JP4413797B2 - Passive optical network system - Google Patents

Description

  In the present invention, a passive device in which a station-side terminal device (OLT: Optical Line Termination) and a subscriber-side terminal device (ONU: Optical Network Unit) are connected using an optical passive element (optical branching element). In particular, the present invention relates to an Ethernet (registered trademark) frame transmission control method using an SDH / SONET (Synchronous Digital Hierarchy / Synchronous Optical NETwork) frame in a gigabit transmission PON system. Here, SDH / SONET is an international standard for high-speed digital communication system using optical fiber, which is standardized as SODH proposed by Bellcore as SDH by the International Telecommunications Union / Telecommunication Standardization Sector (ITU-TS). is there.

  As an optical subscriber access system, a passive optical network (PON) system is known as a configuration in which OLT-ONUs are connected in a point-to-multipoint manner. A passive optical network (PON) system is a system in which one OLT and a plurality of ONUs are connected using an optical fiber cable and an optical passive element (optical coupler).

  The PON system includes an STM-PON that communicates between OLT and ONU (PON section) by an STM (Synchronous Transfer Mode) method, an ATM-PON that communicates by an ATM (Asynchronous Transfer Mode) method, and B -Broadly PON (Broadband PON) and E-PON (Ethernet (registered trademark) PON) communicating by Ethernet (registered trademark) system.

  The former STM-PON, ATM-PON and B-PON are ITU-T (International Telecommunication Union / Telecommunication Standardization Sector) G. 982, G.G. It has been recommended by the 983 series, etc. Recommended as the 984 series. G. In the 984 series, it is possible to transfer TDM signals and packets in a modified form of GFP (Generic Framing Procedure) in addition to the conventional ATM cell format. In addition, the latter E-PON is directed to Ethernet (registered trademark) packet transmission, and a configuration in which a point-to-multipoint connection at a gigabit transmission speed level is standardized as IEEE 802.3ah. Yes.

  In the PON system, the TDM (Time Division Multiplexing) method is adopted for the downlink transmission from the OLT to the ONU. Generally, the frame is broadcast from the OLT, and the corresponding information is based on the destination information of the frame. On the other hand, TDMA (Time Division Multiple Access) is adopted for upstream transmission from the ONU to the OLT, and this is because multiple ONUs simultaneously transmit the frame to the OLT. This is for avoiding the occurrence of a frame collision at the optical coupler (where the frames from the ONU are integrated).

  In order to realize the TDMA scheme, the OLT appropriately transmits a control frame used only in the PON section to each ONU, and each ONU reads a transmission start time and a transmission period specified in the control frame from the OLT, It is possible to transmit a frame to the OLT only during the transmission period from the transmission start time. Therefore, each ONU accumulates the frames received from the subscriber terminals until the transmission start time and stands by, and transmits the accumulated frames to the OLT from the transmission start time to the transmission period.

  An outline of the gigabit PON (high-speed PON optical access system (G-PON / GE-PON)) is shown in FIG. FIG. 11 shows the difference between the conventional technology (ITU-T G.984 series, IEEE Std802.3ah-2004) and the present invention. (A) of the figure is GE-PON (IEEE802.3ah), (b) is G-PON (ITU-T G.984.x), and (c) is the PON system of the present invention.

As a prior art document related to the present invention, a time slot dynamic allocation method in a transmission system in which a subscriber line terminating device performs communication by allocating a time slot to a terminal device by polling is described in Patent Document 1 below. ing. In addition, a plurality of terminal devices are connected by optical transmission paths branched to the network side device, and the polling information is sent from the network side device according to the polling request information from the terminal device, and the terminal device designated by the polling information Patent Document 2 below describes a bandwidth allocation method and bandwidth allocation transmission when a variable length packet is converted into a cell corresponding to a time slot and transmitted in a system for transmitting information converted into cells.
Japanese Patent No. 3490583 JP 2000-196646 A

  With the aim of building an economical PON system, the spread of IEEE 802.3ah-based E-PON is rapidly progressing in Japan. However, the uplink / downlink transmission speed of the E-PON is a Gigabit Ethernet (registered trademark) (GbE: transmission path speed is 1.25 Gbps, information speed is 1 Gbps, and line code is 8B10B). 10 Gbps Ethernet (registered trademark) has a high speed, and an ONU / OLT that receives an optical signal at this speed is still expensive, and is not suitable for application to a PON.

