CN100536399C

CN100536399C - A distributed controllable multicast system of passive optical network and its implementation method

Info

Publication number: CN100536399C
Application number: CNB2007100748370A
Authority: CN
Inventors: 王德强
Original assignee: ZTE Corp
Current assignee: Global Innovation Polymerization LLC
Priority date: 2007-06-06
Filing date: 2007-06-06
Publication date: 2009-09-02
Anticipated expiration: 2027-06-06
Also published as: CN101102210A

Abstract

The method comprises: both ONU and OLT transmit data by using the subscriber virtual channel and multicast virtual channel; said multicast data is transmitted from OLT to ONU via said multicast virtual channel; wherein, said multicast system comprises a IPTV service controlling module and a IPTV service executing module; the IPTV service controlling module is used to save the multicast right of each user; the information about said multicast right is transmitted to the IPTV executing module via said subscriber channel; said IPTV executing module is set on ONU and is used for saving the multicast right of each user; according to the multicast right of user and the request of user, ONU relays the multicast data to the port of each user.

Description

Passive optical network distributed controllable multicast system and implementation method thereof

Technical Field

The invention relates to a multicast system of a passive optical network, in particular to a passive optical network distributed controllable multicast system and an implementation method thereof.

Background

With the rapid development of broadband access, more and more families use broadband internet access services, and multicast services are one of the most important broadband internet access services. The demand of multicast on bandwidth is very large, and the bandwidth of many access technologies is close to the limit, so that the demand of high bandwidth of future home and business users cannot be met.

Therefore, the prior art proposes a Passive Optical Network (PON) technology, which uses an Optical transmission technology, has the advantages of long transmission distance and large transmission bandwidth, and greatly improves maintainability, availability and stability of the PON due to the use of Passive nodes.

Referring to fig. 1, the PON Network includes three parts, an Optical Line Terminal (OLT), an Optical Distribution Network (ODN), and an Optical Network Unit (ONU). The ONU is placed at a position far away from the local side, and converges user data in a downlink direction. The upstream is connected to the ODN via optical fibers. The input signal of the video server is transmitted to the OLT through an IP/ATM (Asynchronous Transfer Mode) network, and the ODN transmits the signal input by the OLT to a plurality of user terminals according to a power average, where the ratio of light splitting is generally 1: 16, 1: 32, or 1: 64.

The OLT aggregates the user data from the ONUs. In the downstream direction, i.e. from the OLT to the ONUs, the data is broadcast. Each data is bound to a specific Identifier, for example, in a GPON (gigabit passive optical network), which is a gem port (GPON encapsulated port), and in an EPON (Ethernet PON, Ethernet passive optical network), which is a Logical Link Identifier (LLID). After receiving the data, the ONU judges whether the data is the data of the ONU or not through the corresponding identification. In the uplink direction, each ONU is allocated with different time slots, thereby realizing the sharing of the link.

Unlike the current most important access technology DSL (Digital Subscriber Loop), the PON network has the following important features:

1) the PON port on one OLT corresponds to a plurality of ONU terminals. In DSL, a DSL port on one DSLAM corresponds to only one Modem (Modem) on the far end.

2) The downlink data adopts a broadcasting mode.

3) Due to the fact that the design is planned in advance, the OLT can actively manage the ONU, and the ONU and the OLT have tighter coupling.

This is very advantageous for multicast since the data in the downstream direction is broadcast, since multicast data is used by a large number of end users. At present, in an existing multicast scheme, a special multicast transmission channel is created from an OLT to an ONU by using the characteristics of data broadcasting in the downstream direction. The OLT acquires the multicast program requested by the user by analyzing all request messages from the user side from IGMP (internet group management protocol). The OLT transmits all the requested multicast streams to each downstream PON optical port, and the ONU filters the multicast streams according to the needs of the ONU after receiving the multicast streams. Although the above multicast scheme can correctly deliver the multicast stream to the ONU, it cannot control the authority of the user. When there are multiple users (ports) under an ONU, the ONU or the OLT cannot accurately control the access of the user ports to the multicast stream.

