JP2020136944A - Station side device, band allocation program, and band allocation method - Google Patents

Abstract

To provide a station side device which suppresses the generation of a delay fluctuation for an existing ONU in a virtual PON system, a band allocation program, and a band allocation method.SOLUTION: A station side device connected via a plurality of subscriber side devices and an optical splitter, comprises a band allocation unit that allocates an incoming band to each of the plurality of subscriber side devices. The incoming band allocation unit virtually divides one physical band into a plurality of groups, and allocates the incoming band of each subscriber side device belonging to the group in each group. When a new subscriber side device is connected, an allocation order of the incoming band of the new subscriber side device is set to an order later than the allocation order of the incoming band of the plurality of subscriber side devices.SELECTED DRAWING: Figure 1

Description

The present invention relates to a station-side device that divides a physical PON band and dynamically allocates a virtual PON that is logically operated as a plurality of PONs, a bandwidth allocation program, and a bandwidth allocation method.

Upstream bandwidth allocation in a PON (Passive Optical Network) system is performed in a time division manner, and is realized by an OLT (Optical Line Terminal) notifying an ONU (Optical Network Unit) of the transmission timing of uplink traffic. An uplink bandwidth allocation algorithm is implemented in the OLT so that the uplink traffic of all the ONUs accommodated in the PON does not collide and the uplink traffic of the user accommodated in each ONU is efficiently transmitted upstream. In the uplink band allocation algorithm, the uplink transmission timing of all ONUs is calculated and allocated.

FIG. 7 is a diagram showing a processing flow of a general uplink bandwidth allocation algorithm. The uplink band allocation algorithm of FIG. 7 executes processing in a constant band allocation cycle T, and realizes band allocation up to the physical optical wavelength band of the PON section. Specifically, first, the logical link information in the link-up state is collected (S101), and the uplink request band of each ONU is calculated based on the collected logical link information (S102). Then, the remaining band of the PON is calculated from the physical upper limit band of the PON and the calculated uplink request band (S103). Next, the best effort bandwidth is allocated to the remaining bandwidth (S104), and the uplink traffic transmission timing is determined (S105).

FIG. 8 shows an example of bandwidth allocation by a general uplink bandwidth allocation algorithm. As shown in FIG. 8, the uplink band of each ONU is assigned to the physical optical wavelength band P of the PON section for each band allocation cycle T.

In recent years, virtualization of a network for constructing a network by controlling software has been proposed (for example, Non-Patent Document 1). FIG. 9 is a diagram illustrating the concept of network virtualization. As shown in FIG. 9, in network virtualization, a network slice 300, which is a virtual concept network for realizing a service provided by an operator 200, is constructed on a physical device 400. The physical device 400 includes network resources such as an OLT, and the network slice 300 is constructed by cutting out the physical resources in the physical device 400 by the network management 500 by the required band.

As a technique for applying network virtualization to PONs, Patent Document 1 proposes a virtual PON that divides the physical band of a PON section and logically operates as a plurality of PONs. Such a virtual PON implementation is useful for accommodating a plurality of different services in the physical band of the PON. In the virtual PON system, by dividing the physical band of the PON so that it can operate as a plurality of virtual PONs, it is possible to realize the virtualization of the network shown in FIG. 9 without wasting the physical band.

ITU-T (International Telecommunication Union Telecommunication Standardization Sector) Recommendation Y. 3150 (01/2018)

Japanese Unexamined Patent Publication No. 2008-227985

FIG. 10 is a diagram showing a configuration example of a virtual PON. FIG. 10 shows a configuration example of a virtual PON having two PONs logically divided in a physical band of a PON section, a virtual PON-M and a virtual PON-N. Further, it is assumed that three ONUs belong to the virtual PON-M and two ONUs belong to the virtual PON0-N. The upper limit band of the virtual PON and the ONU accommodated in the virtual PON are set by the operator who provides the service.

FIG. 11 is a diagram showing a processing flow of an uplink bandwidth allocation algorithm in a virtual PON, which is assumed when the processing flow shown in FIG. 7 is applied to the virtual PON. In the uplink bandwidth allocation algorithm that realizes virtual PON as shown in FIG. 11, steps S101 to S105, which are the same as the processing flow of FIG. 7, are performed for each virtual PON for all virtual PONs (S201). However, in step S103 of FIG. 11, the remaining band is calculated based on the upper limit band of the virtual PON, not the physical upper limit band of the PON.