  On the other hand, SDH / SONET having a transmission rate of 2.4 Gbps is widely used as a network that has already been proven. However, as the transmission speed of Ethernet (registered trademark), only 10 Gbps is standardized at a speed higher than 1 Gbps. Thus, it is desired to construct an economical 2.4 Gbps PON based on Ethernet (registered trademark) transmission.

  In ITU-T, G.75 is intended for communication up to 2.4 Gbps. Although the recommendation has been advanced as the 984 series, the IEEE 802.3ah-based LSI has been advanced and put into practical use, and a PON system based on the IEEE 802.3ah is desired. In addition, simplification of upstream bandwidth setting and dynamic bandwidth allocation of each ONU is also desired. In addition, using a 100 Mbps media converter (MC), a broadband PON system that supports the transfer of 100 Mbps MAX Ethernet (registered trademark) packets to the station, as well as simple bandwidth guarantee and fixed allocation of TDM signals for conventional telephone services, etc. It is hoped that it will also be possible.

  The present invention is directed to a passive optical network (PON) to which a gigabit speed Ethernet (registered trademark) communication system is applied, and based on the ITU-T and IEEE standards, introduces an SDH frame, The introduction of the Ethernet (registered trademark) service is facilitated, and simple dynamic bandwidth allocation is enabled.

  The passive optical network system (PON) of the present invention uses (1) an SDH / SONET frame for a downstream transmission frame from an end station device (OLT) on the station side to an end device (ONU) on the subscriber side. , The PON overhead is stored in the section overhead (SOH) portion of the SDH / SONET frame, the Ethernet (registered trademark) frame is accommodated in the payload portion of the SDH / SONET frame, and the IEEE 802 in the preamble of the Ethernet (registered trademark) frame The logical address for the terminating device (ONU) on the subscriber side is set in the logical link identifier (LLID) field defined in .3ah.

  Also, (2) a terminating device on the subscriber side (LLID) addressed to the logical link identifier (LLID) defined in IEEE802.3ah is attached to the Ethernet (registered trademark) frame accommodated in the payload portion of the downstream transmission frame. ONU), including a gate packet indicating the transmission start time and transmission time of the upstream transmission frame from the station-side terminal device (OLT), the subscriber-side terminal device (ONU) indicates with the gate packet. According to the transmission start time and the transmission time, the transmission frame in the upstream direction is transmitted.

  (3) A frame transmission byte processed in a normal SDH / SONET frame and an error monitoring byte are accommodated in the overhead portion of the PON of the downlink transmission frame, and the payload of the downlink transmission frame is received. A scramble process that is processed by a normal SDH / SONET frame is performed on the portion.

  (4) In the PON overhead portion of the downstream transmission frame, the bandwidth of the upstream transmission frame from each terminal unit (ONU) in units of a predetermined transmission bandwidth and the transmission permission time It is characterized by newly defining and assigning an uplink bandwidth control byte indicating that, and updating the uplink bandwidth control byte at every transmission period of the SDH / SONET frame.

