JP5368513B2 - OLT and frame transfer method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To transfer uplink frames received from an ONU to a host device corresponding to the ONU among a plurality of host devices connected via SNI (Service Node Interface) provided for each of these host devices. <P>SOLUTION: On a LLID table 23, SNI selection information corresponding to a relevant LLID is pre-registered for each LLID of an ONU. When uplink frames are received from the ONU, a frame transfer processing part 20 obtains the SNI selection information corresponding to the uplink frame LLID from the LLID table 23. <P>COPYRIGHT: (C)2013,JPO&amp;INPIT

Description

  The present invention relates to an optical communication technique, and more particularly, to a frame transfer technique in an OLT (Optical Line Terminal) for connecting a PON system to a host device of a provider side network (service network).

  In 2009, standardization of 10G-EPON (10 Gigabit Ethernet Passive Optical Network: Ethernet is a registered trademark) was completed in IEEE 802.3av. The characteristic of 10G-EPON is that 10-times high-speed transmission is possible as compared with GE-PON (Gigabit Ethernet Passive Optical Network: see Non-Patent Document 1) that is already widely used. Furthermore, there is a feature that existing GE-PON and 10G-EPON can be used together.

  When using a mixture of GE-PON and 10G-EPON, use WDM technology that uses different wavelengths for 1G downstream signals and 10G downstream signals, and use TDM technology between 1G downstream signals and between 10G downstream signals. . In the upstream signal, the same wavelength is used for the 1G upstream signal and the 10G upstream signal, and the TDMA technique is used by combining the 1G upstream signal and the 10G upstream signal. That is, three different wavelengths are used for the 1G downstream signal, the 10G downstream signal, and the upstream signal.

  In the conventional GE-PON system, as shown in Non-Patent Document 2, in the OLT that is an in-station device for connecting to a provider's network (service network), an SNI port is provided on the SNI (Service Node Interface) side. When one OLT is connected to a plurality of networks (service networks), a switch (or a router or the like) is inserted between the OLT and the plurality of networks (service networks).

  FIG. 9 is a configuration example of a conventional GE-PON system. FIG. 10 shows another configuration example of the conventional GE-PON system. In the conventional GE-PON system, when it is necessary to change the network (service network) connected to each ONU, the system configuration is as shown in FIG. 9 or FIG. Of these, FIG. 10 shows a case where a switch (or router or the like) is inserted between the OLT and a plurality of networks (service networks). FIG. 11 is a block diagram showing a configuration of a conventional OLT (see Patent Document 1).

First, with reference to FIG. 11, each processing unit of the conventional OLT will be described.
The first transmission / reception circuit 52 is a circuit for transmitting / receiving a frame to / from the ONU via the PON connected to the PON port 51.
The second transmission / reception circuit 58 is a circuit that serves as an interface with the operator network NW connected via the SNI port 59.

The frame separation unit 53 transmits a frame addressed to the OLT (a control frame used for PON control) among the frames input from the first transmission / reception circuit 52 to the control frame processing unit 54 and transmits other frames to the frame. It is a processing unit that transmits to the transfer processing unit 60.
The frame multiplexing unit 56 is a processing unit that multiplexes the downlink frame from the frame transfer processing unit 60 and the control frame from the control frame processing unit 54 in a time division manner and transmits the multiplexed frame to the first transmission / reception circuit 52.

The frame transfer processing unit 60 is a processing unit that performs frame transfer processing based on the destination MAC address of the frame received from both the frame separation unit 53 and the second transmission / reception circuit 58.
The control frame processing unit 54 is a processing unit that performs processing related to PON control, such as discovery processing (Discovery process) for automatically assigning LLIDs to each ONU and arbitration of upstream signals (signals addressed to ONTs from ONUs). is there.
The bandwidth allocation processing unit 55 is a processing unit that allocates bandwidth (transmission start time and transmission data amount) to the ONU in accordance with a request from the control frame processing unit 54.

  In both system configurations of FIGS. 9 and 10, a host device that performs transfer control and the like in the service network is inserted between the SNI and the network NW. At this time, the content of the service that can be realized by the PON system is limited by the host device connected to the OLT. For example, when the host device connected to the OLT is for 1G Ethernet, this PON system is limited to services by 1G Ethernet.

