JP2006262129A - Logical link establishment method and optical termination device in PON system - Google Patents

Abstract

【Task】
Establish links for high-priority users and links used for urgent application applications early.
[Solution]
The center-side optical termination device (OLT) 10 transmits a Discovery Gate message, which is a registration inquiry message, to the user-side optical termination devices (ONU) 18-1 to 18-n. In response to this message, the ONUs 18-1 to 18-n send response messages having user identifier information for specifying the ONUs 18-1 to 18-n themselves and applications applied to the ONUs 18-1 to 18-n to the OLT 10. Send. The LLID adding circuit 35 of the OLT 10 stores the response messages from the ONUs 18-1 to 18-n that have arrived within a predetermined time in the buffer 34, and the ONUs 18-1 in the order according to the priorities described in the priority table 36. A logical link is assigned to each of the applications ˜18-n.
[Selection]
FIG.

Description

  The present invention relates to a logical link establishment method and an optical termination device in a passive optical network system, that is, a PON (Passive Optical Network) system.

  In EPON (Ethernet Passive Optical Network) standardized by IEEE 802.3ah, a new optical terminal unit (ONU: Optical Network Unit) on the user side is newly registered in the optical terminal unit (OLT: Optical Line Terminal) of the center station. In order to establish a link (Logical Link), an LLID registration process called a Discovery process is prepared. “Ethernet” is a registered trademark.

  More specifically, the OLT periodically transmits a Discovery Gate message, that is, a registration inquiry message to all ONUs after power-on. Each ONU responds to this message at random timing within a predetermined time. The OLT sequentially sets a logical link (Logical Link) for each ONU that has responded after a predetermined process such as measurement of the distance between the OLT and the ONU and transmission timing control of the ONU. The logical link is identified by an LLID (Logical Link IDentifier) that is an identification number. This completes the registration of the ONU to the OLT.

  Registration inquiries by this Discovery Gate message are periodically executed. As a result, it is possible to automatically detect and register an ONU that is newly powered on.

  In the conventional Discovery process, ONU priority and application priority are not considered at all. In other words, the OLT sequentially assigns LLIDs to the ONU applications that have responded to the registration inquiry message. Applications can be at least broadcast reception, internet connection and IP phone.

  For the following reasons, as the number of subordinate ONUs increases and the number of applications used in each ONU increases, it takes a longer time to finish assigning LLIDs to all applications of all ONUs. For example, assume a case where the OLT reboots due to an unexpected situation or a firmware update. The OLT broadcasts the Discovery Gate message to the subordinate ONUs, and enters a state of accepting a large number of ONU replies to the Discovery Gate message, specifically, Register_Request requesting the link ID. Even if each ONU transmits a request signal Register_Request with a random response delay with respect to the Discovery Gate message, the OLT substantially accepts a plurality of request signals at a time, and a reception error is likely to occur. The ONU that has not received a reply to the Discovery Gate message waits for the next Discovery Gate message. As a result, it takes a long time for the OLT to establish a logical link with all ONUs.

  In addition, one logical link establishment process from when a Discovery Gate message is transmitted and a Register_Request is received from each ONU to when a logical link is established is started for one logical link. Therefore, when a plurality of logical links are assigned to the ONU, the logical link establishment process is activated by the number of logical links. For example, when allocating three logical links to one ONU in a PON system to which 64 ONUs are connected, 192 logical link establishment requests are transmitted to the OLT within a predetermined time when the OLT is rebooted. Therefore, it takes a considerable time to establish logical links for all ONUs. In the case of this number of logical links, it takes about 30 minutes to establish logical links for all ONUs.

  However, for example, an ONU IP phone installed in a police station or a fire department should be given an LLID in preference to other applications, and should also be given priority to other general user ONUs. . Hospitals and the like should also be given priority over general user ONUs.

  In the conventional method, since the OLT activates the link establishment process in the order of acceptance with respect to a random response from the ONU, unfairness occurs between the ONUs. In addition, there is a problem that it is impossible to deal with high priority users or urgent applications.

  It is an object of the present invention to solve such problems and to provide a logical link establishment method and an optical termination device that can quickly establish a logical link in a PON system.

