JP2001086158A - Data communication method - Google Patents

Abstract

(57) [Problem] To provide a data communication system capable of appropriately and efficiently distributing a multicast packet even if the position of a receiving host changes dynamically. SOLUTION: A multicast packet transmission host is composed of a packet reach control means 201, a packet construction means 202, and a packet transmission means 203.
With this configuration, at the sending host, based on the logical distance information on the network to the receiving host, the packet structuring unit 202 configures the packet whose reach is appropriately restricted by the instruction of the packet reach control unit 201. This packet is sent out by the packet sending means 203. This makes it possible to distribute the multicast packet to an appropriate network range. Therefore, even if the receiving hosts are mixed in the near and far side on the network, it can be surely distributed to all the receiving hosts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a data communication system for performing so-called broadcast type multicast communication, which is a one-to-many communication system.

[0002]

2. Description of the Related Art Conventionally, in a data communication system for performing multicast communication on the Internet, when transmitting a multicast packet, an IP (Internet Protocol) is used.
l) The packet reach distance TTL (T
ime To Live) as a fixed value. TTL
Is decremented by one each time it passes through a relay host (router) on the network, and is discarded when it becomes zero.
This limits the reach. Here, the distance is the number of routers that pass through to reach on the network + 1
Point to.

[0003]

However, in the above-mentioned conventional method, the range in which the multicast packet is distributed is fixed, and in a system in which the position of the receiving host changes dynamically, reception is not possible depending on the position. May disappear. Alternatively, it is necessary to transmit the TTL with the maximum value, and at this time, a multicast packet may flow even in a network without a receiving host, which is a factor of reducing the efficiency of the network.

[0004] The present invention has been made in view of such circumstances, and has as its object to provide a data transmission method capable of appropriately and efficiently distributing a multicast packet even when the position of a receiving host changes dynamically. To provide a communication system.

[0005]

According to a first aspect of the present invention, there is provided a data communication system comprising one transmitting host, a plurality of receiving hosts, and an arbitrary number of relay hosts on a network. A multicast packet distribution system, wherein the transmitting host includes a multicast packet reach distance control unit that controls a packet reach distance in a header, and the receiving host includes a reception start notifying unit that notifies reception start of the multicast packet. The receiving host comprises distance information holding means for holding logical distance information on the network from the sending host to itself, and notifying means for notifying the sending host of the distance information, and the multicast packet reach distance control means, The reach distance in the IP header is set based on the received distance information, and the sending host sets the reach distance. A multicast packet having a reach distance is distributed over the network, wherein the receiving host is configured to receive the multicast packets delivered.

That is, with such a configuration, the receiving host notifies the transmitting host of the distance information simultaneously with the reception start notification. As a result, the sending host can use the packet reach control means to deliver the multicast packet to the network to which the receiving host belongs.

A data communication system according to a second aspect of the present invention comprises one transmitting host, a plurality of receiving hosts, and an arbitrary number of relay hosts on a network, and the transmitting host controls a packet reach distance in a header. A multicast packet distribution system comprising: a multicast packet reach distance control means for receiving a packet; and a receiving host comprising a reception start notifying means for notifying the start of reception of the multicast packet, wherein the transmitting host has a network from itself to the receiving host. A distance information holding unit that holds the above logical distance information, a multicast packet reach distance control unit sets a reach distance in the IP header based on the distance information acquired from the distance information hold unit, Distributes multicast packets with the set reach over the network Characterized in that the receiving host is configured to receive the multicast packets delivered.

That is, the second invention is different from the first invention in that the transmission host has distance information holding means for holding logical distance information between the transmission host and the reception host. . Therefore, with such a configuration, when the transmitting host receives the reception start notification, the transmitting host transmits the multicast packet using the multicast packet reach control unit based on the distance information extracted from its own distance information holding unit. It is possible to distribute to the network to which the receiving host belongs.

Further, the data communication system according to the present invention comprises:
In the invention, the receiving host is provided with distance detecting means for detecting a logical distance on the network from the transmitting host to itself, and is configured to notify the distance information holding means of the distance information detected by the distance detecting means. It is characterized by having.

That is, with such a configuration, the receiving host detects the distance to the transmitting host, and then notifies the transmitting host of the detected distance information together with the reception start notification. As a result, the sending host can distribute the multicast packet to the network to which the receiving host belongs.

