JPH05219095A - Group communication system in atm exchange system - Google Patents

Abstract

PURPOSE:To easily execute a group communication of a connectionless type packet, in the ATM exchange system. CONSTITUTION:In the system, a group communication server 5 is provided, and when a group communication packet is received, each connectionless communication containing part transfers it temporarily to the group communication server 5. From the group communication server 5, a broadcast virtual path for going to an end point of all connectionless communications is set in advance. In such a state, the received group communication packet is broadcast to all the end points by using the broadcast virtual path, and each connectionless communication containing part rejects other packet than the packet in which the own containing end point is contained, in the received group communication packets, to the ground.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a group communication system in an ATM switching system for performing connectionless communication.

[0002]

2. Description of the Related Art An ATM (Asynchronous Tr) for transmitting / receiving and exchanging information by dividing information into fixed-length cell units
The transfer mode (inter-mode) exchange method is regarded as a promising method for realizing next-generation broadband communication. The ATM switching system is based on connection-oriented communication in which a connection is set prior to communication. In connection-oriented communication, the identifiers of paths and connections are set end-to-end in advance, and information is routed on the paths using the identifiers.

On the other hand, in the connectionless system used in data packet communication such as LAN, there is no phase for setting the connection in advance, and the information packet is packet-based on the basis of the destination information written in each information packet. By-routed into packets.

[0004] Such connectionless communication is
As a method of accommodating the TM switching system, a method of semi-fixedly setting a mesh-like path between connectionless communication end points is considered. In this case, if the number of connectionless communication endpoints is n, n2 semi-fixed paths are set. Each switching node knows the destination endpoint by referring to the destination information of the connectionless packet in the accommodation unit, and transmits the cell of the packet on the semi-fixed path to the destination endpoint.

[0005]

The connectionless communication includes group communication performed by designating a plurality of destinations in addition to one-to-one communication. Group communication is performed by writing and transmitting a group identifier instead of the address of the destination endpoint in the destination address area in the data packet. In order to distinguish between one-to-one communication and group communication, a group communication flag area is provided in the destination address area of each data packet.

In order to apply the above-mentioned semi-fixed virtual path method to group communication as well, for each group communication performed by each switching node with respect to all group communication performed by the connectionless communication accommodating unit accommodated in the switching node. Virtual paths to all of the multiple ground points included in must be set in advance.

FIG. 6 shows an example of a connectionless communication packet format and division into cells used in the ATM switching system. The semi-fixed virtual path identifier is written in the cell header portion of the figure,
The switching node routes the cell according to the virtual path identifier in the cell header.

Since group communication is generally bidirectional communication, when group communication composed of m endpoints is set, m virtual paths must be set and managed in the entire network. In addition, a virtual path addressed to a plurality of grounds generally has a tree-like form with the connectionless communication accommodating portion of the source switching node as the apex, and the number of switching nodes forming the path constitutes a path for one-to-one communication. The number of switching nodes must be greater than that of the switching nodes, and the path information must be retained in each of them. It is known that how to determine a route is also very difficult compared to how to determine a route for one-to-one communication.

FIG. 7 shows an example of virtual paths addressed to multiple destinations. In the figure, 1 to 4 are switching nodes, solid lines between the switching nodes are physical inter-station lines between the switching nodes, and A to E are connectionless communication end points. In the figure, an example of a virtual path from A to the other three points when group communication is performed among four endpoints A, B, C, and D is shown by a dotted line. As shown in the figure, each switching node has a branching function and can branch and transfer a cell input from one port to a plurality of ports. In this example, the paths from B to A, C, D, the paths from C to A, B, D and the paths from D to A, B, C must be set in addition to those shown in the figure. ..

In consideration of the fact that the endpoints of a group of group communications exist semi-fixedly, the endpoints are set and released more fluidly. It is not preferable to apply the semi-fixed virtual path method as it is because the burden on the entire network becomes too large.

An object of the present invention is to realize connectionless group communication without setting a virtual path corresponding to each group communication in advance, and it is very easy to manage the entire network. To provide a group communication method in.

[0012]

SUMMARY OF THE INVENTION The present invention is an ATM (Asynchro) for transferring and exchanging information in fixed-length cell units.
In a group communication system in a nose transfer mode switching system, one or more switching nodes having a connectionless type data communication accommodation unit,
The group communication server includes one or more group communication servers and corresponds to all identifiers for group communication used in connectionless communication accommodated in the system. The virtual paths to reach each of the ATM switching nodes are set in advance, and the virtual paths for broadcasting from the group communication server to all the connectionless communication accommodating units of each switching node in the system are set. The accommodating unit temporarily transfers a group communication packet addressed to a plurality of destinations among the input connectionless type data packets to the group communication server, and the group communication server groups the cells written in the destination area of the data packet arriving. Check the communication identifier, if If the virtual path corresponding to the loop communication identifier is previously set, the cell of the data packet is transmitted to the virtual path, if the virtual path corresponding to the group communication identifier is not set in advance, The cell of the data packet is transmitted to the broadcast virtual path, and the connectionless communication accommodating unit of each switching node checks the destination group identifier of the group communication packet received via the broadcast virtual path, and if the destination group identifier is self-accommodated. The feature is that the received packet is transferred to the endpoint accommodated in the self-accommodating unit only when the unit is included as the ground, and the received packet is discarded in other cases.

