JP3006286B2 - ATM switch - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ATM switch.
In particular, it relates to an ATM switch with a multicast function.

[0002]

2. Description of the Related Art An ATM (Asynchronous Tr) which divides information into fixed-length cell units and transmits / receives / exchanges the information.
An answer Mode) switching system is regarded as a promising system for realizing next-generation broadband communication. In the ATM switching system, switching is performed for each cell based on an identifier written in a header area of each cell. On the other hand, there is a form of communication called multicast communication. The multicast communication is to broadcast one information frame to a plurality of destinations (members) in a group. In multicast communication, the transmission source is limited to one specific member.
There are two types: types and m-to-m types where each member broadcasts to all other members. In order to support these multicast communications, ATM switches are generally provided with a 1: m broadcast switching function. This is a function for simultaneously outputting cells input from one input line to a plurality of output lines. In order to do this, it is necessary to set a path from a specific input line to a specific plurality of output lines and an identifier corresponding thereto. This identifier is written in the header area of the cell, and based on the identifier, the cell is switched to a plurality of preset output lines in the ATM switch. 1 above
In order to perform m-to-m multicasting using the m-to-m type broadcast switching function, one-to-m-type paths and identifiers must be set from the corresponding input lines to all outgoing lines belonging to the group. Must. If the number of lines belonging to the group is n, it is necessary to set and manage a total of n paths and identifiers.

[0003] This multicast method will be described with reference to FIG. FIG. 2 is a diagram for explaining a multicast method in a conventional ATM switch. Three sets of lines A, B, and C are accommodated in the ATM switch.

In the ATM switch of the first example shown in FIG. 2A, an output line Bout1 is output from an input line Ain11.
ID = 1 is set as an identifier of the input line by setting a path (shown by a solid line) to the output lines Aout121 and Cout123 from the input line Bin12.
A path (shown by a broken line) to out123 is set, and ID = 2 is set as an identifier of the input line, and the input line Cin1 is set.
3 are output lines Aout121 and Bout122.
ID = 3 is set as an input line identifier by setting a path (shown by a dashed line). That is, in this ATM switch, three identifiers are set corresponding to each path.

FIG. 2B shows an ATM of the second example.
In the switch, output lines Aout121, Bout12 are output from input lines Ain11, Bin12 and Cin13, respectively.
Create a path to out 122 and Cout 123. In this case, the output destinations are all the same (that is, Aout12
1, Bout 122 and Cout 123), so only one identifier (ID = 1) needs to be set.

[0006]

In the ATM switch according to the first conventional example, an individual identifier is set for each path. Therefore, when the number of lines in a group is large, the path and the identifier are set. In addition, there is a problem that management is complicated.

In the ATM switch according to the second conventional example, only one identifier needs to be set, so that the trouble of management can be saved. However, since the cell is also output to the source line,
There is a problem that it cannot be used as it is.

An object of the present invention is to add an input line identifier to each cell on the input line side to detect and discard cells from the own input line on the outgoing line side in the second conventional example. It is an object of the present invention to provide an ATM switch capable of performing such operations.

[0009]

According to the present invention , in an ATM switch for exchanging information divided into fixed-length cell units on the basis of information written in a header area thereof, an input side is connected to each input line. pass the identifier to be added to the input cells
It has an input line identifier sending circuit , and the output side checks the routing information written in the header area of each received cell.
The destination cell for which the input cell is not set for its own output line
Receive file that discards this cell if it has
From the input line identifier sending circuit.
The input line identifier did not match the own line identifier
A gate circuit that allows the input cell to pass and output only when
It Ru ATM switch is obtained, characterized in comprising a.

[0010]

[0011]

According to the present invention, even if cells are broadcast to all lines in the group including the transmission source, the cells can be discarded at the output line of the transmission source, so that multicast communication can be easily performed.

[0012]

Next, the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of an ATM switch with a multicast function according to an embodiment of the present invention. 3 for simplicity
The figure shows an input and three output ATM switch.

