KR100582539B1 - Passive optical network system having a function of protecting and recovering network and method for protecting and recovering network in the system - Google Patents

Abstract

Disclosed are a passive optical subscriber system having a network protection recovery function and a network protection recovery method therefor. A plurality of optical network units (hereinafter referred to as 'ONU') are connected to an optical line terminal (optical end device, referred to as 'OLT') through a splitter, and a trunk is installed between the OLT and the splitter. In a passive optical subscriber system having a network protection recovery function, if the OLT fails to receive a report message from the ONU, the OLT sets a recovery path via one trunk among the plurality of trunks by using the optical switch, and then switches to the ONU. When the gate message is transmitted and the registration request message is received from the ONU, the registration message is transmitted, the ranging is performed, and the second gate message is transmitted to the ONU. The ONU sends a registration request message to the OLT in response to the first gate message, and sends a registration confirmation message in response to the second gate message. Accordingly, by detecting the status of the MPCP message in each OLT and ONU, it is possible to perform an appropriate protection recovery function between the OLT and ONU.

Optical network, Ethernet PON, protection recovery, MPCP message, passive optical subscriber network

Description

Passive optical network system having a function of protecting and recovering network and method for protecting and recovering network in the system

1 is a view showing the structure of a PON to which the present invention is applied;

2 is a flowchart illustrating a process of performing an OLT protection recovery method according to the present invention, and

3 is a flowchart illustrating a process of performing an ONU protection recovery method according to the present invention.

The present invention relates to a passive optical subscriber system having a network protection recovery function and a network protection recovery method in the system. More specifically, the present invention relates to a passive optical subscriber system using a MAC protocol in a structure in which only a trunk portion between an OLT and a splitter is duplicated. A system and method for performing protection recovery of an optical subscriber network.

With the rapid growth of the Internet usage population and the emergence of various Internet-based application services such as IPTV and VoIP, subscribers are demanding quality improvement of services. This trend has been extended not only to business subscribers but also to general residential subscribers. Accordingly, in order to advance the subscriber network, which is considered to be a bottleneck, it is considered to extend the optical transmission technology used only in the existing backbone network to the subscriber network. .

Next-generation optical subscriber transmission technology that can satisfy these requirements is receiving a passive optical network (PON) that provides a connection in the form of FTTx to subscribers within a 20km radius. PON is a technology that splits a single optical channel into multiple strands using an optical splitter, which supports up to 64 ONU / ONT (Optical Network Unit / Optical Network Termination). have. PON is important as next-generation optical subscriber transmission technology because FTTCab, FTTC, FTTB and FTTH, the ultimate subscriber network form, can support various FTTxes in one platform.

In the ITU-T standard, G.983.1, four PON protective recovery schemes are mentioned. <Type A> is a cost-effective structure that duplicates only the trunk portion between the OLT (Optical Line Terminal) and the splitter. <Type B> is a structure in which trunk and OLT line card are duplicated, and <Type C> is a structure in which ODN is duplicated. In the case of <Type B>, it has the advantage of increasing the price / performance ratio by dualizing only the common parts. However, an ONU with various needs cannot be accommodated in a single PON. On the other hand, in the case of <Type C>, 100% protection is possible by redundancy of all parts, but it has a disadvantage of high installation cost of PON. <D Type> is a structure proposed to be able to recover the protection even in case of problems in two lines (branch or trunk) by duplexing the whole ODN and adding a splitter inside. <Type D> provides strong protection and recovery, but has the disadvantage of high installation cost and complicated structure.

The technical problem to be achieved by the present invention is to recover the protection by using EPON MPCP message (gate, REPORT, REGISTER_REQ, REGISTER, REGISTER_ACK) in the <type A> structure, which is the most economical among the other four PON protective recovery structures It is to provide a passive optical subscriber network protection and recovery system and method capable of performing the function.

In the passive optical subscriber system having a network protection recovery function according to the present invention, a plurality of ONUs are connected to an OLT through a splitter, and the OLT and the splitter are connected between the OLT and the splitter. In a passive optical subscriber system having a network protection recovery function in which a trunk having a redundant hardware line is installed, the OLT fails to receive a report message from the ONU, using one of the trunks using an optical switch. After setting the recovery path through the path of the first transmission message to the ONU, and when the registration request message from the ONU transmits a registration message, ranging (Ranging) after performing the (Ranging) Sends a two-gate message, and the ONU sends a registration request message to the OLT in response to the first gate message. And a registration response message in response to the second gate message.

