KR100432937B1 - Multicast routing method and system for delivering multicast data with high-efficient on a mobile network - Google Patents

Abstract

The present invention relates to a method and system for performing multicast routing between a mobile communication terminal and a transmission server in a mobile communication network. The multicast routing method of the present invention receives a junction message sent from a mobile communication terminal. For the mobile communication terminal that sent the join message, the unique identifier of the mobile communication terminal as a multicast member is recorded in the multicast forwarding table. Using the unique identifier of the mobile communication terminal, the multicast packet provided from the transmitting server is transmitted to the mobile communication terminal belonging to the member of the multicast group. When the truncation message is transmitted from the mobile communication terminal, the unique identifier of the corresponding mobile communication terminal can be deleted from the multicast forwarding table.

Description

MULTICAST ROUTING METHOD AND SYSTEM FOR DELIVERING MULTICAST DATA WITH HIGH-EFFICIENT ON A MOBILE NETWORK}

The present invention relates to a method and system for performing efficient multicast routing between a mobile communication terminal and a transmission server in a mobile communication network.

By the early 1990s, only a few people knew how to use a computer, and among those who knew how to use a computer, only a few could use the Internet as a means of communication. The age has come. First launched in 1969 by the US Department of Defense for military purposes under the name ARPANET, the Internet began to gradually spread to the public until the 1990s, and it became popular only a few years ago. The main reason for the leap of the Internet is the commercialization of the World Wide Web (WWW). Recently, various services such as electronic commerce, electronic news, cyber stock trading, and electronic mail (e-mail) have been provided based on the Internet. Internet services are emerging as the most important business as they can be easily serviced.

Generally, the Internet refers to TCP / IP (Transmission Control Protocol / Internet) between a plurality of unit networks divided by IP addresses and a plurality of hosts having individual IP addresses provided in each unit network. Based on the Protocol, a data communication network capable of performing data communication using a Local Area Network (LAN), a Public Switched Telephone Network (PSTN), or an Asymmetric Digital Subscriber Line (ADSL). to be. In this case, the host means that a computer or a computer equipped with a communication modem and a telephone are connected, and mutual communication is possible only with a unique IP address assigned to each host.

1 shows a configuration diagram of such a general wired communication network.

Referring to FIG. 1, a conventional wired communication network includes a transmission server 10 for data transmission, a plurality of reception terminals 14 for receiving data transmitted from the transmission server 10, and a transmission server 10. It may include a transmitting router 12 for providing data to a designated receiving terminal 14.

In order to transmit data from the transmitting server 10 to the plurality of receiving terminals 14, a plurality of lines must be connected between the transmitting router 12 on the one transmitting server 10 side and the plurality of receiving terminals 14. In addition, when the number of receiving terminals 14 increases, the information amount of transmission data increases in proportion to the number of receiving terminals 14 even if the absolute amount of information (bandwidth) of the source information is small, thereby increasing the load on the communication network.

In order to solve this problem, the conventional Internet service using a wired communication network used a method called IP multicast (IP multicast).

2 is a block diagram of a wired communication network using a conventional multicast method.

Referring to FIG. 2, the conventional IP multicast installs a multicast router 20 for multicast communication at a specific point of the Internet network, for example, at a point close to the receiving terminal 14. The transmitting server 10 transmits a multicast packet using a class D multicast address to a destination address of the IP header. The multicast router 20 transmits the multicast packet transmitted from the transmitting router 12. The multicast packet is received and broadcasted to its own subnet network which is physically connected, thereby transmitting the multicast packet to the receiving terminal 14.

In this multicast routing method, a single line is connected between the transmitting router 12 and the multicast router 20 on the sending server 10 side, and between the multicast router 20 and the plurality of receiving terminals 14. It is connected by a plurality of lines. Therefore, since the multicast routing method can reduce the bandwidth of a line, it is a communication method that can achieve a great effect in a long-distance communication line such as a transmission of a large amount of multimedia data or an intercontinental communication line.

In this multicast communication, two protocols are required for the receiving terminal 14 to receive a multicast packet. One is a multicast routing protocol for forming a multicast tree from a multicast router 20 connected to a plurality of receiving terminals 14 to a transmitting router 12 connected to a sending server 10, and the other is a multicast routing protocol. Is IGMP (Internet Group Management Protocol), which is a member management protocol between the multicast router 20 and the receiving terminal 14.