In the control layer, the OLT and the ONU have a precise coupling relation. The PON provides a dedicated OAM (operation, maintenance and management) channel to facilitate control of the ONU by the OLT. And the ONU can only be controlled by the OLT, and the configuration of the ONU is not allowed to be modified by the end user. That is, although the ONUs are at the far end, they are fully controlled by the office OLT. This architecture is well suited for distributed system design.

However, in the prior art, when a large number of interfaces are connected to the ONU and a plurality of end users are connected to the ONU, the OLT needs to process a large number of protocol messages in a unit time by using a centralized multicast system, and thus, the performance of the OLT often cannot meet the requirements. Because a large amount of protocol messages need to be processed, higher performance and more resources are needed for the OLT, and if a processor of the OLT is not strong enough, the protocol messages cannot be processed in time, so that the requirements of a system cannot be met. Meanwhile, by adopting centralized control, the OLT is required to make a judgment and then the ONU is set, so that the time delay of user joining is very long, and the audio-visual experience of the user is influenced.

Accordingly, the prior art is deficient and needs improvement.

Disclosure of Invention

The invention aims to provide a passive optical network distributed controllable multicast system and an implementation method thereof, which realize the control of ONU multicast forwarding and the forwarding of multicast streams from an OLT to an ONU, improve the performance of the OLT for processing a large number of protocol messages and enhance the audio-visual comfort of users.

The technical scheme of the invention is as follows:

a PON distributed controllable multicast system comprises an ONU and an OLT which transmit data through a user virtual channel and a multicast virtual channel, wherein the multicast data are transmitted from the OLT to the ONU through the multicast virtual channel; the multicast system also comprises an IPTV service control module and an IPTV execution module; the IPTV service control module is used for storing the multicast authority of each user and sending the multicast authority to the IPTV execution module through the user virtual channel; the IPTV executing module is arranged on the ONU and used for receiving and storing the multicast authority of each user; and the ONU is used for controlling the multicast data to be forwarded to each user port according to the multicast authority of the user and the user request.

In the multicast system, the IPTV service control module is disposed on the OLT or disposed independently.

In the multicast system, the IPTV service control module is provided with a determination function module, and is configured to send the multicast right to an IPTV execution module when determining that the multicast right of the user is changed.

In the multicast system, the IPTV executing module is provided with a call recording module, and is configured to record a time point when a user requests a multicast service and leaves.

In the multicast system, the IPTV service control module is provided with a channel table for storing program channels, a package table for setting access channel authority, a preview table for setting preview authority, a port package table for setting a package adopted by a port, and a port authority table for recording the use authority of each port on multicast table items; and the IPTV executing module is provided with a preview table for setting preview authority and a port authority table for recording the use authority of each port on the multicast list item.

In the multicast system, the ONU is provided with a first multicast forwarding table, a first switching engine and a first IGMP control module; the OLT sets a second multicast forwarding table, a second switching engine and a second IGMP control module; the first multicast forwarding table is used for storing a mapping relation among a multicast address, a virtual local area network and a user port, and controlling the first switching engine to forward the multicast data to the corresponding user port; the first IGMP control module is used for monitoring and analyzing an IGMP report message passing through an optical network terminal, and updating the first multicast forwarding table and adding table entries thereof according to the multicast authority of a user of the IPTV executing module; the second multicast forwarding table is used for storing a mapping relation among multicast addresses, virtual local area networks and multicast virtual channels of PON ports, and controlling the second switching engine to forward multicast data to the corresponding multicast virtual channels; and the second IGMP control module is used for intercepting and analyzing an IGMP report message passing through an optical line terminal, updating the second multicast forwarding table and increasing the table entry of the second multicast forwarding table.