  The logical link establishment method according to the present invention is a method for establishing a logical link between a center-side optical termination device and a user-side optical termination device in a passive optical network system. The center-side optical terminal device transmits a registration inquiry message to the user-side optical terminal device. In response to the registration inquiry message, the user-side optical termination device sends a response message including user identifier information for identifying the user-side optical termination device itself and an application applied to the user-side optical termination device to the center-side optical termination device. Send to end device. Then, the center-side optical termination device compares the response message from the user-side optical termination device that has arrived within a predetermined time with a priority table that defines the priority of the user-side optical termination device and its application. A logical link is given to each application of the user side optical termination device in the order according to the degree.

  The optical termination device according to the present invention includes a priority table that defines the priority of a plurality of user-side optical termination devices connected via passive optical elements, and a logical link registration inquiry message to the plurality of user-side optical termination devices. A registration inquiry device to be transmitted, a buffer for storing response messages from the plurality of optical terminal devices on the user side in response to the registration inquiry message, and response messages stored in the buffer in order according to the priority of the priority table. And a logical link providing device for providing a logical link to the user-side optical termination device shown.

  In the present invention, priority is given to the user-side optical terminal device and its application, and logical links are given in the order according to the priority. Thereby, the link of the user with a high priority and the link used for the application use with high urgency can be established at an early stage, and the fairness with respect to link establishment can also be ensured.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows a schematic block diagram of an embodiment of the present invention. In this embodiment, logical link establishment between each ONU and its application is managed and identified by a virtual MAC address having the same format as the Ethernet (registered trademark) MAC address. Thereby, communication management by a MAC address can be diverted.

  The OLT 10 is connected to the optical splitter 14 via the optical fiber 12. The optical splitter 14 is connected to the ONUs 18-1 to 18-n via the individual optical fibers 16-1 to 16-n. Each ONU 18-1 to 18-n is typically connected to a set-top box 20, a computer 22 and an IP phone 24 for receiving broadcasts.

  The OLT control circuit 30 receives a discovery gate generation circuit (or program) 32 that issues a discovery gate message for the subordinate ONUs 18-1 to 18-n, and responses from the respective ONUs 18-1 to 18-n to the discovery gate message. A buffer 34 that can store only a fixed amount and a LLID adding circuit (or program) 35 that assigns logical links to responses stored in the buffer 34 in a predetermined priority order are provided. The priority table 36 stores the priorities of the subordinate ONUs 18-1 to 18-n. The priority is defined between the ONUs 18-1 to 18-n, the priority is defined between the ONUs 18-1 to 18-n, and between the applications in each ONU 18-1 to 18-n, and more generally. In particular, it may be defined among all applications of all ONUs 18-1 to 18-n. The LLID table 38 stores the LLID assigned to each application of each ONU 18-1 to 18-n. Although the details will be described later, the LLID assigning circuit 35 refers to the priority table 36 and assigns the LLID to the ONU or application having a high priority in terms of time.

  The OLT 10 serves as an PON interface, an electrical / optical converter 40 that converts a downstream electrical signal into an optical signal, a wavelength division multiplexing (WDM) optical coupler 42 that distributes upstream and downstream light in a predetermined direction, and an upstream optical signal. An optical / electrical converter 44 for converting into an electrical signal is provided. The OLT 10 also includes a network interface 46 that connects to an upper network. In the PON system, the 1.31 μm band is used for the upstream signal light from the ONUs 8-1 to 18-n to the OLT 10, and the 1.49 μm band is used for the downstream signal light from the OLT 10 to the ONUs 18-1 to 18-n. Is used.

  The ONU control circuit 50 of the ONU 18-1 is in charge of processing for establishing a logical link with the OLT 10. The MAC address management table 52 stores the correspondence between each application connected to the ONU 18-1, the virtual MAC address, and the LLID. The ONU 18-1 serves as an PON interface, an electrical / optical converter 54 that converts an upstream electrical signal into an optical signal, a WDM optical coupler 56 that distributes upstream and downstream light in a predetermined direction, and an downstream optical signal as an electrical signal. An optical / electrical converter 58 for conversion is provided. The ONU 18-1 also includes a network interface 60 that connects to the set top box 20, the computer 22, and the IP telephone 24 via a LAN (local area network).

