Abstract:
Provided is a passive optical network (PON) providing system of an Ethernet-based packet transport layer (PTL) scheme, including: a connection management server to manage a unified PTL connection overall over the network by establishing a PTL connection between an optical network unit (ONU)/optical network terminal (ONT) of a customer termination of one party and an ONU/ONT of a customer termination of another party, and by applying a PTL-PON scheme to a PON section between the ONU/ONT and an optical line termination (OLT); an OLT to manage a connection of a received packet, and to convert a format of the packet according to a transmission direction of the packet and thereby transmit the packet; and an ONU/ONT becoming an end point of the PTL connection to convert the format of the packet according to the transmission direction of the received packet and to thereby transmit the packet to a customer terminal or the OLT.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to and the benefit of Korean Patent Application No. 10-2010-0134065 filed in the Korean Intellectual Property Office on Dec. 23, 2010, the entire contents of which are incorporated herein by reference. 
       TECHNICAL FIELD 
       [0002]    The present invention relates to a connection management server, an optical line termination (OLT), an optical network unit (ONU)/optical network terminal (ONT), and a method, and a system for providing a passive optical network (PON) employing a packet transport layer (PTL) technology, and more particularly, to a connection management server, an OLT, an ONU/ONT, and a method and a system for providing a PON of an Ethernet-based PTL scheme for connection management between an ONU or ONT and an OLT. 
         [0003]    The present invention is further embodied based on a PON system and method of a PTL scheme that is a filed patent (application number 2009-0128433). 
       BACKGROUND 
       [0004]    In a current communication network, with the increasing importance of the Internet, all the communication services are being packetized. And to stably provide a voice service of a voice over Internet protocol (VoIP) and an image service of an Internet protocol television (IPTV) in a wired/wireless packet network, a technology of a highly reliable packet transport layer (hereinafter, PTL) scheme is being applied. 
         [0005]    In order to increase the diversity and the reliability of transport, the PTL scheme enables all the communication services to be performed based on a packet, and accurately transports the packet at a circuit level. So, the above scheme guarantees the transport quality of the packet. But because the above scheme is not applied to an access network, there was a problem in that the above scheme does not guarantee transport quality between customer terminations and is limited to communication between local stations. 
         [0006]    An existing passive optical network (hereinafter, PON) scheme includes an Ethernet PON (hereinafter, E-PON) scheme and a gigabit PON (hereinafter, G-PON) scheme. The E-PON scheme is suitable for communication using Ethernet protocol and thus, is applied to an Ethernet network including an Ethernet switch. The G-PON scheme is a scheme enabling an Ethernet and asynchronous transfer mode (ATM) and circuit communication. In general, the above PON schemes are easy to be applied to the Ethernet network and are not suitable for being applied to a PTL network, where connection establishment is needed for guaranteeing the quality. 
         [0007]    The detailed description with respect to the above problem will be described through a PTL scheme applied to E-PON. 
         [0008]    A packet transmitted from an optical network unit (hereinafter, ONU) or an optical network terminal (hereinafter, ONT) of a customer termination is aggregated at a packet switch of one party via an optical line termination (hereinafter, OLT). The aggregated packets are transported to a packet switch of another party via a packet switch or a router of a metro network and a core network and thereby are transmitted to another customer termination. 
         [0009]    In general, in the metro network and the core network, a channel is established by a connection management server and a state of the connection is managed. However, in the access network between an OLT and an ONU/ONT, only a physical link is managed by an E-PON server and a connection of a logical level does not exist. 
         [0010]    Accordingly, when an error occurs in transferred information, there was a problem in that even though it is possible to verify whether the error occurred in the metro network and the core network, it is difficult to verify whether the error occurred in the access network. 
