 
     (Basic Flow at Time of Connecting Router  96 ) 
       FIG.  4    shows the basic flow when the router  96  connects to the ONU  92 . 
     Step S 101 : the router  96  connects to the ONU  92 .
 
Step S 102 : Between the L 2  tunnel connection unit  62  provided in the router  96  and the L 2  tunnel connection unit  32  in the ONU  92 , the router  96  and the ONU  92  constructs an L 2  tunnel using the L 2  tunneling protocol such as L2TP. In this case, for encryption, tunneling protocols having encryption functions, such as Ipsec and PPP, may be combined.
 
Step S 103 : the L 2  tunnel connects the virtual LAN interface unit  31  of the ONU  92  and the virtual LAN interface unit  63  of the router  96  through an L 2  layer.
 
The DHCP server function unit  66  of the router  96  issues an IP address to the virtual LAN interface unit  31  of the ONU  92 , and recognizes the ONU  92  as a device in the local network of the router  96 .
 
     In this case, the DHCP server function unit  66  may use one of IPv4 and IPv6. The DHCP server function unit  66  may also be included in devices disposed at locations other than the location of the router  96  (for example, in the local network of the router  96  or in a high-order network of the ONU  92 ). However, in that case, the DHCP server function unit  66  needs to be reachable to the virtual LAN interface unit  31  of the ONU  92  and the virtual LAN interface unit  63  of the router  96  and be able to allocate the IP address. 
     (Basic Flow at Time of Connecting Terminal Device  94  for Communication) 
       FIG.  5    shows the basic flow at the time of connecting the terminal device  94 .  FIG.  6    shows a sequence diagram at the time of connecting the terminal device  94 . With reference to  FIGS.  5  and  6   , operation at the time of connecting the terminal device  94  in the present embodiment will be described. The L 2  tunnel between the router  96  and the ONU  92  is assumed to be constructed before the terminal device  94  is connected. 
     Step S 111 : the terminal device  94  is connected to the router  96 . 
     Step S 121 : the ID acquisition unit  26  included in the ONU  92  acquires information about the terminal device  94  by an APR request or the like via the L 2  tunnel, and notifies the control unit  24  of the ID information of the terminal device  94 .
 
Step S 122 : the control unit  24  determines the connection identification unit  22  #2 used to connect to the OLT  91 . The control unit  24  then acquires the ID information from the ID acquisition unit  26  and uses the ID information of the terminal device  94  to generate a virtual MAC address of the connection identification unit  22  #2.
 
     The control unit  24  gives a connection instruction using the virtual MAC address to the determined connection identification unit  22  #2. The control unit  24  also notifies the signal processing unit  23  of the LLID and ID information of the connection identification unit  22  #2. 
     Step S 123 : the connection identification unit  22  #2 makes a connection request for terminal device  94  to the OLT. In this case, the connection identification unit  22  #2 makes an authentication request to the OLT  91 .
 
Step S 124 : the control unit  12  of the OLT  91  authenticates the terminal device  94  using the LLID and the virtual MAC address received from the connection identification unit  22  #2 to confirm whether or not connection is permitted. When acquiring the authentication result from the OLT  91 , the connection identification unit  22  #2 notifies the control unit  24  of the authentication result.
 
Step S 125 : when the result of authentication by the OLT  91  is OK, i.e., “permitted (authenticated)”, the control unit  24  shifts to step S 126 . Meanwhile, when the result of authentication is NG, the control unit  24  determines the connection identification unit  22  #1 which is different from the connection identification unit  22  #2.
 
     Here, in step S 122 , the number of ID information pieces acquired by the ID acquisition unit  26  may be any number greater than or equal to 1. The number of and a combination of ID information pieces used by the control unit  24  to generate the virtual MAC address is optional. 
     The ID information may be an identifier that uniquely determines the terminal device  94 . Examples of the ID information may include following identifiers, any of which can be used.
         MAC address   Subscriber identity module (SIM)   International mobile equipment identifier (IMEI)   Phone number   International mobile subscriber identity (IMSI)   IC card identifier (ICCID)   Host name   Production serial number       

     The virtual MAC address can be generated in any way. For example, there is a method of generating a new virtual MAC address from only the ID information of the terminal device  94 , without linking the physical MAC address of the ONU  92  with the ID information of the terminal device  94 . For example, as shown in  FIG.  7   , out of an IMEI (decimal number of up to 15 digits) of the terminal device  94 , a number of up to 14 digits excluding a last check digit is converted to a hexadecimal number. When the digits of the number is less than 12 digits, 0 is appended to upper digits to generate the virtual MAC address, and the generated virtual MAC address is used to identify and authenticate the terminal device  94 . 
     The ID information may have priority set for generation of the virtual MAC address. Examples of the operation of the ID acquisition unit  26  and the control unit  24  may include the followings. 
     The ID acquisition unit  26  acquires a plurality of ID information pieces at once, and the control unit  24  generates the virtual MAC address by using the ID information pieces in a specific priority. When authentication is not obtained in a connection request, the control unit  24  generates the virtual MAC address in sequence by using the ID information pieces specified according to the priority.
 
