KR20060067108A - Method and apparatus for multicast forwarding in broadcast service based on multicast packet - Google Patents

Abstract

The present invention discloses a multicast forwarding method and apparatus capable of efficiently using a bandwidth between a data transmission device and a subscriber station and reducing zapping time. The apparatus of the present invention comprises a multicast forwarding information table; Membership master table; A membership reference count table; Upon receiving the signaling packet according to the remote control operation of the subscriber from the set-top, look up the multicast forwarding table to find the channel ID for the multicast IP, and look up the membership master table by the channel ID to find the corresponding port enable field. If the registration request, the corresponding field is set, and if the withdrawal is reset, the membership reference count table is looked up by the channel ID to find the corresponding port and the port of the adjacent channel that is in the broadcasting service, and counts up if the registration is canceled, and counts down with the withdrawal. A signaling protocol processor; And receiving a multicast packet from the broadcast server through the Internet, looking up the membership reference count table processed by the signaling protocol processing unit, copying the number of ports corresponding to a count value of 1 or more, and outputting the received multicast packet. It consists of a multicast packet processor that forwards to the port.

Multicast Packet, Broadcast, Group Management, Channel Registration, Membership Master Table, Reference Count

Description

TECHNICAL AND APPARATUS FOR MULTICAST FORWARDING IN BROADCAST SERVICE BASED ON MULTICAST PACKET}

1 is a block diagram of a multicast packet-based broadcast service network to which the present invention is applied;

2 is a configuration diagram of a membership master table of a communication system according to the present invention;

3 is a configuration diagram of a membership reference count table of a communication system according to the present invention;

4 is a flowchart illustrating a signaling protocol processing procedure of a communication system according to the present invention;

5 is a flowchart illustrating a multicast packet processing error in a communication system according to the present invention;

6 is a flowchart illustrating a procedure for processing a membership reference count table information error in a communication system according to the present invention.

<Description of the symbols for the main parts of the drawings>

101: communication system 102: server

103: set-top 104: subscriber terminal

The present invention relates to a multicast-based broadcast transmission technology. More particularly, the present invention relates to a multicast forwarding method capable of efficiently using a bandwidth between a data transmission device and a subscriber station and reducing zapping time. Relates to a device. In the present invention, a membership related table is configured adaptively to a subscriber's remote controller operation method, and a method for looking up a membership related table and broadcast data is shown. It may provide a method for transmitting.

In general, IP broadcasting service is a new data broadcasting service due to the convergence of communication and broadcasting technology, and has the characteristics of an interactive service and a customized service that enables two-way communication with customers that conventional terrestrial broadcasting cannot provide. Can provide.

IP broadcasting service is a service that delivers the same content to many recipients, but the current IP broadcasting service structure uses unicast method to transmit traffic redundantly, which can cause network overload or bottleneck, resulting in network bandwidth and content. There is an inefficient problem in terms of server utilization.

In order to solve this problem and efficiently use bandwidth, multicast technology has been widely used in broadcasting, video conferencing, and remote games for transmitting the same content to multiple people. In addition, in recent years, cable operators have developed broadcasting networks into an integrated network that simultaneously receives broadcasting and communications, and in response, existing network operators have made efforts to converge communications and broadcasting. Due to the nature of broadcasting, in which a receiver exists, there is a growing interest in a multicast scheme that can efficiently use a bandwidth of a communication network.

As such, IP multicast-based broadcast service is very efficient in terms of network resource utilization. In particular, unlike the unicast scheme, which is suitable for a live broadcast service having many simultaneous users and is limited by a limited number of subscribers, the multicast scheme can provide a service to almost unlimited subscribers with one multicast address. .

