JPH0879253A - Atm exchange provided with multi-casting function - Google Patents

Abstract

PURPOSE: To provide various ATM exchanges provided with a multi-casting function. CONSTITUTION: Header converters 111 -11N provided in incoming highways #1 in-#Nin add tag information for specifying plural outgoing highways #1out-#Nout to inputted ATM cells, replace VCIs with internal identifiers and perform output. A switching part 12 routes the ATM cells to the plural outgoing highways based on the tag information of the ATM cells and the header converters 131 -13N provided in the respective outgoing highways convert the internal identifiers of the ATM cells to the normal VCIs and perform transmission (an internal copying system). Also, a copy server 331 is provided, plural copy cells are outputted by the copy server, one copy cell is recursively returned to the copy server, the remainder is transmitted to the outgoing highways and the copy cells are recursively routed to the copy server 331 until the required number of the copy cells are multi-casted (a recursive copy type trunk system).

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to an ATM switch,
In particular, an AT having a multicast function for copying one ATM cell to a plurality of designated outgoing highways and sending it out
Regarding the M switch.

[0002]

2. Description of the Related Art There is a growing need for multimedia communication including not only voice communication and data communication but also moving images. Asynchronous Transfer Mode (Asynchronous Transfer Mode) is used as a means for realizing such broadband communication.
: ATM-based B-ISDN (Broadband-I)
SDN) exchange technology has been agreed and is being put to practical use.
The ATM system converts all information into fixed information called cells without depending on continuous information such as voice and moving images or burst information such as data, and does not depend on communication speed of each, and is high-speed. Forward. That is, ATM
In the method, multiple logical links are set up on a physical line to allocate the line to multiple calls. Then, moving image data, voice data, and the like from the terminal corresponding to each call are decomposed into fixed-length information units (called cells) and sequentially sent to the line to realize multiplexing.

As shown in FIG. 19, a cell is composed of a fixed length block of 53 bytes, of which 5 bytes are a header part HD and 48 bytes are an information field (also called payload) DT. The header part HD has a virtual channel number (Virtual Channel Identification) for call identification so that the destination can be known even after the data is divided into blocks.
fier: VCI) is included, and in addition, a virtual path identifier (VPI) that identifies a route
, Generic Flow Control (GFC) used for flow control between links,
Payload Type PTI (Payload Type Identificatio)
n) and header error correction code HEC (Header Error C
ontrol) etc. are included.

FIG. 20 is an AT for explaining the ATM system.
1 is a schematic configuration diagram of an M network, 1a and 1b are ATM terminal devices, and 3 is an ATM network. The ATM network 3 comprises an information network 3a for transmitting data cells and a signal network 3b for transmitting control signals, and each of the ATM exchanges 3c-1 to 3c-n in the information network 3a.
Call processors (CPU) 3d-1 to 3d-n of the signal network 3
It is connected to b. When the calling terminal 1a performs a call operation for calling the called terminal 1b, the cell assembling unit in the calling terminal includes a SET UP message (calling number, called number, terminal type, average cell speed, maximum cell speed, etc.). (Data) is divided into cells, and each divided data is given a signal VCI (predetermined for each terminal) to generate a signal cell, and the signal cell is sent to the ATM network 3.

When the signaling device of the ATM exchange (transmission side exchange) 3c-1 receives a signal cell, it assembles the information contained in the signal cell and notifies the CPU 3d-1. The CPU performs caller service analysis processing, billing processing, based on the received message.
Call processing such as callee digit translation processing is performed, and based on the declared average cell speed, maximum cell speed, etc., the route (V
PI) and call identification information (VCI) are determined, and then NO. According to the No. 7 protocol, connection information including a calling number, a called number, VPI, VCI and other data is sent to the next transit exchange 3c-2. Transit switch 3c
-2 performs the same processing as the originating exchange 3c-1 if it receives the connection information, and in the same way, finally, the originating exchange 3c-1
To the ATM switch (receiver side switch) 3c-n to which the receiving terminal is connected and the relay ATM switches 3c-2, 3c-
3, ... is decided. Upon receiving the connection information including the calling number, the called number, and the VCI of the upper ATM switch 3c-3, the called exchange 3c-n assigns a predetermined VCI to the called terminal and checks whether the called terminal 1b can talk. If the call is possible, the signaling network 3b notifies the caller-side switch 3c-1 that the call is possible, and the caller-side switch assigns a predetermined VCI to the caller terminal 1a.

Each of the ATM exchanges 3c-1 to 3c-n on the path corresponds to the VCI of the upper ATM exchange for each path, and (1)
Information for identifying the output path (outgoing highway) of the cell having the VCI (called routing information or tag information)
(2) New VCI and VPI added to the output cell
To the built-in routing table. From the above,
When a path is formed between the calling terminal 1a and the called terminal 1b,
Both terminals send and receive call cells and reply cells to confirm the communication procedure. Thereafter, the transmitting terminal 1a decomposes the data to be transmitted into a predetermined byte length, attaches a header including the assigned VCI to generate a cell, and sends the cell to the ATM network 3. ATM switches 3c-1 to 3c
-n: When a cell is input from a host exchange via a specified input highway, the VPI / VCI of the input cell is changed with reference to its own routing table and the specified output highway is set based on the tag information. Send out. As a result, the cell output from the originating terminal 1a reaches the terminating side exchange 3c-n via the path determined by the call control. The terminating side exchange 3c-n refers to the routing table, replaces the VCI added to the input cell with the VCI assigned to the terminating terminal, and then sends it to the line to which the terminating terminal 1b is connected.