The multicast system, wherein the ONU further comprises a gigabit ethernet media access controller filter module for selecting multicast data entering the ONU, and the gigabit ethernet media access controller filter module is disposed between the multicast virtual channel and the first switching engine.

A controllable multicast system implementation method under PON environment, it includes the step, A1, stores the multicast authority of every user; a2, the ONU of the multicast system receives the user request and sends the user request to the OLT of the multicast system; a3, OLT receives user request of ONU, judges multicast authority of user, and sends control information to ONU according to result; a4, ONU receives the control information, sets the forwarding of multicast service flow, and controls the access of user port to multicast data.

In the implementation method, in step a1, the multicast authority of each user is stored in the OLT or a separate server.

The method comprises the steps that control information is transmitted between the OLT and the ONU through a user virtual channel, when the OLT receives a user request of the optical network terminal, user authority judgment is carried out according to the multicast authority of the user, and the control information is sent to the ONU.

In the implementation method, in step a3, the OLT sends the control information to the ONU through the PON OAM channel.

The implementation method described above, wherein step a3 specifically includes: b1, the OLT listens and analyzes the IGMP report message; b2, searching the multicast authority of the user; b3, making a judgment whether the user or the port can access the multicast data; and B4, sending the control information to the ONU.

In the implementation method, in step a4, the controlling access of the user port to the multicast data includes: c1, intercepting and analyzing the IGMP report message; c2, searching the multicast authority of the user; c3, executing the operations of allowing, rejecting and previewing according to the multicast authority.

The implementation method further includes, before the step a4, the steps of: and filtering the multicast data.

The implementation method further comprises a step A5 after the step A4: and recording the time point when the user requests the multicast service and leaves.

By adopting the scheme, the invention effectively utilizes the structural characteristics of the PON and effectively reduces the multicast bandwidth from the OLT to the ONU by establishing the multicast virtual channel (Tunnel) shared by a plurality of ONUs; and a mechanism of separating an IPTV control point from an IPTV execution point is used, so that the control of the IPTV is faster; the distributed control structure also improves the expansibility, maintainability and performance of the whole system, and ensures the manageability of the system.

Drawings

Fig. 1 is a basic architecture diagram of a prior art PON access network;

fig. 2 is a diagram of a distributed controllable multicast system architecture in a PON environment according to the present invention;

fig. 3 is a flowchart of processing a REPORT protocol packet under an ONU according to the present invention;

FIG. 4 is a flowchart of the processing of the REPORT protocol message under the OLT according to the present invention;

FIG. 5 is a schematic diagram of a data table of an IPTV control point and its interrelation;

FIG. 6 is a schematic diagram of a multicast virtual channel of the present invention;

fig. 7 is a flow chart of the method of the present invention.

Detailed Description

The following describes in detail preferred embodiments of the present invention.

As shown in fig. 2, the present invention provides a PON distributed controllable multicast system, which includes an ONU and an OLT that transmit data via a user virtual channel and a multicast virtual channel, an IPTV (interactive network television) service control module and an IPTV execution module, where the multicast virtual channel exists between the OLT and the ONU, at least one multicast virtual channel for carrying a downstream multicast stream is provided at each PON port on the OLT, and the multicast virtual channel is shared by all ONUs under the PON port. After receiving the multicast stream, the OLT sends the multicast stream to a multicast virtual channel, that is, multicast data is sent from the OLT to the ONU through the multicast virtual channel.

The IPTV service control module can be arranged in the OLT or independently arranged as an independent server, and is used for storing the multicast authority of each user and sending the information of the multicast authority to the IPTV execution module through the user virtual channel. An IPTV service control module, namely an IPTV decision point, is a user authority configuration point and stores multicast authorities of a plurality of users; it receives and completes the configuration of user (port) authority, and stores IPTV multicast authority of all users (ports). And the IPTV decision point pushes the authority information of the user to the ONU so as to control the forwarding of the multicast stream. When the user authority changes, the IPTV needs to notify the relevant ONU to update in time.