The multicast packet undergoes an IP multicast forwarding process in communication equipment located in a path from the communication network to the receiving terminal. Specifically, when a multicast packet is received in the communication system, the output port registered to the multicast address is found through the multicast address lookup. The multicast packet is copied according to the number of output ports and the packet is transmitted to the registered output port. In the high-capacity communication system, multicast address lookup is performed on the ingress board receiving the multicast packet, and the output port information is extracted from the egress board transmitting the packet. The subscriber station wishing to register or leave the multicast address requests registration or withdrawal from the communication system using a signaling protocol such as Internet Group Management Protocol (IGMP).

On the other hand, when a viewer switches a channel within a short time and checks the contents of the program being broadcast at the same time, it is called zapping. In the broadcasting cable network, all broadcasting data is transmitted to the subscriber terminal, and when the channel of the subscriber changes, If the broadcast data can be directly output to the terminal, there is no difference from the general terrestrial broadcast in terms of zapping time. However, if all the broadcast data is transmitted to the subscriber when providing the broadcast service in the communication network in this way, the bandwidth of the communication network will be seriously wasted.

On the contrary, when only broadcasting data including a multicast address assigned to a broadcasting channel is transmitted to a subscriber station, a zapping time may be lengthened when the subscriber's channel is changed.

The present invention transmits the broadcast data of the channel selected by the subscriber as well as the broadcast data of the channel selected by the subscriber to the port connected to the subscriber terminal of the output port of the communication system to improve the above problems, the network of connecting the communication system and the subscriber terminal It is an object of the present invention to provide a multicast forwarding method and a system capable of reducing zapping time while effectively using bandwidth.

In order to achieve the above object, the apparatus of the present invention comprises: a multicast forwarding information table; Membership master table; A membership reference count table; Upon receiving the signaling packet according to the remote control operation of the subscriber from the set-top, look up the multicast forwarding table to find the channel ID for the multicast IP, and look up the membership master table by the channel ID to find the corresponding port enable field. If the registration request, the corresponding field is set, and if the withdrawal is reset, the membership reference count table is looked up by the channel ID to find the corresponding port and the port of the adjacent channel that is in the broadcasting service, and counts up if the registration is canceled, and counts down with the withdrawal. A signaling protocol processor; And receiving a multicast packet from the broadcast server through the Internet, looking up the membership reference count table processed by the signaling protocol processing unit, copying the number of ports corresponding to a count value of 1 or more, and outputting the received multicast packet. It characterized in that it comprises a multicast packet processing unit for forwarding to the port.

In addition, in order to achieve the above object, the method of the present invention receives a signaling packet according to a remote control operation of a subscriber from a set-top, looks up a multicast forwarding table, finds a channel ID for a multicast IP, Look up the membership master table to find the corresponding port enable field and set the corresponding field if it is a registration request, and reset it if it is withdrawn; look up the membership reference count table by the channel ID and look up the corresponding port and the port of the adjacent channel that is broadcasting service. A signaling protocol processing step of counting up if registration is performed and counting down if leaving the service; and receiving a multicast packet through the Internet from a broadcast server, and looking up the membership reference count table processed by the signaling protocol processing step.A multicast packet processing step of copying the number of ports having a count value of 1 or more and forwarding the received multicast packet to an output port.

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

FIG. 1 is a block diagram of a multicast packet-based broadcast service network which is the background of the present invention. The broadcast server 102 provides an IP broadcast service and receives broadcast data from the server 102 through the Internet. The set-top 103 which is connected to the communication system 101 and the communication system 101 which is distributed to the set-top 103, generates zapping packets for changing channels according to a user's remote control operation and receives selected broadcast data. And a subscriber station 104 for reproducing broadcast data received via the set-top 103.

Referring to FIG. 1, the communication system 101 receives a broadcast packet through the Internet, switches to an output port to which a subscriber station is connected, and receives a zapping signal from the subscriber station and registers or withdraws a group from the multicast group. The communication system 101 of the present invention includes a signaling protocol processor for processing channel registration and channel withdrawal using a multicast forwarding table, a membership master table, and a membership reference count table. The multicast packet processing unit forwards the received multicast packets to the output port using the multicast forwarding table and the membership reference count table, and the membership reference count table which regenerates the membership reference count table using the membership master table when timed out. Information error processing unit.