In addition, in the network protection recovery method according to the present invention for achieving the above technical problem, a plurality of ONU is connected to the OLT through a splitter and the line between the OLT and the splitter between the OLT and the splitter hardware A method for recovering network protection in a Type A passive optical subscriber system having redundant trunks, the method comprising: (a) transmitting a first gate message to the ONU; (b) checking whether a report message including status information is received from the ONU; And (c) allowing the transmission of data by transmitting a second gate message to the ONU when the report message is received within a predetermined time, and performing a recovery process if the report message fails to be received. The recovery process may include: (d) setting a recovery path via one of the trunks using an optical switch; (e) transmitting the first gate message to the ONU through the set recovery path; (f) if the registration request message is received from the ONU, transmitting the registration message, performing ranging, and transmitting the second gate message to the ONU.

According to the present invention, the trunk between the OLT and the splitter, which are commonly used by all ONUs, can be duplicated to provide a basic protection recovery function and to perform a protection recovery function in a simple and economical manner within 50 ms.

In addition, since the existing EPON MPCP message is used for the protection recovery function, a signaling message and a hardware device for processing thereof that are separately required for the protection recovery function are not necessary, and thus, protection recovery can be easily and efficiently performed.

There are five MPCP messages: Gate, REPORT, REGISTER_REQ, REGISTER, and REGISTER_ACK. These are Ethernet MAC control frames that follow the format defined by the IEEE 802.3 ah group.

The OLT sends a gate message to the ONU to allow transmission, and the ONU transmits data at the time allowed by the information in the gate message. At this time, the ONU transmits the status information in its own waiting queue to the OLT using the REPORT message, so that the ULT can inform the OLT of the bandwidth required for the next transmission. The ONU can send data to the OLT only after receiving a gate message from the OLT. The OLT can send the next gate message only after receiving a REPORT message from the ONU.

Hereinafter, with reference to the accompanying drawings will be described in detail a preferred embodiment of a passive optical subscriber network protection recovery method using a MAC protocol according to the present invention.

FIG. 1 is a diagram showing an economical structure of a PON (G.983.1 Type A).

Referring to FIG. 1, the PON 100 includes a plurality of optical network units (hereinafter referred to as “ONUs”) 110 and 120, a splitter 130, and an optical line terminal. OLT ') 140. Each ONU 110, 120 has a line card 115, 125 and is connected to the splitter 130 via light paths 150, 160 connected to the line cards 115, 125. Between the splitter 130 and the OLT 140, a main light path 170 and an auxiliary light path 180 are constructed. The OLT 140 is also connected to the splitter 130 through the line card 145. In this manner, by hardware redundancy of the trunk between the splitter 130 and the OLT 140, which are commonly used parts, the protection recovery function can be added to all ONUs 110 and 120. FIG.

2 is a flowchart illustrating a process of performing an OLT protection recovery method according to the present invention.

Referring to FIG. 2, the OLT 140 checks whether a report is received from the ONUs 110 and 120 (S200). If a signal failure (SF) occurs, the OLT 140 may not receive a report from the ONUs 110 and 120. If the OLT 140 does not receive the REPORT signal by the SF of the entire signal (S202), the path to the recovery path is set by using the optical switch in the protection line card (S204), and the ONU (110, 120) The gate message is transmitted (S206). When receiving the REGISTER_REQ message in response to the gate message from the ONU (110, 120) (S208), OLT 140 transmits a REGISTER message to the ONU (110, 120) (S210). In addition, the OLT 140 performs a ranging (S212) and then transmits a gate message to the ONUs 110 and 120 (S214). When the REGISTER_ACK message is received in response to the gate message from the ONU (110, 120) (S216), the OLT 140 terminates ranging. If no response to the gate message is received from the ONU 110, 120 (208), the OLT 140 determines that the splitter has failed and notifies the operator (218). On the contrary, if the signal is not received from the specific ONUs 110 and 120 by the partial SF (S202), the OLT 140 determines that the branch is broken and notifies the operator (S220).

On the other hand, if the OLT 140 receives the REPORT from the ONU (110, 120) (S200), it checks whether the received signal is normal (S222). Abnormal signals are generated by Signal Degradation (SD) or an error, and when an abnormal signal occurs, it can be classified into the following four types.

Case a: Received REPORT with SD from all ONUs;

Case b: when an SD generated REPORT is received from one ONU;

Case c: when faulty data is received from all ONUs;

Case d: when faulty data is received from one ONU;

If it is confirmed as Case a (S224), the OLT 140 retransmits the gate message to all ONU (110, 120) (S226) and confirms the occurrence of Case a (S228). If Case a occurs again, go to Step A.