  In the case of FIG. 10, a single switch and OLT are shared by a plurality of higher-level devices, that is, the bandwidth for one OLT is divided and used. For this reason, compared with the case of FIG. 9, the band of the downstream frame which can be used by each higher-order apparatus will become small.

In other words, when the network NW connected to each ONU is different, there have been two methods in the past.
Method 1 (FIG. 9): The maximum downlink bandwidth that can be used by each host device can be maximized, but the same number of OLTs as the network NW to be connected is required. Method 2 (FIG. 10): The downlink bandwidth that can be used by each host device is Method 1 ( Although it is smaller than that in FIG. 9 (the downstream bandwidth of the host device cannot be used to the maximum), there is an advantage and disadvantage in both cases where only one OLT is required.

JP 2009-260668 A

“Technology Basic Course [GE-PON Technology] 1st PON”, NTT Technical Journal, Vol.17, No.8, pp.71-74, 2005 “Development of Gigabit Ethernet-PON (GE-PON) System”, NTT Technical Journal, Vol.17, No.3, pp.75-80, 2005

When connecting a plurality of networks (service networks) NW to one OLT, according to method 1 of the two conventional technologies described above, the same number of OLTs as the number of networks (service networks) to be connected is required. Method 2 is desirable when considering the number of OLTs in the entire PON system.
However, according to the method 2, it is necessary to insert a switch (or a router or the like) between the OLT and the host device of each network NW. For this reason, each upper apparatus shares the downstream band of the switch, and there is a problem that the downstream band that can be used by each upper apparatus is limited.

  The present invention is to solve such a problem, and is capable of transferring an upstream frame received from an arbitrary ONU to a higher-level device corresponding to the ONU while avoiding restrictions on the downstream band. The purpose is to provide technology.

  In order to achieve such an object, the OLT according to the present invention is connected to a plurality of ONUs via PONs, and is connected to a plurality of higher-level devices via SNI provided for each higher-level device. Is an OLT that mutually transfers frames exchanged between the host device and the host device, and is provided with a receiving circuit that receives an upstream frame from the ONU via the PON, and a transmission rate that is set in advance. A plurality of transmission circuits that transmit the downstream frame to the SNR at the transmission speed and each SNI, and transmits the upstream frame to the higher-level device via the SNI, and via the SNI A plurality of transmission / reception circuits that receive downstream frames from the higher-level device and an upstream frame received by the reception circuit are transferred to the transmission / reception circuits. A frame transfer processing unit for transferring the received downlink frame to the transmission circuit, and the frame transfer processing unit includes an LLID table in which SNI selection information corresponding to the LLID is registered for each individual LLID in the ONU. The SNI selection information corresponding to the LLID of the upstream frame received by the reception circuit is acquired from the LLID table, and the upstream frame is transferred to the transmission / reception circuit corresponding to the SNI selection information in the transmission / reception circuit. .

  At this time, the frame transfer processing unit receives an SNI selection information corresponding to the LLID of the upstream frame received by the receiving circuit from the LLID table, and the SNI selection acquired by the output destination determining unit among the transmission / reception circuits. An uplink output destination control unit that transfers an uplink frame to a transmission / reception circuit corresponding to the information may be included.

  The frame transfer processing unit further includes a VID table in which the LLID and the downlink output destination selection information related to the downlink frame are registered for each VID for identifying the VLAN to which the downlink frame belongs. The LLID corresponding to the VID of the frame and the downlink output destination selection information are acquired from the VID table, and the LLID is assigned to the downlink frame, and then transferred to the transmission circuit corresponding to the downlink output destination selection information in the transmission circuit. You may do it.

  Also, a plurality of downlink output destination determination units that are provided in the frame transfer processing unit for each transmission / reception circuit and obtain LLID and downlink output destination selection information corresponding to the VID of the downlink frame received by the transmission / reception circuit from the VID table. A plurality of LLID adding units that are provided for each transmission / reception circuit and that give the LLID acquired by the downlink output destination determination unit to a downlink frame received by the transmission / reception circuit; and a transmission circuit that is provided for each transmission / reception circuit. Among them, a plurality of downlink output destination control units that transfer the downlink frame from the LLID adding unit to the transmission circuit corresponding to the downlink output destination selection information acquired by the downlink output destination determination unit may be further included.