A representative example of the multicast routing protocol is the Distance Vector Multicast Routing Protocol (DVMRP), which plays a role in constructing a multicast tree for transmitting multicast packets. In DVMRP, the multicast router initially sends a preceding message to the lower router, and the receiving lower router sends a prune message when there is no member in its sub-network. This truncation message constitutes one source-based shortest path tree that connects all members.

In addition, DVMRP uses a mechanism to regraft previously branched branch routers as needed. That is, since the multicast router that forwarded the truncation message has a new member because it was previously excluded from the multicast tree because it did not have a member, it constructs the multicast tree by forwarding a graft message to neighboring routers. Done. As soon as a multicast router with upstream data is received, it discards the previously received truncation message and reconstructs the tree. Therefore, the multicast router needs to know the multicast group existing in its own network, and does not need to know the terminals belonging to the multicast group.

This DVMRP was first proposed in RFC-1075 Version 1 by the Internet Engineering Task Force (IETF), up to version 3, and is now widely used in MBONE (Multicast backBONE).

DVMRP uses IGMP to route multicast packets. IGMP data packets consist of eight bytes.

3 shows a block diagram of an IGMP data packet.

Referring to FIG. 3, an IGMP data packet consists of a 4-bit IGMP version, a 4-bit IGMP type, a 16-bit checksum and a 32-bit group address. The IGMP type represents a query or report, and the checksum is the 16-bit 1's complement sum of 1's complement for the entire message.

On the other hand, recently, a mobile IP (Mobile IP) technology has been activated that enables users to continuously communicate without changing their IP address even if the user changes their location. Accordingly, multicast communication using a mobile communication terminal such as a cellular phone, Personal Digital Assistants (PDA), Code Division Multiple Access 2000 (CDMA2000), and International Mobile Telecommunication 2000 (IMT2000) is being performed.

4 is a block diagram of a conventional mobile communication network for multicast communication.

Referring to FIG. 4, a conventional mobile communication network includes a PDSN (Packet Data Serving Node) 44 and a PDSN connected to a transmission server 40 through an Internet / Intranet 42 to support mobile IP. A plurality of mobile communication terminals 50 performing multicast mobile communication via 44 are included.

In order to perform mobile communication using a mobile IP, a home agent (HA) and a foreign agent (FA) need help. The home agent (HA) stores the current location of the mobile communication terminal and serves to tunnel the multicast packet when the mobile communication terminal is far from the network. The external agent FA transmits location information of the mobile communication terminal to the home agent HA, and transmits data encapsulated from the home agent HA to the mobile communication terminal.

The PDSN 44 acts as an external agent (FA) for supporting mobile IP in the mobile communication network by establishing and releasing a link layer to the mobile communication terminal. Typically, the communication between the mobile communication terminal and the PDSN 44 in a CDMA2000 communication network consists of a Radio Access Network (RAN).

Typically, for multicast communication in a mobile communication network, DVMRP is used between the transmission server 40 and the PDSN 44, and IGMP is used between the PDSN 44 and the mobile communication terminal 50.

As such, when the method used in the wired communication network is applied to the mobile communication network as it is, the mobile communication terminal 50 must first subscribe to the PDSN 44 serving as a multicast router using IGMP. In the wired communication network, IGMP is suitable because the multicast router broadcasts the subnet as a shared medium. However, in the mobile communication network, there is no broadcasting means, and the mobile communication terminal 50 and the PDSN 44 Since it is mapped one-to-one in a Point-to-Point Protocol (PPP) session, it is not suitable for transmitting a multicast packet to a plurality of mobile communication terminals 50. In order to solve this problem, if the DVMRP is used between the mobile communication terminal 50 and the PDSN 44, the multicast packet can be received through the multicast tree. However, since the conventional DVMRP uses a broadcast / cutting scheme, There is a problem that the load on the PDSN 44 is increased and the waste of bandwidth is increased.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a multicast routing method capable of efficient mobile communication by improving DVMRP to be suitable for multicast communication between a PDSN and a mobile communication terminal.

In addition, an object of the present invention is to provide a multicast routing method capable of mobile communication by modifying the DVMRP of the downlink transmission path without having to implement a new multicast protocol.