Further, the present invention is an ATM (Asynchronous) that transfers and exchanges information in fixed length cell units.
In a group communication method in a Transfer Mode) switching system, the group communication method includes one or more switching nodes having a connectionless type data communication accommodating section and one or more group communication servers, and is used in connectionless communication accommodated in the system. Corresponding to a part of the group communication identifier, a virtual path from the group communication server to a part of a plurality of ground points included in each group communication is set in advance, respectively, and each switching node in the system from the group communication server. A virtual path for broadcasting to some of the connectionless communication accommodating units is set, and the connectionless communication accommodating unit of each ATM switching node selects a group communication packet addressed to a plurality of grounds among the input connectionless type data packets. Once guru Group communication server, and the group communication server checks the group communication identifier written in the destination area of the data packet arriving after being made into a cell, and if the virtual path corresponding to the group communication identifier is set in advance, Sends the cell of the data packet to the virtual path, and if the virtual path corresponding to the group communication identifier is not set in advance, sends the cell of the data packet to the broadcast virtual path, and each switching node The connectionless communication accommodating unit checks the destination group identifier of the group communication packet received via the broadcast virtual path, and only when the destination group identifier includes the self-accommodating unit as the ground, the self-accommodating unit receives the received packet. Transfer to the containing endpoint It is characterized by discarding a received packet in other cases.

[0014]

Embodiments of the present invention will now be described with reference to the drawings.

FIG. 1 is a system configuration diagram showing an embodiment in which the group communication system of the present invention is applied to the system consisting of four switching nodes shown in FIG. 1 in the figure
4 are switching nodes, solid lines are physical lines between switching nodes,
Each of A to E indicates an end point of connectionless communication. In the figure, 5 is a group communication server used in the group communication system of the present invention (the same applies to FIGS. 2 to 5 below).

In the present embodiment, the group communication server 5 is positioned as a trunk module connected to the rear of the switching node 2, but the group communication server 5 may constitute the switching node by itself. Paths a, b, c, d, and e indicated by dotted lines in the figure are end points A,
The semi-fixed virtual paths for transferring cells from B, C, D, E to the group communication server 5 are shown.

Next, FIG. 2 shows the connectionless communication endpoints A, B, C, D, in the system from the group communication server for performing the group communication method of the present invention.
An example of a broadcast virtual path for all Es is shown. A path g indicated by a dotted line in the figure indicates a broadcast virtual path from the group communication server to the endpoints A, B, C, D and E, respectively. In addition to the broadcast virtual path, a specific group communication path may be set from the group communication server.

3 to 5 show examples of paths from the group communication server for supporting group communication between the endpoints A, B, and C as an example. The path ga in FIG.
Returns information from endpoint A to endpoint B,
4 is a path for transferring information from the endpoint B to the endpoints A and C, and path gc in FIG. 5 is a path for transferring information from the endpoint C to the endpoints A and B. Is a path for transferring information to.

Table 1 shows an example of the routing table held by the group communication server in the examples shown in FIGS.

[0020]

[Table 1]

In Table 1, Gbc is a group communication identifier used for communication from A to B, C, and Gac is B to A,
Group communication identifier used for communication to C, Gab
Indicates group communication identifiers used for communication from C to A and B, respectively.

Next, the operation of this embodiment will be described with reference to FIGS. 1 to 5 and Table 1.

First, an example in which A transmits a group communication packet addressed to B and C using the group communication identifier Gbc will be described. In the following example, information comes in the form of a packet from each endpoint to each switching node (connectionless communication accommodating part thereof), and the switching node (connectionless communication accommodating part thereof) makes a packet into a network. However, there is also a case where an endpoint comes into the switching node in the form of being divided into cells.

The switching node 1 accommodating A (the connectionless communication accommodating section thereof) knows from the group communication flag of the destination address section of the packet transmitted from A that the packet is a group communication packet, and The packet is made into cells and transferred to the group communication server 5 via the virtual path a in FIG. The group communication server 5 searches the routing table shown in Table 1 using the destination address Gbc of the group communication packet included in the received head cell. The group communication identifier Gb is included in the routing table.
Since c is registered, the search result virtual path g
a is obtained. The group communication server 5 transfers the cell of the group communication packet to the switching nodes 2 and 3 via the virtual path ga shown in FIG. Switching node 2
And 3 (connectionless communication accommodating section thereof) assemble the cells received from the virtual path ga into packets and transfer them to the endpoints B and C as they are.