Thereafter, the calling terminal 1a sequentially sends cells to the called terminal 1b, and the called terminal assembles the information part DT included in the received cell to restore the original data. The above is a case for one call, but VCs held at both ends of each line between the terminal-ATM switch and between adjacent ATM switches
By changing the I value, it is possible to set up a logical link corresponding to a large number of calls on one line, thereby realizing high-speed multiplex communication. According to the ATM method, since information of information sources having different transmission rates such as moving images, data, and voice can be multiplexed, one transmission line can be effectively used, and packet switching can be performed by software. There is no need for retransmission control and complicated communication procedures as described above, and ultra-high-speed data transmission of 150 Mbps to 600 Mbps is possible. or,
The ATM exchange has a buffering function. With this buffering function, even if a large number of calls are made to the ATM exchange or the receiving terminal, the call can be accepted and sent to the receiving terminal without causing the originating terminal to wait. For example, when a call is simultaneously made from a large number of terminals to the called terminal 1b and the line between the called exchange 3c-n and the called terminal 1b becomes full, a cell cannot be sent to the called terminal.
In such a case, the terminating exchange 3c-n buffers cells that cannot be sent and sends them when the line becomes available so that the call can be accepted and sent to the terminating terminal without causing the originating terminal to wait.

FIG. 21 is a block diagram of a self-routing ATM switch, which has a basic switching unit SWU, a control information adding unit CIAU, and a processor (call control unit) for call processing. This ATM switch is a one-stage self-routing switch module SRM between incoming and outgoing lines.
However, a plurality of self-routing switch modules may be connected in a plurality of stages. The input ends of the module SRM1 are input lines (input highway) # 1 to # via the control information adding circuit CIAU.
3 are connected, and the output end is an output line (output highway) # 1 to # 3
Connected with. The control information addition unit CIAU is
The additional circuits AC1 to AC3 for adding routing information and the like to the input cells corresponding to the respective input lines # 1 to # 3 are provided. , Tag information) and the VCI contained in the cell is replaced and sent to the basic switching unit SWU.

At the time of calling, the call control unit CPU controls the call to determine the VCI and VPI of the cell, determines the routing header according to the location of the receiving terminal, and adds these pieces of information to the cell. Write to the routing table (not shown) of ACi (i = 1, 2, 3). The additional circuit ACi into which the cell is input is known from the information notified by the upper ATM switch during call control. Further, the determined information (VCI, routing header) is written in the routing table of the additional circuit in association with the VCI of the upper ATM switch. When the call control ends and the cell is input to a predetermined incoming line through the upper ATM switch, the additional circuits AC1 to AC3 connected to the incoming line respond to the VCI added to the input cell from the routing table. Read the control information (routing header and VCI). Then, the routing header is added to the cell and the V of the cell is added.
The CI is replaced with the read VCI and sent to the basic switching unit SWU. The self-routing switch module SRM1 of the basic switching unit SWU uses a routing header to send out cells from a predetermined outgoing line. The routing header is removed by a post-processing circuit (not shown) before sending to the outgoing line.

FIG. 22 is a circuit diagram showing a specific example of the self-routing switch module (SRM1). I _{1 to} I ₃
Is a control information detection circuit, D _{1 to} D ₃ are transmission information delay circuits, D
M _{1 to} DM ₃ are demultiplexers, and DEC _{1 to} DEC ₃ are control information decoding circuits.
An ELD is constructed. FM _{11 to} FM ₃₃ are buffer memories, such as a FIFO (First-In First-Out) memory and SEL.
_{1 to} SEL ₃ are selectors, and AOM _{1 to} AOM ₃ are arrival order management FIFOs. Arrival order management FIFO (AOM ₁
~ AOM ₃ ) are control information decoding circuits DEC ₁ ~
Is connected to the output end of the DEC _3, corresponding three buffer memories FM ₁₁ ~FM _{13 to, FM 21 ~FM 23, FM 31} ~FM
_The cell arrival order is stored in ₃₃ , and the corresponding selector S
By controlling EL _{1 to} SEL ₃ , cells are read from the three buffer memories in the cell arrival order and sent to the outgoing lines # 1 to # 3.

The detection circuit Ii (i = 1 to 3) extracts the control information contained in the input cell and decodes the control information DECi (i = i = i).
1 to 3). If the input routing header indicates the output end #j (j = 1 to 3), the decoding circuit DECi operates the demultiplexer DMi by the switching signal Si and sends the transmission information to the FIFO memory FMji. For example, if the routing header included in the information input from the input end # 1 indicates the output end # 2, the decoding circuit DEC ₁ operates the demultiplexer DM ₁ to input the end # 1.
The information from the input to the FM _21. Arrival order management FIFO
(AOMi) is a control information decoding circuit DEC _{1 to} DEC ₃
Of three corresponding buffer memories F connected to the output terminals of
The order of arrival of cells is stored in Mi _{1 to} FMi ₃ . For example, a cell is a buffer memory FM ₁₁ → FM ₁₂ → FM ₁₃ → F
If the order of arrival is M ₁₂ → ..., the arrival order management FIFO
The buffer memory identification code is stored in O (AOM ₁ ) in the order of cell arrival as 1 → 2 → 3 → 2 → .... Thereafter, the arrival order management FIFO (AOMi) controls the corresponding selector SELI to read cells from the _three buffer memories FMi _{1 to} FMi ₃ in the cell arrival order and send them to the outgoing line #i.

In this way, by providing the FIFO memory FMij with a capacity for a plurality of cells, a buffer function is obtained, and it is possible to sufficiently cope with a case where the transmission data temporarily increases. In addition, since cells are read from the buffer memories FMi _{1 to} FMi _{3 in the} order of arrival of cells, an even number of cells are accumulated in each buffer memory FMi _{1 to} FMi ₃ and overflow from the buffer memory and the cells are discarded (Ce
ll Loss Ratio).