Further, the present invention provides the above-mentioned second invention, wherein:
The transmitting host includes distance detecting means for detecting a logical distance on the network from itself to the receiving host, and the distance detecting means is configured to notify the detected distance information to the distance information holding means. Features.

That is, by adopting such a configuration, the transmitting host detects the distance to the receiving host after receiving the reception start notification. As a result, the sending host can distribute the multicast packet to the network to which the receiving host belongs.

According to the present invention, in any one of the above-mentioned inventions, the transmitting host is a receiving host information holding means for holding information relating to a receiving host that is currently receiving and logical distance information to the receiving host. Receiving host information editing means for acquiring logical distance information to the new receiving host when the new receiving host transmits a reception start notification to the transmitting host, and editing the distance information held by the receiving host information holding means; And transmitting the largest logical distance among the current receiving host information to the multicast packet reach distance control means.

That is, by adopting such a configuration, when the transmitting host receives the reception start request from the receiving host, the transmitting host edits the information held therein and changes the logical distance to the farthest receiving host. Is calculated. As a result, the sending host can distribute the multicast packet to the network to which all the receiving hosts belong.

According to the present invention, the receiving host according to the present invention comprises a receiving end notifying means for notifying that the receiving of the multicast packet is ended, and the receiving end notifying means is provided when the multicast packet is transmitted on the network. The transmission of the reception end notification to the transmission host is configured to stop the transmission of the multicast on the network. That is, with such a configuration, after the receiving host notifies the transmitting host of the end of the receiving, the transmitting host deletes the one that has finished the receiving from the current receiving host list. Then, the transmitting host calculates a logical distance from the new list to the farthest receiving host, and sets it as a new TTL. This makes it possible to distribute the multicast packet to an appropriate range.

Further, according to the present invention, the transmission host in the above invention comprises a packet transmission stop means for stopping the transmission of the multicast packet, and when the information held by the transmission host becomes empty, the packet transmission stop means is a multicast packet transmission means. The transmission is stopped. That is, in such a configuration, after the receiving host notifies the transmitting host of the end of the receiving, the transmitting host deletes the receiving host from the current receiving host list. Then, when the receiving host list becomes empty, the transmitting host can stop the packet transmission by the packet transmission stopping means so as not to generate useless traffic.

[0017]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a data communication system according to the present invention will be described in detail with reference to the drawings. FIG. 1 is an overall configuration diagram of a data communication system according to an embodiment of the present invention, FIG. 2 is a configuration diagram of a multicast packet transmitting host applied to the embodiment of the present invention, and FIG. FIG. 1 is a configuration diagram of a multicast packet receiving host applied to an embodiment of the present invention.

In FIG. 1, 101 is a transmitting host for transmitting a multicast packet, 102 to 106 are receiving hosts for receiving a multicast packet, 10
Reference numerals 7 to 110 denote relay hosts (routers) that distribute packets across networks, and reference numerals 111 to 115 denote networks to which the packets are distributed and to which each host belongs.

In FIG. 2, reference numeral 201 denotes a reach distance control means for controlling the reach of a multicast packet;
02 is a packet composing unit for constructing a multicast packet, 203 is a packet transmitting unit for transmitting a multicast packet, 204 is a distance information retaining unit for retaining logical distance information to a receiving host, and 205 is a receiving host information. Holding means, receiving host information editing means for editing receiving host information, receiving start / end notification receiving means for receiving start and end notifications of reception, and distance detecting means for detecting a distance to the receiving host. , 209 are packet transmission stopping means for stopping transmission of packets.

Further, in FIG. 3, 301 is a packet receiving means for receiving a multicast packet, 302 is a reception start / end notification transmission means for transmitting a start and end notification of reception, and 303 is a logical distance to a transmission host. The distance information holding means 304 is a distance detecting means for detecting a logical distance to the transmission host.

Next, the operation of some embodiments of the present invention will be described.

First, in the first embodiment, broadcast-type multicast data over a plurality of networks is
The case of transferring using P multicast will be described. First, the receiving host 104 that wants to receive the multicast data sends distance information to the transmitting host 101.
(In the example of this embodiment, the distance information is 2) The distance information is extracted from the distance information holding unit 303 that statically holds the information, and is transmitted to the transmission host 101 by the reception start / end notification transmitting unit 302 together with the reception start notification. .