  Further, (5) an upstream bandwidth control byte for controlling the bandwidth of an upstream transmission frame from each subscriber-side termination device (ONU) in units of the predetermined transmission bandwidth is transferred to each subscriber-side termination device. (ONU) is updated at every transmission period of the SDH / SONET frame according to the requested amount of uplink transmission band allocation, and when the requested amount exceeds the allocatable band, the terminating device on the subscriber side Depending on the service request level of (ONU), bandwidth is dynamically allocated while maintaining fairness at each subscriber's terminal unit (ONU), and communication is possible if there is a remainder in the band that can be allocated The bandwidth of the terminating device (ONU) on the subscriber side in the state is secured, and the remaining bandwidth that can be allocated is allocated within the range that does not exceed the maximum permitted bandwidth according to the request of the terminating device (ONU) on the subscriber side And wherein the door.

  (6) An area in which monitoring control information is individually exchanged between the terminal unit (ONU) on the subscriber side and the terminal unit (OLT) on the station side in the overhead portion of the PON of the downstream transmission frame And the PON overhead includes an area for exchanging monitoring control information individually with the terminal equipment (OLT) on the station side in the upstream transmission frame from the terminal equipment (ONU) on each subscriber side. It is characterized by.

  (7) An upstream transmission frame from each terminal unit (ONU) on each subscriber side is composed of a PON overhead portion and a payload portion. The PON overhead portion includes a guard time and a laser defined by IEEE 802.3ah. It consists of on / off time, OLT receiver set-up time, clock extraction time, byte phase extraction delimiter time, and payload part contains Ethernet packet (including preamble) specified by IEEE802.3ah. When each subscriber-side terminating device (ONU) has a plurality of logical link identifiers (LLIDs) when instructing transmission of packets for uplink transmission from each subscriber-side terminating device (ONU), the logical link identifier It is characterized by accommodating and transferring a plurality of packets having different (LLID). .

  (8) When the upstream bandwidth control byte is defined and assigned to the PON overhead portion of the downstream transmission frame, a continuous upstream bandwidth is assigned to the same subscriber-side terminating device (ONU). In this case, the same subscriber-side terminal unit (ONU) number is consecutively assigned to the upstream bandwidth control byte, and a packet subsequent to the upstream packet transmitted by the subscriber-side terminal unit (ONU) is transmitted. Is characterized in that the PON overhead is omitted.

  (9) As an Ethernet (registered trademark) frame accommodated in the payload portion of the SDH / SONET frame, ITU-T G. It has an overhead defined by 984.3 and has a port ID as a logical destination for a terminal unit (ONU) on the subscriber side corresponding to a logical link identifier (LLID) defined by IEEE 802.3ah. To do.

  (10) An upstream transmission frame from each terminal unit (ONU) on the subscriber side includes a PON overhead portion and a payload portion. 984.2, which consists of a programmable programmable guard time, receiver set-up time, clock extraction time, byte phase extraction delimiter time as defined in 984.2. The Ethernet (registered trademark) packet (not including the preamble) having the overhead defined in 984.3 is accommodated, and each subscription is instructed when the packet transmission permission of the uplink transmission from each subscriber side termination unit (ONU) is instructed. When the terminating device (ONU) on the subscriber side has a plurality of port IDs, a plurality of packets having different port IDs are accommodated and transferred.

  In addition, (11) a time division multiplexing (TDM) signal that can be used at all times between the terminal device (OLT) on the station side and the terminal device (ONU) on each subscriber side, In the overhead area, transmission in the upstream direction is defined as PON overhead or payload.

  An SDH / SONET frame is used for a downstream transmission frame from the OLT to the ONU, the PON overhead is stored in the section overhead (SOH) portion of the SDH / SONET frame, and the Ethernet ( A registered logical frame is accommodated, and a logical destination for a terminating device (ONU) on the subscriber side is set in a logical link identifier (LLID) field defined in IEEE802.3ah of a preamble of an Ethernet (registered trademark) frame. Thus, an SDH frame can be introduced based on ITU-T and IEEE standards, and an IEEE-based Ethernet (registered trademark) service can be easily introduced.

