JP2002232444A - ATM passive optical network system - Google Patents

Abstract

(57) [Problem] To provide an ATM-PON system which can accurately monitor traffic from a user and can be realized at low cost. SOLUTION: A cell delay of a cell received from a user in an ATM-PON system 6 arranged between a user 8 and a network 7 and connecting a plurality of ONTs 1 accommodating the user to an OLT 2 via a star coupler 3. The shaper 5 for removing the fluctuation is arranged in front of the UPC circuit 4 for monitoring whether the transmission band from the user exceeds the contracted band.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to an ATM-PON (ATM-Passive) connected to a network.
Optical Network (ATM) network, and more particularly,
In the TM-PON system, the present invention relates to an arrangement of a function for monitoring whether or not a transmission band for each connection from a slave station exceeds a contract band.

[0002]

2. Description of the Related Art Here, an AT connected to a network
The M-PON system is a system in which one network-side interface accommodates a plurality of subscribers by using an optical fiber and a star coupler, and can accommodate subscribers at high speed and economically. FIG. 4 and FIG. 5 show such a conventional example shown in, for example, "Transactions of the 1997 IEICE General Conference, B-8-51," Study on Number of Available Connections in ATM-PDS Transmission System "". 1 is a block diagram showing a configuration of an ATM-PON system of FIG.

In FIG. 1, reference numeral 1 denotes an ONT (optical).
Network Terminal), 2 is OLT
(Optical Line Terminal), 3
Is a star coupler, 4 is a UPC (Usage Param)
eter Control; usage parameter control) circuit, 5 is a shaper, and 6 is an ATM-P by them.
It is an ON system. Reference numeral 7 denotes a network to which the ATM-PON system 6 is connected, and reference numeral 8 denotes a user accommodated in the ATM-PON system 6. In addition, FIG.
An ATM-PON system 6 having a user band monitoring mode in which the C circuit 4 is disposed in the ONT 1 and the shaper 5 is disposed in the OLT 2, and FIG.
ATM with monitoring form of user band arranged in LT2
PON system 6 is shown.

Next, the operation will be described. As shown, the ATM-PON system 6 includes a plurality of ONTs 1 as slave stations and an OLT 2 as a master station. On the other hand, in a device that accommodates ATM subscribers,
A function of monitoring whether the transmission band from the user 8 exceeds the contract band is required. This function is called a UPC function, and the UPC circuit 4 that realizes the UPC function is provided at the entrance of the network. That is, the ATM shown in FIG.
-In the PON system 6, this UPC circuit 4
In the ATM-PON system 6 shown in FIG.
The C circuit 4 is provided in the OLT 2.

In the ATM-PON system 6, the interval between the user cells arriving at the ONT 1 and the interval between the user cells arriving at the OLT 2 are generally different from each other, and this difference is usually corrected by a CDV (Cell Delay).
Variation (cell delay fluctuation).
The function of removing this CDV is a shaping function,
In the ATM-PON system 6 shown in FIGS. 4 and 5, a shaper 5 for realizing this shaping function is provided in the OLT 2.

[0006] In the ATM-PON system 6 shown in FIG. 4, cells from each user 8 are stored in the corresponding UPN in the ONT 1.
The CDV is monitored individually by the C circuit 4, and the CDV generated in the section from the user 8 to the OLT 2 is removed by the shaper 5 built in the OLT 2 and transmitted to the network 7.

In the ATM-PON system 6 shown in FIG. 5, cells from the user 8 are collectively monitored by the UPC circuit 4 in the OLT 2, and the CDV generated in the section from the user 8 to the OLT 2 is processed by the shaper 5. It is removed and sent to the network 7. The ATM-PON shown in FIG.
In the UPC circuit 4 of the system 6, the OLT 2
The transmission band from the user 8 is to be monitored in anticipation of the CDV occurring in the section up to.