If the case b is confirmed (S230), the OLT 140 retransmits the gate message to the corresponding ONU (110 or 120) (S232) and confirms the occurrence of Case b (S234). If Case b occurs again, OLT 140 determines that the branch has failed and notifies the operator (236).

When the case c is confirmed (S238), the OLT 140 detects the SD (S240), retransmits the gate message to all ONUs 110 and 120 (S242), and checks whether Case c is generated (S244). If Case c occurs again, go to Step A.

If it is confirmed as the case d (S246), the OLT 140 detects the SD (S248) and retransmits the gate message to the corresponding ONU (110 or 120) (S250) and confirms the occurrence of Case d (S252). If Case d occurs again, the OLT 140 determines that the branch has failed and notifies the operator (S254).

3 is a flowchart illustrating a process of performing an ONU protection recovery method according to the present invention.

Referring to FIG. 3, the ONUs 110 and 120 check whether a gate message has been received (S300). If the ONU 110 or 120 does not receive the gate message from the OLT 140, the ONU 110 and 120 determines that the signal has not been received by the SF (S305). In this case, the ONUs 110 and 120 stop transmission of the report to the OLT 140 (S310). When the ONU 110 or 120 receives the gate message from the OLT 140 within a predetermined time (S315), the ONU 110 and 120 transmits a REGISTER_REQ message to the OLT 140 (S320). When the REGISER message is received from the OLT 140 (S325), the ONUs 110 and 120 perform ranging (S330). When the gate message is received from the OLT 140 (S335), the ONUs 110 and 120 transmit a REGISTER_ACK message to the OLT 140 (S340). On the contrary, if a gate message is not received from the OLT 140 even after a predetermined time has elapsed (S315), the ONUs 110 and 120 determine that the branch or the splitter has failed and notify the operator (S345).

On the other hand, if the ONU (110, 120) receives a gate message from the OLT (140) (S300), it checks whether the received signal is normal (S350). Abnormal signals are caused by signal degradation (SD) or an error, and when an abnormal signal occurs, it can be classified into the following two types.

Case e: Received a report in which SD occurred from the OLT 140;

Case f: when data including an error is received from the OLT 140;

When the ONUs 110 and 120 receive the gate message in which the SD is generated from the OLT 140 (S355), the ONUs 110 and 120 request retransmission of the signal to the OLT 140 (S360). ONU (110, 120) checks the occurrence of Case e (S365). If Case e occurs again, go to Step B.

When the ONUs 110 and 120 receive data containing an error from the OLT 140 (S370), the ONUs 110 and 120 detect the SD (375) and request retransmission of the signal to the OLT 140 ( S380). The ONUs 110 and 120 check whether Case f is generated (S365). If Case f occurs again, the ONUs 110 and 120 determine that the branch is broken and notify the operator (S385).

The invention can also be embodied as computer readable code on a computer readable recording medium. The computer-readable recording medium includes all kinds of recording devices in which data that can be read by a computer device is stored. Examples of computer-readable recording media include ROM, RAM, CD-ROM, magnetic tape, floppy disk, optical data storage, and the like, and may also be implemented in the form of a carrier wave (for example, transmission over the Internet). Include. The computer readable recording medium can also be distributed over network coupled computer devices so that the computer readable code is stored and executed in a distributed fashion.

Although the preferred embodiments of the present invention have been shown and described above, the present invention is not limited to the specific preferred embodiments described above, and the present invention belongs to the present invention without departing from the gist of the present invention as claimed in the claims. Various modifications can be made by those skilled in the art, and such changes are within the scope of the claims.

According to the passive optical subscriber system having a network protection recovery function according to the present invention and a network protection recovery method therefor, the system provides a basic protection recovery function by providing a dual protection of all ONUs and provides excellent cost performance. By using <Type A>, a simple and economical protection recovery function can be performed within 50ms.

