JP3602750B2 - Data sending circuit - Google Patents

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a data transmission circuit that receives transmission permission by an output destination device. In particular, the present invention relates to a data transmission circuit of an optical network unit of a passive optical network.
[0002]
[Prior art]
In a conventional data transmission circuit, data is transmitted only according to transmission permission. Therefore, in the case of a data transmission circuit that accommodates a plurality of connections and receives transmission permission not in connection units but in data transmission circuit units, a part of the plurality of connections is congested in the transmission destination circuit and data is discarded. Even in this case, the data transmission circuit assigns the transmission permission given to the congested connection irrespective of the congestion state and transmits the data, so that the data may be discarded at the transmission destination. As described above, in the conventional circuit, the transmission permission cannot be used efficiently, and especially when a single route with a limited band is shared by a plurality of data transmission circuits, The problem of reduced use efficiency occurs.
[0003]
Examples of accommodating such a plurality of connections, receiving a transmission permission not in connection units, but in data transmission circuit units, and sharing a single route with a plurality of data transmission circuits are ITU recommendations G983.1 and G983. There is an optical network termination (ONT) that constitutes a passive optical network (PON) defined by the above-mentioned.
[0004]
This problem becomes remarkable when accommodating a connection of a guaranteed frame rate (GFR) service class described in Traffic Management Specification 4.1 of the ATM Forum. In GFR, transmission has a guaranteed minimum cell rate (MCR), and transmission of data in a band exceeding the MCR is not guaranteed, but transmission may be allowed.
[0005]
FIG. 1 is a diagram illustrating an example in which bandwidth utilization efficiency is deteriorated when GFR is accommodated. The data transmission circuit 1 accommodates two GFR connections 2 and 3 and receives a single transmission permission for both connections. For the data belonging to the connections 2 and 3, the weighted transmission bandwidth is allocated from the corresponding buffer memories 5 and 6 according to the weight corresponding to the MCR ratio and the like, using the total bandwidth 4 corresponding to the transmission permission. It is transmitted through round robin (WRR) transmission means 7. The transmitted data of both connections is transmitted by different output routes sharing the bandwidth with the different connections in the transmission destination circuit 8, however, due to the congestion situation in each output route, the bandwidth of MCR or more is discarded. May be Therefore, in the transmission device 8 at the subsequent stage of the transmission destination, one connection accommodated by the data transmission circuit 1, that is, the data of the connection 3 is discarded, the other connection 2 is not discarded, and the surplus bandwidth exists in the output route. In this case, the data transmission circuit 1 cannot recognize the congestion state, and in order to transmit the data of both connections 2 and 3 fairly, the total band corresponding to the transmission permission received by the data transmission circuit 1 is set. It cannot be used effectively.
[0006]
In the above, it has been shown that an invalid band occurs in a single data transmission circuit. However, when a limited band of a single route is shared by a plurality of data transmission circuits, the influence on other data transmission circuits cannot be ignored.
[0007]
As a method of suppressing the transmission band, in the available bit rate (ABR) service class, there is a method of using a resource management (RM) cell for performing transmission suppression or transmission permission. However, in this case, although it is possible to suppress transmission for each connection having an individual virtual channel (VC), the bandwidth of a connection or a group of connections mapped to a plurality of VCs belonging to different virtual paths (VPs) can be suppressed. Totals cannot be suppressed. This means that it cannot be used in a PON system that can use only the band permitted for each data transmission circuit. Furthermore, the surplus bandwidth available between connections cannot be used effectively.
[0008]
Further, as a method of giving a bandwidth to another connection group when a surplus bandwidth occurs in a certain connection group, each connection group is set as a priority class having a different priority, and the surplus bandwidth of the priority class is set to a class having a lower priority. There is a method of allocating to a connection belonging to. In this case, priority must be given to the priority in the bandwidth allocation between connections, and there is a problem that the connection group cannot be implemented in the same class, and there is a large amount of data in the high-priority connection group. However, there is a problem that a low priority connection group cannot transmit data.
[0009]
[Problems to be solved by the invention]
SUMMARY OF THE INVENTION An object of the present invention is to provide a data transmission circuit capable of effectively using a transmission band in view of the above-mentioned problems.