Therefore, the ATM-PON having the configuration shown in FIG.
In System 6, as described in the above document,
By performing the UPC at a position close to the user 8, there is no need to anticipate the CDV occurring in the PON section, and accurate monitoring can be performed. However, all ONTs 1
The C circuit 4 is required, and the ONT 1 needs a function of controlling the setting of the UPC parameter, so that the price of the ONT 1 is increased. Furthermore, ATM-
Since the PON system 6 accommodates a plurality of ONTs 1, the price becomes even higher when considered as a whole system.

On the other hand, in the ATM-PON system 6 having the configuration shown in FIG. 5, the UPC circuit 4 is arranged in front of the shaper 5 in the OLT 2 so that the CDV generated in the section from the user 8 to the OLT 2 is anticipated. Since the monitoring is performed and the cell from the user 8 is transmitted to the network 7, the DBA (Dy
natural Bandwidth Associatengen
A problem arises when providing the t (dynamic band allocation) function. The details will be described below.

The DBA function is a function for effectively using the band of the PON section. OLT2 has multiple ONT1s
Are connected via the star coupler 3, and a large number of bands are allocated to the congested ONT 1, and a small band is allocated to the non-congested ONT 1. This is a method of effectively using the band of the section. Congestion / non-congestion is, for example, ONT1
It can be determined based on whether or not a large number of cells are stored in a buffer (not shown). As a bandwidth allocation method by the DBA, for example, a minimum bandwidth and a maximum bandwidth are determined for each ONT 1, and the minimum bandwidth is always allocated regardless of the congestion state of the ONT 1.
There is a method of dividing a surplus band during T1 and assigning it so as not to exceed the maximum band.

Hereinafter, a specific example of the DBA will be described. FIG. 6 shows a case where three ONTs 1 are connected to the OLT 2 via the star coupler 3. In this case, ON
The minimum bandwidth of T # 1 is 10 Mb / s and the maximum bandwidth is 80 Mb
/ S, the minimum bandwidth of ONT # 2 is 15 Mb / s, the maximum bandwidth is 90 Mb / s, and the minimum bandwidth of ONT # 3 is 20 Mb / s.
/ S and the maximum bandwidth are set to 100 Mb / s, respectively. It is assumed that the total bandwidth that can be allocated as a PON section is 135 Mb / s at the maximum. Since the minimum bandwidth is always assigned to each ONT 1, the surplus bandwidth is 135- (10 + 15 + 20) = 90 Mb / s. The surplus bandwidth is allocated to each congested ONT 1 according to the ratio of the minimum bandwidth.

FIG. 7 shows the allocated bandwidth according to the congestion state of each ONT 1. In FIG. Column 1 is ON
This shows a state in which all of T # 1 to ONT # 3 are not congested. In this case, the minimum bandwidths are assigned to ONT # 1 to ONT # 3.

In addition, No. Column 2 is a state in which only ONT # 3 is congested, and ONT # 1 and ONT # 2 are assigned their respective minimum bandwidths. Note that ONT # 3
Is the minimum band (20 Mb / s) and the surplus band (90 Mb / s).
/ S), that is, 20 + 90 = 110 Mb / s. However, since the maximum bandwidth of ONT # 3 is set smaller than that, ONT # 3 has
A maximum bandwidth of 100 Mb / s is allocated instead of 0 Mb / s. No. 3 and No. 3 Similarly, in the case of the column No. 4, band allocation as shown in FIG. 7 is performed.

No. 1 Column 5 is ONT # 2 and ONT
# 3 is in a congested state, a minimum bandwidth is allocated to ONT # 1, and ONT # 2 and ONT # 3 are
A value obtained by adding a band obtained by dividing the surplus band (90 Mb / s) at a ratio of the lowest band of 15:20 is assigned to each of the lowest bands. That is, 15 + 90 × 15 / (15 + 20) = 53.6 Mb / s is assigned to ONT # 2, and 20 + 90 × 20 / (15 + 20) = 71.4 Mb / s is assigned to ONT # 3. In addition, No. 6 and N
o. Column 7 is calculated in the same way, and band allocation as shown in FIG. 7 is performed. In this case, the allocated bandwidth in FIG. 7 is indicated by a rounded value.