[0013]

By the way, recently, VO
Development and plans are being made to realize a video distribution service such as D (Video On Demand) and a distribution service for entertainment software on the ATM network. The video distribution service includes a broadcasting type service such as CATV which is a one-to-many connection, a VOD service which is basically a one-to-one connection,
Furthermore, near VDO (Near VO) located in the middle of both
Services such as D) are being considered. In order to efficiently perform these video distribution services on the ATM network, ATM
It is necessary to add a multicast function to the exchange system. From the above, it is an object of the present invention to provide various ATM switches having a multicast function. Another object of the present invention is to provide an ATM switch that can realize a multicast function without increasing the size of the switch unit. Still another object of the present invention is QOS.
It is an object of the present invention to provide an ATM exchange equipped with a multicast function capable of making (Quarity of Service) uniform.

[0014]

FIG. 1 is a diagram for explaining the principle of the present invention. In FIG. 1A, # 1in to #Nin are incoming highways, # 1out to #Nout are outgoing highways, and 11 ₁ to ₁ 1.
1 _N is a header converter (VC
C1) and 12 are switch units, and 13 _{1 to} 13 _N are header converters (VCC2) provided on each output highway. In FIG. 1B, # 1in to #Nin are incoming highways, # 1o
ut to #Nout are output highways, 31 _{1 to} 31 _N are header converters (VCC1) provided on each input highway, 32 is a switch unit, 33 ₁ is a copy server, and 34 _{1 to} 34x are output links of the copy server. The provided header converter (V
CC2). In FIG. 1C, # 1in to #Nin are incoming highways, # 1out to #Nout are outgoing highways, 51
_{1 to} 51 _N is a header converter (VCC1) provided on each input highway, 52 is a switch unit, 53 ₁ is a copy server, 53 a is a buffer, and 54 _{1 to} 54 x are header conversion provided on the output link of the copy server. Machine (VCC2).

[0015]

The header converters 11 _{1 to} 11 _N provided in each of the incoming highways # 1in to #Nin add tag information for specifying a plurality of outgoing highways # 1out to #Nout to the input ATM cell. , VCI are replaced with a unique internal identifier in the exchange and output. Switch unit 12 is A
The ATM cells are routed to a plurality of outgoing highways based on the tag information of the TM cells, and the header converters 13 _{1 to} 13 _N provided in each outgoing highway convert the internal identifiers of the ATM cells into regular VCIs and send them out. Yes (internal copy method). ... Figure 1 (a)

The incoming highways # 1in~ # header converter 31 ₁ to 31 _N which are provided in each of Nin is entered AT
Tag information for specifying the copy server 33 ₁ is added to the M cell and output. The switch unit 32 routes the ATM cell to the copy server 33 ₁ . Copy server 3
3 ₁ spatially copies one input ATM cell at a time (x ≧ 2) and outputs it. First to first copy server
Header converter 34 ₁ connected to the (x−1) th output link
34x _-1 adds tag information for specifying a predetermined output highway to the copy cells output from the copy server and inputs them to the switch unit 32, and the header converter 34x connected to the xth output link is the copy server. Tag information for routing the copy cell output from 33 ₁ to the copy server is added and input to the switch unit 32. Switch part 3
2 is an AT input from each of the header converters 34 _{1 to} 34 x
Predetermined exit highway # 1ou based on tag information for M cells
It routes t to #Nout and the copy server 33 ₁ , and recursively routes the copy cells to the copy server 33 ₁ until the required number of copies is reached (recursive copy trunk system). ... Figure 1 (b)

The header converters 51 _{1 to} 51 _N provided on the input highways # 1in to #Nin respectively receive the input AT
Tag information for specifying the copy server 53 ₁ is added to the M cell and output. The switch unit 52 routes the ATM cell to the copy server 53 ₁ . Copy server 5
3 ₁ stores _one input ATM cell in the buffer 53a, spatially copies x ATM cells at a time, and outputs it, and then x x at a predetermined time until the designated copy number is reached. Copy and output ATM cells. Header converter 54 provided for x output links of the copy server
Every time _{1 to} 54x outputs a copy cell from the copy server 53 _1, tag information for specifying a predetermined output highway is added and input to the switch unit 52. The switch unit 52 routes the ATM cells input from the header converters 54 _{1 to} 54 x to a predetermined output highway based on the tag information (time copying trunk system). ... FIG. 1 (c) As described above, various ATM exchanges having a multicast function can be provided. Also, copy server 3
By installing 3 ₁ and 53 ₁ externally to the switch,
The multicast function can be realized without increasing the size of the switch unit. Furthermore, if the copy cells are continuously output to x output links of the copy server, the load in the exchange can be made uniform.
Further, since the copy cells are evenly output to the output highway of the switch section, QOS and the like can be held uniformly.

[0018]

【Example】

(a) First Embodiment of the Present Invention (a-1) Configuration FIG. 2 is a configuration diagram of a first embodiment of the present invention, which is a configuration diagram of an ATM exchange by an internal copy system. In the figure, # 1in ~ #
Nin is an input highway, # 1out to #Nout are output highways, 11 _{1 to} 11 _N are header converters (VCC1) provided in each input highway, and 12 is N × N (N input, N output).
Switch unit, 13 _{1 to} 13 _N are header converters (VCC2) provided on the respective output highways, and 14 is a call processor. The header converters 11 _{1 to} 11 _N provided on each of the incoming highways # 1in to #Nin are provided with routine tables (RTBL) 11a _{1 to} 11a _N , respectively. Further, the header converters 13 _{1 to} 13 _N provided on the respective output highways # 1out to #Nout are header conversion tables (HDCV) 13a _{1 to} 13a _N for converting the internal identifier into a regular VCI.
It has.