       SUMMARY 
       [0011]    The present invention has been made in an effort to provide a connection management server, an optical line termination (OLT), an optical network unit (ONU)/optical network terminal (ONT), and a method, and a system for providing a passive optical network (PON) of an Ethernet-based packet transport layer (PTL) scheme that actively enables connection management from a packet switch to an ONU/ONT of a customer termination when a PTL scheme is applied to a PON. 
         [0012]    An exemplary embodiment of the present invention provides a connection management server of a PON providing system of an Ethernet-based PTL scheme, wherein the connection management server manages a unified PTL connection overall over the network by establishing a PTL connection between an ONU/ONT of a customer termination of one party and an ONU/ONT of a customer termination of another party, and by applying a PTL-PON scheme to a PON section between the ONU/ONT and an OLT. 
         [0013]    The connection management server may generate a base connection table including information on a packet and download the base connection table to the OLT. 
         [0014]    Another exemplary embodiment of the present invention provides an OLT of a PON providing system of an Ethernet-based PLT scheme, wherein the OLT manages a connection of a received packet, and converts a format of the packet according to a transmission direction of the packet and thereby transmits the packet to an ONU/ONT or a packet switch. 
         [0015]    The connection management of the packet may be performed by receiving, from a connection management server, a base connection table including information on the packet, by generating a first connection table including identification information of the OLT ports and the ONU/ONT based on the base connection table, by generating a second connection table used by the ONU/ONT based on the first connection table, and by transferring the second connection table to the ONU/ONT. 
         [0016]    Also, when a registration and cancellation request for a new connection is received from the connection management server, the OLT may update the first connection table by receiving information on the new connection and may transfer information on the new connection to the ONU/ONT together with the registration and cancellation request for the new connection. 
         [0017]    In addition, when the packet is inputted, the OLT may determine whether the input packet is a packet registered to the first connection table. When the input packet is not the registered packet, the OLT may discard the input packet, and when the input packet is the registered packet, the OLT may determine whether a direction of the packet is a first direction towards the ONU/ONT or a second direction towards a packet switch. When the transmission direction of the packet is the first direction, the OLT may perform the conversion by adding, to the packet, a PTL-PON header including a logical link identifier for identifying the ONU/ONT and a port number for identifying the output port of the ONU/ONT. When the transmission direction of the packet is the second direction, the OLT may perform the conversion by removing the PTL-PON header from the packet. 
         [0018]    Also, the OLT may include: at least one PON port connected to the ONU/ONT to transmit and receive the packet, and converting the packet to a predetermined format; at least one uplink port connected to a packet switch to transmit and receive the packet, and converting the packet to a predetermined format; a packet switching block connected to the at least one PON port and the at least one uplink port to switch a corresponding packet to a predetermined PON port or an uplink port based on the first connection table; and a control unit to control the packet switching block by using the first connection table. 
         [0019]    Yet another exemplary embodiment of the present invention provides an ONU/ONT of a PON providing system of an Ethernet-based PTL scheme, wherein the ONU/ONT becomes an end point of a PTL connection, convert a format of a received packet according to a transmission direction of the received packet, and thereby transmit the converted packet to a customer terminal or an OLT. 
         [0020]    The ONU/ONT may receive, from the OLT, a second connection table used by the ONU/ONT, and receive a registration and cancellation request for a new connection and information on the new connection to thereby update the second connection table. 
         [0021]    Also, when the packet is inputted, the ONU/ONT may determine whether the input packet is a packet registered to the second connection table. When the input packet is not the registered packet, the ONU/ONT may discard the input packet, and when the input packet is the registered packet, the ONU/ONT may determine whether a direction of the packet is a third direction towards a customer terminal or a fourth direction towards the OLT. When the transmission direction of the packet is the third direction, the ONU/ONT may perform the conversion by removing, from the packet, a PTL-PON header including a logical link identifier for identifying the ONU/ONT and a port number for identifying the output port of the ONU/ONT, and by removing a PTL header including an identifier of a channel belonged by the packet. When the transmission direction of the packet is the fourth direction, the ONU/ONT may perform the conversion by adding the PTL header to the packet and further adding the PTL-PON header to the packet. 