Then, the transmitting host 101 receives the reception start notification by the reception start / end notification receiving unit 207, and when the distance to the receiving host 104 is obtained, transmits the distance to the packet reach control unit 201. Then, the packet reach distance control means 201 causes the packet composition means 202 to set the TTL in the IP header based on this information. As a result, the packet transmitting means 203
Network 1 with TL
To 11

When the router 108 receives this multicast packet, it decrements the TTL by one and transfers it to the network 113 because the TTL is greater than zero. As a result, the multicast packet is distributed to the network 113, and the receiving host 104 receives the multicast packet.

Next, the operation of the second embodiment will be described. The difference between the second embodiment and the first embodiment is that the sending host 101 itself transmits logical distance information to the receiving host 104 ((distance information is 2 in the example of this embodiment)). That is, after the receiving host 104 has transmitted the reception start notification to the transmission host 101 by the reception start / end notification transmission unit 302, the transmission host 101
4 and the logical distance from the receiving host 104 is obtained and transmitted to the packet reach control means 207. As a result, the subsequent operation is the same as in the first embodiment, the multicast packet is distributed to the network 113, and the receiving host 104 receives the multicast packet.

Next, the operation of the third embodiment will be described. In this embodiment, a case where the receiving host 104 detects a logical distance to the transmitting host 101 in the first embodiment will be described. That is,
The receiving host 104 first checks the logical distance to the transmitting host 101 using the distance detecting means 304. As a detection method at this time, a method using an IP option and a method using an ICMP message are generally known. After the logical distance to the sending host 101 (2 in this embodiment) can be detected, the same operation as in the first embodiment is performed, the multicast packet is delivered to the network 113, and the receiving host 104 receives the multicast packet.

Further, the operation of the fourth embodiment will be described. In this embodiment, a case will be described in which the transmission host 101 detects the logical distance to the reception host 104 (2 in this embodiment) in the second embodiment. That is, after the receiving host 104 transmits a reception start notification to the transmission host 101 by the reception start / end notification transmission unit 302, the transmission host 101 checks the logical distance to the reception host 104 by the distance detection unit 208. After the logical distance can be detected, the operation is performed in the same manner as in the second embodiment, the multicast packet is distributed to the network 113, and the receiving host 104 receives the multicast packet.

Further, the operation of the fifth embodiment will be described. In this embodiment, in addition to the above-described first to fourth embodiments, a case where the receiving host 106 newly starts reception during packet distribution will be described. In other words, the sending host 101 is the receiving host 10 currently receiving.
4 and the logical distance information thereof,
06, it is registered in the receiving host information holding means 205. Next, when the new reception host 106 transmits a reception start notification to the transmission host 101, in the transmission host 101, the reception start / end notification reception unit 207 receives the notification, and the logical distance to the reception host 106 (this implementation). In the example of the embodiment, when 3) is taken out, it is passed to the receiving host information editing means 206. Then, the receiving host information editing means 2
06 is based on the received host information holding means 205
Is added to the information on the receiving host 106, and the largest logical distance (3 in this embodiment) among the current receiving host information is transmitted to the packet reach distance control means 201. Accordingly, in the following, in addition to the operation of the above-described first embodiment, the router 110 distributes the multicast packet to the network 115,
The receiving host 106 receives the multicast packet. Further, by such distribution, the transmitting host can distribute the multicast packet to the network to which the farthest receiving host belongs, so that distribution to all the receiving hosts becomes possible.

The operation of the sixth embodiment will be described. In this embodiment, in addition to the fifth embodiment, during the multicast distribution, the receiving host 106
Will be described. That is, when the multicast packet is distributed to the network 115, the receiving host 106 uses the reception start / end notification transmitting unit 302 to transmit a reception end notification to the transmission host 10.
Send to 1. Then, in the sending host 101, the reception start / end notification receiving means 207 receives this and passes it to the receiving host information editing means 206. Then, based on the received host information, the receiving host information editing unit 206 edits the receiving host information holding unit 205 to delete the information on the receiving host 106, and sets the largest logical distance among the current receiving host information (this embodiment). In the example of the mode, 2) is transmitted to the packet reach distance control means 201. Based on this, a multicast packet with a smaller TTL set than before is configured by the packet configuration unit 202. As a result, the following operates in the same manner as in the first embodiment, and the multicast packet is transmitted to the network 11.
3 but is no longer distributed to the network 115.