  In addition, the frame transfer method according to the present invention connects to a plurality of ONUs via PON and connects to a plurality of host devices via SNI provided for each host device, and between these ONUs and host devices. A frame transfer method used in the OLT for mutually transferring a frame exchanged in each of the ONUs, for each individual LLID, storing the SNI selection information corresponding to the LLID in the LLID table, and via the PON Among the transmission / reception circuits provided for each SNI, the SNI selection information corresponding to the LLID of the upstream frame received from the ONU is transmitted from the SLI and transmitted / received to / from the host device via the SNI. A step of transferring the uplink frame to the transmission / reception circuit corresponding to the selection information.

According to the present invention, when an OLT is connected to a plurality of higher-level devices via an SNI provided for each higher-level device, an upstream frame received from any ONU connected to the PON system is It can be transferred to the corresponding host device. In addition, it is possible to process downstream frames input via a plurality of SNI ports in parallel for each input SNI port and transfer them to the destination ONU.
Therefore, one OLT having a port for each SNI between each ONU of the PON system and each higher-level device, and further each carrier network, without a switch between the OLT and the plurality of SNIs. The frame can be transferred. For this reason, it is possible to avoid sharing the downstream band of the switch among the higher-level devices, and to avoid restrictions on the downstream bandwidth that can be used by the individual higher-level devices.

  Also, in a system where 10G-ONU and 1G-ONU are mixed, when one SNI is for 10G-Ethernet and the other is for 1G-Ethernet, 10G-ONU is SNI for 10G-Ethernet and 1G-ONU is An SNI for 1G-Ethernet can be used. As a result, PON systems with different communication speeds can be constructed with one OLT.

It is a block diagram which shows the structure of the PON system concerning this invention. It is a structural example of the frame transmitted in a PON section. It is a block diagram which shows the structure of OLT concerning this invention. It is a block diagram which shows the structural example of a frame transfer process part. It is an example of a structure of a LLID table. It is a flowchart which shows the output destination SNI determination procedure of an upstream frame. It is a structural example of a VID table. It is a flowchart which shows the output destination determination procedure of a downstream frame. It is a structural example of the conventional GE-PON system. It is another example of composition of the conventional GE-PON system. It is a block diagram which shows the structure of the conventional OLT.

Next, embodiments of the present invention will be described with reference to the drawings.
[PON system]
First, a PON system 100 according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a block diagram showing a configuration of a PON system according to the present invention. FIG. 2 is a configuration example of a frame transmitted in the PON section.

As shown in FIG. 1, in this PON system 100, ONUn (n = 1 to 4) is connected to a user apparatus n via a UNI (User Network Interface).
Each ONU is commonly connected to one optical splitter via an optical communication path, and this optical splitter is further connected to one OLT 10 via one optical communication path. Since an upstream signal, a downstream signal addressed to ONU belonging to NW1, and a downstream signal addressed to ONU belonging to NW2 have different wavelengths, an optical demultiplexer (not shown in FIG. 1) is interposed between the optical communication path and the OLT 10. .

The OLT 10 is provided with two SNI ports on the SNI side, and the higher order apparatus 1 and the higher order apparatus 2 are individually connected to each SNI port via the SNI.
Further, a network (service network) NW1 on the operator side is connected to the host device 1, and a network (service network) NW2 on the operator side is connected to the host device 2.

In the PON section of the PON system 100, that is, the section between the ONUn and the OLT 10, data is exchanged in a frame configured as shown in FIG.
In FIG. 2, the preamble is an LLID embedded in the Ethernet preamble.

  The LLID (Logical Link ID) is an identifier that has a one-to-one correspondence with each ONU. It is determined by the OLT at the time of ONU registration (ONU is under the control of the OLT), and the OLT manages the ONU under its control so that duplication of LLID does not occur.

The VLAN tag is a tag including VLAN information. There may be no tag or multiple tags. This VLAN tag includes TPID and TCI.
TPID (Tag Protocol ID) is an Ether Type value indicating that a VLAN tag continues. Usually 0x8100.
TCI (Tag Control Information) is VLAN tag information. This TCI includes PCP, CFI, and VID.

PCP (Priority Code Point) is the priority of the frame.
CFI (Canonical Format Indicator) is a value indicating whether or not the MAC address in the MAC header conforms to the standard format.
The VID or VLAN ID (VLAN Identifier) is a value that specifies the VLAN to which the frame belongs.
Type is an Ether Type value indicating the type of the upper protocol.

