Abstract:
A passive optical network (PON) equipment capable of displaying a connection state and a logical link identifier (LLID) is provided, which aims at solving a problem that equipments in the conventional PON system cannot display connection state and LLID. The PON equipment displays the connection state and the LLID through a programmable logic element and a display unit by utilizing characteristics of multi-point control protocol (MPCP) and LLID, so as to achieve the efficacy of displaying the connection state and the LLID.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of Invention 
         [0002]    The present invention relates to a passive optical network (PON) equipment capable of displaying a connection state and a logical link identifier (LLID). More particularly, the present invention relates to a PON equipment capable of displaying the connection state and a LLID through a programmable logic element and a display unit by means of utilizing the characteristics of multi-point control protocol (MPCP) and LLID. 
         [0003]    2. Related Art 
         [0004]    As the rapid development of Internet, the conventional network cannot meet the requirements of high speed transmission application. However, as the mature of the optoelectronics industry and the diversification of product applications, a wide bandwidth is provided for the rapidly developed Internet. Compared with the conventional cable transmission mode, the optical fiber transmission has the characteristics of a large capacity, a low consumption, and anti-electromagnetic interference capability. Therefore, as the cost of the optical fiber transmission gradually decreases, the optical fiber communication is an inevitable developing trend, and broadband network (FTTx) technologies mainly using the optical fiber are emerged one after another. The FTTx technology is mainly used to make the access network be achieved through optical fibers in a wide range from the central office equipment of a local telecommunication facility to customer premise equipments. The essential central office equipment includes an optical line terminal (OLT); and the customer premise equipment is an optical network unit (ONU), or an optical network terminal (ONT). 
         [0005]    The optical topology mainly includes two forms. The first one is a direct optical connection, which belongs to a topology in a point to point (P2P) manner, and has the characteristics of simple operations, easy management, and exclusive optical bandwidth. However, since a large amount of the optical fiber is required, the cost is high. The other one is a PON technology with the entity topology map shown in  FIG. 1 , which belongs to a topology in a point to multi-point (P2MP) manner, in which an optical splitter  101  is used to split the optical path from the OLT  100  to transmit to the ONU  102  at the customer premise. Since a small number of the optical fiber is required, the cost for establishment and maintenance is saved. Therefore, the PON technology is highly evaluated in the optical topology. 
         [0006]    In the current PON market, on the OLT at the central office, the messages about the connection state and the identification of the ONU are acquired through logging in the OLT management software interface. In this way, only the personnel having the administration priority can login the OLT to acquire the messages about the connection state and the identification of the ONU. However, the common front-line maintenance personnel can only maintain the equipments after acquiring the messages from the personnel having the administration priority. Therefore, not only the maintenance process becomes complicated and inconvenient for being managed, but the disconnection cannot be informed and processed immediately after it occurs. A common ONU at the customer premise only offers indicator display about the basic connection state, instead of offering further identification information for the network administrators&#39; reference. Therefore, when the system has a problem, the difficulty in detection is increased, and thus, it is not a desirable design but needs to be improved. 
         [0007]    In order to facilitate the management and maintenance of the PON system after it has been widely applied, in view of the problems to be urgently solved in the above conventional art, the inventor of the present application considers it is necessary to invent a PON equipment capable of detecting the connection state and the LLID conveniently. After exerting great efforts in thinking and researching to make an improvement and innovation, a PON equipment capable of displaying the connection state and the LLID is accomplished. 
       SUMMARY OF THE INVENTION 
       [0008]    The present invention is directed to a PON equipment capable of displaying a connection state and a logical link identifier (LLID), which aims at utilizing the characteristics of the MPCP and the LLID together with a programmable logic element and a display unit to achieve a PON equipment capable of determining the connection state and identification according to the display unit, so as to solve the problem that PON equipments in the conventional PON system cannot display the connection state and the LLID. In order to achieve the above objective, the present invention provides a PON equipment capable of displaying a connection state and an LLID, in which the PON equipment refers to an OLT and an ONU. The composition structure of the OLT and the ONU and the signal receiving process are further illustrated below. 