         [0022]    In the meantime, the ONU/ONT may include: at least one PON port connected to the OLT to transmit and receive packets; at least one Ethernet port connected to the customer terminal to transmit and receive packets; a packet switching block connected to the at least one PON port and the at least one Ethernet port to switch a corresponding packet to a predetermined PON port or an Ethernet port based on the second connection table; and a control unit to control the packet switching block by using the first connection table. 
         [0023]    Still another exemplary embodiment of the present invention provides a PON providing method of an Ethernet-based PTL scheme enabling a connection management server to establish a connection between an ONU/ONT of a customer termination and an OLT, the method including: receiving, from the connection management server, a base connection table including connection information; generating a first connection table including identification information on the ONU/ONT based on the base connection table; and generating a second connection table used by the ONU/ONT based on the first connection table to transfer the second connection table to the ONU/ONT. 
         [0024]    The method may further include: determining whether a registration request for a new connection or a cancellation request for an existing connection is received from the connection management server; receiving information on the new or existing connection to update the first connection table when the registration request for a new connection or the cancellation request for an existing connection is received; and requesting the ONU/ONT for registration and cancellation. 
         [0025]    Also, the method may further include: determining whether a packet is inputted; determining whether the input packet is a packet registered to the first connection table, when the packet is inputted; discarding the input packet when the input is not the registered packet, and determining whether a direction of the packet is a first direction towards the ONU/ONT or a second direction towards a packet switch, when the input packet is the registered packet; and switching the packet and then converting and outputting the packet by adding, to the packet, a PTL-PON header including a logical link identifier for identifying the ONU/ONT and a port number for identifying the output port of the ONU/ONT when the transmission direction of the packet is the first direction, and converting the packet by removing the PTL-PON header from the packet and then switching and outputting the packet when the transmission direction of the packet is the second direction. 
         [0026]    In addition, the method may further include: determining whether a registration request for a new connection or a cancellation request for an existing connection is received from the OLT; and receiving information on the new or existing connection to update the second connection table, when the registration request for a new connection or the cancellation request for an existing connection is received. 
         [0027]    In the meantime, the method may further include: determining whether a packet is inputted; determining whether the input packet is a packet registered to the second connection table, when the packet is inputted; discarding the input packet when the input packet is not the registered packet, and determining whether a direction of the packet is a third direction towards a customer terminal or a fourth direction towards the OLT, when the input packet is the registered packet; and switching the packet after removing, from the packet, a PTL-PON header including a logical link identifier for identifying the ONU/ONT and a port number for identifying the output port of the ONU/ONT, when the transmission direction of the packet is the third direction, and then converting the packet by removing, from the switched packet, a PTL header including an identifier for a channel belonged by the packet and outputting the packet, and switching the packet after converting the packet by adding the PTL header to the packet, and outputting the packet after further adding the PTL-PON header to the switched packet, when the transmission direction of the packet is the fourth direction. 
         [0028]    Meanwhile, the aforementioned base connection table may include information regarding quality of service (QoS) parameters, a service type, an ingress port of a packet switch, and an egress port of the packet switch by employing a backbone destination address (B-DA) and a backbone virtual local area network identifier (B-VID) as an address with respect to each PTL connection. 
         [0029]    The first connection table may include information regarding an ingress port and an egress port of the OLT, an LLID and a port number of the ONU/ONT, a QoS class, and a service type by employing a B-DA and a B-VID as an address with respect to a PON connection of each PTL scheme. 
         [0030]    The second connection table may include information regarding an LLID for identifying the ONU/ONT, a port number of the ONU/ONT, a QoS class, and a service type by employing a B-DA and a B-VID as an address with respect to a PON connection of each PTL scheme. 
         [0031]    The OLT and the ONU/ONT may perform operation and maintenance (OAM) functions in the access network. 