[0010]
[Means for Solving the Problems]
In order to achieve the above object, a data transmission circuit according to the present invention includes a data transmission circuit that accommodates a plurality of connections and transmits data in a band corresponding to a transmission permission to receive. A certain total bandwidth is allocated to each connection group composed of a single or a plurality of connection units, a group bandwidth allocated to each connection group is allocated to a connection belonging to the connection group, and transmitted to a connection belonging to the connection group. When there is no data to be provided, a configuration is provided in which the surplus bandwidth of the connection group is redistributed to another connection group, and an instruction to suppress transmission of data of a connection where congestion occurs or may occur at the transmission destination is provided. Instruction receiving means for receiving a transmission inhibition instruction to perform transmission, and receiving the instruction by the inhibition instruction receiving means. Characterized in that by the sending inhibition instruction including inhibiting means for inhibiting the delivery of the indicated connection as a deterrent object connection.
[0011]
The received transmission inhibition instruction is transmitted when the bandwidth transmitted by the connection to be inhibited during the past fixed time period and the connection sharing the bandwidth with the connection to be inhibited by the data transmission circuit of the destination to which the data belonging to the connection to be inhibited arrives. A transmission inhibition instruction according to the total bandwidth with the transmitted bandwidth, or a transmission inhibition instruction for inhibiting transmission of data in response to redistribution of a band allocated to a connection group other than the connection group to which the connection to be inhibited belongs. It is preferred that
[0012]
BEST MODE FOR CARRYING OUT THE INVENTION
Next, an embodiment of the data transmission circuit of the present invention will be described.
[0013]
[First embodiment]
FIG. 2 is a diagram showing a configuration of the first embodiment of the data transmission circuit of the present invention and an example of an operation of effectively using a band when the configuration is applied. In this configuration, the data transmission circuit 11 accommodates a plurality of connections 12 and 13, and a total band 14 is allocated to all accommodated connections. For example, in the case of ONTs described in ITU G983.1, this band allocation is performed by dynamically changing the total band described in a PLOAM cell having an information area for notifying the band allocation to each ONT. In this embodiment, it is assumed that a fixed band is statically assigned to the ONT.
[0014]
In order to fairly distribute the allocated bandwidth among the connections in this manner, the WRR that allocates a bandwidth proportional to the weight assigned in advance to the accommodated connections or the waiting time until the bandwidth allocation between the connections is leveled. It is necessary to use bandwidth allocation means such as weighted fair queuing (WFQ). This embodiment will be described using the WRR transmission means 17. Further, an assignment suppression unit 21 and a suppression instruction receiving unit 22 are provided. The inhibition instruction receiving means 22 receives a transmission inhibition instruction for inhibiting transmission to a specific connection from another circuit. The allocation suppression unit 21 performs the allocation suppression on the connection for which the band allocation is to be suppressed according to the suppression instruction received by the suppression instruction receiving unit 22.
[0015]
The WRR transmitting means 17 includes a cell information for each connection of the cell presence / absence identifying means for identifying the presence / absence of a cell for each connection and a weight for identifying whether or not an information amount corresponding to a weight proportional to the weight for each connection is read. Using the unread information corresponding to the weight of the unread identification means, a band is allocated in such a manner that a cell of a connection which can be ANDed between the cell presence information of the cell presence / absence identification means and the unread information of the weight unread identification means is read. Therefore, as a method of suppressing the allocation to the WRR transmitting unit 17, the allocation suppressing unit 21 can suppress the data transmission by setting either or both of the cell presence information and the unread information for the weight to be negative. If a guaranteed bandwidth is set for each connection, transmission of a bandwidth exceeding the guaranteed bandwidth set for each connection is suppressed.
[0016]
As a method of notifying the assignment suppression instruction, a dedicated cell or an area set for notification can be used. In this embodiment, the suppression instruction is received from the per-path congestion observation means 23 of the transmission destination circuit 18 which is the transmission destination. The route-by-route congestion monitoring means 23 of the transmission destination 18 observes the congestion state in the route in which each connection is accommodated, and when congestion occurs, notifies an assignment suppression instruction for suppressing assignment. That is, for example, when the route to which the connection 13 belongs is congested, a transmission inhibition instruction is transmitted to the data transmission circuit 1 according to the congestion information, and the transmission inhibition of the connection 13 is performed according to the transmission inhibition instruction. Since the data of the connection 12 can be transmitted without transmitting the data of the connection 13 discarded after the transmission, the bandwidth can be used effectively. The route-by-route congestion monitoring means 23 transmits congestion according to the total bandwidth of data transmitted by the connection to be inhibited and the connection sharing the route with the connection at a fixed time in the past, and arriving at the destination circuit 18. Notify. The total bandwidth for the past certain time is observed by measuring the amount of arrival data by a counter, measuring the amount of cells remaining in the buffer, and the like.