         [0009]    The OLT is constituted by an optical path, a circuit, an optical transceiver module, a multiplexer/de-multiplexer (Mux/Demux), an OLT system-on-a-chip (SoC), a CPU, a programmable logic element, and a display unit, and determines the connection state and the identification according to the connection state and the LLID. Upon receiving an optical signal through the optical fiber of the optical path, the OLT transmits the optical signal to the optical transceiver module for converting the optical signal into a differential signal. Next, the Mux/Demux de-multiplexes the converted differential signal into an interface signal for being transmitted to the OLT SoC. Then, the OLT SoC converts the interface signal into a packet signal for performing the packet processing. Then, the connection state signal and the LLID signal are obtained during the process of encapsulating/decapsulating the packet, and then, both the two signals are transmitted to the CPU for being encoded. Then, a plurality of corresponding state signals is outputted to the programmable logic element, and the programmable logic element decodes and performs a logical calculation on the received state signals and generates corresponding trigger signals for triggering the display unit, so as to achieve the efficacy that the OLT is capable of displaying the connection state and the LLID. 
         [0010]    The ONU is constituted by an optical path, a circuit, an optical transceiver module, an ONU SoC, a CPU, a programmable logic element, and a display unit, and determines the identification according to the LLID signal. The composition structure and the signal processing flow of the ONU are similar to that of the OLT, which thus is not repeated herein in detail, but only the differences there-between are illustrated below. In terms of the element composition, the ONU optical transceiver module adopts a laser at a lower cost having a wavelength of 1.3 μm to reduce the cost of the customer premise equipment. Moreover, the ONU SoC is integrated with the Mux/Demux, which simplifies the hardware architecture of the ONU. Therefore, during the process of receiving the signals, the optical transceiver module directly transmits the converted differential signal to the ONU SoC, and then, the Mux/Demux in the ONU SoC converts the differential signal into an interface signal. 
         [0011]    In a preferred embodiment of the present invention, the programmable logic element is a complex programmable logic element, the display unit of the OLT is constituted by a matrix LED or an LCD, and the display unit of the ONU is constituted by at least one LED. 
         [0012]    In a point to multi-point (P2MP) network architecture, once being disposed with the PON equipment of the present invention, the OLT at the central office acquires the connection state and the identification of the optical communication equipment, and the ONU at the customer premise displays the LLID of itself, so as to offer the identification information required by the network administrators at the central office to eliminate the network errors. If an error occurs to the ONU connection, the network administrator at the central office can observe the connection state provided by the connected OLT display unit according to the ONU identification information provided by the user, so as to further determine the exact problem. 
         [0013]    In order to make the present invention be further comprehensible, the present invention is illustrated below in great detail with reference to the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]      FIG. 1  is a topology map of a point to multi-point (P2MP) network entity in a PON system. 
           [0015]      FIG. 2  is a schematic view of a P2MP network packet transmission in the PON system. 
           [0016]      FIG. 3  is a schematic view of packet transmission between ONUs in the PON system. 
           [0017]      FIG. 4  is a schematic view of an automatic ONU discovery program in the PON system. 
           [0018]      FIG. 5  is a block diagram of a PON equipment applied in the OLT according to the present invention. 
           [0019]      FIG. 6  is a block diagram of the PON equipment applied in the ONU according to the present invention. 
           [0020]      FIG. 7  is a schematic view of a display mode of the PON equipment applied in the OLT according to an embodiment of the present invention. 
           [0021]      FIG. 8  is a schematic view of a display mode of the PON equipment applied in the ONU according to an embodiment of the present invention. 
           [0022]      FIG. 9  is a schematic view of a display mode of the PON equipment applied in the OLT and the ONU according to an embodiment of the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0023]    The present invention is mainly directed to a PON equipment capable of displaying a connection state and a logical link identifier (LLID). As described above, the PON system is substantially a topology in a P2MP form, and hereinafter, the role that the LLID plays in the packet transmission process in the PON system is illustrated with reference to the drawings, and how the ONU acquires the LLID assigned by the OLT through the MPCP is illustrated in brief. 
         [0024]    First, the packet transmission process in the PON system is illustrated with reference to  FIG. 2 , in which a central office equipment OLT  201 , an optical splitter  203 , four customer premise equipments ONU  205 , and four users  208  together constitute a typical PON system. The users  208  represent devices connected with the ONU, such as computers and handheld personal digital assistants (PDAs). Since the PON is a topology in the form of P2MP, the OLT transmits downlink packets to each user by means of broadcasting. When the OLT  201  transmits the downlink packets  202  to pass through the optical splitter  203 , the optical signal is split into multiple downlink packets  204  for being transmitted to all the ONUs  205 . Each ONU  205  identifies whether a downlink packet is its own downlink packet or not according to the LLID in the multiple downlink packet  204 , then, only receives its own downlink packet  206 , and then transmits its own downlink packet  206  to each user  208 . The LLID is assigned by the OLT  201  when the ONU  205  is added into the PON. When each user  208  uploads data to the OLT  201  through the ONU  205 , uplink packets  207  of each user are gathered to the same optical fiber, such that the process of time-division multiplexing (TDM) or wavelength division multiplexing (WDM) is used for transmission, and thus avoiding the collision between multiple uplink packets  207 . 