         [0032]    Still yet another exemplary embodiment of the present invention provides a PON providing system of an Ethernet-based PTL scheme, including: a connection management server to manage a unified PTL connection overall over the network by establishing a PTL connection between an ONU/ONT of a customer termination of one party and an ONU/ONT of a customer termination of another party, and by applying a PTL-PON scheme to a PON section between the ONU/ONT and an OLT; an OLT to manage a connection of a received packet, and to convert a format of the packet according to a transmission direction of the packet and to thereby transmit the packet; and an ONU/ONT becoming an end point of the PTL connection to convert the format of the packet according to the transmission direction of the received packet and to thereby transmit the packet to a customer terminal or the OLT. 
         [0033]    According to the exemplary embodiments of the present invention, there may be provided a connection management server, an OLT, an ONU/ONT, and a method and a system for providing a PON of an Ethernet-based PTL scheme that enables all of a metro network, a core network, and an access network to be operated and be maintained using a single connection and thereby may transfer highly reliable packets to a customer termination by expanding a technology of a PTL scheme to an ONU/ONT of the customer termination and thereby applying the technology, and establishing and operating a PTL connection even between the ONU/ONT and the OLT. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0034]      FIG. 1  is a conceptual diagram to describe the entire connection configuration including a passive optical network (PON) providing system of an Ethernet-based packet transport layer (PTL) scheme according to an exemplary embodiment of the present invention; 
           [0035]      FIG. 2  is a conceptual diagram to describe a format of a packet including a PTL-PON header and a PTL header according to an exemplary embodiment of the present invention; 
           [0036]      FIG. 3  is a conceptual diagram to describe a process of converting a format of a packet according to an exemplary embodiment of the present invention; 
           [0037]      FIG. 4  is a table to describe a configuration of a base connection table generated by a connection management server of  FIG. 1 ; 
           [0038]      FIG. 5  is a table to describe a configuration of a first connection table generated by an optical line termination (OLT) of  FIG. 1 ; 
           [0039]      FIG. 6  is a block diagram to describe a configuration of the OLT of  FIG. 1 ; 
           [0040]      FIG. 7  is a table to describe a configuration of a second connection table used by an optical network unit (ONU)/optical network terminal (ONT) of  FIG. 1 ; 
           [0041]      FIG. 8  is a block diagram to describe a configuration of the ONU/ONT of  FIG. 1 ; 
           [0042]      FIG. 9  is a flowchart to describe an operation process of an OLT in an embodiment of a PON providing method of a PTL scheme according to an exemplary embodiment of the present invention; and 
           [0043]      FIG. 10  is a flowchart to describe an operation process of an ONU/ONT in an embodiment of a PON providing method of a PTL scheme according to an exemplary embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0044]    Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In this description, when any one element is connected to another element, the corresponding element may be connected directly to another element or with a third element interposed therebetween. First of all, it is to be noted that in giving reference numerals to elements of each drawing, like reference numerals refer to like elements even though like elements are shown in different drawings. The components and operations of the present invention illustrated in the drawings and described with reference to the drawings are described as at least one exemplary embodiment and the spirit and the core components and operation of the present invention are not limited thereto. 
         [0045]      FIG. 1  is a conceptual diagram to describe the entre connection configuration including a passive optical network (PON) providing system of a packet transport layer (PTL) scheme according to an exemplary embodiment of the present invention. 
         [0046]    The PON providing system of the PTL scheme according to the present embodiment includes optical network units (ONUS)/optical network terminals (ONTs)  130  installed in customer terminations P 1 , P 2 , P 3 , P 4 , and P 5 , optical line terminations (OLTs)  120 , remote nodes (RNs) R for optical collection/distribution, and a connection management server  110 . 