Claims (10)

A plurality of ONUs (optical network units) are connected to an optical line terminal (OLT) through a splitter, and the line between the OLT and the splitter is redundantly duplicated between the OLT and the splitter in hardware. In a passive optical subscriber system having a network protection recovery function in which one trunk is installed, If the OLT fails to receive a report message from the ONU, the OLT sets a recovery path via one of the trunks using an optical switch, and then transmits a first gate message to the ONU, and registers a registration request message from the ONU. When receiving the registration message, and performing ranging (Ranging) and transmits the second gate message to the ONU, The ONU transmits a registration request message to the OLT in response to the first gate message, and transmits a registration response message in response to the second gate message. Subscriber system. The method of claim 1, If the OLT determines that the report message received from the ONU is an abnormal signal, the OLT determines the type of an error occurring in the report message, and if the error occurred in the report message is determined as an error type 1 or error type 2, the OLT is transmitted to all ONUs. If a two-gate message is transmitted and an error type 3 or error type 4 is detected, the second gate message is transmitted to the ONU which has a signal attenuation or a report message in which an error exists. , The passive type optical subscriber system with a network protection recovery function is defined as follows. Error form 1: Receive report message from all ONUs with signal loss; Error type 2: Receive report signal message with error from all ONUs; Error type 3: Receive report message from a ONU with decay; Error type 4: Receive report message with error from one ONU. The method of claim 2, When the error type 1 or the error type 3 reoccurs, the OLT sets a recovery path and transmits a report message in which the error exists in case of the error type 3 to all ONUs in the case of the error type 1. Transmit the first gate message to an ONU, and when the registration request message is received from the ONU receiving the first gate message, transmit the registration message, perform ranging, and then the second gate to the ONU. Send a message, And if the error type 2 or the error type 4 reoccurs, determining that the branch of the ONU which has transmitted the report message in which the signal attenuation has occurred is a failure of the passive optical subscriber system having a network protection recovery function. The method of claim 1, If the ONU fails to receive the first gate message from the OLT, the ONU stops transmitting the report message. If the ONU receives the first gate message within a predetermined time, the ONU transmits the registration request message to the OLT. And receiving the registration message in response to the registration request message, performing ranging, and transmitting a registration response message to the OLT. The method of claim 4, wherein And the ONU determines that a failure of a branch or the splitter occurs if reception of the first gate message fails after the predetermined time elapses. The method of claim 1, When the first gate message received from the OLT is determined to be an abnormal message, the ONU determines an error type of the first gate message, and if the error occurring in the first gate message is determined as an error type 1, the ONU determines the error. Request retransmission of the first gate message, if it is determined that the error type 2 is detected, after detecting a signal attenuation of the received first gate message, requesting retransmission of the first gate message to the OLT, The passive type optical subscriber system with a network protection recovery function is defined as follows. Error form 1: Receive first gate message from which signal attenuation occurs; Error type 2: Receive first gate message with error from OLT. The method of claim 6, The ONU suspends transmission of the report message to the OLT when the error type 1 or the error type 2 reoccurs, and then transmits the registration request message to the OLT if the first gate message is successfully received from the OLT. And when the registration message is received in response to the registration request message from the OLT, ranging is performed. If the reception of the first gate message from the OLT fails, the network protection is determined to be a failure of the splitter. Passive optical subscriber system with recovery. A network protection recovery method of a type A passive optical subscriber system in which a plurality of ONUs are connected to an OLT through a splitter and a trunk having a hardware-duplexed trunk line between the OLT and the splitter is installed between the OLT and the splitter. To (a) sending a first gate message to the ONU; (b) checking whether a report message including status information is received from the ONU; And (c) if the report message is received within a predetermined time, transmitting a second gate message to the ONU to permit data transmission, and performing a recovery process if the report message fails to be received. The recovery process, (d) setting a recovery path via one of the trunks using an optical switch; (e) transmitting the first gate message to the ONU through the set recovery path; (f) receiving a registration request message from the ONU, transmitting a registration message, performing ranging, and then transmitting the second gate message to the ONU. . The method of claim 8, Step (c) is, (c1) confirming whether the report message received from the ONU is normal; (c2) if the report message is determined to be an abnormal signal, identifying a type of error occurring in the report message; And (c3) If the error occurring in the report message is identified as error type 1 or error type 2, the second gate message is transmitted to all ONUs, and if it is found as error type 3 or error type 4, signal attenuation occurs or an error exists. And checking whether the error reoccurs after transmitting the second gate message to the ONU which has transmitted the report message. The type of error is a network protection recovery method characterized in that: Error form 1: Receive report message from all ONUs with signal loss; Error type 2: Receive report signal message with error from all ONUs; Error type 3: Receive report message from a ONU with decay; Error type 4: Receive report message with error from one ONU. The method of claim 9, In step (c), if the error type 1 or the error type 3 reoccurs, the recovery process is performed. If the error type 2 or the error type 4 reoccurs, the branch of the ONU which transmits a report message in which the signal attenuation occurs is generated. The network protection recovery method further comprising the step of determining that the failure.

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