Here, consider a case where a new virtual PON is added to the PON system by the operator. For example, consider a case where a virtual PON-A is added by an operator from a state in which the virtual PON-M and the virtual PON-N shown in FIG. 10 are set. FIG. 12 is a diagram showing an example of uplink bandwidth allocation assumed when a virtual PON is added. In FIG. 12, the virtual PON-A and the ONU-A belonging to the virtual PON-A are added in the band allocation cycle T3. In this case, depending on the implementation content of the uplink bandwidth allocation algorithm, the uplink burst interval V of the ONU-1 (existing ONU) may be lengthened by adding the virtual PON-A. That is, the addition of the virtual PON-A may cause a delay D in the upstream traffic frame of the ONU-1.

Further, even when the virtual PON is not added, the delay fluctuation may occur in the upstream traffic frame of the existing ONU by adding a new ONU. For example, when adding an ONU to a virtual PON, if the uplink bandwidth allocation order is not taken into consideration, delay fluctuations occur in the uplink traffic frames of other ONUs (existing ONUs) belonging to the same virtual PON.

As described above, if the conventional processing flow (FIG. 7) is simply applied to the virtual PON, delay fluctuation may occur in the upstream traffic frame for the existing ONU. Delay fluctuations in networks lead to deterioration of service quality, and are issues that require improvement. The above-mentioned Patent Document 1 does not take this point into consideration.

The present invention is based on the above problems, and an object of the present invention is to provide a station-side device, a bandwidth allocation program, and a bandwidth allocation method that suppress the occurrence of delay fluctuations in an existing ONU in a virtual PON system. And.

The station-side device according to the present invention is a station-side device connected to a plurality of subscriber-side devices via an optical splitter, and is an uplink band allocation unit that allocates an uplink band to each of the plurality of subscriber-side devices. The uplink band allocation unit virtually divides one physical band into a plurality of groups and allocates the uplink band of the subscriber side device belonging to the group for each group, and a new subscriber side. When the devices are connected, the uplink allocation order of the new subscriber-side device is set to be later than the uplink band allocation order of the plurality of subscriber-side devices.

The band allocation program according to the present invention is an uplink band allocation unit that allocates an uplink to each of a plurality of subscriber-side devices by using a computer of a station-side device connected to a plurality of subscriber-side devices via an optical splitter. The uplink bandwidth allocation unit virtually divides one physical bandwidth into multiple groups and allocates the uplink bandwidth of the subscriber side devices belonging to that group for each group. When a new subscriber-side device is connected, the uplink allocation order of the new subscriber-side device is set to be later than the uplink band allocation order of the plurality of subscriber-side devices.

The band allocation method according to the present invention is a band allocation method for a plurality of subscriber-side devices and a station-side device connected via an optical splitter, and allocates an uplink band to each of the plurality of subscriber-side devices. The step of allocating the uplink including the step virtually divides one physical bandwidth into a plurality of groups and allocates the uplink of the subscriber side device belonging to the group for each group, and newly joins. When the user-side device is connected, the uplink allocation order of the new subscriber-side device is set to be later than the uplink band allocation order of the plurality of subscriber-side devices.

According to the station-side device, the bandwidth allocation program, and the bandwidth allocation method according to the present invention, it is possible to suppress delay fluctuations in uplink traffic for an existing ONU.

It is a figure which shows the configuration example of the optical communication network system in Embodiment 1. FIG. A configuration example of the logical link information table according to the first embodiment is shown. A configuration example of the virtual PON information table according to the first embodiment is shown. It is a processing flow of the uplink band allocation part in Embodiment 1. It is a figure which shows the example of the uplink band allocation by the uplink band allocation part of Embodiment 1. It is a processing flow of the uplink band allocation part in the modification of Embodiment 1. It is a figure which shows the processing flow of the general uplink band allocation algorithm. An example of bandwidth allocation by a general uplink bandwidth allocation algorithm is shown. It is a figure explaining the concept of network virtualization. It is a figure which shows the configuration example of the virtual PON. It is a figure which shows the processing flow of the uplink band allocation algorithm in virtual PON which is assumed when the processing flow shown in FIG. 7 is applied to virtual PON. It is a figure which shows the example of the uplink band allocation assumed when the virtual PON is added.

Hereinafter, embodiments of the station-side device, the band allocation program, and the band allocation method of the present invention will be described in detail with reference to the drawings.

Embodiment 1.
(Explanation of configuration)
FIG. 1 is a diagram showing a configuration example of the optical communication network system 100 according to the first embodiment. The optical communication network system 100 of the present embodiment includes a station-side device 1 (hereinafter, referred to as “OLT1”) and a plurality of subscriber-side devices 30 (hereinafter, “ONU30”) connected to the OLT 1 via an optical splitter 20. ) And. Further, the optical communication network system 100 of the present embodiment is a virtual system in which the physical band of one PON section is virtually divided into a plurality of groups and logically operated as a plurality of PONs based on a request from the operator 40. It is a PON system. The operator 40 is a telecommunications carrier side device connected to the upper network. In the following description, each of the plurality of virtually divided groups is referred to as "virtual PON".

The OLT 1 includes a control unit 11 and a storage unit 12. The control unit 11 is composed of a CPU (Central Processing Unit), a processor, or a microcomputer that executes a program stored in the storage unit 12. The storage unit 12 is a non-volatile or volatile memory such as RAM, ROM or flash memory.

The control unit 11 has an uplink band allocation unit 111 and a protocol control unit 112. The uplink band allocation unit 111 and the protocol control unit 112 are functional units realized by the control unit 11 executing a program such as an uplink band allocation algorithm. The control unit 11 is composed of dedicated hardware using ASIC (Application Specific Integrated Circuit) or FPGA (Field-Programmable Gate Array), and each functional unit is realized by individual hardware or one hardware. You may.

The uplink band allocation unit 111 determines the uplink traffic transmission timing for the logical link of the ONU 30 in the PON link-up state. Further, the uplink band allocation unit 111 of the present embodiment allocates an uplink band for each virtual PON to which the ONU 30 belongs. The protocol control unit 112 controls the establishment of a logical link between the OLT 1 and the ONU 30 and the traffic conduction. The uplink band allocation unit 111 and the protocol control unit 112 communicate with each other via the first interface 110A and the second interface 110B, and the uplink band allocation unit 111 communicates with the operator 40 via the third interface 110C.

The uplink band allocation unit 111 acquires the logical link information in the PON link-up state from the protocol control unit 112 via the first interface 110A. Then, the uplink band allocation unit 111 outputs the uplink traffic transmission timing information to the protocol control unit 112 via the second interface 110B. When the uplink bandwidth allocation unit 111 determines the uplink traffic transmission timing, the service request parameter from the operator 40 is input to the uplink bandwidth allocation unit 111 via the third interface 110C.

The uplink band allocation unit 111 constructs the logical link information table 50 based on the information collected from the first interface 110A and the third interface 110C. FIG. 2 shows a configuration example of the logical link information table 50 according to the first embodiment. The logical link information table 50 includes an INPUT information area 51 and algorithm WORK data 52. The INPUT information area 51 is composed of a "logical link identifier", a "virtual PON identifier to which each logical link belongs", and a "requested band" which is an uplink band requested by each ONU 30. The “logical link identifier” is the logical link information in the PON link-up state collected via the first interface 110A. The “affiliated virtual PON identifier” and the “requested band” are virtual PON information collected via the third interface 110C.

The algorithm WORK data 52 is a data area for use by the uplink band allocation unit 111. The algorithm WORK data 52 is composed of "grant allocation order" and "allocation grant", which are allocation order information for allocating uplink bands to each logical link. "Grant allocation order" indicates the allocation order of the transmission timing of uplink traffic. In the present embodiment, the order in which the ONU 30 is connected to the OLT 1 is the "grant allocation order". That is, the grant allocation order of the ONU connected later is assigned so as to be later than the grant allocation order of the ONU 30 connected earlier. The “allocated grant” is a variable area that holds the allocated bandwidth value for the logical link calculated in the process of calculation by the uplink bandwidth allocation unit 111. After the processing of the uplink band allocation unit 111 is completed, the holding value of the "allocation grant" becomes one of the output information from the second interface 110B.

Further, the uplink band allocation unit 111 constructs a virtual PON information table 60 based on the information collected from the third interface 110C. FIG. 3 shows a configuration example of the virtual PON information table 60 according to the first embodiment. The virtual PON information table 60 includes an INPUT information area 61 and algorithm WORK data 62. The INPUT information area 61 is composed of a "virtual PON identifier" collected from the third interface 110C and an "upper limit band" of the virtual PON.

The algorithm WORK data 62 is composed of a “remaining bandwidth” in the virtual PON and a “logical link identifier belonging to the virtual PON”. The “remaining bandwidth” is a variable area that holds the unallocated bandwidth value up to the upper limit bandwidth of the virtual PON calculated in the process of processing by the uplink bandwidth allocation unit 111. The initial value of the remaining band is the upper limit band value. The logical link identifier to which the member belongs is configured based on the correspondence information between the logical link and the virtual PON held in the logical link information table 50. The "belonging logical link identifier" is used to access the variable of the "allocation grant" of the logical link information table 50 to be updated when the remaining bandwidth of the virtual PON is allocated to the belonging logical link in the uplink bandwidth allocation unit 111. Referenced to.

(Explanation of operation)
FIG. 4 is a processing flow of the uplink band allocation unit 111 according to the first embodiment. The process of FIG. 4 is executed in a constant band allocation cycle T. At the beginning of the periodic processing, the logical link information of the PON link-up state belonging to the virtual PON is collected (S1). Then, the logical link information table 50 and the virtual PON information table 60 are constructed based on the collected information (S2).

Subsequently, the uplink request band of each ONU 30 is calculated for all the logical links in the logical link information table 50 (S3) (S4). Then, the calculated uplink request band is held in the "allocated grant" variable of the logical link information table 50 (S5). Subsequently, the remaining bandwidth of the virtual PON to which the logical link belongs is calculated (S6). Then, based on the "affiliated virtual PON identifier", the corresponding "remaining bandwidth" of the virtual PON information table 60 is accessed, and the bandwidth is updated to the remaining bandwidth value obtained by subtracting the bandwidth calculated in step S4 (S7).

When steps S4 to S7 are executed for all logical links (S3: Yes), the best effort bandwidth for the "remaining bandwidth" of the virtual PON information table 60 for all virtual PONs in the virtual PON information table 60 (S8). Allocation is made (S9). Then, based on the "belonging logical link identifier", the corresponding "allocated grant" variable in the logical link information table 50 is accessed, and the value is updated to the allocated grant value by adding the calculation result of the best effort band (S10).

When steps S9 to S10 are executed for all virtual PONs (S8: Yes), for all logical links (S11), the "grant allocation order" of the logical link information table 50 is increased according to the "allocation grant". The traffic transmission timing is determined (S12). When the upstream traffic transmission timing is determined for all the logical links (S11: Yes), this process ends.

FIG. 5 is a diagram showing an example of uplink band allocation by the uplink band allocation unit 111 of the first embodiment. As shown in FIG. 5, in the present embodiment, the uplink traffic transmission timing is determined in the “grant allocation order” of the logical link information table 50 regardless of the virtual PON to which the ONU 30 belongs. Further, the "grant allocation order" of the logical link information table 50 is determined according to the registration order. Therefore, even when new virtual PON-A and ONU30 (ONU-A in FIG. 5) are added, the burst interval V of the existing ONU30 (ONU-1 in FIG. 5) is not affected.

As described above, in the present embodiment, as compared with the case where the processing flow of the conventional uplink bandwidth allocation algorithm is applied to the virtual PON, the bandwidth in units of virtual PON is not changed without changing the allocation order of the uplink bandwidth to ONU30. Allocation can be realized. That is, in the present embodiment, since there is no implementation dependency by the algorithm in the band allocation order of each virtual PON, the delay fluctuation of the transmission frame in the band allocation is suppressed even when the ONU 30 is newly added. be able to.

Further, in the present embodiment, there is an effect that the degree of freedom in implementing the best effort bandwidth allocation logic is high. Specifically, in the process shown in FIG. 4, the best effort band allocation process (S8 to S10) is performed after the allocation of the required bandwidth to all the logical links is completed and the remaining bandwidth of the physical PON band is determined through all the virtual PONs. ) Is carried out. Therefore, the entire remaining band with respect to the physical PON band can be allocated as the best effort band.

Specifically, in the case of a processing flow in which the processing flow of the conventional uplink bandwidth allocation algorithm is applied to the virtual PON, the remaining bandwidth within the upper limit bandwidth of the virtual PON-M is allocated to the logical link belonging to the virtual PON within the bandwidth allocation cycle. Is performed, and the remaining band within the upper limit band of the virtual PON-N is assigned to the logical link to which it belongs. In this case, the unused physical remaining bandwidth in the virtual PON remains unused. On the other hand, in the present embodiment, the best effort band may be allocated including the physical remaining band unused in the virtual PON within the band allocation cycle.

FIG. 6 is a processing flow of the uplink band allocation unit 111 in the modified example of the first embodiment. The processing flow of FIG. 6 differs from that of FIG. 4 in that steps S71 and S72 are added between steps S3 and S8. Other steps are the same as in FIG. 4, and the description thereof will be omitted. In this modification, when steps S4 to S7 are executed for all the logical links in the logical link information table 50 (S3: Yes), the remaining physical band is allocated to each virtual PON (S71). In this case, the allocation method may be evenly allocated to each virtual PON, or may be allocated at a different ratio for each virtual PON with a policy of being proportional to the upper limit band, for example. Then, based on the "belonging virtual PON identifier", the corresponding "remaining bandwidth" of the virtual PON information table 60 is accessed, and the bandwidth allocated in step S71 is updated to the added remaining bandwidth value (S72).

As a result, in the best effort bandwidth allocation in step S9 to be performed thereafter, the best effort bandwidth can be allocated to the logical link to which the virtual PON belongs beyond the upper limit bandwidth of the virtual PON, and the physical bandwidth can be used efficiently. it can.

The above is the description of the embodiment of the present invention, but the present invention is not limited to the configuration of the above-described embodiment, and various modifications or combinations are possible within the scope of the technical idea. .. For example, an input parameter from the operator 40 that is required for the uplink bandwidth allocation unit 111 to determine the uplink traffic transmission timing for each logical link may be added to the INPUT information area 51 of the logical link information table 50. For example, the virtual PON remaining bandwidth allocation policy (best strike bandwidth allocation policy) may be added to the logical link information table 50 as an input parameter. In this case, in step S9 of FIG. 4, the remaining bandwidth is allocated according to the allocation policy of the logical link information table 50. As a result, the remaining bandwidth can be allocated according to a different policy according to the service for each virtual PON.

1 station side device, 11 control unit, 12 storage unit, 20 optical splitter, 30 subscriber side device, 40 operator, 50 logical link information table, 51, 61 interface information area, 52, 62 algorithm WORK data, 60 virtual PON information Table, 100 optical communication network system, 110A first interface, 110B second interface, 110C third interface, 111 uplink band allocation unit, 112 protocol control unit, 200 operators, 300 network slices, 400 physical devices, 500 network management.

Claims (8)

A station-side device that is connected to multiple subscriber-side devices via an optical splitter.
An uplink band allocation unit that allocates an uplink band to each of the plurality of subscriber-side devices is provided.
The uplink band allocation unit is
One physical band is virtually divided into a plurality of groups, and the uplink band of the subscriber side device belonging to the group is assigned to each group.
When a new subscriber-side device is connected, the station-side device sets the uplink allocation order of the new subscriber-side device to be later than the uplink band allocation order of the plurality of subscriber-side devices. .. The uplink band allocation unit is
If a new group is added to the plurality of groups and the new subscriber side device belongs to the new group, the allocation order of the uplink band of the new subscriber side device is assigned to the plurality of subscriptions. The station-side device according to claim 1, wherein the uplink band allocation order of the user-side device is later than that of the user-side device. The uplink band allocation unit
The remaining bandwidth in each of the plurality of groups is calculated based on the uplink demand band requested by the plurality of subscriber-side devices and the upper limit bandwidth in each of the plurality of groups.
The remaining band is assigned to the subscriber-side device to which the remaining band belongs for each of the plurality of groups.
The station-side device according to claim 1 or 2, which determines the transmission timing of uplink traffic of the plurality of subscriber-side devices. A protocol control unit that collects logical link information from the plurality of subscriber-side devices is further provided.
The uplink band allocation unit is based on the logical link information.
A logical link information table including the identifiers of the plurality of subscriber-side devices, the identifiers of the group to which each of the plurality of subscriber-side devices belongs, the uplink request band, and the allocation order.
The station-side device according to claim 3, wherein a virtual PON information table including the identifier of the group, the upper limit band, the remaining band, and the identifiers of the plurality of subscriber-side devices is constructed. The uplink band allocation unit is
The station-side device according to claim 3 or 4, wherein the remaining band is assigned to the subscriber-side device to which the remaining band belongs for each of the plurality of groups based on a policy input from the operator. The uplink band allocation unit is
The station-side device according to any one of claims 1 to 5, wherein the remaining band of the physical band is allocated to the plurality of groups. Computers of station-side devices that are connected to multiple subscriber-side devices via an optical splitter,
A bandwidth allocation program that functions as an uplink bandwidth allocation unit that allocates an uplink to each of the plurality of subscriber-side devices.
The uplink band allocation unit is
One physical band is virtually divided into a plurality of groups, and the uplink band of the subscriber side device belonging to the group is assigned to each group.
When a new subscriber-side device is connected, the bandwidth allocation program sets the uplink allocation order of the new subscriber-side device to be later than the uplink band allocation order of the plurality of subscriber-side devices. .. This is a band allocation method for station-side devices connected to multiple subscriber-side devices via an optical splitter.
Including a step of allocating an uplink band to each of the plurality of subscriber-side devices.
The step of allocating the uplink band is
One physical band is virtually divided into a plurality of groups, and the uplink band of the subscriber side device belonging to the group is assigned to each group.
When a new subscriber-side device is connected, a band allocation method in which the uplink band allocation order of the new subscriber-side device is later than the uplink band allocation order of the plurality of subscriber-side devices. ..

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