JP2003249940A - Network system, multicast communicating method, node, node multicast communicating method, program and recording medium - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multicast communicating method capable of reducing a signal processing load in a ring network composed of an RPR. <P>SOLUTION: A transmitting side node converts a multicast packet of a layer 3 into a broadcast packet of a layer 2 describing being multicast and transmits only one broadcast packet to an adjacent node. Respective receiving side nodes prepare a copy of the packet when the broadcast packet arrives to perform packet processing and also transmit the arrived broadcast packet to a downstream node. The respective receiving side nodes store the identifier of each received broadcast packet in a table, retrieve the table prior to participating in the multicast, confirm that the relevant multicast packet does not flow in the network and subsequentially transmit a participation request. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a network system, a multicast communication method, a node, a node multicast communication method, a program, and a recording medium, and more particularly, when performing multicast distribution to multiple points using a ring topology. The present invention relates to a technique effectively applied to the multicast route control of.

[0002]

2. Description of the Related Art FIG. 1 is a diagram showing a schematic configuration of a ring type network system which is a premise of the present invention. In the ring network system shown in FIG. 1, a plurality of nodes (routers) 10 that perform processing up to layer 2 are connected in a ring shape, and layer 2 packets are sequentially transmitted between the nodes. In FIG. 1, reference numeral 11 denotes a node (router) which is a proxy transmission source of multicast. Also, in the following description of this specification, a multicast sender node is referred to as "
All the receiving nodes other than the center and the transmitting node are described as “edges.” First, as a ring configuration technology, a conventional ring topology is used to efficiently perform multicast transfer to multiple points. One of the technologies is RPR (see Reference 1.) RPR is a layer 2 ring configuration technology, and as shown in FIG. Can be distributed from the center to each edge, and the route switching at the time of failure can be performed at high speed without affecting the multicast route control system.

Secondly, as a multicast route control method, there is PIM-SM (see Reference 2) as a general means that does not depend on a routing protocol, but it has the following problems. The route control method called PIM-SM is limited in its application range when those who participate in the multicast exist in high density on the network. The method using IGMP (see Document 3) defeats the purpose of performing multicast route control over the entire network because each ring node subordinate is divided into independent domains. Multicast control methods other than the above depend on the routing protocol.
From the above discussion, as a multicast communication method using the conventional technique, PIM-SM is used to control the multicast route on the ring network configured by RPR. Reference 1: Necdet Uzun et al, "Proposals for Resilient"
Packet Ring "http; // www.ieee802.org/17/documents/d
rafts / gandalf 04Plus.pdf Reference 2; D. Estrin, D. Farinacci, A. Helmy, D. Thaler, S. De
ering, M.Handley, V, Jacobson, C.Liu, P.Sharma, L.Wei, "P
rotocol Independent Multicast-Sparse Mode (PIM-SM):
ProtocolSpecification. "IETF Networking Group RFC
2117, June 1997 Reference 3: W. Fenner, "Internet Group Management Proto
col, Version 2. "IETF Networking Group RFC 2236, No
vember 1997.

[0004]

However, when multicast route control is performed by PIM-SM on a ring network configured by RPR, there are the following problems. As shown in FIG. 8, the ring configuration technology in Layer 2 has an advantage in that the ring topology is not made aware of Layer 3 described above, but on the other hand, in the Layer 3 processing unit that performs multicast processing, The nodes are recognized as being individually connected, and the signaling process for each ground also has the property that the signaling is individually processed between each ground. The problem of this property will be described with reference to the sequence of FIG. "Although the multicast # 1 packet in which a certain edge C has already joined has been delivered to all the edges in the ring, a join request (PIM-Jo
In message) occurs (a in FIG. 9) ", or when" edge B and C are requesting to join multicast # 1, edge C continues to join,
Only the edge B issues a pruning message (PIM-Prune message) ((B) in FIG. 9) ”, and the number of messages cannot be reduced. Further, as shown in the sequence of FIG. 10, there is a case where “it is necessary to sequentially perform signal processing due to a short absence period of the participation request edge despite the presence of the participation request edge under the ring almost constantly”. is there. For this reason, when the viewer performs an operation called "zapping" that is found in current TV broadcasting services, the number of signal processes processed by the center increases, and scalability cannot be secured when the multicast flow increases. There is a point.

The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to reduce the signal processing load in a ring network composed of RPR. A system and a multicast communication method are provided. Also,
Another object of the present invention is to provide a node applied to the above-mentioned network system and a multicast communication method of the node. Another object of the present invention is to provide a program that causes a computer functioning as the node to execute the multicast communication method, and a recording medium having the program recorded therein. The above and other objects and novel features of the present invention will become apparent from the description of this specification and the accompanying drawings.