  In addition, the PON overhead part of the downstream transmission frame indicates the upstream transmission frame band from each terminal unit (ONU) and the transmission permission time in units of a predetermined transmission band. Uplink bandwidth control bytes are newly defined and assigned, and the uplink bandwidth control bytes are updated at every transmission period of the SDH / SONET frame, so that uplink transmission to the terminating device (ONU) on each subscriber side Bandwidth allocation can be performed dynamically and simply.

  FIG. 9 shows a system comparison with a 100 Mbps peak rate guarantee. As an example of a system that guarantees 100 Mbps peak Ethernet (registered trademark) transmission in the PON layer, 16 subscribers of 100 Mbps media converter, two sets of IEEE-based GE-PON (16 subscribers in two pairs of 1 Gbps PON of 1: 8 branch), When comparing the ITU-T based 2.4 Gbps G-PON system (16 subscribers with 16 branches) with the system of the present invention, the system of the present invention is economically promising from the following points: .

  For the main optical modules with the same installation cost, the minimum number of fiber cores, and the equipment cost, the upstream PON overhead may be one for every integral multiple of 50 Mbps, which contributes to the cost reduction of the optical modules. It is easy to introduce a base Ethernet (registered trademark) service mechanism.

Embodiment 1:
FIG. 1 shows the frame structure of SDH / SONET STM (Synchronous Transport Module) -1 and STM-16c. The SOH (Section Over Head) portion of this frame is used as the PON overhead, and the Ethernet (registered trademark) frame is accommodated in the payload portion of the SDH / SONET frame.

  The preamble of the Ethernet (registered trademark) frame has a logical link identifier (LLID) field defined by IEEE 802.3ah, and the logical link identifier (LLID) is used for an optical network terminating device (ONU). A logical destination.

  FIG. 2 shows an Ethernet (registered trademark) frame configuration and a logical link identifier (LLID) field of a preamble defined by IEEE 802.3ah. This Ethernet (registered trademark) frame is mapped to the payload portion of the STM frame.

  FIG. 3 schematically shows the configuration of the first embodiment. As shown in the figure, in downstream transmission from OLT to ONU, SDH / SONET frame is used, SOH part of the frame is used as PON overhead, and Ethernet (registered trademark) frame is accommodated in payload part To do. The preamble of the Ethernet (registered trademark) has a logical link identifier (LLID) defined by IEEE 802.3ah, and the logical link identifier (LLID) is set as a logical destination for an optical network terminating device (ONU). .

Embodiment 2:
A configuration of a gate packet (corresponding to the above-described control frame) transmitted from the OLT to each ONU (strictly speaking, a logical link identifier (LLID)) and indicating the transmission start time and transmission period of the upstream transmission frame of each ONU As shown in FIG. Each ONU has a transmission control function for transmitting an upstream frame according to the transmission start time and the transmission period. The gate packet does not necessarily conform to IEEE 802.3ah, but the same format is desirable as a natural extension.

As opposed to the transmission of scrambled NRZ in the SDH / SONET frame of 2.448 Gbps in the downlink direction,
(1) Uplink direction is a type that performs 8B10B code conversion at 1.224 Gbps. (2) Uplink direction is a scrambled NRZ type at 1.224 Gbps.

Also, as opposed to scrambled NRZ transmission in a 2.448 Gbps SDH / SONET frame in the downlink direction,
(3) A type in which 8B10B code conversion is performed at 2.448 Gbps in the uplink direction. (4) A scrambled NRZ type at 2.448 Gbps is possible in the uplink direction.

  The type (1) is different from the transmission rate 1.25 Gbps defined in IEEE 802.3ah (because of 8B10B coding, 1 Gbps is 1.25 Gbps), and the new synchronous system SDH / SONET sequence rate. And the OLT and the ONU are synchronized.