In the routine table RTBL, tag information (bitmap tag) BMTG for specifying the destination (outgoing highway) of the cell corresponding to the VCI of the input cell at the time of making a call under the control of the call processor 14 is stored. , The internal identifier IVCI valid only in the ATM switch is registered. The bitmap tag BMTG has N bits and makes the output highways # 1out to #Nout correspond to the first to Nth bits. Therefore, when it is desired to send a cell to a predetermined output highway #iout, the i-th bit of the bitmap tag is set to high level (“1”). When multicasting ATM cells to a plurality of outgoing highways, for example, when multicasting to the first, second and Nth outgoing highways,
The first, second and Nth bits of the bitmap tag BMTG are set to "1". The internal identifier IVCI is valid only in the ATM exchange, and has a value corresponding to the incoming highway number, for example. That is, the internal identifier IVCI has a different value for each incoming highway. The regular identifier VCI is registered in the header conversion table HDCV in association with the internal identifier IVCI. The contents of the header conversion table HDCV are different for each output highway, and even the same internal identifier IVCI is converted into a different regular VCI for each output highway.

(A-2) Operation When an ATM cell arrives from the incoming highway # 1in, the header converter 11 ₁ sends the routine table (RTBL) 11a ₁
See Bitmap Tag BMTG and Internal Identifier IV
Find the CI. Then, the bitmap tag BMTG is added to the ATM cell, and the VCI is added to the internal identifier IV.
It is replaced by CI and input to the switch unit 12. The first and Nth bits of the bitmap tag BMTG are "1". The switch unit 12 routes the ATM cell to the first output highway # 1out and the Nth output highway #Nout based on the bitmap tag BMTG added to the ATM cell. Header converter 1
3 ₁ , 13 _{N, when} an ATM cell is input from the switch unit 12, converts the internal identifier IVCI of the ATM cell into a regular VCI by referring to the header conversion table HDCV, and then deletes the bitmap tag BMTG and outputs. Send to the highway. In this case, the contents of the header conversion table HDCV are different for each output highway.
The VCI of the ATM cell transmitted from the output highway has different values.

FIG. 3 is a diagram for explaining the operation of the first embodiment. A
The TM cell receives the header conversion unit (VC
C1) 11₁, The header conversion unit VCC1
From the routine table to the VCI of the input ATM cell
Corresponding bitmap tag BMTG (1101) and internal
An identifier IVCI (for example, # 1) is obtained (FIG. 3 (b)). One
Header converter (VCC1) 11 ₁Is a bitmap
The tag 1101 is added to the cell and the VCI is
Change to Besshi IVCI (= # 1) and enter into switch unit 12.
Force The switch unit 12 has a bitmap tag 1101.
Exit ATM cell based on highways A (# 1out), B
(# 2out), D (# 4out) header converter VCC2
Routing. Each exit highway A (# 1out), B
(# 2out), D (# 4out) header converter VCC2
Refers to the header conversion table to identify the internal identifier IVCI
(= # 1) is converted to the regular VCI value 5, 2, 7
Remove the highway A (# 1
out), B (# 2out), and D (# 4out).

[0022] Also, when the ATM cell is inputted from the incoming highway # 2in header converting unit (VCC1) 11 to _2, the header converting unit VCC1 was the input from the routine table A
Bitmap tag BMTG corresponding to VCI of TM cell
(1010) and the internal identifier IVCI (for example, # 2) are obtained (FIG. 3 (c)). Next, the header converter (VCC1) 1
1 ₂ adds the bitmap tag 1010 to the cell, changes the VCI to the internal identifier IVCI (= # 2), and inputs it to the switch unit 12. The switch unit 12 outputs the ATM cell based on the bitmap tag 1010 and the header conversion unit VCC2 of the highways A (# 1out) and C (# 3out).
Route to. Each exit highway A (# 1out), C
The header conversion unit VCC2 of (# 3out) refers to the header conversion table to convert the internal identifier IVCI (= # 2) into regular VCI values of 1 and 3, and removes the bitmap tag to output the highway A. (# 1out), C (# 3out).

(B) Second Embodiment of the Present Invention (b-1) Configuration FIG. 4 is a configuration diagram of a second embodiment of the present invention, which is a configuration diagram of an ATM switch by a space type trunk system. In the figure, # 1in
~ #Nin is an input highway, # 1out to #Nout is an output highway, 21 _{1 to} 21 _N are header converters (VCC1) provided in each input highway, 22 is a 2N input, (N + 1) output switch section, 23 ₁ is a copy server, ATM
One composed of a 1: N switch for copying an arbitrary number of cells of N or less, 24 _{1 to} 24 _N are header converters (VCC2) provided in each output link of the copy server, and 25 is a call processor. . The copy server 23 ₁ generates the number c (≦ N) of copy cells instructed by the call processor 25 and outputs the copy cells to the output link. Header converters 11 _{1 to} 11 _N provided on each of the incoming highways # 1in to #Nin
Each have a routine table RTBL (not shown). Further, each of the header converters 24 _{1 to} 24 _N is provided with a routine table (not shown) for routing the copy cell to a predetermined output highway.

(B-2) Operation Routine table RTBL of the header converters 11 _{1 to} 11 _N
In the control of the call processor 25 at the time of calling, the tag information (code tag) that specifies the destination of the input cell in correspondence with the VCI of the input cell and the internal information that is valid only within the VCI or ATM switch are included. The identifier IVCI is registered.
That is, in the case of a multicast call, V of the input cell
A code tag for identifying the output highway # (N + 1) out to the copy server 23 ₁ and the internal identifier IVCI are registered in association with the CI. In addition, in the case of a call other than the multicast call, a code tag that identifies one of the outgoing highways # 1out to #Nout and a new VCI are registered in association with the VCI of the input cell. A code tag is a code tag that identifies a destination.

When a normal ATM cell other than a multicast call arrives, the header converters 21 _{1 to} 21 _N send a code tag for routing the ATM cell to the outgoing highway # 1out to #Nout and a new VCI from the routing table. V code as well as adding the code tag to the ATM cell
The CI is replaced with a new VCI and input to the switch unit 22. The switch unit 22 routes the ATM cell to the output highway designated by the code tag and sends it. on the other hand,
When an ATM cell of a multicast call arrives, the header converters 21 _{1 to} 21 _N add a code tag for routing to the copy server 23 ₁ to the ATM cell, and VC
I is replaced with the internal identifier IVCI and input to the switch unit 22. The switch unit 22 routes the ATM cell to the output highway # (N + 1) out designated by the code tag.