  The configuration of other ONUs 18-n is the same as that of the ONU 18-1. However, the virtual MAC address values stored in the MAC address management table 52 are different from each other in each ONU 18-1 to 18-n.

  FIG. 2 shows an example of the structure and contents of the MAC address management table 52. The table 52 includes an LLID field 52a, a virtual MAC address field 52b, and an ID (APL_ID) field 52c for identifying an application.

  The field 52a stores the LLID assigned from the OLT 10 by the LLID addition process described later. The virtual MAC address field 52b stores a virtual MAC address as user identification information for specifying the ONU and its application in the same format as the MAC address. The upper 10 digits of the virtual MAC address stored in the MAC address field 52b indicate the identification value that identifies the ONU 18-1, and the lower 2 digits of the virtual MAC address indicate the identification value that identifies the application.

  In the application ID field 52c, as an application identification value, a MAC address, an IP address, a TOS (Type Of Service) value, a COS (Class Of Service) value of a device (a set top box, a computer, an IP phone, or the like) corresponding to the virtual MAC address. Service) value or port number is stored. In the example shown in FIG. 2, a TOS value or COS value is set for the application ID, application ID = 7 for VoIP, application ID = 4 for broadcasting services, and data communication (Internet). On the other hand, application ID = 0. The values of the fields 52b and 52c are set in each ONU 18-1 to 18-n before installation.

  FIG. 3 shows an example of the contents of the priority table 36. In the example shown in FIG. 3, the priority is set for each ONU 18-1 to 18-n, and the priority is set for the application of each ONU 18-1 to 18-n. In the example shown in FIG. 3, the virtual MAC address AA. BB. CC. DD. 01. The ONU specified by xx is given priority over other ONUs, and the priority of the application is set in the order of VoIP, broadcast, and data communication within the same ONU. Conversely, the priority may be set by the application, and the priority may be set for each ONU within the same application.

  FIG. 4 shows another example of contents of the priority table 36. In FIG. 4, in principle, priorities are set in the order of VoIP, broadcast, and data communication regardless of the ONU, with the exception that two ONU's VoIP (virtual MAC addresses: AA.BB.CC.DD.01. 01 and AA.BB.CC.DD.02.01) are given special priority. In addition to this, one or more applications of one or more specific ONUs may be prioritized over others, and lower priority may be set as appropriate for the remaining ONUs and applications.

  Alternatively, a higher priority may be assigned in descending order of the guaranteed minimum bandwidth specified in the service level agreement (SLA). Furthermore, when there is a virtual MAC address for which the same minimum bandwidth guarantee value is set, a higher priority is assigned in the order in which data communication is performed using the virtual MAC address immediately before the OLT 10 is rebooted.

  The contents of the priority table 36 can be rewritten, for example, by remotely operating the OLT 10 from an upper network.

  The LLID setting procedure in the present embodiment will be described in detail. The Discovery Gate generation circuit 32 of the OLT control circuit 30 broadcasts a Discovery Gate message for LLID setting to the subordinate ONUs 18-1 to 18-n after the OLT 10 is powered on. The Discovery Gate message includes time information of a local timer of the OLT 10. The OLT control circuit 30 applies this Discovery Gate message to the electrical / optical converter 40. The electrical / optical converter 40 converts the Discovery Gate message into an optical signal. The output optical signal of the electrical / optical converter 40 enters each of the ONUs 18-1 to 18-n via the WDM coupler 42, the optical fiber 12, the optical splitter 14, and the optical fibers 16-1 to 16-n. In each ONU 18-1 to 1-n, the WDM optical coupler 56 applies the downstream optical signal from the optical fibers 16-1 to 16-n to the optical / electrical converter 58. The optical / electrical converter 58 converts the input optical signal into an electrical signal and applies it to the ONU control circuit 50.