The server 102 providing the IP broadcast service transmits all broadcast contents provided to the subscriber to the communication system 101 through the Internet, and the communication system 101 responds to the request from the set-top 103 to the server 102. The content received from the transmission to the set-top 103. And the content received by the set-top 103 is played in the subscriber terminal 104.

2 is a block diagram of a membership master table of the communication system 101 configured by the channel registration / departure request of the set-top 103 according to the present invention.

Referring to FIG. 2, the membership master table includes a plurality of channel ID fields 201 (CHID_1 to CHID_MAX) and n port enable fields (CHID_1_P1_EN to CHID_1_Pn_EN,. , CHID_MAX_P1_EN to CHID_MAX_Pn_EN).

The channel ID field 201 is a value assigned to the multicast IP and used to distinguish an entry of the membership master table. The Port 1 through Port n Enable fields 202 indicate presence or absence of channel registration from each port.

3 is a block diagram of a membership reference count table of the communication system 101 configured by the channel registration / departure request of the set-top 103 according to the present invention.

Referring to FIG. 3, the membership reference count table includes a plurality of channel ID fields (CHID_1 to CHID_MAX) and one channel enable field (302: CHID_1_EN to CHID_MAX_EN) connected to each channel ID field (CHID_1 to CHID_MAX). And n port reference count fields (303: CHID_1_P1_REF to CHID_1_Pn_REF, ..., CHID_MAX_P1_REF to CHID_MAX_Pn_REF).

The channel ID field 301 is a value assigned to the multicast IP and used to distinguish an entry of the membership reference count table. The channel enable field 302 indicates whether a multicast IP corresponding to an entry is available, that is, whether content is being served. The port reference count field (Port 1/2 /../ n RefCnt) 303 indicates the number of service references from each port and indicates the number of times referred to by a neighbor entry.

4 shows a flowchart of a signaling protocol processing operation of a communication system according to the present invention.

Referring to FIG. 4, first, a membership master table and a membership reference count table are initialized (401). When the initialization is completed, the set-top 103 waits to receive the signaling protocol packet transmitted (402).

When the packet is received, it is determined whether the packet is for a "channel registration request" (403). In the case of the channel registration request packet, the multicast forwarding information base (FIB) table is looked up using the multicast IP for the channel specified in the channel registration request packet (404).

The membership master table is looked up using a channel ID obtained as a result of a lookup (405). The port enable field of the entry obtained as a result of the lookup is set (step 406).

The Membership Reference Count Table is looked up using the Channel ID (407). In the reference count field for each port of the entry obtained as a result of the lookup, the reference count field for the port that receives the channel registration request packet is increased by “1” (408). The reference count field of the entry adjacent to the entry and the channel enable field of the entry is enabled is increased by “1” (409). .

If the received packet is not a channel registration request, it is determined whether it is for a "channel leaving request" (410). In the case of the channel leaving request packet, the multicast forwarding information base (FIB) table is looked up using the multicast IP for the channel specified in the channel leaving request packet (411). The Membership Master Table is looked up using the Channel ID obtained as a result of the lookup (412). The Port Enable field of the entry obtained as a result of the lookup is reset (413).

The Membership Reference Count Table is looked up using the Channel ID (414). The reference count field for the port that receives the channel exit request packet among the reference count fields of each entry of the entry obtained as a result of the lookup is decreased by “1” (415). The reference count field of the entry adjacent to the entry and having the entry channel enable field enabled is decremented by “1” (416).

5 is a flowchart of a multicast packet processing procedure of a communication system according to the present invention.

Referring to FIG. 5, this process illustrates a process in which the communication system 101 processes a multicast packet received from the server 102. First, wait for packet reception (501). If a packet is received, it is determined whether the packet is a multicast packet (502). If it is not a multicast packet, it waits for packet reception (501).