The copy server 23 ₁ is the exit highway # (N + 1)
When an ATM cell is input from out, the call processor 2
5, the number c (≦ N) of copy cells instructed is generated, and c is instructed by the call processor 25 in the same manner.
Send to a given output link of the book. Header converter 24 ₁
In the routing table of No. 24 _N , the code tag for identifying one outgoing highway among the outgoing highways # 1out to #Nout in correspondence with the internal identifier IVCI under the control of the call processor 25, and the regular call identifier. VCI
Is registered. Therefore, when a copy cell is input from the copy server 23 _1, the c header converters 24 _{1 to} 24 c input by the copy cell route the ATM cell to the output highways # 1out to #Nout using the internal identifier as a key. The code tag for doing so and the regular VCI are obtained from the routing table. Next, each of the header converters 24 _{1 to} 24 c adds a code tag to the ATM cell, replaces the internal identifier with a regular VCI, and inputs it to the switch unit 22. The switch unit 22 routes each of the c ATM cells to the output highway designated by the code tag, removes the code tag, and sends it.

(B-3) Modified Example Modified Example 1 When the number of copies is c, the copy server 23 ₁ has an arbitrary c
The copy cell can be output to the output link of the book and can be multicast to the desired output highway. However, in such a case, the number of copy cells of each output link is not uniform. Therefore, when the number of copies is c (c ≦ N), the copy server 23 ₁ outputs the copy cells from the continuous c output terminals, and thereafter, the copy cells are continuously output from the next output terminal to another multicast call. To output a predetermined number of copy cells. By doing so, the number of copy cells sent from each output link of the copy server becomes uniform, and the load in the exchange can be equalized.

Modification 2 In the above, when the number of copies is c, the copy server 23 ₁
The case where the copy cells are sent to the more predetermined c output links has been described, but the following configuration may be adopted. That is, when the copy number is c (c ≦ N),
The copy server 23 ₁ sends out copy cells to all N output links. Of the _N header converters 24 _{1 to} 24 _N provided on the output side of the copy server 23 ₁ , (N−
c) The header converters do not need to be routed (N
-C) discard the cells and only c header converters
Route the TM cell to the exit highway. Whether to discard or not is to be discarded when, for example, the code tag has a specific value.

FIG. 5 is an explanatory diagram of the above modification, where N = 4.
Is. When ATM cell of the multicast call is inputted from the incoming highway # 1in header converting unit (VCC1) 21 to _1, code tag E the header converting unit VCC1 is corresponding to the VCI of ATM cells the input from the routine table with internal identifier IVCI ( For example, # 1) is calculated (Fig. 5)
(a)). The code tag E is for routing the ATM cell to the copy server. Then, the header conversion unit (VCC1) 21 ₁ adds the code tag E to the ATM cell, changes the VCI into the internal identifier IVCI (= a), and inputs the same to the switch unit 22. The switch unit 22 outputs the ATM cell based on the code tag E and exits the highway (#
5 out). When an ATM cell is input from the output highway # 5out, the copy server 23 ₁ receives N (=
4) Generates and sends out to all output links copy cells.

Header converters (VCC2) 24 ₁ , 24 ₂ ,
The routing table of 24 ₄ contains the internal identifier IVCI.
Corresponding to (= a), exit highway # 1out to #No
A code tag that identifies the exit highway of ut,
The VCI, which is a regular call identifier, is registered. In other words, the header converter 24 _1, output highway # 1out to identify the code tag (= A) and normal VCI (= 5) is registered, highway # 2out out the header converter 24 ₂
Code tag (= B) that identifies the code and a regular VCI (= 2)
Is registered, and the exit highway # 4o is sent to the header converter 24 ₄ .
Code tag (= D) that identifies ut and regular VCI (=
7) is registered. Further, the discard table is registered in the routing table of the header converter 24 ₃ in association with the internal identifier IVCI (= a). As a result, an ATM cell with VCI = 5 is routed to the output highway # 1out, an ATM cell with VCI = 2 is routed to the output highway # 2out, and VCI = is output to the output highway # 4out.
7 ATM cells are routed and transmitted. However, the ATM cell is not routed to the output highway # 3out and is discarded. Therefore, ATM cells are multicast to the outgoing highways # 1out, # 2out, # 4out.
FIG. 5B shows an example in which the data is not discarded but is sent to the full-out highway.

Modification 3 The above is a case where the copy cell transmitted to the output link of the copy server 23 ₁ can be routed to an arbitrary output highway by the header converter 24i (i = 1 to N). However, in such a case, it is necessary to hold the code tag corresponding to the internal identifier in the routing tables of the header converters 24 _{1 to} 24 _N , which increases the size of the routine table. Therefore, as shown in FIG. 6, the output link of the copy server 23 _{1 and} the output highway of the switch unit 22 are associated with each other 1: 1. In this way, in the routing table RLTB of the header converters 24 _{1 to} 24 _N , it is not necessary to hold the code tag corresponding to each internal identifier, and it is sufficient to correspond only the regular VCI to reduce the size of the routine table. Can be made smaller. Modification 4 The above is an example in which one copy server is provided. However, when there are many multicast calls, as shown in FIG.
2) The above copy servers 23 ₁ ... 23 m are provided, and the header converters 24 ₁₁ to 2 are attached to the output links of each copy server.
4 _1N , ..., 24 m _{1 to} 24 m _N may be provided.