  The ONU control circuit 50 of each ONU 18-1 to 18-n synchronizes the internal clock with the time information of the local timer of the OLT 10 included in the Discovery Gate message, and after the random delay time, the transmission time and virtual MAC address information A LLID registration request (Register Request) including is sent to the OLT 10. The LLID registration request may be issued for one virtual MAC address or may be issued for the virtual MAC addresses of all applications registered for use. The LLID registration request output from the ONU control circuit 50 includes the electrical / optical converter 54, the WDM optical coupler 56, the optical fibers 16-1 to 16-n, the optical splitter 14, the optical fiber 12, the WDM optical coupler 42, and the optical / optical The data is input to the buffer 34 of the OLT control circuit 30 through the electrical converter 44.

  The buffer 34 has a capacity that can accommodate a predetermined amount, for example, a plurality of LLID registration requests. The capacity is a maximum capacity that can accommodate all LLID registration requests from all ONUs 18-1 to 18-n connected under the capacity. In the Discovery process, a time (Discovery Window) in which the OLT 10 waits for an LLID registration request from the ONUs 18-1 to 18-n is defined. The OLT 10 stores, in the buffer 34, the LLID registration request that has reached the OLT 10 within the waiting time (Discovery Window) defined by the Discovery Gate. When a plurality of virtual MAC addresses are accommodated in one LLID registration request, the LLID registration request is expanded in advance and stored in the buffer 34 so that it becomes one LLID registration request for one virtual MAC address. This facilitates handling of the LLID registration request in the buffer 34.

  FIG. 5 shows a flowchart of a processing procedure for a plurality of LLID registration requests stored in the buffer 34. The LLID assigning circuit 35 first collates the virtual MAC address of the registration request accommodated in the buffer 34 with the priority table 36, and outputs the highest priority LLID registration request in the order of priority defined by the priority table 36. (S1). The LLID assigning circuit 35 assigns an LLID to the read virtual MAC address with the highest priority, and notifies the corresponding ONU of registration of the LLID with a Register message (S2). The LLID assignment circuit 35 provisionally registers the correspondence between the virtual MAC address and the LLID assigned thereto in the LLID table 38 (S3), and deletes the LLID registration request to which the LLID is assigned from the buffer 34 (S4). Steps S1 to S4 are repeated until there is no LLID registration request stored in the buffer 34 (S5).

  Needless to say, when there are a plurality of registration requests having the same priority, LLIDs are assigned in the order of arrival.

  FIG. 6 shows an example of the structure and contents of the LLID table 38. The LLID table 38 includes a field 38a that stores an LLID and a field 38b that stores a corresponding virtual MAC address. The example shown in FIG. 6 corresponds to the priority order shown in FIG.

  After notifying the corresponding ONU of the registration of the LLID, the LLID adding circuit 35 notifies the ONU of the virtual MAC address to which the LLID has been assigned, by a Gate message, of the transmission possible time and period. Upon receiving this Gate message, the ONU notifies the OLT 10 of an approval response to the Register message for notifying the registration of the LLID within the transmission permission period from the permitted transmission possible time. Each ONU 18-1 to 18-n stores the registered LLID in the LLID field 52a of the MAC address management table 52. When the OLT 10 receives an approval response from the corresponding ONU, the OLT 10 confirms registration of the virtual MAC address and the LLID in the corresponding LLID table 38. This completes the Discovery procedure, that is, the LLID assignment procedure.

  In addition to the LLID assignment procedure at the time of power-on, the Discovery Gate generation circuit 32 of the OLT 10 notifies the Discovery Gate messages to the subordinate ONUs 18-1 to 18-N at regular intervals, and confirms whether there is a new connection. An ONU having an application that has not been given an LLID by the Discovery procedure when the power is turned on can receive a logical link assignment by sending an LLID registration request to the OLT 10 in response to the Discovery Gate message at this stage.

  Although an embodiment has been described in which all the applications of all ONUs 18-1 to 18-n are registered in the priority table 36, the ONU or application to be prioritized is registered in the priority table 36 and is not registered in the priority table 36. You may process ONU or an application as a subordinate rank.