When the IPTV service control module is independently arranged as an independent server, the IPTV decision point can directly establish a communication channel with the ONU and push the authority information to an IPTV execution point on the ONU; or an IPTV service agent is established on the OLT, a communication channel is established between the IPTV decision point and the IPTV service agent on each OLT, and the authority of all the ONUs governed by the OLT is pushed. And finally, the IPTV service agent finally pushes the authorities to the ONU.

The IPTV executing module is arranged on the ONU and used for receiving and storing the multicast authority of each user. The IPTV executing module, namely the IPTV executing point, receives the user authority information from the IPTV decision point and stores the multicast authority of each port. Each time the multicast forwarding table of the ONU is newly added/modified, the module is required to make a judgment, and the addition and the modification can be completed by adopting an IGMP protocol control module.

Thus, through calculation, the IPTV decision point can push the port authority table and the preview table to the IPTV execution point by using an OAM (operation, maintenance and management) channel existing between the OLT and the ONU. Here, only the port right information related to the ONU is pushed, not all. The IPTV decision point may synchronize these modifications to the IPTV enforcement point in time whenever the data table configuration information changes.

And the ONU is used for controlling the multicast data to be forwarded to each user port according to the multicast authority of the user and the user request. The ONU receives multicast data from the multicast virtual channel, and controls the forwarding of multicast streams to each user port according to the request of a user and the definition of user authority.

There may be multiple virtual channels between the ONUs and the OLT, but each PON port of the OLT has a multicast virtual channel shared by all ONUs under the PON port. The multicast virtual channel carries a downstream multicast traffic stream, as shown in fig. 6. The message from ONU to OLT can go through independent user virtual channel, and the multiplexing and transmission process of all cells carrying user information are carried out on the user virtual channel. On the OLT, if an uplink IGMP protocol packet goes through an independent virtual channel, the IGMP protocol processing module on the OLT needs to correctly set a multicast forwarding table and introduce a multicast stream to the multicast virtual channel. The specific implementation mode is as follows: each report packet always corresponds to one source port, i.e. the virtual channel of the user. The IGMP protocol module can find the PON port corresponding to the user virtual channel according to the relevant configuration, and then find the corresponding multicast virtual channel. When writing the multicast forwarding table, the output port uses the multicast virtual channel.

The IPTV service control module can also be provided with a judging function module for sending the information of the multicast authority to the IPTV executing module when judging that the multicast authority of the user is changed, so that the information can be transmitted only when the multicast authority is changed, and the efficiency of the system is increased.

The IPTV executing module may further include a call recording module configured to record a time point when the user requests the multicast service and leaves. In this way, in addition to multicast access control of the user, the IPTV enforcement point may also implement a CDR (Call Detail Record) function. This function may record the point in time when a user requests multicast service and leaves. The operator can realize the value-added functions of service charging, statistics and the like of the user by utilizing the information.

The IPTV service control module is provided with a channel table for storing program channels, a package table for setting access channel authority, a preview table for setting preview authority, a port package table for setting a package adopted by a port, and a port authority table for recording the use authority of each port on a multicast table item; and the IPTV executing module is provided with a preview table for setting preview authority and a port authority table for recording the use authority of each port on the multicast list item.

The IPTV decision point may store multicast right configurations of all users (ports) under the OLT by using the following important data tables, and the relationship between them is shown in fig. 5.

1) Channel table: t _ channel < id, vlan, groupIP, previwd >, id is a key, gIP is a multicast IP address, and the preview-id is associated to an entry of the preview table T _ preview. vlan + groupIP are candidate keys. The previwd is a foreign key pointing to T _ preview.

2) A set of meal table: t _ package < id, channeld, right >, id + channeld are keywords, right identifies rights, there are three types of rights: permit (permit), deny (deny), and preview.

