Abstract:
A packet transport layer passive optical network providing method controls an optical line termination device and an optical network terminal or an optical network unit of the subscriber end to transport packet transport layer passive optical network packets between the optical network terminals or the optical network units and the optical line termination device, and the optical network terminals or the optical network unit of the subscriber end becomes an end point of a packet transport layer connection.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application claims priority to and the benefit of Korean Patent Application No. 10-2009-0128433 filed in the Korean Intellectual Property Office on Dec. 21, 2009, the entire contents of which are incorporated herein by reference. 
     BACKGROUND OF THE INVENTION 
     (a) Field of the Invention 
     The present invention relates to a packet transport layer (PTL) applied passive optical network providing method. 
     (b) Description of the Related Art 
     Regarding recent communication networks, most communication services have been made into packets as the Internet has become more important, and packet transport layer (PTL) skills with great reliability have been applied to the communication networks in order to provide the voice service of the voice over Internet protocol (VoIP) and the video service of the Internet protocol television (IPTV) to the Internet in a secure manner. 
     The PTL type provides the entire communication service with packets in order to increase the Internet&#39;s reliability, and accurately transmits the packets on the circuit level. However, since such type guarantees packet transmission quality but is not applicable to the access network, it is not guaranteed from one subscriber end to another subscriber end and is only applicable to communication between stations. 
     The existing passive optical network (PON) type includes the Ethernet PON (E-PON) type and the gigabit PON (G-PON) type. 
     The E-PON type is appropriate for Ethernet communication configured to Ethernet switches, and the G-PON type is available for not only Ethernet but also asynchronous transfer mode (ATM) and circuit communication. 
     So the PON type is easily applied to the Ethernet, and is not applicable to the PTL network that requires setting a connection in order to guarantee quality. 
       FIG. 1  shows networks to which the existing PTL type is applied and access networks to which the E-PON type is applied. 
     The packets generated at optical network terminals (ONT)  20  or optical network units (ONU)  20  of subscriber ends  10 ,  11 , and  12  are passed through an optical line termination device (OLT)  24  and are concentrated at a first concentration switch  30 . 
     The concentrated packets are passed through a switch or a router of the metro network  100  and the core network  200  and are distributed through a second concentration switch  32 . 
     A PTL path  400  of the metro network  100  and the core network  200  is set by a server (not shown) and managed the path state. However, only physical links of concentration channels  40 ,  41 , and  42  and distribution channels  43 ,  44 , and  45  are set by an E-PON server, but the channel states are not managed. 
     Here, the channels  40 ,  41 , and  42  from the ONT or ONU  20  of the subscriber ends  10 ,  11 , and  12  are concentrated at the first concentration switch  30 , and the distribution channels  43 ,  44 , and  45  are distributed from the second concentration switch  32  to other subscriber ends  13  and  14 . 
     Therefore, when an error occurs during transport of information, it is possible to check whether the error is generated by the metro network  100  and the core network  200 , but it is difficult to check whether it is generated by the access network  300  of the concentration channels  40 ,  41 , and  42  or the access network  300  of the distribution channels  43 ,  44 , and  45 . 
     The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art. 
     SUMMARY OF THE INVENTION 
     The present invention has been made in an effort to provide a packet transport layer passive optical network (PTL-PON) providing system and method. 
     An exemplary embodiment of the present invention provides a method for a PTL connection server to provide a PON of a PTL, the PTL connection server being connected directly to OLT&#39;s and PTL switches, connected indirectly to ONT/ONU&#39;s of subscriber ends, and setting connections, comprising: 
     managing to transmit/receive PTL-PON packets between an ONT/ONU of the subscriber end and an OLT; and setting the ONT/ONU to be an end point of a PTL connection. 