  In the above embodiment, the highest-priority LLID registration request is searched from the LLIDs stored in the buffer 34 in the order of arrival. However, other methods may be adopted as means for detecting the highest-priority LLID registration request. good. FIG. 7 shows a schematic block diagram of the modified example. The buffer 34 is divided into a plurality of storage areas 34a to 34d for each priority. The write circuit 48 determines the priority of the LLID registration request from each of the ONUs 18-1 to 18-n with reference to the priority table 36 and stores it in any of the storage areas 34a to 34d according to the priority. To do. The LLID adding circuit 35 reads out the LLID registration requests in order from the storage areas 34a to 34d that store the LLID registration requests with high priority. Specifically, the LLID grant circuit 35 grants an LLID to all LLID registration requests in the storage area 34a, and thereafter, all LLID registration requests in the storage area 34b, all LLID registration requests in the storage area 34c, and all LLID registration requests in the storage area 34d. LLIDs are assigned in the order of LLID registration requests.

  In the configuration shown in FIG. 7, since the process of searching for the highest priority LLID registration request can be omitted, the highest priority LLID registration request can be detected easily and quickly. The highest priority LLID registration request may be supplied directly from the write circuit 48 to the LLID grant circuit 35, bypassing the buffer 34.

  When rebooting the OLT 10 due to firmware update or error, the LLID may be assigned to all the ONU subordinate applications in order by the same procedure as the Discovery procedure when the power is turned on, but that takes too much time. . The activation by turning on the power is a so-called cold boot, and the reboot by firmware update or the like is a so-called warm boot. In the case of a momentary interruption due to warm boot, there is a high possibility that the logical link before the interruption can be maintained.

  Therefore, for such warm boot, in this embodiment, the logical link is maintained as much as possible as follows. That is, the LLID assigning circuit 35 inquires of each ONU 18-1 to 18-n whether or not the correspondence between the LLID recorded in the LLID table 38 and the virtual MAC address can be maintained. Maintain the assigned LLID. The LLID that could not be confirmed is discarded, and a procedure for giving the LLID to the ONU or application of the discarded LLID is started again. For this reason, the LLID table 38 is stored in a memory that can retain the stored contents even after reboot, for example, a non-volatile memory that can maintain stored data even when the power is turned off, or a memory that can maintain stored data even during reboot.

  Through the above processing, communication is executed between the OLT and the ONU using the registered logical link in the PON system shown in FIG. That is, data is transferred between the OLT 10 and the ONUs 18-1 to 18-n in a form in which the LLID is embedded in the preamble of the MAC frame. The OLT 10 has a function of bridging the MAC address between the upper network and the PON, and the ONUs 18-1 to 18-n are configured with the LLID or the virtual MAC address between the PON and the user devices 20, 22, and 24. And a function of bridging the actual MAC address of the user apparatus. By using the bridge function of the OLT 10 and the ONUs 18-1 to 18-n and the LLID in the PON system in this way, the devices connected to the higher level network and the user devices 20, 22, and 24 exchange desired data with each other. Can communicate.

  Although an embodiment has been described in which the priority of LLID allocation is statically determined, it may be determined dynamically. For example, LLID allocation is performed in descending order of the minimum bandwidth guarantee value defined in the service level agreement (SLA).

  Although the invention has been described with reference to specific illustrative embodiments, various modifications and alterations may be made to the above-described embodiments without departing from the scope of the invention as defined in the claims. This is obvious to an engineer in the field to which the present invention belongs, and such changes and modifications are also included in the technical scope of the present invention.

It is a schematic block diagram of one Example of this invention. It is an example of the structure and contents of the MAC address management table 52. An example of the structure and contents of the priority table 36 is shown. Another example of contents of the priority table 36 is shown. 5 is a flowchart of a processing procedure for a plurality of LLID registration requests stored in a buffer. An example of the structure and contents of the LLID table 38 is shown. It is another structural example of the part which processes a LLID registration request.