         [0025]    After the packet transmission process between the OLT and the ONU has been illustrated, the packet transmission process between the ONUs in the PON system is illustrated below with reference to  FIG. 3 . As known from  FIG. 3  that, the PON system is constituted by a central office equipment OLT  304 , an optical splitter  203 , and three customer premise equipments ONUs  300 . The ONU  300  includes a MAC port  301  and a P2P simulator  302 ; and the OLT  304  includes a P2P simulator  305 , three MAC ports  306  corresponding to the ONUs  300 , and an Ethernet bridge  307 . When the ONU_A  300  intends to transmit a packet to the ONU_B  300 , after being marked with a port number and an LLID through the MAC port  301  and the P2P simulator  302 , the data is encapsulated into a packet  303  for being transmitted through the optical fiber. Then, the packet  303  is transmitted into the P2P simulator  305  of the OLT  304  via the optical splitter  203 , in which the LLID is resolved, and then transmitted to a corresponding MAC port  306 . Then, the packet is transferred by the Ethernet bridge  307  to the MAC port  306  in the OLT corresponding to the ONU_B 300 , and marked with a port number of the ONU_B. Then, the packet is marked with the LLID of the ONU_B  300  through the P2P simulator, and finally, the packet  308  is sent out by means of broadcasting. After the P2P simulators  302  of the ONU_A  300  and the ONU_C  300  receive the packet  308 , the LLID is determined, and then the unmatchable packet  308  is dropped. 
         [0026]    As known from the above two packet transmission processes, the LLID plays a role of identification in the P2P simulation in the P2MP topology architecture. The LLID in the PON is assigned by the OLT at the central office, and is informed to the ONU of the customer premise according to the MPCP. Therefore, the way that the ONU acquires the LLID assigned by the OLT through the MPCP is illustrated through the ONU automatic discovery program in the PON system with reference to  FIG. 4 . The ONU automatic discovery program achieves the automatic discovery of the ONU through the MPCP communication protocol based upon the IEEE802.3ah standard. As known from  FIG. 4  that, the whole ONU automatic discovery program includes packet transmission process such as a discovery packet  401 , register allowance timeslot  402 , a random delay  403 , a register request packet  404 , a register response packet  405 , an acknowledgement packet  406 , and a register acknowledgement packet  407 . First, an OLT broadcasts the discovery packet  401  including an OLT register allowance timeslot  402  for informing the newly-added ONU about when to register. After the newly-added ONU has received the information and entered the register allowance timeslot  402 , in order to avoid the collision caused by the simultaneous registration of multiple newly-added ONUs, a period of random delay  403  is required, and after the random delay  403 , the register request packet  404  is sent out to make registration to the OLT. Upon receiving the register request packet  404  in the register allowance timeslot  402 , the OLT sends the register response packet  405  including the LLID assigned to the ONU to the ONU, then the OLT sends a standard acknowledgement packet  406 , and finally, the ONU returns the register acknowledgement packet  407  to the OLT, so as to accomplish the automatic discovery of the ONU. 
         [0027]    In view of the disadvantages commonly existed for the PON equipments in the conventional PON system, once the customer premise feedbacks that an interruption of the network connection occurs, the network administrators at the central office must login the connected OLT administration interface to acquire the connection state of the customer premise, so as to make further processing. 
         [0028]    Therefore, the present invention provides a PON equipment capable of displaying connection state and LLID, which is provided for the network administrator to acquire the state of the customer premise through the display unit of the OLT, so as to avoid the complicated process of logging in the administration interface. Furthermore, a common user can also acquire the LLID obtained by the OLT through the display unit of the ONU, so as to offer the required identification information to the network administrator. 