[0017]
The connection in this embodiment may be a single VP or VC used in ATM, a VP group in which a plurality of VPs are combined, or a VC group in which a plurality of VCs are combined. The route in this embodiment may be a physical route, or may be a network virtual path (NVP) that divides the physical route and treats the divided band as a virtual route.
[0018]
[Second embodiment]
In this embodiment, when a bandwidth is allocated for each connection, there is provided means for accommodating unused allocation permitted bandwidth between the connections. FIG. 3 is a diagram showing this embodiment. For simplicity, the data transmission circuit 30 uses a constant bit rate (CBR) connection 31 that does not use a band other than the fixedly allocated band 34, the allocated band 35 and the allocated band 34 of the connection 31. When possible, it accommodates a connection group consisting of GFR connections 32 and 33 for fairly distributing an unused band not used by the connection 31 in the allocated band 34. The total band of the data transmission circuit 30 is the sum of the allocated band 34 and the allocated band 35.
[0019]
The data transmission circuit 30 includes an unused band allocation identification unit 38, a WRR transmission unit 39, an allocation suppression unit 40, and a suppression instruction reception unit 41. The unused bandwidth allocation identifying means 38 identifies unused bandwidth allocation of the connection 31. The WRR transmitting means 39 allocates the unused bandwidth of the connection 31 identified by the unused bandwidth allocation identifying means 38 and the bandwidth allocation to the connections 32 and 33 according to the bandwidth allocation originally allocated to the connections 32 and 33. I do. The inhibition instruction receiving unit 41 receives an allocation inhibition instruction for each connection from the route-specific congestion observation unit 51 of the transmission destination circuit 50. The assignment suppression unit 40 suppresses the assignment of each connection based on the suppression instruction received by the suppression instruction receiving unit 41.
[0020]
In the above description, a combination of CBR and GFR has been described. However, the connection 31 is an unspecified bit rate (UBR) connection without a guaranteed bandwidth, and the bandwidth allocated to each connection can be interchanged. There is a difference from the conventional data transmission circuit using a class-based buffer that forms a class for each priority and allocates a band in order from the class with the highest priority.
[0021]
As described above, according to this embodiment, different service classes of ATM can be accommodated. In the case of a CBR connection, the service class set for each connection can be changed without changing the configuration and settings of the data transmission circuit by always suppressing the use of the bandwidth allocated to other connections in response to the transmission suppression instruction. Can be. In this case, since the transmission inhibition instruction is always generated for the CBR connection, the transmission inhibition instruction is sent to the “start of inhibition” for each connection in order to reduce the bandwidth consumption by notifying the transmission inhibition instruction. And two signals meaning "end of inhibition".
[0022]
If it is necessary to send data to a transmission path on the assumption that an identification number such as VPI or VCI is attached to each connection and send the data, the tag for identifying the connection is replaced and sent. You will need to add the tags back later. As described above, in this embodiment, the bandwidth can be effectively used even in the case of a connection to which a bandwidth is individually assigned.
[0023]
[Third embodiment]
This embodiment has means for reporting the difference between the transmission permission received for each connection and the amount of data arriving for each connection to a circuit that issues the transmission permission. With this configuration, when the service class of the connection accommodated in the data transmission circuit is CBR, the data of the connection arriving at the data transmission circuit can be contracted without explicitly indicating that the service class has been set in the CBR. Whether or not the parameter is violated can be identified. In the case of CBR, a suppression instruction for suppressing the use of the surplus bandwidth of another connection group is always received.