Explanation of symbols

10: OLT
12: Optical fiber 14: Optical splitters 16-1 to 16-n: Optical fibers 18-1 to 18-n: ONU
20: set top box 22: computer 24: IP phone 30: OLT control circuit 32: Discovery Gate generation circuit (or program)
34: buffer 35: LLID assignment circuit 36: priority table 38: LLID table 38a: LLID field 38b: virtual MAC address field 40: electrical / optical converter 42: wavelength division multiplexing (WDM) optical coupler 44: optical / electrical conversion Unit 46: Network interface 48: Write circuit 50: ONU control circuit 52: MAC address management table 52a: LLID field 52b: Virtual MAC address field 52c: APL_ID field 54: Electrical / optical converter 56: WDM optical coupler 58: Optical / Electrical converter 60: network interface

Claims (8)

A method for establishing a logical link between a center side optical terminator (10) and a user side optical terminator (18-1 to 18-n) in a passive optical network system, comprising:
(A) The center side optical termination device (10) transmits a registration inquiry message to the user side optical termination device (18-1 to 18-n),
(B) In response to the registration inquiry message, the user side optical terminator (18-1 to 18-n) and the user side optical terminator (18-1 to 18-n) itself and the user side optical terminator A response message having user identifier information for identifying an application applied to the device (18-1 to 18-n) is transmitted to the center-side optical terminal device (10);
(C) The center-side optical termination device (10) receives a response message from the user-side optical termination device (18-1 to 18-n) that has arrived within a predetermined time, and gives priority to the user-side optical termination device and its application. A logical link establishment method characterized in that a logical link is assigned to each application of the user-side optical terminal device in an order according to the priority by comparing with a priority table that defines the degree. The step (C)
(C1) The center-side optical termination device (10) stores each response message from the user-side optical termination device (18-1 to 18-n) that has reached within a predetermined time in the buffer (34),
(C2) Search for the highest priority from the response messages stored in the buffer (34),
(C3) While giving a logical link to each application of the user side optical termination device indicated by the highest priority response message, delete the response message from the buffer (34),
(C4) The logical link establishment method according to claim 1, comprising repeating steps C2 and C3. The step (C)
(C1) The center-side optical termination device (10) assigns each response message from the user-side optical termination device (18-1 to 18-n) that has arrived within a predetermined time to the priority specified in the priority table. According to the degree, store in the corresponding storage area of the buffer (34) having a storage area divided for each priority,
(C2) A logical link is provided to each application of the user side optical terminal device indicated by the response message stored in a high-priority storage area of the buffer (34). The logical link establishment method described in 1.   The user identifier is expressed by a virtual MAC address in the same format as the MAC address, and the higher order of the virtual MAC address identifies the user side optical terminal device (18-1 to 18-n) itself, and the virtual MAC address The logical link establishment method according to any one of claims 1 to 3, wherein an application applied to the user-side optical terminal device (18-1 to 18-n) is specified at a lower level. A priority table (36) that defines priorities of a plurality of user-side optical terminators (18-1 to 18-n) connected via passive optical elements;
A registration inquiry device (32) that transmits a logical link registration inquiry message to a plurality of user side optical terminal devices (18-1 to 18-n);
A buffer (34) for storing response messages from the plurality of user side optical terminal devices (18-1 to 18-n) in response to the registration inquiry message;
Logical link assignment device (35) for assigning logical links to the user-side optical terminal device indicated by the response message stored in the buffer in the order according to the priority of the priority table.
An optical terminal device comprising: The buffer has a plurality of storage areas partitioned according to the priority;
The optical terminal device further refers to the priority table, and sends response messages from the plurality of user side optical terminal devices (18-1 to 18-n) to the buffer storage area according to the priority. A writing circuit (48) for writing,
6. The optical termination device according to claim 5, wherein the logical link providing device (35) assigns logical links in order from the response message stored in a high-priority storage area of the buffer (34). .   7. The optical termination device according to claim 5, wherein the response message includes a user-side optical termination device (18-1 to 18-n) that is a transmission source and a user identifier that identifies the application.   The user identifier is expressed by a virtual MAC address in the same format as the MAC address, and the higher order of the virtual MAC address identifies the user side optical terminal device (18-1 to 18-n) itself, and the virtual MAC address The optical terminal device according to claim 7, characterized in that an application applied to the user-side optical terminal device (18-1 to 18-n) is specified at a lower level.

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