3) Pre-browsing the table: t _ preview < id, blackout, count, duration >, id being a key, blackout identifying the minimum waiting time between two previews, count representing the maximum number of previews per day, duration representing the maximum duration of each preview.

4) Port package table: t _ portPackage < port, PackageID >, port + PackageID are keys. That is, one port can apply several packages. Here, a port refers to a UNI (User Network Interface) port on an ONU. The port is unique within the scope of the OLT.

5) Port authority table: t _ portRight < port, vlan, groupMAC, right, previewID >. Unlike the other tables, the port authority table is automatically calculated and generated by using the other four tables, and is not the contents directly configured by the user. The specific calculation method belongs to the prior art, and is not described in detail herein again. port + vlan + groupMAC are keywords, and since the groupMAC and the groupIP address have a mapping relation, the groupMAC can be always calculated from the groupIP of T _ changle. The port authority table records the use authority of each port to the multicast table item. right contains the deny, allow and preview rights. When right is preview, i.e. preview rights, the preview id is used to find the corresponding preview table, so that the preview parameters can be known.

An administrator can configure each data table of the IPTV service control module to set multicast permissions, including a channel table, a package table, a preview table, a port package table, and the like, through a command line, telnet, or through SNMP (Simple network management Protocol). For example, a CLI interface is adopted, and the four data tables are connected to equipment in a serial port or telnet mode to complete the configuration of the four data tables; data can also be configured through a network management interface of an NMS (network management System) in an SNMP (simple network management protocol) network management mode, and after configuration is finished, the data is pushed to the OLT through an SNMP protocol, and multicast authority configuration of a plurality of OLTs can be managed through the NMS. In actual implementation, one or more of the above methods may be used.

An example of the pre-browsing table of the IPTV executing module is as follows: t _ preview < id, blackout, count, duration >, id being a key, blackout identifying the minimum waiting time between two previews, count representing the maximum number of previews per day, duration representing the maximum duration of each preview.

An example of the port authority table of the IPTV executive module is as follows: t _ portRight < port, vlan, groupMAC, right, previewID >. port + vlan + groupMAC is a key. The port authority table records the use authority of each port to the multicast table item. Right contains three rights, allow, deny, and preview. When right is preview, i.e. preview rights, the preview id is used to find the corresponding preview table, so that the preview parameters can be known.

The multicast system can set a first multicast forwarding table, a first switching engine and a first IGMP control module at an ONU; in addition, a second multicast forwarding table, a second switching engine and a second IGMP control module are arranged on the OLT; this is explained in detail below.

The first multicast forwarding table is used for storing a mapping relationship between a multicast address, a Virtual Local Area Network (VLAN) and a user port, and controlling the first switching engine to forward multicast data, that is, a multicast stream, to a corresponding user port. The multicast forwarding table is the core of multicast service forwarding, and T _ multicast may be used to indicate that the multicast forwarding table < vlan, groupMAC, port, aggregation-timer >, and vlan + groupMAC are keywords. The access device is a two-layer device and the multicast forwarding table uses multicast MAC addresses. The aging-timer aging time is initially set to the maximum aging time. The system automatically reduces this parameter until 0. If 0 is reached, the system automatically deletes the entry.

As described above, the first switching engine, i.e. the forwarding engine, forwards the multicast data stream according to the first multicast forwarding table. The forwarding engine may be a data exchange chip in which there is an image of T _ multicast, but no aging-timer is needed; and the forwarding engine forwards the multicast data according to the multicast forwarding table.