No. Column 8 is a state where all of ONT # 1 to ONT # 3 are congested, and each of ONT # 1 to ONT # 3 has a surplus bandwidth (90 Mb /
A band obtained by dividing s) by the lowest band ratio of 10:15:20 is allocated. That is, 10 + 90 × 10 / (10 + 15 + 20) = 30 Mb /
s is 15 + 90 × 15 / (10 + 15 + 20) = 45 Mb / for ONT # 2.
s is 20 + 90 × 20 / (10 + 15 + 20) = 60 Mb / for ONT # 3
s are respectively assigned.

FIG. 8 is a block diagram showing the internal configuration of the ONT 1 shown in FIG. 5. In FIG. 8, reference numeral 9 denotes a buffer in which cells from the user 8 are temporarily stored. FIG.
FIG. 6 is an explanatory diagram showing the setting of the VC accommodated in the ONT1, and here, an example of setting the ONT # 1 shown in FIG. 6 is shown.

In the ONT 1 configured as described above, cells of a plurality of connections are input from the user 8 and are temporarily stored in the buffer 9 before being transmitted to the PON section.
Here, ONT # 1 shown in FIG.
It is assumed that VCs (VC # 1 to VC # 4) are accommodated. In other words, each of these VCs has its own MCR (Mi
A connection having parameters of minimum cell rate (lowest cell rate) and PCR (peak cell rate; maximum cell rate) as parameters.
The MCRs of # 1 to VC # 4 are 1 Mb / s, 2 Mb / s, 3
Mb / s, 4 Mb / s, PCR of VC # 1 to VC # 4 is 10 Mb / s, 20 Mb / s, 20 Mb / s, 30 Mb
/ S.

For ONT # 1, the minimum bandwidth as a DBA is as follows to guarantee the MCR of these four VCs:
1 + 2 + 3 + 4 = 10 Mb / s, which is the sum of MCRs. In addition, when four VCs are simultaneously transmitted by PCR, the maximum bandwidth as the DBA is the sum of PCRs so that the cells of the four VCs can be transmitted in the PON section without being discarded. It is desirable to set 10 + 20 + 20 + 30 = 80 Mb / s. The minimum band (10 Mb / s) and the maximum band (80 Mb / s) correspond to ONT # 1 shown in FIG.
ON by DBA
The band of T # 1 can take the values shown in FIG.

Here, when ONT # 2 and ONT # 3 are always in a non-congestion state, in ONT # 1, only cells of VC # 2 become PCR = 20 Mb / Suppose you start arriving at s. In this case, in a state where no cell has come from the user 8 (non-congestion state), the ONT # 1 is No. 1 in FIG. 10 Mb / s, which is the allocated bandwidth shown in column 1, is allocated.

When the cell of VC # 2 starts arriving at 20 Mb / s, it starts to accumulate in the buffer 9 in the ONT # 1 and enters a congestion state. As a result, DBA of FIG.
o. 80 Mb / s shown in column 4 will be allocated. Here, the allocated bandwidth is 10Mb / s to 80M
b / s, the buffer 9 in the ONT # 1
Are transmitted to the PON section at 80 Mb / s. 20 Mb / s from user 8 at that time
Since the cell has arrived at the buffer 9 in the ONT # 1,
The data is transmitted at 80 Mb / s until no cells remain in the cell. After that, it becomes non-congested state and DBA
Since the band is changed from 0 Mb / s to 10 Mb / s, cells are accumulated in the buffer 9 and a congestion state occurs. The above operation is repeated.

At this time, the ATM-PON system 6
As shown in the figure, when the UPC circuit 4 is arranged in the OLT 2, the UPC circuit 4 in the OLT 2 has a VC #
2 cells arrive at 10 Mb / s initially, then 80
Arriving at Mb / s will be repeated.
Since the UPC circuit 4 in the OLT 2 performs monitoring according to the PCR of each VC, PCR = 20 for VC # 2.
Monitor at Mb / s. Therefore, when a cell arrives at 80 Mb / s, the UPC circuit 4 determines that the PCR is over, and the cell is discarded.