[0024]
If the service class of the connection is GFR, transmission permission is assigned only to the band corresponding to the MCR to the connection, and the data transmission circuit has a means for notifying whether or not the connection has dropped cells, the GFR Without explicitly indicating that the service class has been set in the data transmission circuit, whether or not a cell drop has occurred in the data transmission circuit even though the data of the connection arriving at the data transmission circuit does not exceed the MCR. be able to. In the case of this GFR, a dummy connection or the like that is unlikely to be transmitted is set, and this dummy connection is accommodated in the same connection group as the GFR connection, and a bandwidth equal to or more than the MCR is allocated to the GFR connection. It is also possible.
[0025]
[Fourth embodiment]
In this embodiment, priorities are given between connections when allocating a free band. In the above-described second embodiment, the connections 32 and 33 fairly share the unused allocated bandwidth of the connection 31. In this embodiment, however, the allocated bandwidth of the connection 31 is first used by the connection 32, and there is still surplus. Only when it is assigned to the connection 33. According to this priority assignment, for example, when the user A owns the connections 31 and 32 and the user B has the belonging condition that the user 33 owns the connection 33, first, only the surplus bandwidth of the user A can be given to the user B. Therefore, fairness among users can be realized.
[0026]
[Fifth embodiment]
This embodiment is applied to the PON ONT specified in ITU recommendation G983.1. In this embodiment, a "Reserved" byte included in a PLOAM cell that is specified in G983.1 and that performs band allocation for each ONT is used for notification of an allocation suppression instruction. The congestion information of each output route is mapped to each bit of the “reserved” byte. If the number of output routes is, for example, 32, 32 bits, that is, 4 bytes of "reserved" bytes are used. The data transmission circuit according to the present embodiment suppresses the bandwidth allocation of the connection accommodated in the route showing congestion according to the output route information for each connection accommodated in the OLT which is the output destination of each connection. According to this embodiment, it is possible to improve the band use efficiency by making a slight modification to the existing ITU standard G983.1.
[0027]
[Sixth embodiment]
In this embodiment, a plurality of PLOAM cells are grouped, and congestion information of an individual output route is mapped over the entire "reserved" area of each group of PLOAM cells. For example, if four PLOAM cells included in a T frame are set as one set and allocation suppression information is dispersed and arranged, a "reserved" area of 1 byte per PLOAM cell is used even in the case of 32 output routes. Stay on. According to this embodiment, the "reserved" area of each PLOAM cell occupies a smaller number of "reserved" areas as compared with the fifth embodiment, which occupies the number of routes, and the band use efficiency can be improved.
[0028]
[Seventh embodiment]
In this embodiment, an upper limit is set for the amount of transmission data for each connection, and data is not transmitted exceeding the upper limit for each connection even if there is a margin in the transmission permission assigned to the data transmission circuit. According to this embodiment, the transmission is not performed beyond the band that is allowed to be transmitted by the user parameter control (UPC) or the network parameter control (NPC) installed at the transmission destination, and the cell is not transmitted by the UPC or the NPC. The effect of reducing the possibility of being discarded can be expected.
[0029]
[Eighth embodiment]
In this embodiment, the weight value of the WRR transmitting means for allocating a bandwidth between the connection groups is set according to the number of active connections among the connections accommodated in the connection group. An active connection is a connection that currently has data waiting to be transmitted, a connection that has transmitted data within a certain period of time in the past, or a cell that constitutes a packet when data is handled by a packet composed of a plurality of cells. Is a connection that has not arrived, a connection that has been notified from an external device that it is active, or a connection that has been determined to be active from a destination circuit, or a combination thereof.
[0030]
This embodiment is suitable for a data transmission circuit or the like that transmits data from an access point that accommodates a wireless terminal that dynamically changes an access point to be connected when the number of active connections dynamically changes. . It is particularly suitable for dynamically changing the total band allocated to the data transmission circuit according to the number of connections to be accommodated.
[0031]
[Ninth embodiment]
In this embodiment, there is provided a WRR transmitting means for temporarily allocating the weight value of the WRR transmitting means for allocating a bandwidth to one connection by reducing the weight in accordance with the bandwidth transmitted by the connection in the past fixed time. In this embodiment, when the total bandwidth allocated to the data transmission circuit fluctuates according to the usage status in the past fixed time, the allocation to the connection not used within the predetermined time when the usage status is observed is reduced. Accordingly, there is an advantage that it is not necessary to change the allocated bandwidth of the connection in which the allocated bandwidth has been consumed during the observation time.