It is also an object of the present invention to provide a multicast routing method that can reduce the load of the PDSN and prevent the reduction of bandwidth.

Accordingly, the present invention is to improve the protocol for transmitting multicast packets to be suitable for a mobile communication network, to reduce the investment cost for the mobile communication network, to provide an efficient multicast routing method and system that can provide a large capacity multimedia service do.

1 is a block diagram of such a general wired communication network.

2 is a block diagram of a wired communication network using a conventional multicast method.

3 is a block diagram of an IGMP data packet.

4 is a block diagram of a conventional mobile communication network for multicast communication.

5 is a block diagram of a mobile communication network for multicast communication according to an embodiment of the present invention.

6A is a diagram illustrating a configuration of a multicast forwarding table of DVMRP used in a wired communication network.

6B is a diagram illustrating a configuration of a multicast forwarding table of a PDSN modified to be suitable for a mobile communication network in a multicast routing method according to an exemplary embodiment of the present invention.

7 is a diagram illustrating a structure of a multicast packet transmitted through DVMRP in a wired communication network.

8 is a structural diagram showing the type of multicast packet using DVMRP;

9A is a structural diagram of a joint message (graft) or a joint acknowledgment message (graft-ack) in a multicast routing method according to a preferred embodiment of the present invention.

9B is a structural diagram of a truncation message in a multicast routing method according to a preferred embodiment of the present invention.

10 is a diagram illustrating a state diagram of a PDSN in a multicast routing method according to a preferred embodiment of the present invention.

11 is a diagram illustrating a state diagram of a mobile communication terminal in a multicast routing method according to an exemplary embodiment of the present invention.

(Name of the code for the main part of the drawing)

40: sending server 42: internet / intranet

44: PDSN 50: mobile communication terminal

In order to achieve the above object, the multicast routing system for mobile communication of the present invention is a system for performing multicast communication between a mobile communication terminal and a transmission server through a mobile communication network, for communication with a higher multicast router. A memory system having an uplink interface, a downlink interface for communicating with at least one mobile communication terminal, a multicast routing table and a multicast forwarding table formed by periodically exchanging update messages with an adjacent multicast router; And a control unit for performing multicast communication between a transmitting server and a mobile communication terminal using a multicast routing table and a multicast forwarding table, wherein the control unit corresponds to a corresponding mobile communication terminal according to a junction message transmitted from the mobile communication terminal. By recording the terminal's unique identifier in the multicast forwarding table, a multicast group is formed, and multicast packets provided from the transmitting server through the upper multicast router can be transmitted to the corresponding multicast group.

The multicast forwarding table may include at least one of an address of a source subnet to which a transmission server belongs, an address of a multicast group, uplink interface information, and downlink interface information for recording a unique identifier of the mobile communication terminal.

The unique identifier of the mobile communication terminal may be a PPP session ID.

The multicast packet includes an IP header and a multicast routing message, wherein the multicast routing message is a junction message for forming a multicast tree with a mobile communication terminal, and a truncation for truncating the multicast tree with a mobile communication terminal. And a join acknowledgment message indicating a join acknowledgment for the join message transmitted from the mobile communication terminal.

The mobile communication network may be at least one of CDMA, FDMA, and TDMA.

In the multicast routing system for mobile communication, the multicast routing protocol for communication with a mobile communication terminal may be DVMRP.

In addition, the mobile communication terminal of the present invention is a mobile communication system for performing multicast communication with a multicast routing system through a mobile communication network, the wireless interface for communication with the multicast routing system, and for receiving a multicast packet And a control unit for controlling the multicast tree formation with the multicast routing system, wherein the control unit forms a multicast tree with the multicast routing system and transmits a truncation message by transmitting a join message to the multicast routing system. This allows truncation of the multicast tree with the multicast routing system.

In addition, the multicast routing method in a mobile communication network of the present invention comprises the steps of: performing a multicast routing between a mobile communication terminal and a transmission server through a mobile communication network, receiving a junction message transmitted from the mobile communication terminal; Recording, in a multicast forwarding table, a unique identifier of the mobile communication terminal that has transmitted the join message as a member of a multicast group; and using the unique identifier of the mobile communication terminal, multicasting the multicast packet provided from the sending server. Transmitting to a mobile communication terminal belonging to a member of the cast group; and when a disconnect message is transmitted from the mobile communication terminal, deleting a unique identifier of the corresponding mobile communication terminal from the multicast forwarding table. .

