JP2007074256A - Multiple llid processing device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiple LLID processing device in GE-PON capable of avoiding high cost, by using a structure in which two or more LLIDs can be processed by one ONU. <P>SOLUTION: As base layers of ONU are set from the lowest in the order of PMD layer, PMA layer, FEC layer, PCS layer, RS layer, MAC layer, MPCP layer, and OAM layer. As a set of the base layers, RS layer, MAC layer, MPCP layer, and OAM layer are set in order as high level layers from the PCS layer. In this case, a MUX unit is provided for controlling the connection of the PCS layer as a base layer, the RS layer also one of the base layers, and the RS layer arranged as one of the set of base layers. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention uses a topology such as a Gigabit Ethernet (registered trademark) passive optical network (GE-PON) type, and the Ethernet widely used in user networks. The present invention relates to a multiple LLID (Logical Link Identifier) processing device in a GE-PON for an access system that accommodates a (registered trademark) packet and has a function of connecting to a core network.

  GE-PON is a technology that realizes gigabit FTTH (Fiber To The Home) service and the like. In other words, it refers to a technology that incorporates the Gigabit Ethernet (registered trademark) technology into the PON technology and realizes optical fiber access section communication at an ultra-high speed of 1 Gbps.

  FIG. 5 shows an example of a conventionally known configuration of an access system using E-PON (Ethernet (registered trademark) -passive oputical network: standard name) in the case of 1: n (n is a natural number) connection.

  In FIG. 5, the OLT (Optical Line Terminal: Optical Subscriber Line Termination Device) installed on the center side and the ONU (Optical Network Unit: Optical Subscriber Line Network Device) installed on the user side are arranged between the two. The optical splitter 10 forms an E-PON interface. The OLT is connected to a core network (such as the Internet) 14 by an edge router (such as an L2SW connected to the Internet line) 12 via an Ether interface of a standard such as 100/1000 BASE-T or 1000BASE-SX / L. Similarly, the ONU is connected to a user terminal such as a personal computer 16 via an Ether interface of a standard such as 10/100/1000 BASE-T.

  The FTTH service is generally a service that uses an optical fiber to connect to the Internet. Even if the speed of the FTTH service can be increased by using an optical fiber, it is widely used for economic reasons if the introduction cost is too high compared to copper wire. It becomes difficult to do. Therefore, in order to reduce the usage fee of the FTTH service as much as possible, a PON (Passive Optical Network) that shares one optical fiber among a plurality of users has been devised. PON refers to a star network in which an optical splitter 10 or the like is provided in the middle of an optical fiber to branch the transmission path into 2 to 32 lines.

  Here, an optical splitter is a device capable of branching one optical signal into two or more outputs and combining two or more optical input signals into one output. Since optical splitters do not require a power supply and are maintenance-free, a flexible network can be designed while being installed at multiple locations on the transmission path.

  Conventionally, a multicast LLID transmission confirmation method in an Ethernet (registered trademark) passive optical subscriber network is known as an access system using this type of PON technology (see, for example, Patent Document 1).

  In this patent document, a technique for realizing optical fiber access section communication is disclosed in E-PON in which Ethernet (registered trademark) technology is incorporated into PON technology.

  Specifically, according to this technology, in E-PON, communication is performed between an OLT (Optical Line Terminal) provided on the center side and an ONU (Optical Network Unit) provided on the user side. In addition, a MAC (Media Access Control) frame (also referred to as a Mac access frame) in which an LLID is assigned to a conventional Ethernet (registered trademark) preamble area is used.

  The MAC frame will be briefly described with reference to FIG. FIG. 6 is a diagram showing a MAC frame in which a LLID is added to a conventional Ethernet (registered trademark) preamble area used only in an E-PON section. In FIG. 6, FCS (Frame Check Sequence) is a frame check sequence, and SLD (Start Of LLID Delimiter) indicates that LLID is described in a preamble area of a conventional Ethernet (registered trademark) MAC frame. . CRC (Cyclic Redundancy Check) is a code error check from SLD to LLID. These are standardized by IEEE 802.3ah (American Institute of Electrical and Electronics Engineers).