The first IGMP control module is used for intercepting and analyzing an IGMP report message passing through the ONU and controlling a multicast forwarding table according to the multicast authority of a user of the IPTV execution module; in particular, the controlling includes updating the first multicast forwarding table and adding its entries. The IGMP protocol control module processes the protocol message to realize the IGMP snooping function. The method can be realized by adopting an IGMP module to control a switching chip, the switching chip enables an IGMP protocol message to be captured into the IGMP protocol module, but the IGMP module only processes a report message from a user, the IGMP protocol control module directly controls the addition and the update of a multicast forwarding table, and then an IPTV execution point judges the request of the IGMP protocol control module and judges whether the user has access authority to the multicast.

The ONU may further include a gigabit ethernet media access controller filter module for selecting multicast data entering the ONU, and the gigabit ethernet media access controller filter module is disposed between the multicast virtual channel and the first switching engine. Because the multicast communication from the OLT to the ONU adopts a broadcast mode, for a specific ONU, multicast streams which do not need to flow in certainly exist, and if the multicast streams are not controlled, the switching chip needs to forward the multicast streams, so that the switching performance is consumed wastefully. Pre-filtering of the multicast stream before entering the switch chip is necessary to provide system performance.

As shown in fig. 2, the present invention may also add a GMAC (gigabit ethernet media access controller) filter module. This module is placed in the PON optical processing hardware. For example, in the GMAC filter module, there is a filter table T _ filter < vlan, groupMAC >. Only the entries in the filter table exist, the corresponding multicast stream can enter the switching engine.

The IGMP protocol control module controls the addition and update of the T _ filter. For this reason, an image of the T _ filter needs to be added to the IGMP protocol module, but one more field, the aging-timer. When the aging-timer is overtime, the system automatically deletes the table entry corresponding to the T _ filter. The entry aging time of the T _ filter needs to be guaranteed to be the same as the aging time of the T _ multicast entry.

When the IGMP protocol control module adds a new T _ multicast entry, a new T _ filter entry is added by using the < vlan, groupMAC > information of the T _ multicast, and the timing of the aging-timer of the T _ filter entry is set as the aging time of the system configuration. Whenever the IGMP protocol control module updates the T _ multicast representation, IGMP also updates the T _ filter entry. It should be noted that some well-known multicast addresses, such as the multicast address used by IGMP protocol, such as 224.0.0.1, need to be put in the T _ filter in advance. These addresses do not age.

The second multicast forwarding table is used for storing a mapping relation among multicast addresses, virtual local area networks and multicast virtual channels of PON ports, and controlling the second switching engine to forward multicast data to the corresponding multicast virtual channels; its function is fully consistent with the first multicast forwarding table in the ONU and the function of the second switching engine is also fully consistent with the first switching engine in the ONU.

And the second IGMP control module is used for intercepting and analyzing an IGMP report message passing through the OLT, updating the second multicast forwarding table and increasing the table entry of the second multicast forwarding table. Its function is basically identical to the first IGMP control module in the ONU, but there are the following differences:

i. there is no need to be under the control of an IPTV enforcement point. That is, the module has no judgment problem of user authority, and allows the module only by the request of the user.

There is no GMAC filtering module, and control of the GMAC filtering module may not be required since no filtering information is required.

On the basis of the multicast system, as shown in fig. 7, the present invention further provides a method for implementing a controllable multicast system in a PON environment, which includes the following steps.

A1, storing the multicast authority of each user; the multicast authority of each user is stored in the OLT or a separate server. Specifically, as described above, the IPTV service control module or other modules with storage function may be used to implement the function, and these functional modules may be integrated in the OLT or implemented by using an independent server.

A2, the ONU of the multicast system receives the user request and sends the user request to the OLT; and the OLT and the ONU transmit control information through a user virtual channel.

A3, OLT of the multicast system receives user request of ONU, judges multicast authority of user, and sends control information to ONU according to result; the OLT may send the control information to the ONUs through the PON OAM channel. When the OLT receives the request of the ONU through the user virtual channel, the user authority is judged according to the multicast authority of the user, and control information is sent to the ONU. Step a3 may specifically include: b1, the OLT listens and analyzes the IGMP report message; b2, searching the multicast authority of the user; b3, making a judgment whether the user or the port can access the multicast data; and B4, sending the control information to the ONU.