         [0047]    Here, when the customer terminations P 1 , P 2 , P 3 , P 4 , and P 5  provide a port to a single subscriber, it refers to ONT  130 . When the customer terminations P 1 , P 2 , P 3 , P 4 , and P 5  provide a plurality of ports to a plurality of subscribers, it refers to ONU  130 . The present embodiment groups the ONT and the ONU and thereby indicates them as the ONU/ONT  130 . 
         [0048]    A packet transmitted from the ONU/ONT  130  is aggregated at a packet switch SW 1  via the OLT  120 . Among aggregated packets, packets to be transported into the same direction are grouped together and then are transmitted to a counter party via a metro network and a core network. In this instance, the connection management server  110  sets a packet transport path as channels C 1 , C 2 , and C 3 , and thereby manages the packet transport path. The connection management server  110  groups channels having the same source and destination into a PTL channel group  10  and thereby manages the channels. Here, the channels C 1 , C 2 , and C 3  indicate channels connected between the ONUs/ONTs  130  of one side and the ONUs/ONTs  130  of another side. The PTL channel group  10  indicates a connection passage of channels connecting between packet switches SW 1 , SW 2 , SW 3 , and SW 4 . Each channel or channel group is managed using a PTL connection. 
         [0049]    The connection management server  110  manages the connection states of all the sections by setting the channels C 1 , C 2 , and C 3 , and the channel group  10 . Here, the channels C 1 , C 2 , and C 3  set by the connection management server  110  are managed by applying a PTL-PON scheme to the ONU/ONT  130  and the OLT  120  of an access network, by applying a PTL scheme between local stations, or by setting the channel group  10  between the local stations. 
         [0050]    With respect to the PTL connection in the access network, the metro network, and the core network, the packet switches SW 1 , SW 2 , SW 3 , and SW 4 , the OLT  120 , and the ONU/ONT  130  perform a connection state monitoring function such as a continuity check, a loopback check, alarm indication signal/remote detection indication (AIS/RDI) state notification, and the like, that is an operation and maintenance (OAM) function defined in a provider backbone bridges-traffic engineering (PBB-TE). 
         [0051]    Next, the OLT  120  is described. 
         [0052]    The OLT  120  functions to download a base connection table from the aforementioned connection management server  110 , to generate and update a first connection table including information capable of identifying a connection of a packet based on the base connection table, to generate a second connection table used by the ONU/ONT  130 , and to download the second connection table to the ONU/ONT  130  to be described later. 
         [0053]      FIG. 2  is a conceptual diagram to describe a format of a packet including a PTL-PON header and a PTL header according to an exemplary embodiment of the present invention. 
         [0054]    Initially, when briefly describing the OLT  120  employing a PTL technology, the OLT  120  converts a format of a packet so that the packet may be applied in a section between the OLT  120  and the ONU/ONT  130 . 
         [0055]    That is, a format of a PTL-PON packet is used in the section between the OLT  120  and the ONU/ONT  130  and a format of a PTL packet is used in a metro network and a core network. As shown in  FIG. 2 , the format of the PTL-PON packet indicates a format of additionally adding, to a header (H 1  of  FIG. 2 , hereinafter, a PTL header) including an identifier of a packet such as “B-DA” and “B-VID”, a header (H 2  of  FIG. 2 , hereinafter, a PTL-PON header) including a logical link identifier (LLID) for identifying the ONU/ONT  130  and a port number for identifying the output port of the ONU/ONT  130 . 
         [0056]    Here, the logical link identifier corresponds to an identifier for identifying a plurality of virtual links. The plurality of ONTs/ONUs  130  are connected to a single port of the OLT  120  and in this instance, the logical link identifier is used to identify a corresponding ONU/ONT. Also, the port number indicates a port number of the ONU/ONT  130 . For example, when an Internet protocol (IP) telephone and an IPTV are connected to the ONU/ONT  130 , the port number is classified into two ports. 
         [0057]      FIG. 3  is a conceptual diagram to describe a process of converting a format of a packet according to an exemplary embodiment of the present invention. 