The ID acquisition unit  26  acquires a plurality of ID information pieces at once, the control unit  24  combines the plurality of ID information pieces to generate the virtual MAC address, and the control unit  24  uses the virtual MAC address to perform authentication. The authentication is performed by matching the respective ID information pieces included in the virtual MAC address. In this case, the control unit  24  may change a high-order connection destination of the OLT  91  based on the matching state of the plurality of ID information pieces.
 
     Note that when connection is rejected in authentication determination performed in step S 125 , the control unit  24  may return to acquire the ID information (S 121 ). In this case, examples of the processing by the ONU  92  may be as shown below. 
     The ID acquisition unit  26  acquires information from various types of ID information according to a specific priority. The flow of steps S 121  to S 125  is sequentially repeated until authentication “permitted” is achieved.
 
The ID acquisition unit  26  performs a plurality of acquisition methods to acquire the same ID information according to a specific priority. The flow of steps S 121  to S 125  is sequentially repeated while the acquisition methods performed by the ID acquisition unit are changed until authentication “permitted” is achieved.
 
     Step S 127 : the connection identification unit  22  #2 generates a logical path between the ONU  92  and the OLT  91 . Once the logical path is generated, the connection identification unit  22  #2 notifies the control unit  24  that generation of the logical path is completed. In this case, the connection identification unit  22  #2 may also notify the control unit  24  that the authentication result is OK. 
     Step S 128 : the control unit  24  instructs the signal processing unit  23  to start transmission between the connection identification unit #2 and the terminal device  94 . Step S 112 : the terminal device  94  starts to use network services. 
     The connection processing for the terminal device  94  is completed by the OLT  91  and the ONU  92  performing the above processing. Note that the authentication processing in step S 125  can be performed after the logical path is generated or at the same time when the logical path is generated. 
       FIG.  7    shows examples of a logical path for each terminal device  94  (or each user). The logical path for each terminal device  94  is generated one application for each terminal device  94  as shown in  FIG.  7 ( a ) , for example. When one terminal device  94  runs a plurality of applications, the ONU  92  may generate a single logical path for the plurality of applications as shown in  FIG.  7 ( b ) . When the plurality of terminal devices  94  run a common application, the ONU  92  may generate a logical path for each of the terminal device  94  as shown in  FIG.  7 ( c ) . Here, the logical path may be generated for each terminal device group or for each type of the terminal devices  94  instead of for each terminal device  94 . As shown in  FIG.  7 ( d ) , the ONU  92  may also generate a logical path different for each connection method (WiFi, wired, etc.) used between the terminal device  94  and the router  96 . The method of logical path generation is also applicable to the cases without using a device, such as the router  96 , to connect the terminal device  94  to the ONU  92 . 
       FIG.  8    shows examples of a logical path for each service. The logical path is generated one application for each terminal device  94  as shown in  FIG.  8 ( a )  for example. When one terminal device  94  runs a plurality of applications, the ONU  92  may generate a plurality of logical paths for the one terminal device  94  according to the number of applications as shown in  FIG.  8 ( b ) . When the plurality of terminal devices  94  run a common application, the ONU  92  may generate a common logical path for the plurality of terminal device  94  as shown in  FIG.  8 ( c ) . Here, the logical path may be generated for each application group or application type instead of for each application. As shown in  FIG.  8 ( d ) , the ONU  92  may also generate a logical path different for each communication protocol for one terminal device  94 . The method of logical path generation is also applicable to the cases without using a device, such as the router  96 , to connect the terminal device  94  to the ONU  92 . 
     INDUSTRIAL APPLICABILITY 
     This disclosure may be applied to the information and communications industry. 
     REFERENCE SIGNS LIST 
     
         
         
           
               11 ,  21  Optical signal processing unit 
               12 ,  24  Control unit 
               13  Network connection unit 
               22  Connection identification unit 
               23  Signal processing unit 
               25  Terminal connection unit 
               26  ID acquisition Unit 
               31 ,  63  Virtual LAN interface 
               32 ,  62  L 2  tunnel connection unit 
               61  ONU connection unit 
               64  Virtual WAN interface 
               65  NAPT function unit 
               66  DHCP server function unit 
               90  PON system 
               91  OLT 
               92  ONU 
               93  Optical transmission line 
               94  Terminal device 
               95  Network 
               96  Router