Further, the operation of the seventh embodiment will be described. In this embodiment, in addition to the sixth embodiment, the receiving host 104
Will be described when the reception ends and the receiving host disappears. The multicast packet is sent to the network 11
When the reception host 104 transmits the reception start / end notification to the transmission host 101 by the reception start / end notification transmission unit 302 during the distribution to the transmission host 10, the transmission host 10
In step 1, the reception start / end notification receiving means 207 receives this and passes it to the receiving host information editing means 206. Then
The receiving host information editing means 206 edits the receiving host information holding means 205 based on the
Then, the largest logical distance (0 in this embodiment) among the current receiving host information is transmitted to the packet reach distance control means 201. At this time, if the held receiving host information becomes empty, the packet transmission stopping means 20
9, transmission of packets is suppressed.

[0031]

As is apparent from the above description, according to the data communication system of the present invention, the packet reach distance is controlled based on the logical distance from the sending host to the receiving host. As a result, it is possible to distribute the multicast to the network where the farthest receiving host exists, and it is surely distributed to all the receiving hosts. Further, when there is no receiving host, distribution can be suppressed, and the load on the network can be reduced.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a data communication system according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a multicast packet transmission host applied to the embodiment of the present invention;

FIG. 3 is a configuration diagram of a multicast packet receiving host applied to the embodiment of the present invention;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 101 Multicast packet transmission host 102-106 Multicast packet transmission host 107-110 Relay host (router) 111-115 Network 201 Packet arrival distance control means 202 Packet construction means 203 Packet transmission means 204 Distance information holding means 205 Receiving host information holding means 206 Reception host information editing means 207 Reception start / end notification reception means 208 Distance detection means 209 Packet transmission stop means 301 Packet reception means 302 Reception start / end notification transmission means 303 Distance information holding means 304 Distance detection means

Claims (7)

[Claims] The present invention comprises a sending host, a plurality of receiving hosts, and an arbitrary number of relay hosts on a network, wherein the sending host includes a multicast packet reach control means for controlling a packet reach in a header, And the receiving host is a multicast packet distribution system including reception start notifying means for notifying the start of receiving a multicast packet, wherein the receiving host has a logical distance information on the network from the transmitting host to itself. And a notifying means for notifying the transmitting host of the distance information, wherein the multicast packet reach distance control means sets a reach distance in an IP header based on the received distance information. A multicast packet in which the sending host has a set reach The delivered over the network, the receiving host, the data communication method is characterized in that is configured to receive a distributed multicast packets. 2. A multicast packet reach distance control means comprising one sending host, a plurality of receiving hosts, and an arbitrary number of relay hosts on a network, wherein the sending host comprises a multicast packet reach distance control means for controlling a packet reach distance in a header. And a multicast packet distribution system, wherein the receiving host includes a reception start notifying unit for notifying reception start of the multicast packet, wherein the transmission host has a logical distance information on a network from itself to the reception host. The multicast packet reachable distance control means, based on the distance information acquired from the distance information hold means.
Setting a reach distance in a header, the transmitting host distributes a multicast packet having the set reach distance on the network, and the receiving host is configured to receive the distributed multicast packet. A data communication method characterized by the following. 3. The receiving host includes distance detecting means for detecting a logical distance from the transmitting host to itself on the network, and the distance detecting means notifies the distance information holding means of the detected distance information. The data communication system according to claim 1, wherein the data communication system is configured as follows. 4. A transmission host comprising distance detecting means for detecting a logical distance on the network from itself to a receiving host, wherein the distance detecting means notifies the distance information holding means of the detected distance information. The data communication system according to claim 2, wherein the data communication system is configured as follows. 5. A sending host, receiving host information holding means for holding information on a receiving host that is currently receiving and logical distance information to the receiving host, and a new receiving host sends a reception start notification to the receiving host. Receiving host information editing means for acquiring logical distance information to a new receiving host when transmitting to the sending host, and editing the distance information held by the receiving host information holding means; Wherein the largest logical distance among the information is transmitted to the multicast packet reach distance control means.
The data communication method according to any one of the above. 6. A receiving host includes a receiving end notifying unit for notifying that the receiving of the multicast packet is ended, and when the multicast packet is being transmitted on the network, the receiving end notifying unit sends the receiving end notifying unit to the transmitting host. The data communication system according to claim 5, wherein the transmission of the multicast on the network is stopped when the reception end notification is transmitted. 7. The transmission host includes packet transmission stop means for stopping transmission of a multicast packet, and when the information held by the transmission host becomes empty, the packet transmission stop means stops transmission of the multicast packet. 7. A structure according to claim 6, wherein
Data communication method described in 1.