[OLT]
Next, the configuration of the OLT 10 according to the present embodiment will be described with reference to FIG. FIG. 3 is a block diagram showing a configuration of the OLT according to the present invention.
The difference in configuration of the OLT 10 according to this embodiment from the conventional OLT is that an SNI port, a transmission / reception circuit, a frame multiplexing unit, and a transmission circuit are provided for each transmission system having different transmission speeds.

With reference to FIG. 3, each processing unit of the OLT 10 according to the present embodiment will be described.
The PON port 11 is a circuit for exchanging frames with the ONU via the PON.
The receiving circuit 12 is a circuit for receiving an upstream frame from the ONU via the PON and the PON port 11.
A transmission circuit (system 0) 17A and a transmission circuit (system 1) 17B are provided for each preset transmission speed, and are respectively ONU (system 0) and ONU (system 1) via the PON port 11 and PON. ) To a downstream frame at the transmission rate. In the present invention, the 0 system indicates a transmission system with a transmission rate of 1 Gbps, and the 1 system indicates a transmission system with a transmission speed of 10 Gbps.

The SNI port (system 0) 19A and the SNI port 19B (system 1) are circuit units that are provided for each host device and exchange frames with the host device via the SNI.
The transmission / reception circuit (system 0) 18A and the transmission / reception circuit (system 1) 18B are provided for each higher-level device, that is, for each SNI, and are respectively connected to the operator via the SNI ports 19A and 19B and the corresponding higher-level devices 1 and 2. This is a circuit unit that transmits and receives frames between the network (0 system) NW1 and the carrier network (1 system) NW2.

The frame separation unit 13 transmits a frame addressed to the OLT 10 (control frame used for PON control) among the frames input from the reception circuit 12 to the control frame processing unit 14 and transmits other frames to the frame transfer processing unit. 20 is a processing unit that transmits data to 20.
The frame multiplexing unit (system 0) 16A multiplexes the downstream frame addressed to the ONU (system 0) from the frame transfer processing unit 20 and the control frame from the control frame processing unit 14 in a time division manner, and transmits the transmission circuit (system 0). ) A processing unit that transmits to 17A.
The frame multiplexing unit (system 1) 16B multiplexes the downlink frame addressed to the ONU (system 1) from the frame transfer processing unit 20 and the control frame from the control frame processing unit 14 in a time division manner, and transmits the transmission circuit (system 1). ) A processing unit that transmits to 17B.

  Based on the SNI selection information corresponding to the LLID of the upstream frame acquired from the LLID table 23, the frame transfer processing unit 20 receives the upstream frame received by the reception circuit 12 and input from the frame separation unit 13 from the transmission / reception circuit 18A. , 18B (0 system or 1 system), and the downstream frame received by the transmission / reception circuits 18A, 18B is converted into the downstream output destination selection information corresponding to the downstream frame VID acquired from the VID table 35. Based on this, it is a processing unit that performs a transfer process to one of the frame multiplexing units 16A and 16B (system 0 or system 1).

The control frame processing unit 14 is a processing unit that performs processing related to PON control such as discovery processing (Discovery process) for automatically assigning LLIDs to each ONU and arbitration of upstream signals (signals addressed to the OLT from the ONUs). .
The band allocation processing unit 15 is a processing unit that allocates a band (transmission start time and transmission data amount) to the ONU in accordance with a request from the control frame processing unit 14.

  Next, the frame transfer processing unit 20 used in the OLT according to the present embodiment will be described in detail with reference to FIGS. FIG. 4 is a block diagram illustrating a configuration example of the frame transfer processing unit. FIG. 5 is a configuration example of the LLID table. FIG. 6 is a flowchart showing an upstream frame output destination SNI determination procedure. FIG. 7 is a configuration example of the VID table. FIG. 8 is a flowchart showing a procedure for determining an output destination of a downstream frame.

First, the operation in which the frame transfer processing unit 20 determines the output destination of the upstream frame will be described.
If the upstream frame received at the PON port 11 is not a PON control frame, the frame transfer processing unit 20 determines to which provider network NW the received upstream frame is to be output as follows.

The frame transfer processing unit 20 includes an LLID table 23 as shown in FIG. In the LLID table 23, entry valid / invalid and SNI selection information are registered for each LLID of the ONU. The entry valid / invalid is information indicating validity / invalidity of the entry, that is, registered / unregistered of the LLID.
The output destination SNI determination unit 22 reads the SNI selection information from the LLID table 23 based on the LLID of the upstream frame, determines the output destination SNI by the procedure of FIG. 6, and determines the output destination SNI information as the upstream output destination control. Part 24 is given.