Embodiment 3:
In the SDH / SONET frame shown in FIG. 1, SOH A1, A2 bytes (A1 = 0xF6, A2 = 0x28) are used for frame synchronization, and B1, B2 bytes (bit interleave parity) are used for error monitoring. In addition, the scramble process is performed on the payload portion. Therefore, the frame synchronization pattern may be 32 bits and may be 4 bytes of A1, A1, A2, and A2 bytes. Alternatively, ITU-T G. 0xB6AB31E0 defined by 984 series (G-PON) may be used. Further, the frame configuration may be the same, but the positions of the B1 and B2 bytes may be different, and the SOH byte may be newly redefined.

Embodiment 4:
A new upstream bandwidth control byte indicating the upstream bandwidth and transmission permission time from each ONU in units of about 50 Mbps is newly defined and assigned to the overhead portion of the PON of the downstream frame, for each SDH / SONET frame. Update this byte (every 125 μs). For example, when a 2.448 Gbps SDH / SONET frame is used for downstream transmission, a 48-byte area is secured in the PON overhead, and each 48-byte byte is transmitted in an upstream bandwidth of about 50 Mbps in order. By using an ONU number assigned to each byte as an instruction information, the ONU of that number can transmit an upstream band (reference: 51.84 Mbps × 48 = 2.488 Gbps). When the uplink transmission rate is 1.224 Gbps, the unit of the uplink band is about 25 Mbps, which is half (when 48 bytes are used for the uplink band control byte). At this time, the IEEE 802.3ah gate packet is not used, and the second embodiment is not applied.

  FIG. 5 shows a mode of bandwidth allocation in which bandwidth control is performed using the overhead of the SDH / SONET frame described above. As shown in the figure, a 48-byte upstream bandwidth control byte is defined in the overhead portion of the PON of the downstream frame, and, for example, as an ONU number for which transmission is permitted in the 48-byte upstream bandwidth control byte, In the first example, No. 1, No. 2, No. 3,-(not specified) and No. 7 are assigned in order. In the second example, No. 1, No. 2, No. 3, No. 2, No. 2 are assigned in order. assign.

  In the case of the first example described above, the first ONU, the second ONU, and the third ONU are permitted to transmit uplink data of about 50 Mbps in order, and then the ONU of No. 7 is about 50 Mbps of upstream data. Sending is allowed. In the case of the second example, the first ONU, the second ONU, and the third ONU are permitted to transmit upstream data of about 50 Mbps in order, and then the second ONU continuously transmits upstream data of about 50 Mbps. Sending is allowed.

  Each byte of the upstream bandwidth control byte can accommodate a plurality of packets having different logical link identifiers (LLIDs), and only one PON header of this packet is required. At this time, each ONU is notified of a delay adjustment value (or RTT: round trip time) from the OLT. Accordingly, each ONU can respond to transmission permission so that it is virtually 20 km away from the OLT, for example.

Embodiment 5:
Each ONU notifies the OLT of the queue length of transmission data accumulated in each ONU, and the OLT allocates a bandwidth using the above-described overhead based on this notification information. For example, the notification information may be notified in a report format defined in IEEE802.3ah as shown in FIG. Alternatively, a 1-byte report area is simply defined in the PON overhead of the upstream frame, and the number of bands remaining in the 50 Mbps unit is necessary to clear the queue. For example, if another 150 Mbps bandwidth is required, 3 (= 150 Mbps ÷ 50 Mbps) is notified as the number of unit bands to be notified.

Embodiment 5 ′:
In the upstream bandwidth allocation described above, when the upstream bandwidth allocation request from each ONU exceeds the bandwidth that can be allocated, the bandwidth is dynamically allocated according to the service request level of each ONU while maintaining fairness in each ONU. For example, when a bandwidth of 50 Mbps is first allocated to an active ONU, and then a bandwidth is sequentially allocated to an ONU that requires more bandwidth than 50 Mbps in an upstream bandwidth allocation request, and a shortage occurs, the bandwidth of the next frame At the time of allocation, the bandwidth is allocated with priority given to the ONU that was not allocated last time. For ONUs that do not have an upstream bandwidth allocation request, skip without allocating bandwidth. When there is a surplus in the bandwidth that can be allocated to the upstream bandwidth, bandwidth is sequentially allocated to ONUs that have requested upstream bandwidth allocation.