[0006]

Among the inventions disclosed in the present application, a brief description will be given to the outline of typical ones.
It is as follows. That is, the present invention is a network system in which a plurality of nodes that perform processing up to layer 2 are connected in a ring shape and layer 2 packets are sequentially transmitted between nodes. The node converts the multicast packet into a layer 2 broadcast packet indicating that the packet is multicast, sends only one broadcast packet to the adjacent node, and each receiving side other than the transmitting side node When the node arrives at the broadcast packet, the node makes a copy of the packet to perform packet processing, and also transmits the arrived broadcast packet to a downstream node. In a preferred embodiment of the present invention, each receiving node stores the identifier of each received broadcast packet in a table, and the node that should receive the multicast packet stores the table before joining the multicast. The request for participation is issued after searching and confirming that the multicast packet does not flow in the network. According to the present invention, for a multicast flow that has already been delivered to a certain receiving side node in the network, another receiving side node (because it is a new participation request under its control), a participation request (PIM- It is possible to suppress the output of Join message).

In a preferred embodiment of the present invention, the transmitting side node collectively outputs the reception confirmation information for a plurality of multicasts transmitted by itself, into one packet,
When the receiving side node receives the reception confirmation information, it adds a transmission confirmation bit to the portion of the reception confirmation information regarding the multicast received by itself, and then transmits the reception confirmation information to the downstream node. , The transmission side node confirms the transmission confirmation bit in the reception confirmation information that has returned around the network and returned, and considers that the multicast without the transmission confirmation bit is no longer requested to participate Stop sending packets. According to the present invention, since the sending node periodically outputs the pruning message (PIM-Prune message), it is possible to suppress the real-time pruning message (PIM-Prune message) transmission from the receiving node. Is possible.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In all the drawings for explaining the embodiments, the same reference numerals are given to those having the same function, and the repeated description thereof will be omitted. The ring network system according to the embodiment of the present invention is the same as that shown in FIG. 1, and thus detailed description thereof will be omitted. In the multicast communication method of the present embodiment, regarding the method of constructing the distribution tree and the method of linking with the routing information, the current method is used.
Use PIM-SM as it is. FIG. 3 is a block diagram showing a schematic configuration of the node 10 shown in FIG. In FIG. 3, 21 is a Rig side layer 2 processing unit, 22 is Ether
Net side layer 2 processing unit, 23 is a layer 3 processing unit, 24
Is an internal bus, 25, 26 and 27 are recording media, 29 is a table, and 30 is an Ethernet device.

In this embodiment, as shown in FIG. 2A, the center (transmission side node) (A) that first receives the layer 3 multicast packet is the layer 3 processing unit 23, and the layer 3 Is converted into a layer 2 broadcast packet indicating that the packet is a multicast, and only one broadcast packet is added to the adjacent edge (edge B or edge D) via the Rig side layer 2 processing unit 21. Send to. When each of the edges (B, C, D) arrives at the broadcast packet, the Rig side layer 2 processing unit 21 makes a copy of the packet and transfers the arrived broadcast packet to the downstream edge. The Rig side layer 2 processing unit 21 of each edge (B, C, D) processes the received broadcast packet in the layer 3 processing unit 23.
The layer 3 processing unit 23 processes the received broadcast packet. At this time, the layer 3 processing unit 2
3 is the layer 3 of the received broadcast packet
Read the information, and even if it is a multicast flow that is not transferred under your control,
It is stored in the table 29 in the recording medium 26. The table 29 is refreshed after a fixed time. FIG. 4 is a diagram showing the contents of an example of the table 29 shown in FIG. In FIG. 4, # 1 and # 2 are identifiers indicating multicast, SA is a source address, and GA is information indicating a multicast distribution destination group.

The first feature of the multicast communication method of the present embodiment will be described below with reference to FIG. Also in the present embodiment, the edge (edge (C) in FIG. 5) that should receive the multicast packet first transmits a request to join the multicast (PIM-Join message) to the center (A). In this case, as shown in FIG. 5, the edge (C) searches the table 29 and confirms that the multicast packet is not flowing in the network before issuing a request to join the multicast. Send a request for participation. According to the present embodiment, the edge that should receive the multicast packet searches the table 29 before issuing a request to join the multicast,
Since it is confirmed that the relevant multicast packet is not flowing in the network, other edges (when under their control a new join request are sent to the multicast flow already delivered to one edge in the network) Therefore, it is possible to suppress the request for participation.