In the case of a multicast packet, the multicast forwarding information base (FIB) table is looked up using the multicast IP of the destination specified in the packet (503).

The Membership Reference Count Table is looked up using the Channel ID obtained as a result of the lookup (504). After the packet is copied as many as the number of ports whose Reference Count field value of each entry of the entry obtained as a lookup result is "1" or more (505), the packet is transmitted (506). Then wait again for packet reception (501).

6 is a flowchart of an information error processing procedure of a membership reference count table of a communication system according to the present invention. Referring to FIG. 6, in this process, an error that may be in the process of updating a membership reference count table performed when a channel registration / departure request from the set-top 103 is requested is performed. Use it periodically.

First, the timer is started (601) at system 101 startup. It is determined whether the timer has timed out (602). In the case of timeout, a reference count field for each port of the membership reference count table is regenerated using the membership master table (603).

The Port Count Reference Count field value of each entry in the Membership Reference Count Table indicates the entry of the corresponding Membership Master Table and its neighbors. Membership Reference Count Table Entry, which is determined by the value of the Enable field value of each port, and if the value of the Enable field value of each port of the Entry is ENABLE. Increase the reference count field value of each port by “1”.

Although the present invention has been described in more detail with reference to some embodiments, the present invention is not necessarily limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention.

As described above, according to the present invention, in accordance with the subscriber's channel registration / withdrawal request, it manages the membership master table and the membership reference count table to transmit not only the selected channel but also the broadcast data of the adjacent channel in which the broadcast is served, thereby providing bandwidth of the communication network. Efficient use of this provides the effect of reducing zapping time. That is, according to the present invention, first, a zapping time is reduced by performing a membership table update operation in a communication system performed when a subscriber's broadcasting channel is changed. Second, a zapping time that can be obtained when broadcast data of all channels are transmitted to the subscriber station can be obtained by transmitting broadcast data for a small number of adjacent channels.

Claims (15)