     Another exemplary embodiment of the present invention provides a packet transport layer-passive optical network (PTL-PON) providing system connected to optical network terminals or optical network units (ONT/ONU&#39;s) and an optical line termination device (OLT) and setting a connection, including: a PTL connection server for setting a PTL channel in whole networks between an ONT/ONU of a subscriber end and another ONT/ONU of the opposite side of a subscriber end, bundling a plurality of the set PTL channels to set the same as a PTL path in a metro network and a core network, and managing the connection states of entire intervals through the set PTL channel and the PTL path; and an OLT located between the ONT/ONU and the PTL switch, controlling the ONT/ONU&#39;s, and converting a format of the packet into another according to a transport direction of the received packet, and transporting the same. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  shows networks to which the existing PTL type is applied and an access network to which the E-PON type is applied. 
         FIG. 2  shows networks to which a PTL-PON providing system according to an exemplary embodiment of the present invention is applied. 
         FIG. 3  shows a block diagram of an inner configuration of an OLT of a PTL according to an exemplary embodiment of the present invention. 
         FIG. 4  shows a format of a PTL-PON packet according to an exemplary embodiment of the present invention. 
         FIG. 5  shows a conversion process when packets are transported according to an exemplary embodiment of the present invention. 
         FIG. 6  shows a PTL-PON providing method according to an exemplary embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     In the following detailed description, only certain exemplary embodiments of the present invention have been shown and described, simply by way of illustration. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. Accordingly, the drawings and description are to be regarded as illustrative in nature and not restrictive. Like reference numerals designate like elements throughout the specification. 
     Throughout the specification, unless explicitly described to the contrary, the word “comprise” and variations such as “comprises” or “comprising” will be understood to imply the inclusion of stated elements but not the exclusion of any other elements. 
       FIG. 2  shows networks to which a PTL-PON providing system according to an exemplary embodiment of the present invention is applied. 
     The PTL-PON providing system includes an OLT  800  for the PTL and a PTL connection server  900 . In addition, the PTL-PON providing system includes an ONT/ONU  600  for the PTL-PON installed in subscriber ends  500 ,  510 , and  520  and a remote node (RN)  610 . 
     Provision for a single subscriber will be called an ONT, and provision for a plurality of subscribers will be referred to as an ONU. In the embodiment of the present invention, the ONT and the ONU will be combined to be an ONT/ONU. 
     The OLT  800  converts the packets into a specific format and transports the same depending on whether the transport direction of the packets received between the ONT/ONU  600  of the subscriber ends  500 ,  510 ,  520 ,  530 , and  540  and the PTL switches  810  and  820  is the direction of the subscriber ends  500 ,  510 , and  520  (i.e., downward direction) or the direction of the PTL switches  810  and  820  (i.e., upward direction). 
     The OLT  800  collects the packets generated by the ONT/ONU  600  of the subscriber ends  500 ,  510 ,  520 ,  530 , and  540 . And then The PTL switch  810  or  820  collects the packets secondly by bundling the channels  700 ,  710 , and  720  and transports packets in the same direction through a PTL path  400  in the metro network  100  and the core network  200 . 
     The PTL connection server  900  sets the PTL path  400  and the PTL channels  700 ,  710 , and  720  to control the connection states of all intervals. In this instance, the PTL channels  700 ,  710 , and  720  are connected between the ONT/ONU  600  and the opposite side of subscriber ends. 
     On the metro network  100  and the core network  200  the PTL method is applied, and on the access network  300  the PTL-PON method is applied thereto. The PTL connection server  900  sets a PTL connection including the PTL channels  700 ,  710 , and  720  and the PTL path  400  and manages the same. 
     In the case of setting the PTL channels  700 ,  710 , and  720 , the PTL connection server  900  makes a mapping table mapping the PTL header to the PTL-PON header and delivers the mapping table to the OLT  800 , wherein the PTL-PON headers may include a logical link identifier (LLID) and a port number. 
     The ONT/ONU  600 , the OLT  800 , and the PTL switches  810  and  820  control connection states by using the functions, such as continuity check, loopback check, and alarm indication signal/remote detect indication (AIS/RDI) for the PTL connection that are the operation and maintenance (OAM) functions defined by provider backbone bridges (PBB), on the access network  300 , the metro network  100 , and the core network  200 . 