The multicast routing method in the mobile communication network may further include transmitting a join acknowledgment message to the mobile communication terminal that transmitted the join message.

In addition, the multicast communication method of the mobile communication terminal of the present invention is a method of performing multicast communication with a multicast routing system through a mobile communication network, by transmitting a junction message to the multicast routing system, Forming a cast tree, receiving a multicast packet from a multicast routing system in which the multicast tree is formed, and truncating the multicast routing system and the multicast tree by sending a truncation message to the multicast routing system. It may include.

The multicast communication method of the mobile communication terminal may further include retransmitting the join message when the join acknowledgment message is not transmitted from the multicast routing system for a reference time after transmitting the join message.

The multicast communication method of the mobile communication terminal may further include retransmitting the truncation message when the multicast packet is received even after the truncation message is transmitted.

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

5 is a block diagram of a mobile communication network for multicast communication according to a preferred embodiment of the present invention.

Referring to FIG. 5, the mobile communication network of the present invention uses DVMRP between the transmission server 40 and the PDSN 44, and also uses the DVMRP between the PDSN 44 and the mobile communication terminal 50.

In general, the multicast router has a multicast routing table and a multicast forwarding information base in addition to the unicast routing table of the unicast router. Since DVMRP is also a protocol developed for multicast traffic transmission, it has a multicast routing table and a multicast forwarding table for multicast communication. Here, the multicast routing table is formed by the multicast router periodically exchanging update messages with neighboring routers. The multicast routing table is formed independently of the unicast routing table and includes items such as a source subnet, a subnet mask, a gateway, and a time-to-live (TTL). However, since the multicast routing table does not include group member information, a separate multicast forwarding table must be configured.

6A is a diagram illustrating a configuration of a multicast forwarding table of DVMRP used in a wired communication network.

Referring to FIG. 6A, the multicast forwarding table of DVMRP is composed of a source subnet, a multicast group, an input interface, and an output interface. Specifically, the source subnet is the address of the subnet where the multicast transmission server is located, and the multicast group is the address of the group to join. The input interface is an interface to which a multicast packet is input, and the output interface is an interface to externally output the multicast packet input through the input interface. Pr of the input interface indicates that a truncation message has been sent to the upper multicast router, and p of the output interface indicates that a truncation message has been received from the lower multicast router. When the multicast packet is received, the multicast forwarding table checks whether the multicast packet is input through the correct input interface, and copies the multicast packet to the output interface when the multicast packet is authorized through the correct input interface. Therefore, the multicast forwarding table is used to recognize tree information of the shortest path in the sending server and the multicast group.

When configuring the mobile communication network, it can be used in the PDSN without changing the multicast routing table used in the DVMRP of the wired communication network. However, the multicast forwarding table of DVMRP should be modified to suit the mobile communication network for the virtual PPP interface.

FIG. 6B is a diagram illustrating a configuration of a multicast forwarding table of a PDSN modified to be suitable for a mobile communication network in the multicast routing method according to an exemplary embodiment of the present invention.

Referring to FIG. 6B, the output interface of the multicast forwarding table is changed to the PPP session ID of the mobile communication terminal for multicast communication in the mobile communication network. That is, since the output interface of the PDSN can be thought of as a PPP interface which is a virtual interface, the unique PPP session ID of the mobile communication terminal is recorded in the output interface. Therefore, when a join message (graft) is transmitted from the mobile communication terminal, the unique PPP session ID of the mobile communication terminal corresponding to the output interface is recorded. Then, upon receiving the multicast packet from the upper multicast router, the multicast packet is transmitted to the mobile communication terminal recorded on the output interface. On the other hand, when a prune message is transmitted from the mobile communication terminal, the PPP session ID recorded in the output interface is deleted.

7 is a diagram illustrating a structure of a multicast packet transmitted through DVMRP in a wired communication network.

Referring to FIG. 7, a multicast packet transmitted through DVMRP includes an IP header and a DVMRP message part.