(C) Third Embodiment of the Present Invention (c-1) Configuration FIG. 8 is a configuration diagram of a third embodiment of the present invention, which is a configuration diagram of an ATM exchange by a recursive copy trunk system. In the figure,
# 1in to #Nin are incoming highways, # 1out to #Nout are outgoing highways, 31 _{1 to} 31 _N are header converters (VCC1) provided in each incoming highway, 32 is a switch unit, 33
_{1 to} 33 m are copy servers (1: 2 copy server) that generate two copy cells from one ATM cell and output them simultaneously, 34 _{11 to} 34 ₁₂ , ..., 34 m _{1 to} 34 m ₂ are copy servers of each copy server. It is a header converter (VCC2) provided on two output links. In addition, although the case where m copy servers are provided is shown, the number of copy servers may be one. Therefore, in the following description, the case where only the copy server 33 ₁ exists will be described. In the second embodiment,
The copy server has generated N copy cells from one ATM cell and outputs them at the same time. According to the second embodiment, there is an advantage that c (≦ N) copy cells can be generated and output by one copy. However, there is a problem in that a switch unit of 2 · N input and (N + 1) output is required, and the switch unit becomes large. The third embodiment can have a multicast function even if the switch unit is small.

(C-2) Operation Routine table RTBL of header converters 31 _{1 to} 31 _N
(Not shown) is a control of a call processor (not shown) at the time of calling, and tag information (code tag) for identifying the transmission destination of the cell corresponding to the VCI of the input cell, and the VC
I or internal identifier I valid only within the ATM switch
The VCI is registered. That is, in the case of a multicast call, a code tag that specifies the outgoing highway # (N + 1) out to the copy server 33 ₁ and the internal identifier IVCI are registered in association with the VCI of the input cell. or,
In cases other than the multicast call, one of the outgoing highways # 1out to #Nout is associated with the VCI of the input cell.
Code tag that identifies two exit highways and a new V
The CI is registered.

When a normal ATM cell other than a multicast call arrives, the header converters 31 _{1 to} 31 _N send a code tag for routing the ATM cell to the outgoing highway # 1out to #Nout and a new VCI from the routing table. V code as well as adding the code tag to the ATM cell
The CI is replaced with a new VCI and input to the switch unit 32. The switch unit 32 routes the ATM cell to the output highway designated by the code tag and sends it. on the other hand,
When an ATM cell of a multicast call arrives, the header converters 31 _{1 to} 31 _N add a code tag for routing to the copy server 33 ₁ to the ATM cell, and VC
I is replaced with the internal identifier IVCI and input to the switch unit 32. The switch unit 32 routes the ATM cell to the output highway # (N + 1) out designated by the code tag.

The copy server 33 ₁ is the exit highway # (N + 1)
When an ATM cell is input from out, two copy cells are generated and sent to two output links. Header converter 34
The routing table of ₁ corresponds to the internal identifier IVCI under the control of the call processor, and the output highway #
A code tag that identifies one outgoing highway from 1out to #Nout and a VCI that is a regular call identifier are registered. Also, the routing table of the header converter 34 _2, corresponding to the internal identifier IVCI in control of the call processor, output highway # 1out~ # (N + 1) code tag identifying one of the exits highways of the out And the regular call identifier VCI or internal identifier is registered.

Therefore, when two copy cells are output from the copy server 33 ₁ , the header converter 34 ₁ outputs the copy cells using the internal identifier as a key.
A code tag for routing from out to #Nout,
The regular VCI is obtained from the routing table. Then, the header converter 34 ₁ adds the code tag to the copy cell, replaces the internal identifier with a regular VCI, and inputs it to the switch unit 32. The switch unit 32 routes the copy cell to the output highway designated by the code tag, removes the code tag, and sends it. As described above, one copy cell is transmitted from the predetermined output highway. On the other hand, the header converter 34 ₂ uses the internal identifier as a key,
A code tag for routing the copy cell to the output highway # 1out to # (N + 1) out and a regular VCI or internal identifier are obtained from the routing table. Copy cells are sent to the output highway one by one,
When the number of remaining copies to be multicast is two or more, a code tag for routing the copy cell to the output highway # (N + 1) out and another internal identifier are read from the routine table of the header converter 34 _2. Is obtained from the routing table.

The header converter 34 ₂ adds the code tag to the copy cell, replaces the internal identifier with a new internal identifier, and inputs it to the switch unit 32. Switch part 3
2 routes the copy cell to the output highway # (N + 1) out designated by the code tag. When the ATM cell (copy cell) is input from the output highway # (N + 1) out, the copy server 33 ₁ again generates two copy cells and sends them to the two output links. The header converters 34 ₁ and 34 ₂ repeat the above processing, and thereafter, recursively route the copy cells to the copy server 33 ₁ and repeat the above operation until the required number of copy cells are multicast to the output highway. When the above recursive operation is repeated and the number of remaining copy cells to be multicast reaches one, the header converter 3
4 ₂ discards the input copy cell, and the header converter 3
4 ₁ only completes a multicast operation by sending a copy cell to a predetermined output highway # 1out~ # Nout via the switch unit 32 performs the above operation.

When the above recursive operation is repeated and the number of remaining copy cells to be multicast becomes two,
Each of the header converters 34 ₁ and 34 ₂ outputs the copy cell using the internal identifier of the copy cell as a key.
A code tag for routing from out to #Nout,
The regular VCI is obtained from the routing table. Next, each of the header converters 34 ₁ and 34 ₂ adds the code tag to the copy cell, replaces the internal identifier with the regular VCI, and inputs it to the switch unit 32. The switch unit 32 routes each copy cell to the output highway designated by the code tag, removes the code tag, and sends it.
With the above, the multicast operation is completed.

FIG. 9 is a diagram for explaining the above operation. When ATM cell of the multicast call is inputted from the incoming highway # 1in header converting unit (VCC1) 31 to _1, code tag E and internal identifier IVC the header converting unit VCC1 is corresponding to the VCI of ATM cells the input from the routine table
I (for example, a) is obtained (FIG. 9 (a)). In addition, code tag E
Is for routing the ATM cell to the copy server 33 ₁ . Next, the header conversion unit (VCC1) 3
1 ₁ with the addition of code tag E in the ATM cell, V
The CI is changed to the internal identifier IVCI (= a) and input to the switch unit 32. The switch unit 32 routes the ATM cell to the output highway (# (N + 1) out) based on the code tag E. The copy server 33 ₁ is the exit highway # (N + 1)
When an ATM cell is input from out, two copy cells are generated and sent to two output links.