Here, the ATM-PON having the configuration shown in FIG.
As described above, since the system 6 performs the UPC in consideration of the CDV in the PON section, the CDV considers that the cell arrives at 80 Mb / s until the cells stored in the buffer 9 in the ONT 1 are exhausted, and that the CDV If UPC can be performed in consideration of the above, no problem occurs. However, the above CDV
Is the PCR of the connection, the allocated bandwidth of ONT1,
It varies depending on the size of the buffer 9 in the ONT 1 and the congestion state of the other ONTs 1, and is very difficult to predict.

As described above, as the DBA bandwidth allocation algorithm, the minimum bandwidth and the maximum bandwidth are determined for each ONT 1, and the minimum bandwidth is used during non-congestion, and the excess bandwidth is used during congestion.
Has been described using the method of dividing by the lowest bandwidth ratio, but the bandwidth allocated to the ONT 1 may exceed the PCR of the VC even if another allocated bandwidth algorithm is used, and the same problem occurs.

In the case of the ATM-PON system 6 having the configuration shown in FIG. 4, if the UPC circuit 4 is located in front of the buffer 9 of the ONT 1, the CDV does not matter at the position of the UPC circuit 4 even if DBA is performed. , Accurate UPC monitoring can be performed. However, as mentioned earlier, ONT1
Since the PC circuit 4 needs to be mounted, there is a problem that the price of the ONT 1 increases.

[0025] In addition, as a document which describes a technique related to such an ATM-PON system, there is another document such as Japanese Unexamined Patent Publication (Kokai) No. Hei 10-64, which performs shaping in the case of multicasting in the downstream direction from the OLT to the ONT. 11-
No. 215416 and ATM-PON
Although not premised on a system, Japanese Patent Application Laid-Open No.
No. 4, JP-A-7-170270 and the like.

[0026]

SUMMARY OF THE INVENTION Conventional ATM-PON
Since the system is configured as described above, the UPC circuit 4 is arranged at the entrance of the OLT 2, and when the bandwidth of the DBA changes greatly and the PCR of the connection appears to increase, the UPC circuit 4 is erroneously detected. Judge,
There has been a problem that cells may be discarded.

It is also possible to arrange the UPC circuit 4 in the ONT 1, but in such a case, the
Since the C circuit 4 is required for each ONT 1, there is a problem that the price of the ONT 1 and eventually the price of the ATM-PON system 6 as a whole increase.

The present invention has been made to solve the above-described problems, and is an ATM-PO which can accurately monitor traffic from a user and can be realized at low cost.
The aim is to obtain an N system.

[0029]

An ATM passive optical network system according to the present invention is connected between a network and a user, and is used to monitor whether a transmission band of a cell from the user exceeds a contract band. A quantity parameter control function, and a shaping function for removing cell delay fluctuation of a cell received from a user, a master station that performs usage parameter control and shaping of a cell from a user and sends it to a network, and a star coupler. A plurality of slave stations connected to a master station via a base station for transmitting cells received from a user to the master station, and realizes a shaping function in an ATM passive optical network system for transmitting / receiving cells between a user and a network. For the usage parameter control function. It is obtained so as to place in front of the motor control circuit.

An ATM passive optical network system according to the present invention is connected between a network and a user, and uses a usage parameter control function for monitoring whether a transmission band of a cell from the user exceeds a contract band, It has a shaping function to remove the cell delay fluctuation of the cell received from the user, and connects to the master station that sends the cell from the user to the network by performing usage parameter control and shaping, and to the master station via a star coupler. In the ATM passive optical network system that includes a plurality of slave stations that transmit cells received from the user to the master station and that transmits and receives cells between the user and the network, a shaper for implementing a shaping function includes: By shaping the cells from the user to the maximum cell rate of the contract bandwidth, Te, in which so as to achieve even usage parameter control function.