     The packets generated by the subscriber ends  500 ,  510 ,  520 ,  530 , and  540  are controlled during transport and are then transported to the other subscriber end. 
       FIG. 3  shows a block diagram of an inner configuration of an OLT  800  of a PTL according to an exemplary embodiment of the present invention,  FIG. 4  shows a format of a PTL-PON packet according to an exemplary embodiment of the present invention, and  FIG. 5  shows a conversion process when packets are transported according to an exemplary embodiment of the present invention. 
     The OLT  800  for the PTL includes a header mapping table  804  and a packet converter  806 . 
     The OLT  800  receives the header mapping table  804  from the PTL connection server  900 , in which the PTL header  940  and the PTL-PON header  950  are mapped. 
     As shown in  FIG. 4 , the metro network  100  and the core network  200  use the PTL packet format and the access network  300  uses the PTL-PON packet format. The PTL-PON packet format further includes a LLID for identifying the ONT/ONU and a port number for identifying the port of the ONT/ONU in addition to the PTL packet format. 
     Upon receiving a PTL packet, the packet converter  806  checks the header of the PTL packet to determine whether the PTL packet is transported in the direction of the ONT/ONU&#39;s  600  (i.e., downward direction) or in the direction of the PTL switches  810  and  820  (i.e., upward direction.) 
     When the transport direction of a PTL packet is downward, the packet converter  806  attaches the LLID and the port number of the corresponding ONT/ONU  600  to the PTL packet by using the header mapping table, converts the same into the PTL-PON format, and transports it to the ONT/ONU  600  through the RN  610 . In this instance, the LLID represents an identifier for identifying a plurality of branches of an optical link, and it is used to identify the ONT/ONU  600 , where a plurality of ONT/ONU&#39;s  600  are connected to the OLT  800 . The port number identifies ports of the ONT  600  or the ONU  600 . For example, if an IP phone and an IPTV are connected to the ONT  600  of a subscriber end, the port number for IP phone is one and that for IPTV is two. 
     When the transport direction of a PTL packet is upward, the packet converter  806  detaches the PTL-PON header  950  from the PTL-PON packet and transports it to the PTL switches  810  and  820 . 
       FIG. 6  shows a PTL-PON providing method according to an exemplary embodiment of the present invention. 
     The PTL connection server  900  sets the channels  700 ,  710 , and  720  on which packets generated by the ONT/ONU&#39;s  600  of the subscriber ends  500 ,  510 , and  520  are concentrated at the PTL switch  810 , transported continuously to the PTL switch  820 , and distributed to the opposite side of the subscriber ends  530 ,  540 , and etc. (S 100 ). 
     The PTL connection server  900  bundles the set PTL channels  700 ,  710 , and  720  and sets them to be a PTL path  400  in the metro network  100  and the core network  200  (S 102 ). 
     The PTL connection server  900  manages the connection states of the entire connections, such as the PTL channels  700 ,  710 , and  720  and the PTL path  400  (S 104 ). 
     The PTL connection server  900  generates a header mapping table by using the PTL header  940  and the PTL-PON header  950  (LLID, port number) that are set when the PTL channel is set, and delivers the header mapping table to the OLT  800 . Accordingly, the OLT  800  converts the packet format according to the transport direction of the received packet by using the mapping table provided by the PTL connection server  900 . 
     According to an embodiment of the present invention, the PTL skill is applied to the access network to manage connections with end-to-end. The PTL skill that is used in the metro network and the core network is extensively applied to the access network to transport highly reliable packet information to the subscriber end. 
     The above-described embodiments can be realized through a program for realizing functions corresponding to the configuration of the embodiments or a recording medium for recording the program in addition to through the above-described device and/or method, which is easily realized by a person skilled in the art. 
     While this invention has been described in connection with what is presently considered to be practical exemplary embodiments, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.