In the uplink frame output destination SNI determination procedure in FIG. 6, the output destination SNI determination unit 22 first determines whether the LLID in the LLID table 23 is based on the LLID entry validity / invalidity of the received uplink frame. (Step 100).
Here, when the “valid” state is set as the entry valid / invalid, that is, when the LLID is registered (step 100: YES), the output destination SNI determination unit 22 reads the LLID from the LLID table 23. SNI selection information corresponding to is acquired and specified as an output destination of a downstream frame (step 101), and a series of processing ends.

  On the other hand, when the “invalid” state is set as the entry valid / invalid, that is, when the LLID of the received upstream frame is not registered in the LLID table 23 (step 100: NO), the output destination SNI determining unit 22 Then, discard of the uplink frame is determined (step 102), and a series of processing is terminated.

In parallel with such an upstream frame output destination SNI determination procedure, the upstream latency absorption unit 21 adds a delay to the received upstream frame and absorbs the latency due to the output destination SNI determination process in the output destination SNI determination unit 22. To do.
The uplink output destination control unit 24 transfers the uplink frame from the uplink latency absorbing unit 21 to the corresponding uplink output timing adjustment units 25A and 25B according to the SNI selection information determined by the output destination SNI determination unit 22.

Upstream output timing adjustment units 25A and 25B are provided for each of the transmission / reception circuits 18A and 18B, and adjust the output order of each upstream frame based on the priority determined by the PCP included in each upstream frame. The upstream frame from the upstream output destination control unit 24 is transferred to the corresponding transmission / reception circuits 18A and 18B.
When frame discard is notified from the output destination SNI determination unit 22, the uplink output destination control unit 24 performs discard processing on the uplink frame.

  The values in the LLID table 23 are set by determining which network NW1 or NW2 is connected by external hardware or software (not shown in FIG. 3) when the ONU is registered in the control frame processing unit 14. For example, in a system in which 10G-ONU and 1G-ONU are mixed and one of the SNIs is for 10G-Ethernet, and the other is for 1G-Ethernet, the 10G-ONU SNI for 10G-Ethernet, 1G- For the ONU, an SNI for 1G-Ethernet can be specified.

Next, the operation in which the frame transfer processing unit 20 determines the output destination of the downstream frame will be described.
The frame transfer processing unit 20 determines from which transmission circuit 17A, 17B the received downlink frame is transmitted, that is, to which downlink system having a different speed, the data is output as follows.

  The frame transfer processing unit 20 includes a VID table 35 as shown in FIG. In the VID table 35, LLID, downlink output destination selection information, and entry valid / invalid are registered for each VID. VID (VLAN Identifier) is a value that specifies the VLAN to which the downlink frame belongs. The entry valid / invalid is information indicating the validity / invalidity of the entry, that is, the registered / unregistered of the VID.

  The downlink output destination determination unit (system 0) 34A and the downlink output destination determination unit (system 1) 34B are provided for each of the transmission / reception circuits 18A and 18B, and based on the received VID of the downstream frame, the LLID is obtained from the VID table 35. And the downlink output destination selection information are read out, and the assigned LLID and output destination of the downlink frame are determined by the procedure of FIG. The information of the determined LLID is given as the destination LLID to the LLID giving unit (0 system) 32A and the LLID giving unit (1 system) 32B of the corresponding system.

In the downlink output destination determination procedure of the downlink frame in FIG. 8, the downlink output destination determination units 34A and 34B first confirm whether or not the VLAN tag is included in the received downlink frame (step 110).
Here, when the VLAN tag is included (step 110: YES), the downlink output destination determination units 34A and 34B, based on the validity / invalidity of the VID entry of the received downlink frame in the VID table 35, It is confirmed whether or not the VID is registered in the VID table 35 (step 111).

  Here, when the “valid” state is set as the entry valid / invalid, that is, when the VID is registered (step 111: YES), the downlink output destination determination units 34A and 34B The LLID corresponding to the VID is acquired and specified as the destination LLID of the downlink frame (step 112), the downlink output destination selection information corresponding to the VID is acquired from the VID table 35, and the output system of the downlink frame is determined. Specify (step 113) and end the series of processing.