Version in the IP header is a version indicating the version of the IP protocol, the header length represents the length of the IP header in 32-bit units. Type of Service (TOS) indicates the priority, delay, throughput, and security required in the IP header. The total length is the total length of the multicast packet including the IP header and the DVMRP message, and may be up to 65,536 bytes in length. One message can be transmitted in a multi-packet packet divided in the network, the ID is to distinguish them so that they can be collected again at the receiving end. Fragment Offset indicates a position away from the start of a message when there are several multicast packets belonging to the same message. Time-To-Live represents the maximum time a multicast packet can exist on the network. Protocol is a part that refers to the protocol to which the multicast packet belongs, and if a wired network is used, it will correspond to IGMP. The header checksum is a part for checking an error of a multicast packet. The source address and destination address indicate the IP address of the sender and the IP address of the receiver that transmit the multicast packet. Option may indicate security, routing, type of data to be transmitted, and the like, and padding may be used as needed to configure a 32-bit multicast packet.

The DVMRP message part consists of the type and code of the message, the checksum for error checking, the minor version, the major version and the data being sent. At this time, the DVMRP code can be classified into five types according to the type of multicast packet transmitted in the wired communication network.

8 is a structural diagram illustrating a type of a multicast packet using DVMRP.

Referring to FIG. 8, types of multicast packets using DVMRP may be classified into probes, reports, prunes, grafts, and graft-acks. Probes are used to search for neighboring multicast routers, and reports are used to route routing tables. Prunes are used to truncate multicast trees, grafts are used to truncate multicast trees, and graft-acks are used to send acknowledgment messages for grafts. .

In this case, when the broadcasting / cutting mechanism used in the wired network is applied to the downlink transmission of the mobile network as it is, a probe message is transmitted to all mobile terminals to which the PPP session is established at about 10 second intervals. The report message is sent at about 60 second intervals. In particular, since the PDSN receives the multicast packet from the upper router and sends it to the mobile terminal in a batch, the mobile terminal receives the multicast packet once and then sends a pruning message when the PDSN does not want it. Will be sent to. Therefore, with the waste of the bandwidth of the mobile communication network, the load of the PDSN greatly increases. Thus, the multicast routing method of the present invention utilizes a grafting / disconnection mechanism that uses a graft-ack message for the downlink transmission of the PDSN without using probe and report messages.

In other words, using a mechanism to disconnect the connection with the corresponding mobile communication terminal by sending a preceding message from the PDSN to all mobile communication terminals and receiving a truncation message from the mobile communication terminal that does not want a multicast packet. Inefficient for multicast communication. Therefore, a joint message (graft) is received in advance from the mobile communication terminal that desires the multicast packet, and the multicast packet is transmitted to the mobile communication terminal that has transmitted the joint message (graft). Accordingly, when a join message (graft) is transmitted from the mobile communication terminal, the PDSN transmits a join acknowledgment message (graft-ack) to the corresponding mobile communication terminal and records the PPP session ID. Therefore, when the PDSN receives a graft or truncation message from the mobile communication terminal, it must update the multicast forwarding table accordingly.

As a result, when the multicast routing method of the present invention is implemented using DVMRP in the mobile communication network, the downlink broadcasting function is removed from the PDSN, and only the mobile communication terminals recorded in the multicast forwarding table are transmitted. . Accordingly, the mobile communication terminal only needs to have an uplink transmission function for the PDSN. As a result, the mobile communication terminal can join the multicast group by sending a join message (graft) to the PDSN and receive a join-acknowledgement message (graft-ack) sent from the PDSN to receive the multicast packet. In order to leave a multicast group, a prune message may be transmitted to a corresponding PDSN.

9A illustrates a structure diagram of a joint message or a grant acknowledgment message in a multicast routing method according to an exemplary embodiment of the present invention, and FIG. 9B illustrates a structure diagram of a prune message. will be.

9A and 9B, a joint message (graft) sent from a mobile communication terminal to a PDSN and a joint acknowledgment message (graft-ack) sent from a PDSN to a mobile communication terminal are the same type of message, code, and checksum. , A version, a source address indicating a transmission server, a group address indicating a multicast group, and a network mask of the source. Accordingly, the PDSN records the ID of the mobile communication terminal that has transmitted the multicast packet through a joint message sent from the mobile communication terminal, and the mobile communication terminal identifies the PDSN in which the multicast group is formed. Meanwhile, the truncation message prune transmitted to the PDSN for the withdrawal of the multicast group from the mobile communication terminal may further include a prune life time indicating a time for effectively storing the truncation message.