Next, a case where group communication packets from A to B, C and D are transmitted will be described. A to B, C,
The group communication identifier addressed to D is Gbcd. The switching node 1 knows that the packet is a group communication packet from the group communication flag of the destination address part of the received packet, as in the above example, cellizes the packet, and the group communication server 5 via the virtual path a. Transfer to. The group communication server 5 searches the routing table shown in Table 1 using the destination address Gbcd of the group communication packet included in the received head cell. Since the group communication identifier Gbcd is not registered in the routing table, the cells of the group communication packet are transferred to all the end points via the broadcast virtual path g shown in FIG.

In each of the switching nodes 1 to 4 (connectionless communication accommodating section thereof), a broadcast virtual path g
The destination address Gbcd included in the first cell is checked for the cell received via the group communication identifier Gbc
Only when the ground of d includes the self-accommodation unit, it is assembled into a packet and transferred to the endpoint. For this purpose, each switching node (the connectionless communication accommodating section thereof) needs to hold a list of group communication identifiers including the endpoint accommodated by the self accommodating section as the ground.
In this example, the packet is forwarded only to endpoints B, C, D.

[0027]

As described above, according to the present invention, it is not necessary to set a semi-fixed virtual path in advance for all group communication set by connectionless communication, and at least all of the group communication server can set the virtual path. All the group communication can be supported by setting only the broadcast path to the connectionless communication accommodating part of, and the packet of the group communication that does not set the virtual path is transmitted via the broadcast path. Since it is transferred to all the accommodating units, the group communication group can be set / released in a fluid manner, and the management of the entire network becomes very easy.

[Brief description of drawings]

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

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram showing an embodiment of the present invention.

FIG. 4 is a block diagram showing an embodiment of the present invention.

FIG. 5 is a block diagram showing an embodiment of the present invention.

FIG. 6 is an explanatory diagram showing formats of a frame and a cell.

FIG. 7 is an explanatory diagram showing a virtual path for group communication according to a conventional method.

[Explanation of symbols]

 1-4 switching nodes 5 group communication server A, B, C, D, E endpoint

Claims (2)

[Claims] 1. An ATM (Asynchronous Transfer) for transferring and exchanging information in fixed length cell units.
In a group communication method in a mode switching system, a group used in connectionless communication accommodated in the system, which includes one or more switching nodes having a connectionless type data communication accommodation unit and one or more group communication servers. Corresponding to all identifiers for communication,
For setting the virtual paths from the group communication server to all of the multiple destinations included in each group communication in advance, and for broadcasting from the group communication server to all connectionless communication accommodating units of each switching node in the system A virtual path is set in advance, and the connectionless communication accommodating unit of each ATM switching node
Of the input connectionless type data packets, group communication packets addressed to multiple destinations are temporarily transferred to the group communication server, and the group communication server checks the group communication identifier written in the destination area of the data packet that arrives after being made into cells. , If the virtual path corresponding to the group communication identifier has been set in advance, the cell of the data packet is transmitted to the virtual path, and if the virtual path corresponding to the group communication identifier has not been set in advance, Sends the cell of the data packet to the broadcast virtual path, and the connectionless communication accommodating unit of each switching node checks the destination group identifier of the group communication packet received via the broadcast virtual path, and if the destination group identifier is Self Group communication in an ATM switching system characterized in that the received packet is transferred to the endpoint accommodated in the self-accommodating unit only when the capacity unit is included as the destination, and the received packet is discarded in other cases. method. 2. An ATM (Asynchronous Transfer) for transferring and exchanging information in fixed length cell units.
In a group communication method in a mode switching system, a group used in connectionless communication accommodated in the system, which includes one or more switching nodes having a connectionless type data communication accommodation unit and one or more group communication servers. Corresponding to a part of the communication identifier, a virtual path from the group communication server to a part of a plurality of grounds included in each group communication is set in advance, respectively, and the group communication server connects each switching node in the system. A broadcast virtual path to a part of the connectionless communication accommodating unit is set, and the connectionless communication accommodating unit of each ATM switching node
Of the input connectionless type data packets, group communication packets addressed to multiple destinations are temporarily transferred to the group communication server, and the group communication server checks the group communication identifier written in the destination area of the data packet that arrives after being made into cells. , If the virtual path corresponding to the group communication identifier has been set in advance, the cell of the data packet is transmitted to the virtual path, and if the virtual path corresponding to the group communication identifier has not been set in advance, Sends the cell of the data packet to the broadcast virtual path, and the connectionless communication accommodating unit of each switching node checks the destination group identifier of the group communication packet received via the broadcast virtual path. Income Group communication method in an ATM switching system characterized in that the received packet is transferred to the endpoint accommodated in the self-accommodating section only when the section is included as a destination, and the received packet is discarded in other cases. ..