[0031]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Embodiment 1 FIG. FIG. 1 shows A according to Embodiment 1 of the present invention.
FIG. 2 is a block diagram illustrating a configuration of a TM-PON system.
In the figure, 1 is a plurality of ONTs as slave stations, 2 is an OLT as a master station, and 3 is a plurality of ONTs in the OLT 2.
It is a star coupler connecting T1. Reference numeral 4 denotes a UPC circuit for realizing a UPC function for monitoring whether a transmission band of a cell from a user does not exceed a contract band, and 5 denotes shaping for removing cell delay fluctuation of a cell received from a user. It is a shaper that realizes functions. In addition,
These are both provided in the OLT 2 and the shaper 5 is
It is arranged before the PC circuit 4. 6 is the ONT
ATM- composed of 1, OLT 2 and star coupler 3
A PON system 7 is a network to which the ATM-PON system 6 is connected, and 8 is an ATM-PO system.
The user is housed in the N system 6.

Next, the operation will be described. ATM-
The PON system is a system in which one network-side interface accommodates a plurality of subscribers by means of an optical fiber and a star coupler, and can accommodate subscribers at high speed and economically. This ATM-PO
The N system 6 includes a plurality of ONTs 1 as slave stations and an OLT 2 as a master station. On the other hand, a device that accommodates ATM subscribers needs a function of monitoring whether the transmission band from the user 8 exceeds the contracted band. This function is called the UPC function, and the ATM shown in FIG.
In the PON system 6, the UPC circuit 4 for realizing the UPC function is provided after the shaper 5 in the OLT 2.

Further, in the ATM-PON system 6, in the upstream communication from the ONT 1 to the OLT 2, the time slot that each ONT 1 may transmit is set to the OL.
T2 instructs ONT1 to TDMA (Time
Division Multiplexing Ac
ESS), each ONT 1 transmits an ATM cell. For this reason, as shown in FIG. 8, each ONT 1 performs control such that a cell received from the user 8 is temporarily stored in a buffer 9 in the ONT 1 and the cell is transmitted to a time slot where transmission is possible. Accordingly, the interval between the user cells arriving at the ONT 1 and the interval between the user cells arriving at the OLT 2 are generally different, and the difference is called CDV.
In the ATM-PON system 6 shown in FIG. 1, the shaper 5 for realizing the shaping function for removing the CDV generated in this manner is provided by the UPC circuit 4 in the OLT 2.
Deployed before.

In the ATM-PON system 6 according to the first embodiment, each ONT 1 transmits a cell received from the user 8 to the OLT 2 via the star coupler 3. OL
In T2, the cell from the user 8 is received by the shaper 5,
After removing the CDV generated in the section from the user 8 to the OLT 2, the signal is input to the UPC circuit 4.

As described above, the cells output from the user 8 are first shaped in the OLT 2 after passing through the shaper 5 and then input to the UPC circuit 4. FIG. 2 shows an example of the internal configuration of the shaper 5. In FIG. 2, 1
Reference numeral 1 denotes a distribution circuit that distributes input cells for each VC. Reference numeral 12 denotes a buffer for holding the sorted cells, and reference numerals 21 to 2n denote buffer circuits provided in the buffer 12 corresponding to the VCs # 1 to VC # n. Reference numeral 13 denotes a multiplexing circuit for multiplexing the cells once held in each of the buffer circuits 21 to 2n.

In the OLT 2, the cells transmitted from the ONT 1 via the star coupler 3 are received by the shaper 5. The shaper 5 sorts the input cells by the sorting circuit 11 for each of VC # 1 to VC # n, sends the cells to the buffer 12, and temporarily stores them in the corresponding buffer circuits 21 to 2n.
The cells stored in these buffer circuits 21 to 2n are:
It is read out by the corresponding PCR of VC # 1 to VC # n.
The multiplexing circuit 13 multiplexes cells from the buffer circuits 21 to 2n and outputs the multiplexed cells to the UPC circuit 4. As described above, in the cell input via the star coupler 3, the CDV generated in the section from the user 8 to the OLT 2 is removed by the shaping function of the shaper 5, and the cell between the user cell arriving at the ONT 1 and the cell arriving at the OLT 2 There is no deviation in the interval between user cells.