         [0029]      FIGS. 5 and 6  show a PON equipment capable of displaying connection state and LLID.  FIG. 5  is a block diagram of a PON equipment applied in an OLT  500 , which is constituted by a circuit  501 , an optical path  502 , an optical transceiver module  503 , a multiplexer/de-multiplexer (Mux/Demux)  504 , an OLT system-on-a-chip (SoC)  505 , a CPU  507 , a programmable logic element  508 , and a display unit  509 . The optical transceiver module  503  is used to perform a conversion between an optical signal and a differential signal. The Mux/Demux  504  is used to perform a conversion between the differential signal and an interface signal. The interface signal can be ten bit interface (TBI), a Gigabit media independent interface (GMII), a reduced ten bit interface (RTBI), or a reduced Gigabit media independent interface (RGMII). The OLT SoC  505  compliant with the IEEE 802.3ah standard is used to perform media access control (MAC), dynamic bandwidth allocation (DBA), operations, administration and maintenance (OAM), and security for the PON system. The OLT SoC  505  is used to perform a conversion between the interface signal and a packet signal and encapsulate/decapsulate the packet, and acquire the connection state signal and the LLID signal during the process of encapsulating/decapsulating the packet. The CPU  507  is used to receive the connection state signal and the LLID signal  506  transmitted from the OLT SoC  505 , and output a plurality of corresponding state signals after an encoding process. The programmable logic element  508  is a complex programmable logic element. The programmable logic element  508  is used to receive the plurality of state signals, and decode and perform a logical calculation on the state signals to generate corresponding trigger signals. The display unit  509  is a liquid crystal display (LCD) or at least a light emitting diode (LED). The display unit  509  is used to receive the corresponding trigger signals for triggering the display unit  509  to display the connection state and the LLID of the PON equipment. In the OLT  500 , the display unit  509  displays the connection states and LLIDs of the 32 ONUs by using indicators of different colors and bright/dark states of 4×8 matrix LED. 
         [0030]    As shown in  FIG. 5 , the OLT  500  receives the optical signal transmitted from the optical fiber through the optical path  502 . After entering an amplifier, a filter, and a decoder in the optical transceiver module  503 , the optical signal becomes a differential electrical signal, and then, the differential electrical signal is converted into a ten bit interface (TBI) signal or a Gigabit media independent interface (GMII) signal through the Mux/Demux  504 , and then transmitted to the OLT SoC  505  compliant with the IEEE802.3ah standard. The OLT SoC  505  is responsible for processing the MPCP protocol and transmitting the connection state and the LLID signal  506  to the CPU  507 . After receiving and encoding the connection state and the LLID signal  506  transmitted from the OLT SoC  505 , the CPU  507  transmits a plurality of state signals to the programmable logic element  508 . Then, the programmable logic element  508  receives the state signals outputted from the CPU  507 , and decodes and performs a logical calculation on the state signals, and then outputs the result to the display unit  509 . Finally, the display unit  509  displays the connection state and the identification according to the signal outputted after the decoding and logical calculation process of the programmable logic element  508 . 
         [0031]      FIG. 6  is a block diagram of a PON equipment applied in an ONU  600 , which is constituted by a circuit  602 , an optical path  601 , an optical transceiver module  603 , an ONU system-on-a-chip (SoC)  604 , a CPU  606 , a programmable logic element  607 , and a display unit  608 . The function of each element for the ONU is similar to that of the above OLT, which thus is not repeated in detail, but only the difference is illustrated. In the ONU  600 , the ONU SoC  604  is integrated with the Mux/Demux, such that the ONU SoC  604  is used to perform a conversion between a differential signal and an interface signal and encapsulate/decapsulate the packet, and after the LLID is acquired during the process of encapsulating/decapsulating the packet, the LLID signal  605  is transmitted to the CPU  606 . Furthermore, the display unit  608  is an LED row constituted by five LEDs, which shows 32 LLID changes by utilizing the on/off state of indicators. 
         [0032]    After being transmitted to the optical transceiver module  603  through the optical path  602 , the optical signal enters the amplifier, the filter, and the decoder in the optical transceiver module  603  and becomes a differential electrical signal. Then, the differential electrical signal is transmitted to the ONU SoC  604  compliant with IEEE802.3ah standard, for being converted into a TBI or a GMII signal through the Mux/Demux in the ONU SoC  604 , and then, the differential electrical signal is transmitted to a media access controller responsible for processing the MPCP and transmitting the LLID signal  605  to the CPU  606 . After receiving and encoding the LLID signal  605  transmitted from the ONU SoC  604 , the CPU  606  transmits a plurality of state signals to the programmable logic element  607 . Then, the programmable logic element  607  receives the state signals outputted by the CPU  606 , and decodes and performs a logical calculation on the state signals and outputs the result to the display unit  608 . Finally, the display unit  608  displays the identification according to the signal outputted after the decoding and logical calculation process of the programmable logic element  607 . 