When the destination of a packet is from the OLT to the ONU (downward), the ONU has the same LLID in the packet as the LLID assigned to it in advance by the OLT Discovery process. Check whether or not there is a packet and determine whether or not the packet can be received. When the destination of the packet is from ONU to OLT (upward direction), the OLT uses the LLID in the packet and the LLID registered in the OLT. The contents of the list are compared to determine whether to receive a packet.
Japanese Patent Application Laid-Open No. 2004-1112813 (pages 2 to 5, FIGS. 1 and 3)

  According to the technique disclosed in Patent Document 1, the access system is basically configured to receive (receive) only one LLID per ONU, and is not configured to set a plurality of LLIDs. When trying to process, it has a plurality of optical PMD layers, PMA layers, FEC layers (optional), PCS layers, RS layers, MAC layers, MPCP layers, OAM layers, etc., that is, another ONU There is a problem in that it is necessary to provide it, and the cost becomes very expensive.

  The PMD (Physical Midium Dependent) layer defines an optical interface, and the PMA (Phisical Medium Attachment) layer converts between a logical transmission bit string encoded by the PCS layer and a signal string transmitted on the medium. The FEC (Forward Error Correction) layer specifies forward error correction (this layer may be omitted), and the PCS (Physical Coding Sublayer) layer is suitable for data transmission. The RS (Reconciliation Sublayer) layer defines the preamble and LLID processing added to the MAC frame, and the MAC (Media Access Control) layer transmits and receives frames. Method, frame format, error detection method, etc. MPCP (MULTI-POINT MAC CONTROL) Ear is one that defines the control protocol of the MAC frame forwarding, OAM (Operations, Administration, and Maintenance) layer maintenance, operation, it is a protocol for managing.

  Accordingly, an object of the present invention is to provide a multiple LLID processing apparatus that does not increase the cost by adopting a configuration capable of processing a plurality of LLIDs in one ONU.

  The multiple LLID processing device of the present invention is a LLID processing device that processes multiple LLIDs used in GE-PON for an access system that accommodates Ethernet (registered trademark) packets in an E-PON type topology. The access system is configured by one OLT and at least one ONU connected to the OLT. The LLID processing device is incorporated in the ONU as the same number of LLID processing function means as the number of LLIDs. Each of the LLID processing function means shares a common base layer and individually has a dedicated base layer. The common base layer includes a PMD layer, a PMA layer, and a PCS layer in order from the bottom. The dedicated base layer is a layer higher than the PCS layer of the base layer, and the RS layer and the MAC layer in order from the bottom. , MPCP layer, and OAM layer. Further, each of the LLID processing function means shares a multiplexer that controls connection between the PCS layer of the common base layer and each RS layer of the dedicated base layer.

  In the present invention, the multiplexer preferably has connection means for sending a downstream signal from the OLT side to the ONU side directly from the PCS layer of the common base layer to the RS layer of each dedicated base layer, and from the ONU side to the OLT side. For the upstream signal to the side, it is preferable that the output signal from the RS layer of each dedicated base layer is multiplexed with a predetermined logic and sent to the PCS layer of the common base layer .

  According to the present invention, the base layer of the ONU is provided in the order of the lower layer, the PMD layer, the PMA layer, the PCS layer, the RS layer, the MAC layer, the MPCP layer, and the OAM layer. Since the RS layer, the MAC layer, the MPCP layer, and the OAM layer, which are higher layers, are sequentially provided, a layer lower than the RS layer can be shared, and the cost can be reduced.

  In addition, since a layer higher than the RS layer can be made independent, the user interface can be managed for each LLID, and MPCP control and control of each layer can be performed individually according to the application.

  In addition, since the PMA layer is shared, the loss of light due to optical splitter branching, which is a disadvantage of PON, can be reduced, so the number of LLIDs that can be managed under 1 OLT without affecting the transmission distance of light. Can be increased. Alternatively, the transmission distance can be extended without changing the maximum number of LLIDs to be managed.

  Also, a multiplexer is provided in the ONU so that the output signals (upstream signals) from the respective RS layers of the dedicated base layer are multiplexed by the multiplexing means, and the output signals from the respective RS layers are timed by the OLT DBA processing. Therefore, the signals can be output as upstream signals without colliding with each other.