Embodiment 5 ":
When defining the area (upstream bandwidth control byte) indicating the upstream bandwidth from each ONU in units of about 50 Mbps, the active ONU (communication is possible) to satisfy the minimum bandwidth requirement for upstream bandwidth allocation from each ONU. The remaining bandwidth is allocated within a range that does not exceed the maximum permitted bandwidth according to the request of each ONU.

Embodiment 6:
In the PON overhead portion (SOH portion) of the downstream frame, for example, 13 bytes are defined for each ONU as an area of the monitoring control byte in which each ONU and the OLT individually exchange monitoring control information. The 13 bytes given here as an example are bytes used in B-PON as an OMCI (ONT Management Control Interface) channel.
Embodiment 6 ′:
Further, in the upstream frame from each ONU, for example, an area of 13 bytes / 125 μs per ONU is provided in the PON overhead as an area for exchanging monitoring control information with the OLT. Alternatively, it has a function of transmitting a 64 byte / 125 μs packet for each ONU. In this way, by defining the monitoring control byte of each ONU in the upstream direction, it is possible to smoothly transfer the monitoring control information to and from the OLT.

Embodiment 7:
The upstream signal from each ONU is composed of a PON overhead portion and a payload portion. As shown in FIG. 7, the PON overhead portion includes a guard time, a laser on / off time, an OLT receiver set− defined by IEEE 802.3ah. It consists of an up time, a clock extraction time, and a byte phase extraction delimiter time, and the payload portion accommodates the form of an Ethernet (registered trademark) packet (including a preamble) as defined in IEEE 802.3ah. The preamble has a logical link identifier (LLID) (FIG. 2).

Embodiment 7 ′:
When each ONU has a plurality of logical link identifiers (LLIDs) when instructing transmission of an upstream frame from each ONU described in the fourth embodiment or the fifth embodiment, packets having different logical link identifiers (LLIDs) are accommodated. And transfer. As shown in FIG. 5, by making it possible to accommodate packets having different logical link identifiers (LLIDs), it is possible to improve the efficiency of bandwidth use.

Embodiment 8:
As described in Embodiment 4 above, a certain ONU has an upstream bandwidth control byte that indicates the upstream bandwidth and transmission permission time from each ONU in units of about 50 Mbps in the overhead portion of the PON of the downstream frame. When the upstream band is continuously allocated, the ONU is configured to transmit the packet by omitting the PON overhead of the subsequent packet of the continuously transmitted upstream packet.

  In the above description, it has been described that only one PON header in the 50 Mbps band is required. However, the PON overhead can be similarly omitted when a band that is an integral multiple of 50 Mbps is allocated. By doing so, the cost of the optical module can be reduced.

Embodiment 9:
As shown in FIG. 1 in the first embodiment, a packet accommodated in the payload portion of the SDH / SONET frame is an ITU-T G. It has an overhead defined by 984.3, and a port ID is a logical destination for an optical network termination unit (ONU) equivalent to a logical link identifier (LLID) defined by IEEE 802.3ah. The packet accommodated in the payload portion can be configured to include not only an Ethernet (registered trademark) packet defined by IEEE but also an ITU-T standard.

Embodiment 9 ′:
In the first embodiment, the packet accommodated in the payload portion of the SDH / SONET frame has an overhead defined by IEEE 802.3ah, or the ITU-T G. Packet type identification information indicating whether or not it has the overhead defined in 984.3 is expressed using a specific byte or bit of the PON overhead.