A4, ONU receives the control information, sets the forwarding of multicast service flow, and controls the access of user port to multicast data. And multicast data is sent from the OLT to the ONU through the multicast virtual channel. In step a4, the controlling the access of the user port to the multicast data includes: c1, intercepting and analyzing the IGMP report message; c2, searching the multicast authority of the user; c3, executing the operations of allowing, rejecting and previewing according to the multicast authority.

Before the step a4, the method may further include the steps of: and filtering the multicast data.

Step a5 may also be included after step a 4: and recording the time point when the user requests the multicast service and leaves.

Specifically, as shown in fig. 3, the flow of processing the REPORT protocol message on the ONU is as follows.

1) And starting.

2) IGMP listens to the REPORT message, and supposing that the content of the REPORT message is: user port P_iWant to access VLAN_jLower multicast group G_k. IGMP queries the IPTV enforcement point.

3) The IPTV execution point looks at T _ portRight to see if there is any<P_i，VLAN_j，G_k>The table entry of (2). If the permission is allowed, turning to 4; if the authority is previewed and meets the requirement of browsing times, turning to 7); otherwise, go to 8).

4) IGMP queries the T _ multicast table for judgment<VLAN_j，G_k，P_i>Whether or not it is present. If not, executing step 5); otherwise go to 6).

5) Newly add one<VLAN_j，G_k，P_i，aging-time>To T _ multicast, where the aging-time is set to the port default aging time. Go to step 10).

6) And refreshing the marking-timer of the corresponding table entry, and resetting the time of the marking-timer to be the default aging time of the port. Go to step 10).

7) For this entry of T _ portRight, a preview timer is started according to the preview parameters. Go to step 4).

8) Determining whether there is any T _ multicast table<VLAN_j，G_k，P_i>And (4) table entries. If notExistence, go to 10) and end the process. Otherwise, the following steps are performed.

9) The corresponding entry in T _ multicast is deleted.

10) And (6) ending.

As shown in fig. 4, the processing flow of the REPORT protocol message on the OLT is as follows.

1) Start of

2) The IGMP module listens for the Report message. Assume that the content of the report message is: user port P_iWant to access VLAN_jLower multicast group G_k。

3) IGMP inquires the T _ multicast module to judge whether there is any<VLAN_j，G_k，P_i>The entry exists. If not, step 4) is executed, otherwise 5) is turned.

4) Newly add one<VLAN_j，G_k，P_i，aging-time>To T _ multicast, where the aging-time is set to the configured aging time. Turn 6).

5) And refreshing the marking-timer of the corresponding table entry, and resetting the time of the marking-timer to be the default aging time of the port.

6) And (6) ending.

In the prior art, a decision point and an execution point are combined, the key point of the invention is to separate the decision point from the execution point, an ONU is the execution point, and the decision point pushes information to the ONU. The IPTV decision point and the IPTV execution point on the ONU form an IPTV service control subsystem of the whole multicast system. By adopting the distributed design mode, the control and management of operators are simplified, and the flexibility of the system is also increased.

It will be understood that modifications and variations can be made by persons skilled in the art in light of the above teachings and all such modifications and variations are intended to be included within the scope of the invention as defined in the appended claims.

Claims

1. A passive optical network distributed controllable multicast system comprises an optical network terminal and an optical line terminal which transmit data through a user virtual channel and a multicast virtual channel, wherein the multicast data are sent to the optical network terminal from the optical line terminal through the multicast virtual channel; the multicast system is characterized by also comprising an interactive network television service control module and an interactive network television execution module; wherein,

the interactive network television service control module is used for storing the multicast authority of each user and sending the multicast authority to the interactive network television execution module through the user virtual channel;

the interactive network television execution module is arranged on the optical network terminal and used for receiving and storing the multicast authority of each user;

the optical network terminal is used for controlling the multicast data to be forwarded to each user port according to the multicast authority of the user and the user request.