The second feature of the multicast communication method of the present embodiment will be described below with reference to FIG. In the present embodiment, the center (A) is connected to each edge (B,
It manages the request for participation in the multicast in C, D), and sends out only the multicast packet to which one or more of the edges request the participation, to the network. Therefore, in the present embodiment, as shown in FIG. 6, the center (A) creates a list of currently transferred multicasts in the layer 3 processing unit 23, and
Create a list with a confirmation bit added to the list. The center (A) adds a confirmation bit to the list,
As the reception confirmation message 33, it is sent from the Ring side layer 2 processing unit 21 to the adjacent node in the cycle T. At each edge (B, C, D), in the layer 3 processing unit 23,
When the reception confirmation message 33 is received, if there is a multicast of (SA, GA) which is currently transferred to the subordinate, a confirmation bit is set in the payload part and the result is sent to the adjacent edge. In the case of FIG. 6, the edge (B)
Sets a confirmation bit in the payload part of the # 2 multicast in the reception confirmation message 33, and the edge (C)
Transfer to. In addition, the edges (B, C, D) are already #
Because the reception of the multicast of 1 is stopped,
If the confirmation bit is not set in the payload part of the # 1 multicast in the reception confirmation message 33, the center (A)
Transfer to.

When the reception confirmation message 33 goes around the network and returns, the center (A) does not need to transfer the multicast with no confirmation bit to the network in the layer 3 processing section 23. It judges and issues a pruning message (PIM-Prune message) to the node 11 via the Ethernet side layer 2 processing unit 22. In the case of FIG. 6, since the confirmation bit is not set in the # 1 multicast, the transmission of the # 1 multicast packet is stopped and the # 11 multicast is sent to the node 11 via the Ethernet side layer 2 processing unit 22. Issue a reaping message (PIM-Prune message). According to the present embodiment, since the center (A) periodically outputs the reaping message, it is possible to suppress the real-time reaping message transmission from the edges (B, C, D). .

FIG. 7 is a diagram showing a sequence of the multicast communication method of the present embodiment. As shown in FIG. 7, as an effect of the edge suppressing the participation request (PIM-Join message) for the multicast of the delivered (SA, GA) set, the edge of the delivered (SA, GA) set is multicast. , It is possible to reduce meaningless participation requests. Further, as shown in FIG. 7, as an effect of issuing the reception confirmation message 33 in the cycle T, it is possible to reduce the signal for a short-time viewing request due to zapping, and the short-term viewing request reaches the node 11. It is possible to avoid the event that a large traffic fluctuation occurs in a wide area of the network. These effects make it possible to dynamically perform multicast route control while reducing the signal processing load associated with zapping using the traffic characteristics of the ring topology. In the above description, the node 10 can also be executed by a computer, and in that case, the multicast communication method of the node 10 is performed by the computer executing a program stored in a hard disk or the like in the computer. Done. This program is a CD-RO
It is supplied by M or by downloading via the network. Although the invention made by the present inventor has been specifically described based on the above-described embodiment, the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention. Of course,

[0014]

The effects obtained by the typical ones of the inventions disclosed in the present application will be briefly described as follows. According to the present invention, it is possible to dynamically perform multicast route control while reducing the signal processing load associated with zapping by utilizing the traffic characteristics of the ring topology.

[Brief description of drawings]

FIG. 1 is a diagram showing a schematic configuration of a ring network system which is a premise of the present invention.

FIG. 2 is a diagram illustrating an operation of multicast packet transfer according to the embodiment of the present invention and an operation of a conventional multicast packet transfer.

FIG. 3 is a block diagram showing a schematic configuration of a node shown in FIG.

FIG. 4 is a diagram showing the contents of an example of the table shown in FIG.

FIG. 5 is a diagram illustrating operations of each node and signaling operations in the multicast communication method according to the embodiment of the present invention.

FIG. 6 is a diagram illustrating operations of each node and signaling operations in the multicast communication method according to the embodiment of the present invention.

FIG. 7 is a diagram illustrating a sequence in the multicast communication method according to the embodiment of this invention.

FIG. 8 is a diagram illustrating a topology recognized by a ring node in the network shown in FIG.

FIG. 9 is a diagram illustrating an example of a PIM-SM sequence.

FIG. 10 is a diagram illustrating another example of a PIM-SM sequence.