Although FIG. 2 shows a configuration having separate buffer circuits 21 to 2n for each of VC # 1 to VC # n, all VCs have one common buffer and have a shaping function by address control. It is also possible to realize.

As described above, the cell from which the CDV has been removed by the shaping function of the shaper 5 is a UPC.
The signal is sent to the circuit 4 to monitor the transmission band. Therefore,
In the ATM-PON system according to the first embodiment, the UP
Since the UPC by the C circuit 4 is performed on the cell from which the CDV has been removed, there is no need to anticipate the CDV occurring in the PON section. Therefore, the UPC circuit 4
If it is provided only in T2, it becomes possible to accurately monitor the transmission band, so that the price of the ONT 1 can be reduced, and the price of the entire system can be reduced. The cells output by monitoring the transmission band by the UPC circuit 4 are transmitted to the network 7.

Further, the DBA is used in the ATM-PON system.
When providing the function, the bandwidth of the PON section is DB
Even if the change greatly occurs due to A, the UPC circuit 4
Since it is located after the shaper 5 in the OLT 2 instead of the entrance of the LT 2, the PCR
Even when the number of cells increases, the UPC circuit 4 does not erroneously discard cells.

As described above, according to the first embodiment, since the shaper 5 is provided before the UPC circuit 4, the CDV generated in the PON section is deleted by the shaper 5 and input to the UPC circuit 4. At this time, since the CDV is removed, the UPC circuit 4 does not erroneously discard cells, and by arranging the UPC circuit 4 in the OLT 2, monitoring of cells from a plurality of ONTs 1 can be performed. U
Since multiple ONTs 1 can be shared by PC circuit 4,
An effect is obtained that a system can be configured at a lower cost than when the circuit 4 is provided.

Embodiment 2 FIG. 3 is a block diagram showing a configuration of an ATM-PON system according to Embodiment 2 of the present invention. In the figure, 1 is ONT, 2 is OLT, 3
Is a star coupler, 6 is an ATM-PON system, 7 is a network, 8 is a user, and these are the same parts as those shown in FIG. Reference numeral 5 also realizes a shaping function for removing the CDV of the cell received from the user 8 and also realizes a UPC function for monitoring whether the transmission band of the cell from the user 8 exceeds the contracted band. In this respect, the shaper is different from the shaper denoted by reference numeral 5 in FIG. The shaper 5 is configured as shown in FIG. 2, for example, as in the case of the first embodiment.

Next, the operation will be described. In the ATM-PON system according to the second embodiment, cells output from the user 8 are sent to the OLT 2 via the star coupler 3. In the OLT 2, the received cell is input to the shaper 5 and shaped into a PCR to remove the CDV of the cell received from the user 8. By this shaper 5, PC
Unlike the case of the first embodiment, the cells shaped to R are output to the network 7 without passing through the UPC circuit 4. Violated cells are not detected in the cells shaped into the PCR by the shaper 5 even if they pass through the UPC circuit 4. Therefore, the cell is not discarded, and the UPC circuit 4 is provided to
There is no need for monitoring.

On the contrary, the UPC circuit 4
The cell discarding corresponding to discarding by the shaper 5
Can be caused by overflowing of the buffer 12 in the inside. The shaper 5 is configured as shown in FIG. 2, for example, as described above. The speed at which cells are read from the buffer circuits 21 to 2n for each VC depends on the PC of each VC.
R. Therefore, if the speed at which cells are input to the buffers 21 to 2n is higher than the PCR and the time is long, the buffers 21 to 2n will overflow and the cells will be discarded. This is the UPC circuit 4
This is equivalent to monitoring R.