  On the other hand, if no VLAN tag is included in the received downlink frame in step 110 (step 110: NO), or if “invalid” state is set as entry valid / invalid in step 111, that is, receive If the downstream frame VID is not registered in the VID table 35 (step 111: NO), the downstream output destination determination units 34A and 34B decide to discard the downstream frame (step 114) and end the series of processes. To do.

In parallel with the downlink output destination determination procedure for the downlink frame, the downlink latency absorbing unit (system 0) 31A and the downlink latency absorbing unit (system 1) 31B provided for each of the transmission / reception circuits 18A and 18B receive A delay is added to the downstream frame to absorb the latency due to the downstream output destination determination processing in the downstream output destination determination units 34A and 34B.
The LLID assigning unit (0 system) 32A and the LLID providing unit (1 system) 32B are provided for each of the transmission / reception circuits 18A and 18B, and the downlink latency absorbing unit 31A according to the LLID determined by the downlink output destination determination units 34A and 34B. , 31B, the destination LLID is assigned to the downstream frame.

  The downlink output destination control unit (system 0) 33A and the downlink output destination control unit (system 1) 33B are provided for each of the transmission / reception circuits 18A and 18B, and follow the output destination information determined by the downlink output destination determination units 34A and 34B. Downstream from the LLID adding units 32A and 32B to the transmission circuits 17A and 17B corresponding to the downlink output destination selection information via the corresponding 0-system downlink output timing adjustment unit 36A or 1-system downlink output timing adjustment unit 36B. Forward the frame.

The downlink output timing adjustment unit (system 0) 36A and the downlink output timing adjustment unit (system 1) 36B are provided for each transmission rate (transmission system), and are based on the priority such as PCP included in the downlink frame. Then, the output order of each downlink frame is adjusted, and the downlink frame is transferred to the corresponding transmission circuits 17A and 17B via the corresponding frame multiplexing unit (0 system) 16A and the frame multiplexing unit (1 system) 16B. For example, in a system in which 10G-ONU and 1G-ONU coexist, 10G (802.3av specification) output may be specified for 10G-ONU, and 1G (802.3ah specification) output may be specified for 1G-ONU.
When the downlink output destination determination units 34A and 34B determine that the packet is to be discarded, the downlink output destination control units 33A and 33B perform a process of discarding the downlink frame.

  When a downlink frame is transferred from the 0-system downlink output destination control unit 33A to the 1-system downlink output timing adjustment unit 36A, or from the 1-system downlink output destination control unit 33B to the 1-system downlink output timing adjustment unit 36B An example of a case where a downstream frame is transferred includes a system in which GE-PON and 10G-EPON coexist. In the present invention, the 0 system indicates a transmission system with a transmission rate of 1 Gbps, and the 1 system indicates a transmission system with a transmission speed of 10 Gbps.

In such a case, when the destination user apparatus of the downlink frame having a transmission rate of 10 Gbps input from the SNI port (system 1) is under the ONU for GE-PON, the GE having the transmission rate of 1 Gbps is transmitted from the PON port 11 in the OLT 10. -It is necessary to output as a PON frame.
For this purpose, the frame transfer processing unit 20 needs to output the downlink frame received from the 1 system from the 0 system. Such a technique is necessary in the transition period from GE-PON to 10G-EPON.

  The values in the VID table 35 are determined and set by the external hardware or software (not shown in FIG. 4) when the ONU is registered in the control frame processing unit 14.

  In the downstream processing, it is necessary to process the frames input from the two transmission / reception circuits 18A and 18B in parallel. However, as shown in the configuration of FIG. The frame input throughput can be used up to the upper limit. At this time, since the upper limit of throughput when the 10G output is 802.3av specification is about 8.7 Gbps, the upper limit of the throughput of the SNI input for 10G output in that case is about 8.7 Gbps.

[Effects of the present embodiment]
As described above, in this embodiment, when the SNI selection information corresponding to the LLID is registered for each LLID of the ONU in the LLID table 23 and an upstream frame is received from the ONU, the frame transfer processing unit 20 The SNI selection information corresponding to the LLID of the uplink frame is obtained from the LLID table 23. Further, when the LLID corresponding to the VID and the downlink output destination selection information are registered for each VID in the VID table 35 and a downlink frame is received from the higher-level device, the frame transfer processing unit 20 selects each input SNI port. In parallel, the LLID corresponding to the VID of the uplink frame and the downlink output destination selection information are acquired from the VID table 35.