[0032]
【The invention's effect】
As described above, according to the data transmission circuit of the present invention, the transmission band can be used effectively.
[Brief description of the drawings]
FIG. 1 is a diagram illustrating a conventional example.
FIG. 2 is a diagram illustrating a configuration of a first embodiment of a data transmission circuit according to the present invention and an example of an operation of effectively using a band when the configuration is applied.
FIG. 3 is a diagram showing a configuration of a third embodiment of the data transmission circuit of the present invention and an example of an operation of effectively using a band when the third embodiment is applied.
[Explanation of symbols]
1 Data transmission circuit 2, 3 GFR connection 4 Total bandwidth 5, 6 Buffer memory 7 WRR transmission means 8 Transmission destination circuit 11 Data transmission circuits 12, 13 Connection 14 Total bandwidth 15, 16 Buffer memory 17 WRR transmission means 18 Transmission destination Circuit 21 Allocation suppression means 22 Suppression instruction receiving means 23 Route-specific congestion observation means 30 Data transmission circuits 31, 32, 33 Connections 34, 35 Assigned bandwidth 36, 37 Buffer memory 38 Unused bandwidth allocation identification means 39 WRR transmission means 40 Allocation Inhibiting means 41 Inhibiting instruction receiving means 50 Transmission destination circuit 51 Route-specific congestion observing means

Claims (10)

In a data transmission circuit that accommodates a plurality of connections and transmits data in a band corresponding to a transmission permission to receive, a connection configured by a single or a plurality of connection units as a total band which is a band corresponding to all reception permission to be received. Allocated to each connection group, the group bandwidth allocated to each connection group is allocated to the connection belonging to the connection group, and if there is no data to be transmitted to the connection belonging to the connection group, the surplus bandwidth of the connection group is changed to another. A suppression instruction receiving means for receiving a transmission suppression instruction for giving an instruction to suppress transmission of data of a connection in which congestion occurs or may occur at a transmission destination, and Instructed as connection to be inhibited by transmission inhibition instruction received by inhibition instruction receiving means Data transmission circuit, characterized in that it comprises a suppression means for suppressing the transmission of connection that was. A group is formed by the connection group, and when there is no data to be transmitted to one connection group, the surplus bandwidth of the connection group is redistributed with priority over other connection groups belonging to the same group. 2. The data transmission circuit according to claim 1, wherein Means for reporting the difference between the data transmission amount permitted by the transmission permission assigned to each connection and the data amount arriving for each connection to a circuit for issuing the transmission permission. 2. The data transmission circuit according to 1. Even if the connection has data that can be transmitted and the transmission permission for transmitting the data is distributed, the connection does not transmit data in excess of a preset upper limit value. Item 2. The data transmission circuit according to Item 1. When a surplus bandwidth of another connection or another connection group is generated, and data to be transmitted in response to the redistribution of the surplus bandwidth is transmitted with the number assigned to the connection in which the surplus bandwidth has occurred. 2. The data transmission circuit according to claim 1, wherein: 2. The data transmission circuit according to claim 1, wherein a bandwidth is assigned to each connection group according to the number of active connections accommodated by the connection group. 2. The data transmission circuit according to claim 1, wherein a bandwidth of the connection is allocated according to a bandwidth transmitted by the connection in a past fixed time. The received transmission suppression instruction is transmitted between the band transmitted by the connection to be inhibited during the past fixed time period and the connection sharing the bandwidth with the connection to be inhibited by the data transmission circuit at the transmission destination where data belonging to the connection to be inhibited arrives. 2. The data transmission circuit according to claim 1, wherein the transmission inhibition instruction is a transmission suppression instruction according to a total band with the set band. 2. The transmission inhibition instruction to be received, wherein the transmission inhibition instruction is a transmission inhibition instruction for inhibiting transmission of data in response to redistribution of a bandwidth allocated to a connection group other than the connection group to which the connection to be inhibited belongs. 3. A data transmission circuit according to claim 1. The data transmission circuit according to claim 1, wherein the data transmission circuit is applied to optical network termination of a passive optical network and receives a transmission suppression instruction using a "reserved" area of a PLOAM cell defined by the passive optical network.

Images