As described above, the cells from the user 8 that have been shaped and UPCed by the shaper 5 are:
The OLT 2 sends it to the network 7.

As described above, according to the second embodiment, the shaper 5 also monitors whether the transmission band from the user 8 exceeds the contracted band. Can be deleted, and an effect that the system can be configured at lower cost as compared with the first embodiment can be obtained.

[0046]

As described above, according to the present invention, the shaper is arranged in front of the UPC circuit, the CDV generated in the PON section is deleted by the shaper, and the cell from which the CDV has been removed is input to the UPC circuit. Since the CDV is removed at the time of input to the UPC circuit,
No cells are accidentally discarded and the UPC
Since the circuit is provided in the OLT, the monitoring of cells from a plurality of ONTs can be shared by one UPC circuit, and an ATM-PON system can be realized at a lower cost than the UPC circuit is provided in a plurality of ONTs. There is an effect that it can be obtained.

According to the present invention, since the UPC circuit is also monitored by the shaper, the UPC circuit becomes unnecessary and the ATM-PON system can be realized at a lower cost.

[Brief description of the drawings]

FIG. 1 shows an ATM-PO according to a first embodiment of the present invention.
FIG. 1 is a diagram illustrating a configuration of an N system.

FIG. 2 is a block diagram illustrating an example of an internal configuration of a shaper according to the first embodiment.

FIG. 3 shows an ATM-PO according to a second embodiment of the present invention.
FIG. 1 is a diagram illustrating a configuration of an N system.

FIG. 4 is a block diagram showing a configuration of a conventional ATM-PON system.

FIG. 5 is a block diagram showing another configuration of the conventional ATM-PON system.

FIG. 6 is a block diagram illustrating a setting example when performing DBA.

FIG. 7 is an explanatory diagram showing an example of a bandwidth allocated by a DBA.

FIG. 8 is a block diagram illustrating an example of the internal configuration of the ONT.

FIG. 9 is an explanatory diagram showing an example of setting VCs accommodated in an ONT.

[Explanation of symbols]

1 ONT, 2 OLT, 3 star coupler, 4 UP
C circuit, 5 shaper, 6 ATM-PON system,
7 networks, 8 users, 11 distribution circuits,
12 buffers, 13 multiplexing circuits, 21-2n buffer circuits.

Continued on the front page (72) Inventor Takamasa Suzuki 2-3-2 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Electric Corporation F-term (reference) 5K030 GA05 GA08 HA10 HC14 JA01 JL03 JL08 LC02 LC13 MB09 5K033 AA04 AA05 CB06 DA15 DB02 DB22 EA06

Claims (2)

[Claims] 1. A usage parameter control function connected between a network and a user for monitoring whether a transmission bandwidth of a cell from the user exceeds a contract bandwidth, and a cell of a cell received from the user. A master station that has a shaping function for removing delay fluctuations, performs usage parameter control and shaping of cells from the user to the network, and sends the cells to the master station via a star coupler; An ATM passive optical network system for transmitting and receiving cells between the user and the network, comprising a plurality of slave stations transmitting cells received from the master station to the master station, a shaper for realizing the shaping function, Placed before the usage parameter control circuit to realize the usage parameter control function AT characterized the door
M passive optical network system. 2. A usage parameter control function connected between a network and a user for monitoring whether a transmission bandwidth of a cell from the user exceeds a contract bandwidth, and a cell of a cell received from the user. A master station that has a shaping function for removing delay fluctuations, performs usage parameter control and shaping of cells from the user to the network, and sends the cells to the master station via a star coupler; An ATM passive optical network system comprising a plurality of slave stations for transmitting cells received from the master station to the master station, and transmitting and receiving cells between the user and the network, wherein a shaper for implementing the shaping function comprises: By shaping the cells from the user to the maximum cell rate of the contracted bandwidth, ATM passive optical network system, characterized by also implementing dose parameter control feature.