Embodiment 10:
As shown in FIG. 7, the upstream signal from each ONU is composed of a PON overhead portion and a payload portion. 984.2, which consists of a programmable programmable guard time, receiver set-up time, clock extraction time, byte phase extraction delimiter time as defined in 984.2. It is configured to accommodate a form of an Ethernet (registered trademark) packet (not including a preamble) having overhead (packet length, port ID, etc.) defined in 984.3. In contrast to the seventh embodiment, an upstream signal from each ONU is configured to accommodate an ITU-T based Ethernet (registered trademark) packet. FIG. 8 shows an upstream PON signal configuration (ITU-T G.984 series).

Embodiment 10 ′:
The upstream signal from each ONU is composed of a PON overhead portion and a payload portion as in the tenth embodiment, and each ONU has a plurality of ONUs when instructing an upstream bandwidth packet permission from each ONU in the fourth or fifth embodiment. When the port ID is included, packets with different port IDs can be accommodated and transferred. This is a configuration for accommodating an ITU-T based Ethernet (registered trademark) packet of Embodiment 7 ′.

Embodiment 11:
A TDM signal (for example, a telephone service byte) that can always be used between the OLT and each ONU is defined in the PON overhead area in the downstream frame and in the PON overhead or payload in the upstream frame. The area of the PON overhead of the downstream frame may be defined in the SOH portion of the SDH / SONET frame. For example, in the case of the seventh and seventh embodiments, the upstream frame is 64 bytes / 125 μs per ONU in the PON payload area. Are defined after the delimiter in the PON overhead area. Thereby, the band of the TDM signal that can always be used can be secured.

It is a figure which shows the PON frame structure method by the SDH / SONET frame by this invention. It is a figure which shows an Ethernet (trademark) frame structure. It is a figure which shows the structure of the Example of this invention. It is a figure which shows the structure of a gate packet. It is a figure which shows the aspect of the band allocation by this invention. It is a figure which shows the report format prescribed | regulated by IEEE802.3ah. It is a figure which shows the upstream signal from ONU. It is a figure which shows an upstream PON signal structure (ITU-T G.984 series). It is a figure which shows the system comparison in a 100Mbps peak rate guarantee. It is a figure which shows a high-speed PON optical access system (G-PON / GE-PON). It is a figure which shows the outline | summary of gigabit PON.

Explanation of symbols

ONU Terminating equipment on the subscriber side OLT Terminal equipment on the station side PON Passive optical network

Claims (2)

In a passive optical network (PON) system,
The SDH / SONET frame is used for the transmission frame in the downstream direction from the terminal device (OLT) on the station side to the terminal device (ONU) on the subscriber side, and the PON is set in the section overhead (SOH) portion of the SDH / SONET frame. The overhead is stored, the Ethernet (registered trademark) frame is accommodated in the payload portion of the SDH / SONET frame, and the logical link identifier (LLID) field defined in IEEE 802.3ah of the preamble of the Ethernet (registered trademark) frame is joined. Means for setting a logical destination for the terminating device (ONU) on the user side ;
In the overhead portion of the PON of the downstream transmission frame, the upstream transmission frame band from each terminal unit (ONU) and the transmission permission time in units of a predetermined transmission band Means for newly defining and assigning a bandwidth control byte, and updating the upstream bandwidth control byte for each transmission period of the SDH / SONET frame;
Passive optical network system comprising the. An upstream bandwidth control byte for controlling the bandwidth of an upstream transmission frame from each subscriber-side termination device (ONU) in units of the predetermined transmission bandwidth is transmitted from each subscriber-side termination device (ONU). When the SDH / SONET frame transmission period is updated according to the uplink transmission band allocation request amount, and the allocation request amount exceeds the allocatable band, the service of the terminating device (ONU) on the subscriber side Depending on the request level, bandwidth is dynamically allocated while maintaining fairness at each subscriber's terminal unit (ONU). The bandwidth of the terminating device (ONU) on the subscriber side is secured, and the remaining bandwidth that can be allocated is allocated within a range that does not exceed the maximum permitted bandwidth in response to a request from the terminating device (ONU) on the subscriber side. Passive optical network system according to claim 1 that.

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