10 is a diagram illustrating a state diagram of a PDSN in a multicast routing method according to an exemplary embodiment of the present invention.

Referring to FIG. 10, the PDSN does not broadcast a multicast packet to a plurality of mobile communication terminals in an initial state, but waits until a junction message (graft) from the mobile communication terminal is transmitted. When a junction message (graft) is transmitted from the mobile communication terminal, the PDSN transmits a graft-ack to the corresponding mobile communication terminal, the mobile terminal corresponding to the output interface of the multicast forwarding table Record the PPP session ID of the communication terminal. Accordingly, the PDSN only transmits the multicast packet to the mobile communication terminal recorded on the output interface. On the other hand, when a truncation message is transmitted from the mobile communication terminal, the PPP session ID of the corresponding mobile communication terminal is deleted from the output interface of the multicast forwarding table.

11 is a diagram illustrating a state diagram of a mobile communication terminal in a multicast routing method according to an exemplary embodiment of the present invention.

Referring to FIG. 11, the mobile communication terminal transmits a join message (graft) to the PDSN in order to receive a multicast packet from the PDSN. After sending the junction message (PDSN), it is in a state of confirming that it is a member of a multicast group until receiving a junction acknowledgment message (graft-ack) from the PDSN, and from the PDSN for a reference time, If ack) is not received, retransmit the join message (graft). When a joint acknowledgment message (graft-ack) is received and a member of the multicast group, the multicast packet can be received from the PDSN. If no longer a multicast packet is desired, a prune is sent to the PDSN. When the truncation message is transmitted, the multicast group becomes a non-member state. When the multicast packet is transmitted even when the truncation message is transmitted, the truncation message is retransmitted. At this time, the joint message (graft) and truncation message (prune) transmitted from the mobile communication terminal to the PDSN will include the source address and the group address of the desired transmission server.

Although the multicast routing method of the present invention is typically applicable to the CDMA scheme, it will be apparent that the multicast routing method can be applied to various mobile communication networks such as frequency division multiple access (FDMA) and time division multiple access (TDMA).

As described above, the multicast routing method of the present invention enables efficient multicast communication by using a modified DVMRP between the mobile communication terminal and the PDSN interworking with one-to-one mapping. Accordingly, multicast communication can be easily performed in a mobile communication network without implementing a separate protocol for mobile communication.

In addition, in the multicast routing method of the present invention, the existing DVMRP is used as it is for uplink transmission and the DVMRP is modified in the downlink transmission, so that the multicast router used in the wired communication network can be used as it is, and thus the cost and maintenance cost of the multicast implementation are maintained. Can reduce the cost.

In addition, the multicast routing method of the present invention can reduce the bandwidth of 1 / n between the PDSN and the transmitting server when there are n mobile communication terminals, compared to the unicast scheme.

In addition, since the multicast routing method of the present invention does not use the router discovery function and the routing table exchange function used in the DVMRP of the wired communication network, the load of the PDSN can be reduced and the bandwidth can be reduced. In addition, since the mobile communication terminal does not have to periodically respond to the multicast router, battery consumption can be reduced.

As a result, the multicast routing method of the present invention can not only effectively cope with the evolution of the mobile communication network by implementing a multicast technology suitable for the mobile communication network, but also effectively manage the investment cost and efficiently manage the large capacity multimedia service. Can provide.

In the above, the multicast routing method and system according to the present invention have been described in detail through preferred embodiments, but the contents are not limited to the field of the present invention described in the following claims. In addition, in the art, it will be apparent to those skilled in the art that various changes or modifications are made within the scope of the present invention.