         [0033]      FIG. 7  shows a display mode of the PON equipment at the OLT of the present invention. In order to easily demonstrate, we use a configuration of different mesh points in  FIG. 7  to indicate the LEDs of different colors and states, in which the display unit of the OLT  700  at the central office is a matrix LED  701 . The matrix LED  701  has totally 32 LEDs marked with numbers 1-32 from left to right and from top to bottom respectively, and each LED represents a corresponding ONU. Therefore, each OLT  700  can at least represent ONU states of 32 customer premises. However, this is only one embodiment, and actually different designs can be made according to different requirements, in which the green LED  708  represents a normal connection, the blinking green LED  708  represents that the packet is being transmitted, the red LED  704  represents no connection or connection failure, the dark LEDs  705  represents no connection assignation. The bright red LEDs  704  of Number 21, Number 25, and Number 29 represent connection failure for the ONUs of the three numbers. 
         [0034]      FIG. 8  shows a display mode of the PON equipment at the ONU of the present invention. The display unit of the ONU  800  at the customer premise is constituted by five LEDs  801 , marked with Number 4, Number 3, Number 2, Number 1, and Number 0 sequentially from top to bottom, which respectively represent 4 th  power of 2, 3 rd  power of 2, 2 nd  power of 2, 1 st  power of 2, and 0 th  power of 2, so as to display 32 types of LLIDs. 
         [0035]    As shown in  FIG. 8 , for example, if the LEDs of Number 4, Number 3, Number 2, and Number 1 are in a bright state at the same time, it represents a sum of 4 th  power of 2, 3 rd  power of 2, 2 nd  power of 2, 1 st  power of 2, and 0 th  power of 2, so that the LLID of the ONU is 31, and thus, the user can easily determine the identification of the ONU  800 . 
         [0036]    Hereinafter, an embodiment is given below to illustrate the display mode for the PON equipment of the present invention. Referring to  FIGS. 4 ,  5 ,  6 , and  9 , when being added into the optical fiber network topology, the ONU  800  receives a discovery packet  401  transmitted from the OLT  700  by broadcasting through the optical fiber  901 . The discovery packet  401  enters the optical transceiver module  603  through the ONU optical path  602  connected with the optical fiber  901 , for being converted into a differential electrical signal. Then, the ONU SoC  604  receives the differential signal, and then, sends the register request packet  404  according to the register allowance timeslot  402  message in the received discovery packet  401 , after entering the register allowance timeslot  402  and after a period of random delay  403 . 
         [0037]    The register request packet  404  is transmitted to the optical path  502  of the OLT through the optical fiber  901  and entered the optical transceiver module  503  for being converted into a differential signal. The Mux/Demux  504  receives the differential signal and converts the differential signal into a TBI or a GMII signal. The OLT SoC  505  receives a network protocol of MPCP for processing the TBI or GMII signals, and allocates an LLID of Number 31 corresponding to the ONU, adds the LLID of Number 31 into the register response packet  405  for being transmitted to the ONU, and displays that the green LED  703  is blinked in the LED of Number 31 of the matrix LED  701 . After the register response packet  405  has been transmitted, a period of time is delayed and then, the OLT transmits the acknowledgement packet  406 . 
         [0038]    After the ONU receives the register response packet  405  transmitted from the OLT  700  through the optical fiber  901 , the LLID is extracted from the packet in a P2P simulator of the ONU SoC  604 , and after acquiring that the LLID is corresponding to Number 31, an LLID signal  605  is outputted, and then, the register acknowledgement packet  407  is transmitted to the OLT. After the CPU  606  receives the LLID outputted from the ONU SoC  604 , it outputs a plurality of state signals after a decoding process. After receiving the state signals outputted from the CPU  606 , the programmable logic element  607  decodes and performs a logical calculation on the state signals to generate at least one trigger signal. The display unit  608  receives the trigger signal for triggering the LEDs of Number 4, Number 3, Number 2, and Number 1. 
         [0039]    After the OLT receives the register acknowledgement packet  407 , the LED of Number 31 of the matrix LED  701  changes from the blinking green LED  703  into the green LED  702 . If the MPCP handshaking process fails, the LED of Number 31 of the matrix LED  701  changes from the blinking green LED  703  into the red LED  704 . 
         [0040]    Therefore, once the user at the customer premise found that a connection interruption occurs, the message displayed by the display unit  801  of the ONU  800  is informed to the network administrator at the central office. Upon acquiring the LLID fed back from the customer premise, the network administrator can know that a connection failure occurs to the current customer premise of Number 31, instead of no connection. 
         [0041]    It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents.