JP2000253043A - Packet communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To apply a packet communication method even to a large scale network by relieving a processing load required for transfer of a permission list and reducing the storage capacity required for a transfer node in the case of realizing communication with limited transmission and reception terminals. SOLUTION: A communication server 140 that grasps what terminal a transfer node accommodates and sets a packet transfer path between transfer nodes centrally receives applications from terminals capable of transmission/reception to set a transfer path between the transfer nodes only when a reception request from the reception terminal is permitted in advance. Furthermore, the communication control server 140 sets the transmission permission list of the terminals capable of transmission only to the transfer node accommodating the terminal capable of transmission so as to reduce a storage area required for the transfer node and to reduce the number of messages between the communication control server 140 and the transfer node.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to communication for limiting a transmitting terminal and a receiving terminal, and for example, to a packet communication method applicable to multicast communication.

[0002]

2. Description of the Related Art In multicast communication, a receiving terminal requests a network to receive a packet addressed to a multicast address, a transmitting terminal sends a packet addressed to a multicast address to a network, and the network transmits the packet. This is a communication method in which packets are duplicated by the number of receiving terminals that have made a reception request, and the duplicated packets are transferred to the receiving terminals.

In the multicast communication, a plurality of receiving terminals can make a reception request to one multicast address, and a plurality of transmitting terminals can transmit a packet to one multicast address. Therefore, it has the feature that communication can be performed between many terminals at the same time. In addition, when multicast communication is used, the transmitting terminal can transmit packets to a plurality of receiving terminals by transmitting only one packet, so that the transmitting terminal does not need to duplicate packets for the number of receiving terminals.
It has the feature that the load on the terminal can be reduced.

For this reason, the multicast communication is a technique capable of realizing a broadcast, data distribution, and conference system at low cost. However, in multicast communication,
Since the transmitting terminal can transmit packets to many terminals at the same time by transmitting one packet addressed to the multicast address, a malicious terminal transmits a large number of packets to the multicast address, thereby transmitting many packets on the network. It is possible to cause congestion by causing the presence of packets of the same type, and to prevent this, it is necessary to limit the terminals that can transmit packets addressed to the multicast address.

[0005] Also, since the receiving terminal receives a multicast packet transfer from the network by making a reception request for the multicast address, a malicious terminal requests reception of a large number of multicast addresses.
It is possible to cause a network to duplicate a large number of packets and cause congestion. To prevent this, it is necessary to limit the terminals that can receive packets addressed to a multicast address.

[0006] In the conventional multicast communication, a transfer node existing on a network controls the route of the multicast communication. That is, the receiving terminal issues a request for receiving the multicast address to the forwarding node, and the forwarding node notifies other forwarding nodes in the network that the receiving terminal exists under the own forwarding node, and the forwarding is notified. The node creates a list of forwarding nodes where the multicast address and the receiving terminal exist, and the forwarding node receiving the multicast packet refers to the list and forwards the multicast packet to the forwarding node where the receiving terminal exists.

In the conventional multicast communication, the following two methods are conceivable as methods for restricting the transmitting terminal and the receiving terminal.

In the first method, a list (permission list) of a transmittable terminal address and a receivable terminal address for each multicast address communicated on the network is set in each transfer node, and the transmission terminal transmits the list to the transfer node. Of the transmitted multicast packets, the forwarding node forwards only those multicast packets whose destination address and source address have been confirmed to match the permission list, or the requested address in the reception request from the receiving terminal to the forwarding node. This is a method in which the transfer node accepts only a reception request that confirms that the requesting terminal address matches the permission list.

[0009] Since the forwarding node may be involved in all multicast communications on the network, this method requires that all forwarding lists be set in all the forwarding nodes. Therefore, there is a problem that the load of the permission list setting process on the transfer node is high, and the storage capacity required for holding the permission list of the transfer node is large. For this reason, the first method can be applied only to a small-scale network having few permission lists and forwarding nodes.

[0010] The second method is to install a server (permission list server) that holds a permission list on a network, and when a forwarding node receives a multicast packet or a reception request for multicast, a packet is received. This method analyzes the terminal that has made a transmission or reception request of the request, makes an inquiry to the permission list server, and transfers only packets that match the inquiry result, or accepts a reception request that matches.

According to this method, each transfer node does not need to hold the permission list, and the storage area of the transfer node is reduced. However, since the inquiry to the permission list server is performed after the arrival of the multicast packet or the reception request, the processing takes a long time, and the transmission delay of the multicast packet and the frequent exchange of the message between the permission list server and the node are reduced. As a result, the processing load on the forwarding node increases. For this reason, the second method can be applied only to a small-scale network having a small number of transfer nodes.

[0012]

When the above-described method is used, the storage capacity required for the transfer node is large, or the communication processing load between the permission list server and the transfer node is high, so that the method cannot be applied to a large-scale network. There was a problem.

According to the present invention, a server (communication control server) for determining which terminals are accommodated by a transfer node and setting a packet transfer path between the transfer nodes concentrates the reception of reports for transceivable terminals. By doing so, the purpose is to eliminate the need for setting to all forwarding nodes. In addition, the communication control server sets only the permission list for the transmittable terminals accommodated in the transfer node in the transfer node, thereby reducing the storage area required for the transfer node and reducing the messages between the communication control server and the transfer node. The purpose is to do.

[0014]

According to the present invention, in order to solve the above-mentioned problems, when limiting a receiving terminal, a communication control client sends a communication destination address (DA) to a communication control server. And a receiving terminal identifier that permits reception of a packet to which the terminal address is assigned as DA. When this report is made, the communication control server creates and manages a set (reception permission list) of a terminal address serving as DA and a reception terminal identifier permitted to receive a packet with the terminal address given as DA.

When the receiving terminal transmits to the communication control server a reception request composed of a set of the DA requesting reception and its own terminal identifier, the reception request in the reception request received by the communication control server is received. The set of the DA and the identifier of the terminal that made the request matches the set of the terminal address that is the DA and the identifier of the receiving terminal that is permitted to receive the packet assigned the terminal address as the DA, which is included in the reception permission list. The communication control server sets a transfer path from the source node to the destination node for the packet whose DA is the terminal address only when the communication control server confirms that the terminal address has been checked.

On the other hand, if the received address does not match the set of the terminal address serving as the DA and the receiving terminal identifier permitted to receive the packet assigned the terminal address as the DA, or the communication control server If the reception permission list does not exist, the communication control server does not accept the reception request and does not set the transfer route from the source node to the destination node. , Enable the reception of the packet to which the DA requesting the reception is added. Here, setting of a transfer path between transfer nodes means, for example, setting information of transferable destination nodes in a transfer table managed by the transfer node for packet transfer.

Further, when restricting the transmission terminal, the communication control client transmits to the communication control server a terminal address that is a DA and a transmission terminal address that permits transmission of a packet to which the terminal address is assigned as the DA. Report the pair. When this report is made, the communication control server creates a set (transmission permission list) of the terminal address serving as DA and the transmission terminal address permitted to transmit the packet in which the terminal address is given as DA, and permits transmission. A transmission permission list is set in the source node that accommodates the specified transmission terminal.

The transmitting terminal is the source node, the DA is the terminal address for which the DA is permitted, and the source address (SA: Source A)
ddress) transmits a packet having its own terminal address, and the source node transmits the DA of the received packet and the DA of the transmission permission list and the SA of the packet including the DA transmits the DA of the transmission permission list. The packet is forwarded to the destination node only when it is confirmed that the address matches the terminal address that permits the packet transmission.
If the set does not match the set of DAs included in the transmission permission list and the terminal addresses permitted to transmit, or if the transmission permission list does not exist at the source node, the source node transmits the packet transmitted by the transmission terminal. By discarding, only the transmitting terminal permitted to transmit a packet to the terminal address declared by the communication control client to the communication control server can transmit the packet with the receiving terminal address given as DA to the receiving terminal.

The operation of the present invention is as follows. According to the present invention, by declaring a terminal capable of transmitting and receiving an address to the communication control server, the communication control server accepts only a reception request from a permitted terminal, sets a route between destination and destination nodes, and By setting a permission list in the source node accommodating the permitted transmitting terminal and transferring only the packets transmitted by the permitted transmitting terminal, the transmitting node can perform communication only between the permitted transmitting and receiving terminals. .

In the present invention, since the communication control server manages the permission list in a centralized manner, it is not necessary for each transfer node to accept the reception permission, thereby reducing the processing load on the transfer node. Can be.

Further, since the communication control server, which knows the terminals accommodated by the transfer nodes, distributes only the permission list relating to the transmission terminals to only the transfer nodes accommodating the transmission-permitted terminals, the permission control for all the transmission terminals is performed. Compared to the method of distributing lists, the amount of permission lists that the forwarding node needs to hold can be reduced, and the processing load required for permit list transfer and the storage capacity required for the forwarding nodes are reduced. be able to.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS [First Embodiment] FIG. 1 is a diagram for explaining a first embodiment of the present invention, in which a terminal is connected to a network in which a communication control server 140 exists. This shows a situation where multicast communication is being performed. In the figure, reference numerals 120 to 121 denote transmission terminals, of which 120 are transmission terminals which have been declared as transmittable terminals, 1
Reference numeral 21 denotes an unreported transmitting terminal. 130-1
31 is a receiving terminal, of which 130 is a receiving terminal that has been declared as a receivable terminal, and 131 is a receiving terminal that has not been reported. Reference numerals 101 to 104 denote forwarding nodes, of which the forwarding nodes 101 to 102 are originating nodes accommodating transmitting terminals, and the forwarding nodes 103 to 104 are destination nodes accommodating receiving terminals. 110 is a communication control client. Reference numeral 140 denotes a communication control server, 141 denotes a transmission / reception permission report receiving unit which is an internal mechanism of the communication control server 140, and 142 denotes a reception request receiving unit. Reference numeral 200 denotes a report of a terminal capable of transmitting and receiving from the communication control client 110 to the communication control server 140. Reference numeral 210 denotes registration of a permission list to the source node. Reference numeral 211 denotes setting information of a packet transfer path to the transfer node. Reference numerals 220 and 221 represent reception requests from the receiving terminals 130 and 131, respectively. 23
0,231 indicates a multicast packet.

Hereinafter, with reference to FIG. 1, FIG. 2, and FIG. 3, an operation until a receiving terminal receives a packet will be described as a first embodiment of the present invention. In FIG. 1, the communication control client 110 declares to the communication control server 140 a set of a multicast address and a receiving terminal identifier that permits reception of a packet to which the multicast address is assigned as DA. FIG. 2A shows a specific example of information to be declared. The communication control client 110 reports to the communication control server 140 one or more reception-permitted terminal identifiers for the multicast address. The communication control server 140 creates a list (reception permission list) of the multicast addresses and the identifiers of the receiving terminals that are permitted to receive the packet with the multicast address assigned as DA, based on the declared information.

The operation so far is shown in the flowchart of FIG. In step S1, a report of a set of (a receiving terminal identifier capable of receiving a packet with address 1 and address 1 as DA) is accepted. In response to this report, in step S2, a packet with (address 1 and address 1 as DA) A reception permission list of reception terminal identifiers (reception terminal identifiers capable of receiving the URL) is created.

In this example, the receiving terminal 130 described in the receiving permission list transmits the receiving request 220 to the receiving request receiving unit 14.
Going to 2. FIG. 2B shows a specific example of the reception request. Reception request receiving unit 14 of communication control server 140
When the reception request 220 is received from the reception terminal 130, the reception request 220 is analyzed, and the reception request multicast address and the reception request terminal identifier are changed to a packet in which the multicast address in the reception permission list and the multicast address are assigned as DA. Since the received ID matches the set of receiving terminal identifiers permitted to receive the
0, and the setting information 2 of the transfer route to the receiving terminal 130
11 is set so that the receiving terminal 130 can receive the multicast packet 230.

On the other hand, the receiving terminal 131 not described in the receiving permission list transmits the receiving request 221 to the receiving request receiving unit 142.
The reception request receiving unit 142 analyzes the reception request 221 and determines that the reception request multicast address and the reception terminal identifier do not match the reception permission list.
Is not received, and the setting based on the transfer path setting information 211 is not performed. Therefore, the multicast packet 232 is
It does not reach the receiving terminal 131.

The operation so far is shown in the flowchart of FIG. First, in step S10, a reception request is received. In step S11, it is checked whether or not a reception permission list exists. If not, the process proceeds to step S15, and the reception request is rejected. If there is a reception permission list, step S
In step 12, it is checked whether the set of (reception request address and reception request source terminal identifier) matches the reception permission list. If not, the process proceeds to step S15 and the reception request is rejected. If they match, the reception request is accepted in step S13, and a transfer path is set between the outgoing and incoming transfer nodes in step S14. Thereafter, the process returns to step S10 to wait for another reception request.

As described above, according to the present embodiment, since the above-described operation is performed, only the specific terminal that has declared can receive the multicast packet. In addition, since the present embodiment has the above-described configuration, the effect thereof is that the processing load required for setting the permission list, the processing load required for transferring the permission list, The storage capacity required for the transfer node can be reduced, and there is an effect that communication that limits the number of receiving terminals and has scalability with respect to the network scale and the communication scale can be provided.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIG. Figure 1
The figure shows a situation in which a terminal is connected to the network where the communication control server 140 exists and is performing multicast communication. The description of the components in the figure is the same as in the first embodiment.

Hereinafter, with reference to FIG. 1, FIG. 4, and FIG. 5, an operation from a transmitting terminal transmitting a packet to a receiving terminal receiving the packet will be described as a second embodiment of the present invention. In FIG. 1, the communication control client 110 reports to the communication control server 140 a set of a multicast address and a transmission terminal address that permits transmission of a packet with the multicast address assigned as DA.

FIG. 4A shows a specific example of information to be declared. The communication control client 110 reports to the communication control server 140 one or more transmission-permitted terminal addresses for the multicast address. The communication control server 140 creates a list (transmission permission list) of a set of a multicast address and a transmission terminal address permitted to transmit a packet to which the multicast address is assigned as a DA based on the declared information, and transmits the list. The transmission permission list is registered 210 in the transfer node 101 which is the source node that accommodates the transmission terminal 120 described in the permission list.

The operation so far is shown in the flowchart of FIG. In step S20, a report of (transmission terminal address capable of transmitting a packet with address 1 and address 1 as DA) is accepted. In contrast, step S2
In step 1, a transmission permission list of (transmission terminal address capable of transmitting a packet having address 1 and address 1 as DA) is created, and in step S22, the transmission permission list is registered in the transfer node accommodating the transmission terminal.

Transmission terminal 12 described in transmission permission list
0 transmits the multicast packet 230 to the forwarding node (originating node) 101. FIG. 4B is a specific example of a multicast packet transmitted by the transmitting terminal. When the forwarding node 101 receives the multicast packet 230 from the transmitting terminal 120, the forwarding node 101 analyzes the multicast packet 230, and the DA and the SA determine the multicast address of the transmission permission list and the packet of the packet assigned the multicast address as DA. The multicast packet 230 is transmitted to the forwarding node (destination node) 1 because it matches the pair with the transmission terminal address that permits transmission.
Transfer to 03.

On the other hand, when the transmitting terminal 121 not described in the transmission permission list transmits the multicast packet 231 to the forwarding node (source node) 102, the forwarding node 102
Discards the multicast packet 231 when the transmission permission list is not set, and analyzes the multicast packet 231 when the transmission permission list is set. Here, since the DA and SA do not match the set of the multicast address in the transmission permission list and the transmission terminal address that permits transmission of the packet assigned the multicast address as DA, the transfer node 102
Discards the multicast packet 231.

The operation up to this point is shown in the flowchart of FIG. In step S30, transmission of the multicast packet is detected, and in step S31, it is checked whether or not there is a transmission permission list. If there is no transmission permission list, the process proceeds to step S34, where the multicast packet is discarded. If there is a transmission permission list, it is checked in step S32 whether the set of (destination address, transmission source address) matches the transmission permission list.
Proceed to step S34 to discard the multicast packet. Only when they match, the multicast packet is transferred in step S33.

As described above, according to the present embodiment, only the declared specific terminal can transmit the multicast packet to the receiving terminal because of the above-described operation. In addition, since the present embodiment has the above-described configuration, the effect thereof is that the processing load required for setting the permission list, the processing load required for transferring the permission list, The storage capacity required for the transfer node can be reduced, and there is an effect that communication that limits the transmitting terminal and has scalability with respect to the network scale and the communication scale can be provided.

[Third Embodiment] In the third embodiment, the above-described first embodiment and the second embodiment are simultaneously realized. FIG. 1 shows the third embodiment of the present invention.
FIG. 3 is a diagram for explaining an embodiment of the present invention, and shows a communication control server 1;
This shows a situation in which a terminal is connected to the network in which 40 exists and performing multicast communication. The description of the components in the figure is the same as in the first embodiment.

By the operation of the first and second embodiments, only the declared transmitting / receiving terminal performs the multicast communication, and the other terminals can provide a multicast service in which the multicast communication cannot be performed. . Further, since the present embodiment has the above-described configuration, the effect thereof is as compared with the conventional method.
A transmission / reception terminal that can reduce the processing load required for setting the permission list, reduce the processing load required for transferring the permission list, and reduce the storage capacity required for the transfer node, and has scalability for the network scale and communication scale. There is an effect that communication can be provided for limiting

[0039]

As described above, according to the present invention,
Since it is possible to provide a multicast communication environment where only specific terminals can use multicast communication,
It can provide essential functions for commercial use of multicast communication, such as eliminating transmission interference from unauthorized users, preventing inflow of multicast packets due to reception of unauthorized users, and limiting senders and receivers to multicast addresses in pay broadcasting. effective.

In particular, the present invention is applicable not only to multicast communication, but also to communication in which transmission and reception terminals need to be limited.
Applicable.

Also, compared to other communication systems that limit the terminals capable of transmitting and receiving, (1) since the communication control server manages the permission list in a centralized manner, each transfer node does not need to hold the permission list. The storage area necessary for holding the list can be reduced. (2) Since the communication control server collectively receives declarations of terminals capable of transmitting and receiving, the number of declarations made by the communication control client can be reduced as compared with the method of registering the permission list in all transfer nodes on the network. (3) The communication control server grasps the terminal accommodated by the transfer node, and distributes the permission list for all the transmission terminals only to the transfer node where the transmission terminal exists. Can reduce the setting operation to the forwarding node and reduce the amount of permission lists that the forwarding node needs to retain compared to the method that retains them, thus reducing the processing load required for forwarding the permission list. , And the storage capacity required for the transfer node can be reduced. Due to the above advantages, the present invention has an effect of providing communication that is scalable with respect to a network scale and a communication scale and that limits transmission and reception terminals.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention.

FIG. 2 is a diagram illustrating a specific example of a receivable terminal declaration and a specific example of a reception request.

FIG. 3 is a flowchart illustrating a report process and a reception request reception process of a receivable terminal.

FIG. 4 is a diagram showing a specific example of a transmittable terminal report and a specific example of a multicast packet transmitted by a transmitting terminal.

FIG. 5 is a flowchart illustrating a report process and a transmission packet process of a transmission capable terminal.

[Explanation of symbols]

 101-104 Forwarding node 110 Communication control client 120,121 Transmission terminal 130,131 Receiving terminal 140 Communication control server 141 Transmission / reception permission report receiving unit 142 Receive request receiving unit 220,221 Receive request 230-232 Multicast packet

Continuing on the front page (72) Inventor Jun Shingu, Nippon Telegraph and Telephone Corporation 3-9-1-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo (72) Inventor Hiroyuki Ichikawa 3-192-2 Nishi-Shinjuku, Shinjuku-ku, Tokyo Nippon Telegraph and Telephone Telephone Co., Ltd. (72) Inventor Nobuaki Tanaka 223-1 Yamashita-cho, Naka-ku, Yokohama-shi, NTT Software Corporation (72) Inventor Keigo Niwa 223 Yamashita-cho, Naka-ku, Yokohama-shi, Kanagawa No. 1 F-term in NTT Software Corporation (reference) 5K030 GA06 HA08 HD09 JA07 LB05 LC01 LD06 LD11

Claims (3)

[Claims] 1. A packet communication method for transferring a packet between an outgoing and incoming transfer node only when a communication control server sets a transfer route from an outgoing / forwarding node accommodating a transmitting terminal to an incoming / outgoing transfer node accommodating a receiving terminal. The communication control server receives in advance a report of a set of a terminal address serving as a transmission destination address and a reception terminal identifier permitting reception of a packet having the terminal address given as the transmission destination address, and based on the report. , A reception permission list including a pair of a terminal address serving as a transmission destination address and a reception terminal identifier permitted to receive a packet having the terminal address assigned as the transmission destination address is created, Reception consisting of a set of the transmission destination address for requesting reception to the communication control server and the own terminal identifier When the communication control server that has transmitted the request and received the reception request confirms that the combination of the transmission destination address requested to be received in the reception request and the terminal identifier that made the request is included in the reception permission list. Only when the communication control server does not have the reception permission list or when the reception request is received, the transmission path from the originating transfer node to the destination transfer node for the packet whose transmission destination address is the terminal address is set. When the set of the requested transmission destination address and the identifier of the terminal that made the request is not included in the reception permission list, the reception request is not accepted and the transfer route from the originating transfer node to the destination transfer node is not set. A packet communication method characterized by the above-mentioned. 2. A packet communication method for transferring a packet between an outgoing and incoming transfer node only when a communication control server sets a transfer path from an outgoing and forward node that accommodates a transmitting terminal to an incoming and outgoing forward node that houses a receiving terminal. The communication control server receives in advance a report of a set of a terminal address serving as a transmission destination address and a transmission terminal address permitting transmission of a packet having the terminal address given as the transmission destination address, and based on the report. , A transmission permission list comprising a pair of a terminal address serving as a transmission destination address and a transmission terminal address permitted to transmit a packet to which the terminal address is assigned as a transmission destination address, and transmitting the created transmission permission list, The originating / forwarding node that accommodates the authorized transmitting terminal is set, and the transmitting / receiving node transmits When the received packet is received, it checks whether the set of the transmission destination address and the source address of the received packet is included in the transmission permission list, and if the packet is included, transfers the packet to the destination transfer node. On the other hand, when the transmission permission list does not exist in the originating and forwarding node, or when the set of the transmission destination address and the transmission source address of the received packet is not included in the transmission permission list, the packet transmitted by the transmission terminal is received and transferred. A packet communication method characterized by not transferring the packet to a node. 3. A packet communication method in which a packet is transferred between an outgoing and incoming transfer node only when a communication control server sets a transfer path from an outgoing and forward transfer node that accommodates a transmitting terminal to an incoming and outgoing transfer node that houses a receiving terminal. The communication control server receives in advance a report of a set of a terminal address serving as a transmission destination address and a reception terminal identifier permitting reception of a packet having the terminal address given as the transmission destination address, and based on the report. , A reception permission list including a pair of a terminal address serving as a transmission destination address and a reception terminal identifier permitted to receive a packet having the terminal address assigned as the transmission destination address is created, Reception consisting of a set of the transmission destination address for requesting reception to the communication control server and the own terminal identifier When the communication control server that has transmitted the request and received the reception request confirms that the combination of the transmission destination address requested to be received in the reception request and the terminal identifier that made the request is included in the reception permission list. Only when the communication control server does not have the reception permission list or when the reception request is received, the transmission path from the originating transfer node to the destination transfer node for the packet whose transmission destination address is the terminal address is set. If the set of the requested transmission destination address and the identifier of the terminal that made the request are not included in the reception permission list, the reception request is not accepted and the transfer route from the originating transfer node to the destination transfer node is not set. And the communication control server sends a terminal address as a transmission destination address and a packet to which the terminal address is assigned as the transmission destination address. A report of a set of a transmission terminal address to which transmission is permitted is received in advance, and based on the report, a terminal address serving as a transmission destination address and a transmission terminal permitted to transmit a packet to which the terminal address is assigned as a transmission destination address A transmission permission list composed of a set of addresses is created, and the created transmission permission list is set in a calling / forwarding node accommodating a sending terminal permitted to send, and the calling / forwarding node transmits a packet transmitted by the sending terminal. Upon reception, it is checked whether the set of the transmission destination address and the source address of the received packet is included in the transmission permission list, and if the pair is included, the packet is transferred to the destination forwarding node. When the transmission permission list does not exist in the forwarding node or when the transmission destination address and the source address of the received packet are If you said not included in the transmission permission list,
A packet communication method, wherein a packet transmitted by a transmitting terminal is not transferred to a destination transfer node.