As a result, when the OLT is connected to a plurality of higher-level devices via the SNI provided for each higher-level device, an upstream frame received from any ONU connected to the PON system Can be transferred to the device. In addition, it is possible to process downstream frames input via a plurality of SNI ports in parallel for each input SNI port and transfer them to the destination ONU.
Therefore, one OLT having a port for each SNI between each ONU of the PON system and each higher-level device, and further each carrier network, without a switch between the OLT and the plurality of SNIs. The frame can be transferred. For this reason, it is possible to avoid sharing the downstream band of the switch among the higher-level devices, and to avoid restrictions on the downstream bandwidth that can be used by the individual higher-level devices.

  In this embodiment, in a system in which 10G-ONU and 1G-ONU are mixed, when one of the SNIs is for 10G-Ethernet and the other is for 1G-Ethernet, the 10G-ONU is the SNI for 10G-Ethernet. For 1G-ONU, an SNI for 1G-Ethernet can be used. As a result, PON systems with different communication speeds can be constructed with one OLT.

  In this case, all frames input from the 10G-Ethernet SNI are destined for the 10G-ONU, and all frames input from the 1G-Ethernet SNI are destined for the 1G-ONU. The downlink transfer capability (transmission speed) in the section can be used up to the upper limit. As a result, unlike the conventional configuration of FIG. 10, the downstream band is not shared by the two higher-level devices.

  When the downlink output addressed to 10G-ONU is 802.3av specification, the upper limit of the downlink throughput in the PON section is about 8.7 Gbps, so the upper limit of the SNI input throughput for 10G-ONU in that case is about 8.7 Gbps. Downstream bandwidth limitation is necessary in the host device for 10G-ONU. However, this band limitation is the same even when only one host device for 10G-ONU is connected, and the effectiveness of the present invention is not denied.

If an OLT having only one 10G-Ethernet SNI is configured in the prior art, the upper limit of the downlink throughput when the 802.3av specification and the 802.3ah specification are mixed is approximately the same as the present invention. Although 8.7 Gbps + 1 Gbps = about 9.7 Gbps, a switch or the like is required to connect to a plurality of host devices.
Also, in this embodiment, if the specification of the downlink output addressed to 10G-ONU is changed to a specification that enables throughput of 10 Gbps instead of 802.3av specification, 10G-ONU and 1G-ONU are mixed The maximum downstream downlink throughput is 10 Gbps + 1 Gbps = 11 Gbps, and no downstream bandwidth limitation is required in the host device.

  When the frame transfer processing unit 20 is configured as shown in FIG. 4, it is possible to use a 10G-Ethernet SNI as the 1G-ONU SNI. However, in this case, it is necessary for the host device to limit the downstream band to 1 Gbps or less. Conversely, a 1G-Ethernet SNI can be used as a 10G-ONU SNI. In this case, the downlink transfer capability in the PON section cannot be used up to the upper limit.

  Moreover, although this Embodiment demonstrated as an example the system in which 10G-ONU and 1G-ONU were mixed, it is not limited to this. For example, the ONU to be accommodated is only a 10G-ONU, but the present invention can also be applied when connecting to different networks for each ONU. The OLT in this case may be equipped with a plurality of 10G-Ethernet SNIs and a plurality of downstream PON outputs equivalent to the 802.3av specification. However, the downstream wavelength may be changed for each downstream output port, and may be changed for each higher-level network to which the WDM filter mounted on the ONU is connected as necessary.

[Extended embodiment]
The present invention has been described above with reference to the embodiments, but the present invention is not limited to the above embodiments. Various changes that can be understood by those skilled in the art can be made to the configuration and details of the present invention within the scope of the present invention.

  DESCRIPTION OF SYMBOLS 100 ... PON system, 10 ... OLT, 11 ... PON port, 12 ... Reception circuit, 13 ... Frame separation part, 14 ... Control frame processing part, 15 ... Band allocation processing part, 16A ... Frame multiplexing part (system 0), 16B ... Frame multiplexing unit (1 system), 17A ... Transmission circuit (0 system), 17B ... Transmission circuit (1 system), 18A ... Transmission / reception circuit (0 system), 18B ... Transmission / reception circuit (1 system), 19A ... SNI port ( 0 system), 19B ... SNI port (1 system), 20 ... frame transfer processing section, 21 ... uplink latency absorbing section, 22 ... output destination SNI determining section, 23 ... LLID table, 24 ... uplink output destination control section, 25A ... Upstream output timing adjustment unit (system 0), 25B ... Upstream output timing adjustment unit (system 1), 31A: Downstream latency absorption unit (system 0), 31B: Downstream latency absorption unit (system 1), 3 A ... LLID assigning unit (system 0), 32B ... LLID assigning unit (system 1), 33A ... downstream output destination control unit (system 0), 33B ... downstream output destination control unit (system 1), 34A ... downstream output destination determination Part (0 system), 34B ... downlink output destination determination part (1 system), 35 ... VID table, 36A ... downlink output timing adjustment part (0 system), 36B ... downlink output timing adjustment part (1 system).

Claims (5)

In addition to connecting to a plurality of ONUs via a PON, connecting to a plurality of higher-level devices via SNI (Service Node Interface) provided for each higher-level device, and frames exchanged between these ONUs and the higher-level devices are mutually connected. OLT to transfer to
A receiving circuit for receiving an upstream frame from the ONU via the PON;
A plurality of transmission circuits that are provided for each transmission rate set in advance, and transmit a downstream frame to the ONU at the transmission rate via the PON;
A plurality of transmission / reception circuits provided for each of the SNIs, for transmitting the uplink frame to the host device via the SNI and receiving the downlink frame from the host device via the SNI;
A frame transfer processing unit that transfers the uplink frame received by the reception circuit to the transmission / reception circuit, and transfers the downlink frame received by the transmission / reception circuit to the transmission circuit;
The frame transfer processing unit
Each LLID (Logical Link ID) in the ONU includes an LLID table in which SNI selection information corresponding to the LLID is registered,
SNI selection information corresponding to the LLID of the uplink frame received by the reception circuit is acquired from the LLID table, and the uplink frame is transferred to the transmission / reception circuit corresponding to the SNI selection information in the transmission / reception circuit. OLT. The OLT according to claim 1,
The frame transfer processing unit
An output destination determination unit that acquires, from the LLID table, SNI selection information corresponding to the LLID of the uplink frame received by the reception circuit;
An OLT comprising: an uplink output destination control unit that transfers the uplink frame to a transmission / reception circuit corresponding to the SNI selection information acquired by the output destination determination unit in the transmission / reception circuit. In the OLT according to claim 1 or 2,
The frame transfer processing unit
For each VID (VLAN Identifier) for identifying the VLAN to which the downlink frame belongs, further includes a VID table in which LLID and downlink output destination selection information related to the downlink frame are registered,
After acquiring the LLID and downlink output destination selection information corresponding to the VID of the downlink frame received by the transmission / reception circuit from the VID table and assigning the LLID to the downlink frame, the downlink output destination of the transmission circuit The OLT is transferred to the transmission circuit corresponding to the selection information. The OLT according to claim 3, wherein
The frame transfer processing unit
A plurality of downlink output destination determination units that are provided for each of the transmission / reception circuits and obtain LLID and downlink output destination selection information corresponding to the VID of the downlink frame received by the transceiver circuit from the VID table;
A plurality of LLID provision units provided for each of the transmission / reception circuits, and configured to append the LLID acquired by the downlink output destination determination unit to the downlink frame received by the transmission / reception circuit;
A plurality of the transmission / reception circuits that transfer the downlink frame from the LLID adding unit to the transmission circuit corresponding to the downlink output destination selection information acquired by the downlink output destination determination unit among the transmission circuits. The OLT further includes a downstream output destination control unit. In addition to connecting to a plurality of ONUs via a PON, connecting to a plurality of higher-level devices via SNI (Service Node Interface) provided for each higher-level device, and frames exchanged between these ONUs and the higher-level devices are mutually connected. A frame transfer method used in the OLT for transfer processing to
For each LLID (Logical Link ID) in the ONU, storing SNI selection information corresponding to the LLID in an LLID table;
The SNI selection information corresponding to the LLID of the upstream frame received from the ONU via the PON is acquired from the LLID table, and the frame is provided for each SNI and transmitted / received to / from the host device via the SNI. And a step of transferring the uplink frame to a transmission / reception circuit corresponding to the SNI selection information.

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