  Hereinafter, an embodiment of a multiple LLID processing apparatus, which is an access system in which an Ethernet (registered trademark) packet is accommodated in an E-PON type topology of the present invention, will be described with reference to the drawings.

[Configuration of the Invention]
FIG. 1 is a diagram for explaining an embodiment of the present invention. An OLT (center part (station side)) and n ONUs (user parts) are connected by optical fibers via an optical splitter 10. It is the figure which showed the place connected in the shape.

  In FIG. 1, the OLT and the ONU are 1: n connected (the transmission medium is shared), but the E-PON system is logically a point-to-point configuration and is called LLID (Logical Link identifire). The transmission / reception control can be performed in units of the LLID by the logical identifier. Incidentally, regarding transmission control, the bandwidth, that is, the time during which transmission can be performed for n users (m LLIDs: m ≧ n) according to the communication amount or the like by DBA (Dynamic Bandwidth Allocation) inside the OLT. This transmission control can be realized by changing it dynamically.

  In the configuration example of FIG. 1, as an example, a case where two LLIDs are defined in one ONU-1 is described. First, the basic layer of ONU-1 is provided in the order of the PMD layer, PMA layer, FEC layer, PCS layer, RS layer, MAC layer, MPCP layer, and OAM layer from the lower layer (LLID-1: right side in the figure). This is standardized by IEEE 802.3ah (American Institute of Electrical and Electronics Engineers). The ONU-1 further includes an RS layer, a MAC layer, an MPCP layer, and an OAM layer in this order as another upper layer from the PCS layer (LLID-2: left side in the figure). A MUX unit (multiplexer) that controls connection between the PCS layer, the LLID-1 side RS layer, and the LLID-2 side RS layer is provided.

  Hereinafter, layers commonly used on the LLID-1 side and the LLID-2 side, that is, the PMD layer, the PMA layer, the FEC layer, and the PCS layer are referred to as a common basic layer, and the LLID-1 side, LLID-2 On the side, the layers used exclusively, that is, the RS layer, the MAC layer, the MPCP layer, and the OAM layer are referred to as a dedicated base layer.

[Operation of the Invention]
FIG. 2 is a diagram for explaining the operation of the multiple LLID processing apparatus in the GE-PON of the present invention. FIG. 2 shows the multiplexer (ie, MUX unit) in FIG. 1 in detail. 2, components having the same configuration and function as those in FIG. 1 are denoted by the same reference numerals, and description thereof is omitted or simplified.

  The MAX unit includes connection means and multiplexing means. The connection means directly transmits a signal from the PCS layer of the common base layer to each RS layer of the dedicated base layer, and the multiplexing means sends an output signal from each RS layer of the dedicated base layer to a predetermined logic. Multiplexed by (for example, a logical operation described later) and sent to the PCS layer of the common base layer.

  In FIG. 2, a selector 20 is arranged for uplink (OLT direction) between the multiplexing unit 18, the RS layer, and the PCS layer, and the output from the multiplexing unit 18 (signal C) or the signal from the RS layer (signal A ) Which signal is sent to the PCS layer is selected. The selector 20 can be switched so that input / output can be performed from outside this basic configuration. Once the initial setting is made, the selector 20 is used without change. Further, the control in each layer is controlled by software by the CPU 22.

  In this example, the uplink (OLT direction) is output from the output signal A from the RS layer in the dedicated base layer on the LLID-1 processing side and the RS layer in the dedicated base layer on the LLID-2 processing side. The output signal B is multiplexed (described later) by the multiplexer 18. After being multiplexed, this signal is supplied as a signal C to the selector 20 on the LLID-1 side. The selector 20 receives the signal C from the multiplexing unit 18 and the signal A from the RS layer in the dedicated base layer on the LLID-1 processing side. In this case (since there are two LLIDs) The signal C is selected by the selector 20 and supplied to the PCS layer in the common base layer.

  On the other hand, in the downstream (ONU direction), the output signal D from the PCS layer is supplied to the RS layer in the dedicated base layer on the LLID-1 processing side as well as to the RS layer of LLID-2. That is, a path 24 for directly supplying the output signal D as it is is provided as a connection means between the PCS layer and the RS layer of each dedicated base layer.