         [0058]    A PTL connection is connected from a user of one side to a user of another side. A packet of a PTL format flows in a section between OLTs and packet switches SW 1 , SW 2 , SW 3 , and SW 4 . A packet of a PTL-PON format is transported between the OLT  120  and the ONU/ONT  130  to which a PTL-PON scheme is applied. 
         [0059]    As described above, in addition to the PLT header H 1 , the PLT-PON header H 2  is further included in the format of the PTL-PON packet. As shown in  FIG. 3 , when the packet is transported towards the ONU/ONT  130 , the OLT  120  generates the PTL-PON packet in which the PTL-PON header H 2  is further added to the PTL packet, and transports the PTL-PON packet to the ONU/ONT  130  via an RN (R). When the packet is transported towards the packet switch SW 1 , the OLT  120  transports, to the packet switch SW 1 , the PTL packet in which the PTL-PON header H 2  is removed from the PTL-PON packet transported from the ONU/ONT  130 . 
         [0060]      FIG. 4  is a table to describe a configuration of a base connection table generated by the connection management server  110  of  FIG. 1 . 
         [0061]    In the meantime, the configuration of the base connection table generated by the connection management server  110  may be verified through  FIG. 4 . 
         [0062]    As shown in  FIG. 4 , the base connection table includes a variety of connection information based on an identifier of a channel (connection) belonged by a packet. That is, each parameter of the connection, a QoS parameter, a service type, an ingress port and an egress port of a packet switch SW 1 , SW 2 , SW 3 , and SW 4 , and the like are stored in the base connection table by employing “B-DA” and “B-VID” as an address with respect to a PTL connection. 
         [0063]    Here, B-DA indicates a backbone destination address (hereinafter, B-DA), and B-VID indicates a backbone VLAN identifier (hereinafter, B-VID) and thus, are used as an identifier of the packet. 
         [0064]      FIG. 5  is a table to describe a configuration of a first connection table generated by the OLT  120  of  FIG. 1 . As shown in  FIG. 5 , the OLT  120  generates the first connection table including information used when the OLT  120  and the ONU/ONT  130  allocate a bandwidth to the connection and switch a packet, and identification information of the ONU/ONT  130 , and has the generated first connection table. 
         [0065]    The first connection table is generated by the OLT  120  based on a base connection table. The first connection table includes an ingress port and an egress port of the OLT  120 , a logical link identifier (LLID) for identifying the ONU/ONT  130 , a port number (port #) of the output of the ONU/ONT  130 , a QoS class of the PTL connection, a service type, and the like, by employing “B-DA” and “B-VID” as an address with respect to the PTL connection. 
         [0066]    Meanwhile, when new connection information is transferred from the connection management server  110 , the OLT  120  updates the first connection table. That is, when a cancellation request for an existing PTL connection or a registration request for a new connection is received, the OLT  120  performs a procedure of cancelling or registering a corresponding PTL connection in the first connection table by employing “B-DA” and “B-VID” as an address. In this instance, the OLT  120  requests the ONU/ONT  130  to update the second connection table by downloading new connection information to the ONU/ONT  130 . 
         [0067]    When a packet is inputted in the OLT  120 , the OLT  120  determines whether a corresponding packet is registered to the first connection table. When the corresponding packet is not registered, the OLT  120  discards the corresponding packet. When the corresponding packet is registered, the OLT  120  converts a format of the corresponding packet according to a transmission direction, which is described above. 
         [0068]      FIG. 6  is a block diagram to describe a configuration of the OLT  120  of  FIG. 1 . 
         [0069]    As shown in  FIG. 6 , the OLT  120  includes a plurality of PON ports  121  connected to the ONUs/ONTs  130 , uplink ports  123  connected to a packet switch SW 1  or SW 4 , a packet switching block  122 , and a control unit  124  including the first connection table. 