Referring to FIG. 1 , an ATM switch with a multicast function according to the present embodiment has input lines Ain11 and AinB.
cell transmission circuits (hereinafter, referred to as CLS) 21, 22, and 23 respectively connected to in12 and Cin13;
Input line identifier transmission circuits (hereinafter, referred to as IDS) 31, 32 and 33 for transmitting an identifier for each input line;
21, ..., 23 and IDS31, ..., (hereinafter referred to as SC) transmission control circuit for sending a control signal to the 33 and 60, (hereinafter referred to as BUS) time division bus 50 and through CLS21,2
2 and 23 (hereinafter, REC)
REC7, 71, 72 and 73, identification circuits (hereinafter referred to as IDF) 101, 102 and 103 for checking input line identifiers on the BUS 40, respectively.
Buffers (hereinafter, referred to as BUF) 111, 112 and 113 for temporarily taking in cells passing through 1, 72 and 73
Ru Tei equipped with a door.

For example, the REC 71 checks a destination identifier in a header of a cell input from the CLS 21 and discards a cell having a destination identifier that is not set, and a reception filtering circuit (hereinafter, referred to as FIL) 81 and an IDF 1
And a gate (hereinafter referred to as GT) 91 for gating the output of the FIL 81 in response to a control signal from the FIL 81.
Similarly, REC 72 has FIL 82 and GT 92, and R
The EC 73 includes the FIL 83 and the GT 93.

Next , the operation of this embodiment will be described.
For example, the CLS 21 transmits a cell input from the input line Ain11 to the BUS 50 according to a control signal from the SC 60. At the same time, the IDS 31 sends the identifier of the input line Ain 11 to the BUS 40. Each REC 71, ..., 7
3 Once captures all of the cells on the BUS50, each FIL81, ..., input to 83. FIL81,
, 83 check the destination identifier in the header of the input cell, and if the input cell is set for its own output line, this cell is referred to as GT91. , 93, and discards cells having a destination identifier that is not set.

On the other hand, IDFs 101, ...
40, receives the input line identifier on its own and compares it with its own line identifier.
91, ..., FIL81 open the 93, ..., and passed through a cell from the 83, this passes the cell BUF111, ...,
, 123 are input once to output lines 121,.
Is output to Cells input from the input line Bin12 or Cin13 are processed similarly.

As described above, in this embodiment, even if the multicast path is set to all output lines, the output is not output to its own line because the filtering is performed by the input line identifier.

[0018]

As described above, the present invention has a fixed length.
Information divided into cells is written in the header area.
In the ATM switch that exchanges information based on information, the input side
Is an input that sends an identifier to be added to the input cell of each input line.
The output side is connected to each receiving cell.
Check the routing information written in the
Destination identification with no power cell set for its own output line
Receive filter that discards this cell if it has
Circuit and the input line identifier from the input line identifier sending circuit.
Enter only if the identifier does not match the identifier of your line
And a gate circuit for passing and outputting the cell.
Therefore, even if a cell is broadcast to all lines in the group including the source , the broadcast cell is discarded so as not to be output to the output line of the source. There is an effect that m-to-m bidirectional multicast can be easily performed.

[Brief description of the drawings]

FIG. 1 is a block diagram of an ATM switch with a multicast function according to an embodiment of the present invention.

FIG. 2 is a diagram for explaining a conventional multicast method of an ATM switch.

[Explanation of symbols]

11, 12, 13 Input line (Ain, Bin, Ci)
n) 21, 22, 23 Cell transmission circuit (CLS) 31, 32, 33 Input line identifier transmission circuit (ID
S) 40,50 Time division bus (BUS) 60 Transmission control circuit (SC) 71,72,73 Receiving unit (REC) 81,82,83 Reception filtering circuit (FI)
L) 91, 92, 93 Gate (GT) 101, 102, 103 Identification circuit (IDF) 111, 112, 113 Buffer (BUF) 121, 122, 123 Output line (Aout, Bo)
ut, Cout)

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-162153 (JP, A) JP-A-62-30444 (JP, A) JP-A-62-30445 (JP, A) JP-A-2-302 76436 (JP, A) IEICE Technical Report, SSE88-172 (1989-2-18), Hiroshi Suzuki et al., Configuration of output buffer type ATM switch, p. 37-42 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 12/28 H04L 12/56

Claims (1)

(57) [Claims] 1. A were divided into units of cells of fixed length information in an ATM switch for exchanging based on the information written in the header area, the input side transmits the identifier to be added to the input cells of the input line An input line identifier transmission circuit for
The output side checks the routing information written in the header area of each reception cell, and checks that the input cell
This cell if it has a destination identifier that is not set
A receiving filtering circuit for discarding the
The identifier of the input line from the separate transmission circuit is the identification of the own line.
Passes through the input cell only if it does not match
Characterized by having a gate circuit for powering
switch.