Multicast forwarding information table; Membership master table; A membership reference count table; Upon receiving the signaling packet according to the remote control operation of the subscriber from the set-top, look up the multicast forwarding table to find the channel ID for the multicast IP, and look up the membership master table by the channel ID to find the corresponding port enable field. If the registration request, the corresponding field is set, and if the withdrawal is reset, the membership reference count table is looked up by the channel ID to find the corresponding port and the port of the adjacent channel that is in the broadcasting service, and counts up if the registration is canceled, and counts down with the withdrawal. A signaling protocol processor; And When receiving a multicast packet from the broadcast server via the Internet, the membership reference count table processed by the signaling protocol processing unit is looked up, and the received multicast packet is copied by the number of ports whose count value is 1 or more. Multicast packet processor Multicast forwarding apparatus in a multicast packet-based broadcast service comprising a. According to claim 1, The multicasting forwarding device, If the timeout elapses after a predetermined time, the multicast forwarding in the multicast packet-based broadcast service further comprises a membership reference count table information error processing unit for regenerating the membership reference count table using the membership master table. Device. The method of claim 1, wherein the membership master table is A multicast forwarding apparatus in a multicast packet-based broadcast service, comprising: a plurality of channel ID fields and n port enable fields connected to each channel ID field. The method of claim 3, wherein the channel ID field is a value assigned to a multicast IP, and identifies an entry of a membership master table. The port 1 to port n enable field indicates the presence or absence of channel registration from each port multicast forwarding apparatus in the multicast packet-based broadcast service. The method of claim 1, wherein the membership reference count table is In a multicast packet-based broadcast service, a plurality of channel ID fields, one channel enable field connected to each channel ID field, and n port reference count fields connected to each channel enable field are provided. Multicast forwarding device. 6. The method of claim 5, wherein the channel ID field is a value assigned to a multicast IP and identifies an entry of a membership reference count table. The channel enable field indicates whether the multicast IP corresponding to the entry is available or not. 6. The apparatus of claim 5, wherein the port reference count field indicates the number of service references from each port and the number of times referred to by an adjacent entry. Upon receiving the signaling packet according to the remote control operation of the subscriber from the set-top, look up the multicast forwarding table to find the channel ID for the multicast IP, and look up the membership master table by the channel ID to find the corresponding port enable field. If the registration request, the corresponding field is set, and if the withdrawal is reset, the membership reference count table is looked up by the channel ID to find the corresponding port and the port of the adjacent channel that is in the broadcasting service, and counts up if the registration is canceled, and counts down with the withdrawal. Signaling protocol processing step; And When receiving a multicast packet through the Internet from a broadcast server, the membership reference count table processed by the signaling protocol processing step is looked up, the number of ports having a count value of 1 or more is copied, and the received multicast packet is forwarded to an output port. Multicast packet processing steps Multicast forwarding method in a multicast packet-based broadcast service comprising a. The method of claim 8, wherein the membership master table is It consists of a plurality of channel ID fields and n port enable fields connected to each channel ID field, The membership reference count table is In a multicast packet-based broadcast service, a plurality of channel ID fields, one channel enable field connected to each channel ID field, and n port reference count fields connected to each channel enable field are provided. Multicast forwarding device. The method of claim 9, wherein the signaling protocol processing step, Initializing the membership master table and the membership reference count table and receiving a signaling packet according to a remote controller operation of the subscriber from the settop; Determining the received packet and processing a channel registration request using the membership master table and the membership reference count table if it is a channel registration request packet; And If the received packet is determined and the withdrawal request packet is processed, processing the withdrawal request using the membership master table and the membership reference count table; Multicast forwarding method in a multicast packet-based broadcast service comprising a. The method of claim 10, wherein the registration request processing step Looking up the multicast forwarding information table using the multicast IP for the channel specified in the channel registration request packet to find a channel ID; Looking up the membership master table with the channel ID and setting a port enable field of the corresponding entry); Looking up the membership reference count table using the channel ID and incrementing a reference count field of a port that has received a channel registration request packet among port reference count fields of a corresponding entry by “1”; And Incrementing the reference count field of the entry adjacent to the corresponding entry and having the channel enable field of the entry enabled by &quot; 1 &quot; Multicast forwarding method in a multicast packet-based broadcast service, characterized in that consisting of. The method of claim 10, wherein the channel leaving request processing step Looking up the multicast forwarding information table using the multicast IP for the channel specified in the channel leaving request packet to obtain a channel ID; Looking up a membership master table using the channel ID and resetting a port enable field of an entry obtained as a result of the lookup; Looking up a membership reference count table using the channel ID and decreasing a reference count field of a port that has received a channel exit request packet from a port reference count field of a corresponding entry by “1”; And decrementing the reference count field of the entry adjacent to the corresponding entry and having an entry channel enable field enabled by "1". The method of claim 9, wherein the multicast packet processing step, If the packet received from the network is a multicast packet, looking up the multicast forwarding information table using the multicast IP of the destination specified in the packet to obtain a channel ID; And After looking up the membership reference count table using the channel ID, copying packets by the number of ports whose reference count field value of the corresponding port is “1” or more and transmitting the packet to the corresponding port. Multicast forwarding method in a multicast packet-based broadcast service comprising a. The method of claim 8, wherein the multicast forwarding method comprises: If a timeout elapses after a predetermined time, multicasting in a multicast packet-based broadcast service, further comprising: processing a membership reference count table information error to regenerate the membership reference count table using the membership master table. Forwarding method. 15. The method of claim 14, wherein the information error processing step The port-based reference count field value of each entry of the regenerated membership reference count table is determined as the port-enabled field value of the entry of the corresponding membership master table and its adjacent entries. Multicast forwarding method in.

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