         [0070]    When a packet is inputted into the uplink port  123 , the corresponding packet may be switched to a predetermined PON port  121  by the packet switching block  122  based on information on the first connection table of the control unit  124 , and the format of the packet may be converted by further adding a PTL-PON header to the packet and thereby be outputted to the corresponding PON port  121 . The transmission direction of the above packet may be determined as a direction towards the ONU/ONT  130 . 
         [0071]    On the other hand, when a packet is inputted into the PON port  121 , the corresponding packet may be switched to a predetermined uplink port  123  by the packet switching block  122  based on information on the first connection table of the control unit  124  and be outputted to the corresponding uplink port  123  in a format converted state in which the PTL-PON header is removed from the packet. 
         [0072]    The transmission direction of the above packet is determined as a direction towards the packet switches SW 1  and SW 4 . 
         [0073]    Meanwhile, the OLT  120  generates the second connection table including information used to allocate a bandwidth to the connection and switch the packet, and thereby downloads the second connection table to the ONU/ONT  130 . Accordingly, the second connection table is held by the ONU/ONT  130 . 
         [0074]      FIG. 7  is a table to describe a configuration of a second connection table used by the ONU/ONT  130  of  FIG. 1 . 
         [0075]    As shown in  FIG. 7 , the second connection table includes an LLID and a port number (port #) of the ONU/ONT  130 , a QoS class, a service type, and the like by employing “B-DA” and “B-VID” as an address. 
         [0076]    Next, the ONU/ONT  130  will be described. 
         [0077]    The ONU/ONT  130  functions to download and thereby use the second connection table from the OLT  120 , and to update the second connection table when receiving new connection information. 
         [0078]      FIG. 8  is a block diagram to describe a configuration of the ONU/ONT  130  of  FIG. 1 . 
         [0079]    The ONU/ONT  130  constitutes a PLT-PON system together with the OLT  120 , and thereby converts a format of a packet so that a PTL-PON format may be applied to a PTL-PON section. 
         [0080]    Hereinafter, the configuration of the ONU/ONT  130  operating based on the second connection table will be described with reference to  FIG. 8 . 
         [0081]    As shown in  FIG. 8 , the ONU/ONT  130  includes a PON port  133  connected to the OLT  120 , Ethernet ports  131  connected to customer terminals, a packet switching block  132 , and a control unit  134  including the second connection table. 
         [0082]    When a packet is inputted into the PON port  133 , the corresponding packet may be switched to a predetermined Ethernet port  131  by the packet switching block  132  based on information on the second connection table of the control unit  134 , and be outputted to the corresponding Ethernet port  131  in a format converted state in which the PTL-PON header and the PTL header are removed from the packet. The transmission direction of the above packet is determined as a direction towards the customer terminal. 
         [0083]    On the other hand, when a packet is inputted into the Ethernet port  131 , the corresponding packet may be switched to a predetermined PON port  133  by the packet switching block  132  by adding the PTL header to the corresponding packet based on information on the second connection table of the control unit  134 , the format of the packet may be converted by further adding the PTL-PON header to the packet, and thereby the packet may be outputted to the corresponding PON port  133 . The transmission direction of the above packet is determined as a direction towards the OLT  120 . 
         [0084]    The above ONU/ONT  130  becomes an end point enabling the connection management server  110  to manage the connection using the PTL scheme. 
         [0085]    Hereinafter, a PON providing method of a PTL scheme according to embodiments will be described. 
         [0086]      FIG. 9  illustrates a flowchart to describe an operation process of an OLT in an embodiment of a PON providing method of a PTL scheme according to an exemplary embodiment of the present invention, and  FIG. 10  illustrates a flowchart to describe an operation process of an ONU/ONT in an embodiment of a PON providing method of a PTL scheme according to the present invention. 
         [0087]    As shown in  FIG. 9 , the OLT  120  initially downloads a base connection table from the connection management server  110  during an initialization process(S 110 ). 