  Here, the logic of the selector 20 is such that the path is fixedly switched when a plurality of LLIDs are supported. This switching is performed by software control by the CPU 22 or fixed logic on the board when the apparatus is started up. Also good.

  By the way, in general, an Ethernet (registered trademark) device operates by simply connecting a cable (plug and play). Therefore, it is considered that the OLT and the ONU are automatically prepared for connection (registering the LLID in the user interface) without special setting in the E-PON. This is standardized by IEEE 802.3ah (American Institute of Electrical and Electronics Engineers). When a plurality of LLID processing apparatuses in the GE-PON of FIG. 2 are started up, LLID-1 or LLID-2 is registered for each predetermined user interface by MPCP-Discovery (registration sequence) which is a PON protocol. The details of registration are not essential matters of the present invention, so the description thereof will be omitted, but refer to IEEE 802.3ah.

  At this time, for the downlink direction, PMD layer (common: meaning common to LLID-1 and 2), PMA layer (common) → FEC layer (common) → PCS layer (common) → RS Layer (LLID-1) ..., PMD layer (common)-> PMA layer (common)-> FEC layer (common)-> PCS layer (common)-> RS layer (LLID-2) ... Delivered.

  Also, for the uplink direction, the RS layer (LLID-1) → multiplexer (common) → selector (common) → PCS layer (common) → FEC layer (common) → PMA layer (common) → PMD layer ( Common), and RS layer (LLID-2) → multiplexer (common) → selector (common) → PCS layer (common) → FEC layer (common) → PMA layer (common) → PMD layer (common) Become a flow.

  In the RS layer, since the registered LLID number is given to the Ethernet (registered trademark) MAC frame transmitted from the OLT, all the LLID frames not addressed to itself are discarded and only the matching LLID frame is captured. As a result, only signals registered in LLID-1 or LLID-2 are transmitted (supplied) to the user interface.

  Next, when the E-PON Discovery process ends, temporal control by MPCP is performed. This control is conventionally performed by a command (time and band control signal (Gate frame)) from the OLT. A report frame is declared from the ONU, and the OLT sends a gate frame to the ONU according to the reports and DBAs (Dynamic Bandwidth Allocation) from all the ONUs. Thereafter, as defined in IEEE 802.3ah, OAM-Discovery (maintenance sequence), which is a PON protocol, is performed, and user data is conducted.

  In the uplink multiplexing unit 18 in FIG. 2, the transmission time and transmission band (Length) are managed by this Gate frame for each LLID, so that data can be transmitted without collision.

  Incidentally, the upstream and downstream data have different wavelengths of light for both upstream and downstream, so that even if they are transmitted simultaneously, it is possible to transmit and receive frames without causing data collision. In IEEE 802.3ah, the wavelength of the upstream frame is defined as 1270 to 1360 [nm], and the wavelength of the downstream frame is defined as 1480 to 1500 [nm].

  Now, as described above, for downstream communication, all frames from the OLT reach the ONU RS layer. Specific data between the PCS layer and the RS layer includes data (Dw_dat: a signal passed from the PCS layer to the RS layer for processing the preamble and LLID) as shown in FIG. 3, and data enable ( dw_dat_en: a signal for causing the RS layer to recognize the beginning of the frame), and is transferred without being particularly processed in the MUX unit. The data enable indicates an effective range of a packet recognized by encoding processed in the PCS layer.

  As described above, for upstream communication, the amount of frames to be transmitted from the ONU is reported to the OLT as a report frame, and the OLT reports to the ONU according to reports from all ONUs and DBA (Dynamic bandwidth Allocation). To send a Gate frame. Since this Gate includes a transmission start time and a transmission band, the ONU sends out a frame accordingly. In the uplink, transmission control is performed in accordance with a transmission start time instruction from the OLT in the MPCP layer, an LLID number registered in the RS layer is assigned, and signals are transmitted without colliding.

  The uplink multiplexed image includes data (Up_dat: signal for 8B / 10B encoding in the PCS layer) and data enable (Up_dat_en: signal for causing the PCS layer to recognize the beginning and end of the frame) as shown in FIG. ) And a timing signal for causing the optical device to emit light in the PMD layer (Up_bias: an enable signal for outputting light only in a band given from the OLT side) can be multiplexed with the following logic to perform a plurality of LLID processes without collision. . An example of the case where there are two LLIDs (multiplex processing performed in the multiplexing unit 18) is shown below.