Claims (14)

A system for performing multicast communication between a mobile communication terminal and a transmission server through a mobile communication network, An up interface for communicating with an upper multicast router; A downlink interface for communicating with at least one mobile communication terminal; A memory system having a multicast routing table and a multicast forwarding table formed by periodically exchanging update messages with adjacent multicast routers; And A control unit for performing multicast communication between a transmitting server and a mobile communication terminal using the multicast routing table and the multicast forwarding table Including, The control unit A multicast group is formed by recording a unique identifier of a corresponding mobile communication terminal in a multicast forwarding table according to a junction message transmitted from the mobile communication terminal. Multicast routing system for mobile communication that transmits to the multicast group. The method of claim 1, The multicast forwarding table is At least one of an address of a source subnet to which a sending server belongs, an address of a multicast group, uplink interface information, and downlink interface information recording a unique identifier of a mobile communication terminal; Multicast routing system for mobile communication comprising a. The method of claim 1, The unique identifier of the mobile communication terminal Multicast routing system for mobile communications, which is a PPP session ID. The method of claim 1, Messages sent and received with the mobile terminal A join message for forming a multicast tree with a mobile communication terminal; Truncation message for truncating a multicast tree with a mobile communication terminal; And At least one of a join acknowledgment message informing of the join acknowledgment, for the join message transmitted from the mobile communication terminal Multicast routing system for mobile communication comprising a. The method of claim 1, The mobile communication network A multicast routing system for mobile communications that is at least one of CDMA, FDMA, and TDMA. The method of claim 1, A multicast routing protocol for communication with a mobile terminal is DVMRP. A mobile communication system performing multicast communication with a multicast routing system through a mobile communication network, An air interface for communicating with a multicast routing system; And Control unit for controlling multicast tree formation with a multicast routing system to receive multicast packets Including, The control unit And a truncated multicast tree with the multicast routing system by sending a junction message to the multicast routing system to form a multicast tree with the multicast routing system and sending a truncation message. A method of performing multicast routing between a mobile communication terminal and a sending server through a mobile communication network, Receiving a join message sent from a mobile communication terminal; Recording, in a multicast forwarding table, a unique identifier of the mobile communication terminal that sent the join message as a member of a multicast group; Transmitting a multicast packet provided from a transmitting server to a mobile communication terminal belonging to a member of the multicast group using a unique identifier of the mobile communication terminal; And Deleting the unique identifier of the corresponding mobile communication terminal from the multicast forwarding table when the truncation message is sent from the mobile communication terminal; Multicast routing method in a mobile communication network comprising a. The method of claim 8, Transmitting a join acknowledgment message to the mobile communication terminal that sent the join message; Multicast routing method in a mobile communication network further comprising. In the method for performing multicast communication with a multicast routing system via a mobile communication network, Sending a join message to the multicast routing system to form a multicast tree with the multicast routing system; Receiving a multicast packet from a multicast routing system with a multicast tree formed; And Truncating the multicast routing system and the multicast tree by sending a truncation message to the multicast routing system Multicast communication method of a mobile communication terminal comprising a. The method of claim 10, After sending the junction message, if the junction acknowledgment message is not sent from the multicast routing system during the reference time, retransmitting the junction message. Multicast communication method of a mobile communication terminal further comprising. The method of claim 10, Resending the truncation message if a multicast packet is received even after sending the truncation message Multicast communication method of a mobile communication terminal further comprising. In order to perform multicast routing between the mobile communication terminal and the transmission server through the mobile communication network, a program of instructions that can be executed by the digital processing apparatus is tangibly implemented and recorded on a recording medium that can be read by the digital processing apparatus. In The multicast routing method, Receiving a join message sent from a mobile communication terminal; Recording, in a multicast forwarding table, a unique identifier of the mobile communication terminal that sent the join message as a member of a multicast group; Transmitting a multicast packet provided from a transmitting server to a mobile communication terminal belonging to a member of the multicast group using a unique identifier of the mobile communication terminal; And Deleting the unique identifier of the corresponding mobile communication terminal from the multicast forwarding table when the truncation message is sent from the mobile communication terminal; Computer program product comprising a. In order to perform multicast communication with a multicast routing system through a mobile communication network, a program of instructions that can be executed by a digital processing apparatus is tangibly implemented, and in a recording medium that can be read by a digital processing apparatus, The multicast communication method, Sending a join message to the multicast routing system to form a multicast tree with the multicast routing system; Receiving a multicast packet from a multicast routing system with a multicast tree formed; And Truncating the multicast routing system and the multicast tree by sending a truncation message to the multicast routing system Computer program product comprising a.