         [0088]    Next, in operation  5120 , the OLT  120  generates the first connection table including identification information of the OLT  120  and the ONU/ONT  130  based on the base connection table (S 120 ). The OLT  120  generates a second connection table of a PTL-PON scheme used by the ONU/ONT  130  based on the first connection table and thereby downloads the second connection table to the ONU/ONT  130  (S 130 ). 
         [0089]    Next, when the initialization process is terminated, the OLT  120  determines whether new connection information is received from the connection management server  110  as a general operation (S 140 ). Here, as described above, the new connection information relates to cancellation of an existing PTL connection or registration of a new connection. When the new connection information is received, the OLT  120  updates the first connection table (S 141 ). 
         [0090]    Updating of the first connection table is performed by performing a procedure of cancelling or registering a corresponding PTL connection in the first connection table by employing “B-DA” and “B-VID” as an address. Next, the OLT  120  downloads the new connection information to the ONU/ONT  130  and thereby requests the ONU/ONT  130  to update the second connection table (S 142 ). 
         [0091]    As a next process, the OLT  120  determines whether an input packet exists (S 150 ). When the input packet exists, the OLT  120  determines whether the corresponding packet is a packet registered to the first connection table (S 160 ). When the corresponding packet is not the registered packet, the OLT  120  discards the corresponding packet (S 161 ). When the corresponding packet is the registered packet, the OLT  120  determines a transmission direction of the corresponding packet (S 170 ). 
         [0092]    When the transmission direction of the corresponding packet is towards the ONU/ONT  130 , the OLT  120  switches the corresponding packet to the PON port  121  and then converts a format of the packet by adding a PTL-PON header to the packet and thereby outputs the packet (S 171 ). On the other hand, when the transmission direction of the packet is towards the packet switches SW 1 , the OLT  120  converts the format of the packet by removing the PTL-PON header from the packet and switches the packet to the uplink port  123  and thereby outputs the packet (S 172 ). 
         [0093]    As shown in  FIG. 10 , in a self-initialization, the ONU/ONT  130  initially downloads the second connection table from the OLT  120  (S 210 ). When the initialization is terminated, the ONU/ONT  130  determines whether new connection information is received from the OLT  120  (S 220 ). When the new connection information is received, the ONU/ONT  130  updates the second connection table (S 221 ). 
         [0094]    Updating of the second connection table is performed by performing a procedure of cancelling or registering a corresponding PTL connection in the second connection table by employing “B-DA” and “B-VID” as an address. 
         [0095]    As a next process, the ONU/ONT  130  determines whether an input packet exists (S 230 ). When the input packet exists, the ONU/ONT  130  determines whether the corresponding packet is a packet registered to the second connection table (S 240 ). When the corresponding packet is not the registered packet, the ONU/ONT  130  discards the corresponding packet (S 241 ). When the corresponding packet is the registered packet, the ONU/ONT  130  determines a transmission direction of the corresponding packet (S 250 ). 
         [0096]    When the transmission direction of the corresponding packet is towards the OLT  120 , the ONU/ONT  130  adds a PTL header to the packet in the egress Ethernet port  131  (S 251 ), and switches the packet to the PON port  133  and then further adds a PTL-PON header to the packet, and thereby converts a format of the packet and outputs the packet (S 252 ). On the other hand, when the transmission direction of the packet is towards a customer terminal, the ONU/ONT  130  removes the PTL-PON header from the packet and then switches the packet to the Ethernet port  131 , removes the PTL header and outputs the packet (S 254 ). 
         [0097]    As described above, the exemplary embodiments have been described and illustrated in the drawings and the specification. Herein, specific terms have been used, but are just used for the purpose of describing the present invention and are not used for defining the meaning or limiting the scope of the present invention, which is disclosed in the appended claims. Therefore, it will be appreciated to those skilled in the art that various modifications are made and other equivalent embodiments are available. Accordingly, the actual technical protection scope of the present invention must be determined by the spirit of the appended claims.