Up_bias = (Up_bias_1) | (Up_bias_2)
Up_dat = (Up_bias_1 & Up_dat_1) | (Up_bias_2 & Up_dat_2)
Up_dat_en = (Up_bias_1 & Up_dat_en_1) | (Up_bias_2 & Up_dat_en_2)
* The last number is the LLID number, "&" is AND, and "|" is OR.

  Note that the data enable indicates a packet valid range necessary for encoding processing in the PCS layer. The timing signal for causing the optical device to emit light is a signal that is asserted for the transmission bandwidth specified by Gate. That is, this timing signal is a signal that specifies a time for transmitting an optical signal from the PMD layer to the OLT.

  As described above, in the present embodiment, the case where two LLIDs are secured in one ONU has been described. However, in addition to the ONU-1, another two, three, etc. as a set, a dedicated basic layer (as an upper layer from the PCS layer) By providing a plurality of RS layers, MAC layers, MPCP layers, and OAM layers, it is possible to provide a plurality of LLIDs.

(Modification of embodiment)
It should be noted that the present invention is not limited to the above-described embodiment, and modifications, improvements, etc. within a scope that can achieve the object of the present invention are included in the present invention.

  For example, the best configuration for carrying out the present invention has been disclosed in the above description, but the present invention is not limited to this. That is, the present invention has been illustrated and described with particular reference to particular embodiments, but may be configured with respect to the above-described embodiments without departing from the scope of the technical idea and objects of the invention. Various modifications can be made by those skilled in the art in operation, quantity, and other detailed configurations.

  Therefore, the description limited to the configuration, operation, etc. disclosed above is exemplary for easy understanding of the present invention, and does not limit the present invention. The description of the name of the configuration excluding a part or all of the limitation is included in the present invention.

  In the above-described embodiment of the present invention, the case where the E-PON technology is applied to the Internet has been described. However, the present invention is not limited to data transmission / reception via the Internet, but includes audio, video distribution, monitoring, and the like. The present invention can be applied to a device that requires a plurality of LLIDs in a single ONU.

It is the figure which showed the place where OLT (center part (station side)) and n ONUs (user part) are connected in star shape via the optical splitter with an optical fiber. It is a figure for demonstrating taking operation of one ONU as an example about operation | movement of the multiple LLID processing apparatus in GE-PON of this invention. It is the figure which showed the specific example of data (downlink) between a PCS layer and RS layer. It is the figure which showed the specific example of data (up) between a PCS layer and RS layer. It is the figure which showed an example of the structure of the access system using E-PON in the case of 1: n (n is a natural number) connection. It is the figure which showed the MAC frame which provided LLID to the preamble area | region of the conventional Ethernet (trademark) used only for the area of E-PON.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Optical splitter 12 ... Edge router 14 ... Core network 16 ... User interface (PC)
18 ... Multiplexer 20 ... Selector 22 ... CPU
24 ... Route

Claims (2)

An LLID processing device for processing a plurality of LLIDs used in a GE-PON for an access system that accommodates an Ethernet (registered trademark) packet in an E-PON type topology,
The access system is composed of one OLT and at least one ONU connected to the OLT,
The LLID processing device is incorporated in the ONU as LLID processing function means equal in number to the LLID,
Each of the LLID processing function means shares a common base layer and has a dedicated base layer individually.
The common base layer includes a PMD layer, a PMA layer, and a PCS layer in order from the bottom,
The dedicated base layer is a layer higher than the PCS layer of the base layer, and includes an RS layer, a MAC layer, an MPCP layer, and an OAM layer in order from the lower layer,
Further, each of the LLID processing function means shares a multiplexer that controls connection between the PCS layer of the common base layer and each RS layer of the dedicated base layer. . The multiplexer is
Connection means for sending a downstream signal from the OLT side to the ONU side directly from the PCS layer of the common base layer to the RS layer of each dedicated base layer;
Multiplexing means for multiplexing an output signal from each RS layer of the dedicated base layer to a PCS layer of the common base layer for an upstream signal from the ONU side to the OLT side. When,
The multiple LLID processing apparatus according to claim 1, wherein:

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