2. The multicast system according to claim 1, wherein the interactive network television service control module is disposed on the olt or independently.

3. The multicast system according to claim 1, wherein the interactive network television service control module is provided with a judgment function module, and is configured to send the multicast right to the interactive network television execution module when the multicast right of the user is judged to be changed.

4. The multicasting system of claim 1 wherein the interactive network television execution module sets a call recording module for recording the time point when the user requests the multicasting service and leaves.

5. The multicast system according to claim 1, wherein the interactive network television service control module sets a channel table for storing program channels, a package table for setting access channel rights, a preview table for setting preview rights, a port package table for setting port adoption packages, and a port rights table for recording usage rights of multicast entries by each port;

and the interactive network television execution module is provided with a preview list for setting preview authority and a port authority list for recording the use authority of each port on the multicast list item.

6. The multicast system according to claim 1, wherein the optical network terminal is provided with a first multicast forwarding table, a first switching engine and a first internet group management protocol control module; the optical line terminal is provided with a second multicast forwarding table, a second switching engine and a second internet group management protocol control module; wherein,

the first multicast forwarding table is used for storing a mapping relation among a multicast address, a virtual local area network and a user port and controlling the first switching engine to forward the multicast data to the corresponding user port;

the first internet group management protocol control module is used for monitoring and analyzing an internet group management protocol report message passing through an optical network terminal, and updating the first multicast forwarding table and adding table items thereof according to the multicast authority of a user of the interactive network television execution module;

the second multicast forwarding table is used for storing a mapping relation among multicast addresses, virtual local area networks and multicast virtual channels of the passive optical network port and controlling the second switching engine to forward multicast data to the corresponding multicast virtual channels;

the second internet group management protocol control module is used for monitoring and analyzing the internet group management protocol report message passing through the optical line terminal, updating the second multicast forwarding table and adding the table entry thereof.

7. The multicast system according to claim 6, wherein the onu further comprises a gigabit ethernet mac filter module disposed between the multicast virtual channel and the first switching engine for selecting multicast data entering the onu.

8. A method for realizing a controllable multicast system in a passive optical network environment comprises the steps of,

a1, storing the multicast authority of each user;

a2, the optical network terminal of the multicast system receives the user request and sends it to the optical line terminal of the multicast system;

a3, the optical line terminal receives the user request of the optical network terminal, judges the multicast authority of the user, and sends control information to the optical network terminal according to the result;

a4, the optical network terminal receives the control information, sets the forwarding of multicast service flow, and controls the access of user port to multicast data.

9. The method according to claim 8, wherein in step a1, the multicast right of each user is stored in the olt or a separate server.

10. The method of claim 8, wherein the control information is transmitted between the olt and the onu, and when the olt receives a user request from the onu, the olt determines the user permission according to the multicast permission of the user, and sends the control information to the onu.

11. The method according to claim 8, wherein in step a3, the olt sends control information to the onu through an operation maintenance management channel of the pon.

12. The implementation method of claim 8, wherein step a3 specifically includes:

b1, the optical line terminal monitors and analyzes the report message of the Internet group management protocol;

b2, searching the multicast authority of the user;

b3, making a judgment whether the user or the port can access the multicast data;

and B4, sending the control information to the optical network terminal.

13. The method according to claim 8, wherein in step a4, the controlling the access of the user port to the multicast data includes:

c1, monitoring and analyzing the report message of Internet group management protocol;

c2, searching the multicast authority of the user;

c3, executing the operations of allowing, rejecting and previewing according to the multicast authority.

14. The method of claim 8, wherein step a4 is preceded by the steps of: and filtering the multicast data.

15. The method of claim 8, wherein the step A4 is further followed by the step A5: and recording the time point when the user requests the multicast service and leaves.