[Explanation of Codes] 10 ... Node, 11 ... Node (router) serving as proxy transmission source of multicast, 21 ... Layer 2 processing unit on Rig side,
22 ... Ethernet side layer 2 processing unit, 23 ... Layer 3 processing unit, 24 ... Internal bus, 25, 26, 27 ... Recording medium, 29 ... Table, 30 ... Ethernet device,
33 ... Receipt confirmation message.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Ichiro Inoue             2-3-1, Otemachi, Chiyoda-ku, Tokyo             Inside Telegraph and Telephone Corporation F term (reference) 5K030 GA03 HB28 HC14 HD03 JA07                       KA05 KX28 LA02 LD02 MD07                 5K031 AA02 AA05 CB17 CC03 DA14

Claims (19)

[Claims] 1. A network system in which a plurality of nodes that perform processing up to layer 2 are connected in a ring shape and layer 2 packets are sequentially transmitted between the nodes, wherein a transmitting side node receives a received layer 3 multicast. Layer 2 that describes the packet as being multicast
Of the receiving device other than the transmitting node, the receiving device receiving the broadcast packet. A network system comprising: first means for making a copy of the broadcast packet to perform packet processing; and second means for transmitting the received broadcast packet to a downstream node. 2. The transmission side node receives a request for participation in a specific multicast from each of the reception side nodes for a certain period of time or more, as a response to the reception confirmation, and second means for sending out a reception confirmation at regular intervals. If there is no request for participation in the multicast, the third node for stopping the transmission of the multicast packet is considered, and each of the reception side nodes receives the reception confirmation and participates. Issue a request to participate in a live multicast
The network system according to claim 1, further comprising: 3. The second means of the sending node,
As the reception confirmation, the reception confirmation information for a plurality of multicasts being transmitted is collectively transmitted in one packet, and the third means of the transmission-side node returns the reception confirmation information after making one round of the network. The transmission confirmation bit in the inside is confirmed, the multicast to which the transmission confirmation bit is not added is considered to have disappeared from the request for participation, and the transmission of the multicast packet is stopped. After receiving the reception confirmation information and assigning the transmission confirmation bit as the request for participation to the portion of the reception confirmation information regarding the received multicast related confirmation bit, the reception confirmation information is transmitted to the downstream node. The network system according to claim 2, wherein: 4. Each of the reception side nodes stores a fourth means for storing an identifier of each of the received broadcast packets, and, when participating in a multicast, searches for the fourth means and stores the multicast in the network. The network system according to any one of claims 1 to 3, further comprising: fifth means for confirming that no packet is flowing and issuing a participation request for multicast. 5. A multicast communication method in a network system in which a plurality of nodes that perform processing up to layer 2 are connected in a ring shape and layer 2 packets are sequentially transmitted between the nodes. The transmitting side node that has received the packet converts the multicast packet into a layer 2 broadcast packet indicating that it is a multicast, and sends only one broadcast packet to the adjacent node, except for the transmitting side node. Each of the receiving side nodes makes a copy of the packet when the broadcast packet arrives, performs packet processing, and transfers the arrived broadcast packet to a downstream side node. 6. A node that should receive a multicast packet first transmits a request to participate in multicast to a transmitting side node, and the transmitting side node that has received the request to participate in multicast determines whether or not there is a request to participate in the multicast. The multicast communication method according to claim 5, wherein by managing, only one or more of the receiving side nodes, among the receiving side nodes, sends out only the multicast packets that the receiving side node desires to join to the network. 7. A node, which should receive a multicast packet, sends a participation request after confirming that the multicast packet is not flowing in the network before issuing a participation request to the multicast. Item 7. The multicast communication method according to Item 6. 8. The transmission is performed by the transmission-side node periodically transmitting a reception confirmation, the reception-side node receiving the reception confirmation, and issuing a participation request to a participating multicast. 7. The multicast communication method according to claim 6, wherein when the side node does not receive the request for participation for a certain period of time or more, it is considered that the request for participation in the multicast has disappeared and the transmission of the multicast packet is stopped. 9. As the reception confirmation, the reception confirmation information for a plurality of multicasts transmitted by the transmission side node is sent in one packet, and the reception side node receives the reception confirmation information. At that time, in the position of the confirmation bit regarding the multicast that is itself received in the reception confirmation information, after adding a transmission confirmation bit as the participation request, transmits the reception confirmation information to the downstream node, the transmission side node, Confirm the transmission confirmation bit in the reception confirmation information that has returned after one round of the network, and consider that the multicast without the transmission confirmation bit is considered to have lost the request for participation and stop sending the multicast packet. 9. The multicast communication method according to claim 8, wherein. 10. A transmission side node in a network system in which a plurality of nodes that perform processing up to layer 2 are connected in a ring shape and layer 2 packets are sequentially transmitted between the nodes, and a received layer 3 multicast packet. Is converted to a layer 2 broadcast packet indicating that it is a multicast, and only one broadcast packet is transmitted to the adjacent node, and reception confirmation information for a plurality of multicasts being transmitted. Second packet that is sent periodically