[0040] The routing table of the header converter (VCC2) 34 _1, in association with the internal identifier IVCI (= a), output highway # and code tag A identifying the 1out, VCI is a call identifier of the normal (= 5) is registered. Further, in the routing table of the header converter (VCC2) 34 ₂ , a code tag E for identifying the output highway # (N + 1) out and another internal identifier (corresponding to the internal identifier IVCI (= a) are stored. = B) is registered. As a result, the copy cell of VCI = 5 is routed and sent to the output highway # 1out. Further, the copy cell having the internal identifier = b is routed to the output highway # (N + 1) out, and the copy server 33 ₁ is sent from the output highway.
Will be recursed to. Copy server 33 ₁ exits highway # (N +
1) When an ATM cell is input from out, two copy cells are generated again and sent to two output links.

[0041] The routing table of the header converter (VCC2) 34 _1, in association with the internal identifier IVCI (= b), output highway # and code tag B to identify the 2out, VCI is a call identifier of the normal (= 2) is registered. Further, in the routing table of the header converter (VCC2) 34 ₂ , the code tag D for identifying the outgoing highway #Nout and the VCI (= 3) which is a regular call identifier are associated with the internal identifier IVCI (= b). ) Is registered. As a result, the VC on the exit highway # 2out
The copy cell of I = 2 is routed and transmitted, and
The copy cell with VCI = 3 is routed to the output highway #Nout and transmitted. As described above, one ATM cell is recursively copied to three outgoing highways and multicasted. Note that FIG. 9B shows an example in which an ATM cell of a multicast call arrives from the incoming highway # 2, and it can be understood in the same manner as in FIG. 9A.

In the above, the second output link of the copy server 33 ₁ is used both for the recursive copy cell and for the routing to the outgoing highway, but it may be dedicated to the recursive.
In the case of recursion only, if the number of copy cells to be multicast is n, the copy cells are recurred to the copy server n times, and one copy cell is sent from the predetermined output highway for each recursion. In the case of dual use, (n-1) recursion is performed. (c-3) Modified Example Modified Example 1 The above is an example in which one copy server is provided. However, when there are many multicast calls, as shown by the dotted line in FIG.
(≧ 2) or more copy servers 33 ₁ ... 33 m are provided,
The header converters 34 _{11 to} 3 are attached to the output links of the respective copy servers.
4 ₁₂ may be configured to provide a ··· 34m ₁ ~34m _2.

[0043] In Modification 2 or more, the call processor is to create a routing table RTBL during a call may be registered to the header converter 34 _1, 34 _2, the header converter 34 _1, 34 ₂ the routing table The first copy cell output from the copy server 33 ₁ by reference is sent to the output highway, and the second copy cell is recursed to the copy server. And
The copy cell is routed (recursive) to the copy server 33 _1.
Multicast ends when it is no longer available. That is, in the third embodiment, the internal identifiers of the copy cells are sequentially changed, one copy cell is sent to the output highway corresponding to the internal identifier, and the copy cells are copied by the copy server 33 _1.
The multicast is terminated when it is no longer recursed to. As described above, the internal identifiers of the copy cells may be sequentially changed, but the internal identifiers are not changed, and instead, the recursion count (count) m is added to the copy cells, and the combination of the internal identifier and the recursion count m is changed. It can be regarded as a new internal identifier. That is, based on the combination of the internal identifier and the recursive count m, the first copy cell is routed to a predetermined output highway, and the second copy cell is recursed to the copy server. Then, when the number of recursion becomes equal to the number instructed by the call processor, the multicast operation is terminated.

FIG. 10 is an operation explanatory view of such a modified example, FIG.
1 is a block diagram of an incoming highway header converter 31 ₁ .
2 is a block diagram of the copy server, and FIG. 13 is a block diagram of the header converter 34 ₁ on the copy server output side. The header converter 34 ₂ is not always necessary. At the time of calling, a call processor (not shown) executes routing table RTBL (see FIG. 1).
1), RTBL '(Fig. 13) is created and the header converter 3
Register 1 ₁ and 34 ₁ . AT for multicast call
M cell is the header conversion unit (VCC
1) When inputting to 31 ₁ , as shown in FIG. 11, the header processing unit HPR of the header converting unit (VCC1) 31 ₁ receives the VCI of the input ATM cell from the routine table RTBL.
Then, the code tag E corresponding to, the internal identifier IVCI (for example, a), and the recursive number m (= 3) are obtained.

Next, the header conversion unit (VCC1) 31 ₁
Adds the code tag E and the number of recursion m (= 3) to the ATM cell, changes the VCI to the internal identifier IVCI (= a), and inputs it to the switch unit 32. The switch unit 32 outputs the ATM cell based on the code tag E and exits the highway (#
Routing to (N + 1) out). When the ATM cell is input from the output highway # (N + 1) out, the copy server 33 ₁ stores it in the buffer BFR. Further, the copy completion judging unit CED checks whether m = 0. If m ≠ 0, the recursive number subtraction unit RCS subtracts one from the recursive number m to set m = “2”.
Next, the copy unit CPY has an internal identifier = a and a recursive number m.
= 2, two copy cells are generated and sent to two output links.