And the transmission confirmation bit in the reception confirmation information that has returned after one round of the network, and considers that the multicast without the transmission confirmation bit is no longer requested, and sends the multicast packet. And a third means for stopping the transmission. 11. A receiving side node in a network system in which a plurality of nodes for performing processing up to layer 2 are connected in a ring shape and a layer 2 packet is sequentially transmitted between the nodes, the broadcast packet from the transmitting side node. Receiving means for making a copy of the broadcast packet to perform packet processing; second means for transmitting the received broadcast packet to a downstream node; and a transmitting side node to a transmitting side node. Received confirmation information for a plurality of multicasts transmitted by, and after adding a transmission confirmation bit to the portion of the confirmation bit related to the multicast itself received in the reception confirmation information, the reception confirmation information to the downstream node And a third means for transmitting, the receiving side node. 12. A fourth means for storing an identifier of each of the received broadcast packets, and a method of searching the fourth means when participating in a multicast to check that the multicast packet does not flow in the network. The receiving side node according to claim 11, further comprising: a fifth means for confirming and issuing a participation request for multicast. 13. A multicast communication method of a transmitting side node in a network system, wherein a plurality of nodes performing processing up to layer 2 are connected in a ring shape, and a layer 2 packet is sequentially transmitted between the nodes. 3. A multicast communication method for a transmitting node, which comprises converting a multicast packet of No. 3 into a layer 2 broadcast packet indicating that the packet is a multicast, and sending only one broadcast packet to an adjacent node. 14. The reception confirmation information for a plurality of multicasts being transmitted is collected in one packet, periodically transmitted, and the transmission confirmation bit in the reception confirmation information returned after one round of the network is confirmed. 14. The multicast communication method of a transmission-side node according to claim 13, wherein the transmission of the multicast packet is stopped by regarding that the multicast to which the transmission confirmation bit is not added is considered to have disappeared. 15. A multicast communication method for a receiving side node in a network system, wherein a plurality of nodes for performing processing up to layer 2 are connected in a ring shape, and layer 2 packets are sequentially transmitted between the nodes. A multicast communication method for a receiving side node, comprising: receiving a broadcast packet from a node, making a copy of the broadcast packet, performing packet processing, and transmitting the received broadcast packet to a downstream side node. 16. The reception confirmation information for a plurality of multicasts transmitted by the transmission side node is received from the transmission side node, and the transmission confirmation is carried out at the confirmation bit portion of the reception confirmation information regarding the multicast itself being received. 16. The multicast communication method of the receiving side node according to claim 15, wherein the reception confirmation information is transmitted to the downstream node after adding the bit. 17. A multicast communication method is executed to a computer that functions as a transmission side node in a network system in which a plurality of nodes that perform processing up to layer 2 are connected in a ring shape and layer 2 packets are sequentially transmitted between the nodes A program for converting the received layer 3 multicast packet into a layer 2 broadcast packet indicating that it is a multicast, and a program for transmitting only one broadcast packet to an adjacent node. The procedure for sending out, the reception confirmation information for a plurality of multicasts that are being sent together in one packet, and the procedure for sending it out periodically, and the transmission confirmation bit in the reception confirmation information returned after one round of the network. Confirm and send confirmation bit is attached Without multicasting, and a procedure for stopping the transmission of the multicast packets deemed to have gone participation request, a program for causing a computer to execute. 18. A multicast communication method is executed to a computer that functions as a reception side node in a network system that connects a plurality of nodes that perform processing up to layer 2 in a ring shape and sequentially transmits layer 2 packets between the nodes. A program for causing the program to receive a broadcast packet from a transmitting side node, make a copy of the broadcast packet and execute packet processing, and the received broadcast packet to a downstream side node. Procedure for transmission and reception confirmation information for a plurality of multicasts transmitted by the transmission side node from the transmission side node, and transmission confirmation is made in the confirmation bit part of the reception confirmation information relating to the multicast received by itself. Gave me a bit Then, a program for causing a computer to execute the procedure for transmitting the reception confirmation information to the downstream node. 19. A recording medium on which the program according to claim 17 or 18 is recorded.