[0046] The header converter (VCC2) 34 ₁ of the routing table RTBL 'as shown in FIG. 13, internal identifier IVCI (= a) and in correspondence with the recursion depth m (= 2), the output highway # 1out Code tag A to specify
, And the VCI (= 5) which is a regular call identifier is registered. As a result, the header processing unit HPR 'adds the code tag A to the copy cell and sets the internal identifier a to VC.
It is replaced with I = 5, or the recursion count m is deleted and input to the switch unit 32. The switch unit 32 routes the copy cell to the output highway # 1out according to the code tag. As a result, the copy cell with VCI = 5 is transmitted from the output highway # 1out. In addition, a header converter (VCC
2) Since 34 ₂ is designed to output the input copy cell as it is, the copy cell with the internal identifier = a and m = 2 is routed to the output highway # (N + 1) out.
The copy highway is returned to the copy server 33 ₁ .

The copy server 33 ₁ is the exit highway # (N + 1)
When an ATM cell (copy cell) is input from out, m =
0 is checked, and if m ≠ 0, the number of recursion m is subtracted by 1 to set m = “1”, and then two copy cells of m = 1 are generated and sent to two output links. . In the routing table of the header converter (VCC2) 34 ₁ , the code tag B for identifying the outgoing highway # 2out in association with the internal identifier IVCI (= a) and the recursive number m (= 1)
And VCI (= 2), which is a regular call identifier, is registered. As a result, VCI =
Two copy cells are routed and sent. Since the header converter (VCC2) 34 ₂ outputs the input copy cell as it is, the output highway # (N + 1) out has a copy cell with an internal identifier = a and m = 1. Routed, copy server 3 from the exit highway
It recurses to 3 ₁ .

The copy server 33 ₁ is the exit highway # (N + 1)
When an ATM cell is input from out, it is checked whether m = 0. Since m = 1, the recursion count m is decremented by 1 and m =
It is set to “0”, and then two copy cells of m = 0 are generated and transmitted to the two output links. Header converter (VC
C2) The routing table of 34 ₁ contains the internal identifier I
Corresponding to VCI (= a) and recursion count m (= 0),
A code tag D that identifies the outgoing highway #Nout and a VCI (= 3) that is a regular call identifier are registered.
As a result, the copy cell of VCI = 3 is routed and transmitted to the output highway #Nout. Further, since the header converter (VCC2) 34 ₂ outputs the input copy cell as it is, the output highway # (N +
1) A copy cell having an internal identifier = a and m = 0 is routed to out, and the copy server 33 ₁ is recurred from the output highway. The copy server 33 ₁ is the exit highway # (N + 1)
When an ATM cell is input from out, it is checked whether m = 0. In this case, since m = 0, it is determined that the multicast has ended, and the generation of copy cells ends. In the above, the number of recursion is subtracted, and when m = 0, it is determined that the multicast has ended. However, the recursion number M is set in the copy server by the call processor, and the number of recursion m ( The initial value may be incremented by 0), and when m = M, it may be determined that the multicast has ended.

Modification 3 In the third embodiment, the copy server 33 is one ATM.
Generate two copy cells from a cell and output them simultaneously 1:
It was a 2 copy server. According to the third embodiment, the size of the switch unit can be reduced, but since c copy cells must be recursively copied and output one by one, there is a problem that the multicast takes time. . Therefore, AT is used for relatively small-sized and high-speed multicast using a 1: x copy server that generates x (≧ 3) copy cells from one ATM cell and outputs them at the same time.
It is also possible to configure an M switch.

FIG. 14 uses such a 1: x copy server.
It is a block diagram of a case. In the figure, # 1in to #Nin are incoming highways
Ah, # 1out- # Nout is the exit highway, 41₁~ 41_N
Is a header converter (VCC
1), 42 is a switch unit, 43 ₁Is one ATM cell
X (N ≧ x ≧ 3) copy cells are generated and output at the same time.
Powerful copy server (1: x copy server), 44₁₁~ 4
4₁x is a link to x output links of the copy server.
It is a HUD converter (VCC2). In addition, multicast call
If there are many, there are more than m (≧ 2)
Pea server 43₁・ ・ ・ ・ ・ ・ 43m, each copy server
To the output link of the header conversion unit 44₁₁~ 44₁x, ・ ・ ・ 4
4m₁It can also be configured to provide ~ 44mx.

In the routine table RTBL (not shown) of the header converters 41 _{1 to} 41 _N , the call processor is controlled when a call is made, and the destination of the cell is specified in association with the VCI of the input cell. Tag information (code tag) and VC
I or internal identifier I valid only within the ATM switch
The VCI is registered. That is, in the case of a multicast call, a code tag that specifies the outgoing highway # (N + 1) out to the copy server 43 ₁ and the internal identifier IVCI are registered in association with the VCI of the input cell. In the case of a call other than the multicast call, a code tag for identifying one of the outgoing highways # 1out to #Nout and a new VCI corresponding to the VCI of the input cell.
Is registered.

When a normal ATM cell other than a multicast call arrives, the header converters 41 _{1 to} 41 _N send a code tag for routing the ATM cell to the outgoing highway # 1out to #Nout and a new VCI from the routing table. V code as well as adding the code tag to the ATM cell
The CI is replaced with a new VCI and input to the switch unit 42. The switch unit 42 routes the ATM cell to the output highway designated by the code tag and sends it. on the other hand,
When an ATM cell of a multicast call arrives, the header converters 41 _{1 to} 41 _N add a code tag for routing to the copy server 43 ₁ to the ATM cell, and VC
I is replaced with the internal identifier IVCI and input to the switch unit 42. The switch unit 42 routes the ATM cell to the output highway # (N + 1) out designated by the code tag.
Copy server 43 ₁ AT from output highway # (N + 1) out
When M cells are input, x copy cells are generated and sent to x output links.

In the routing tables of the header converters 44 _{1 to} 44 _(x-1) , the output highways # 1out to #No are associated with the internal identifier IVCI under the control of the call processor.
A code tag that identifies the exit highway of ut,
The VCI, which is a regular call identifier, is registered. or,
In the routing table of the header converter 44 _x , in correspondence with the internal identifier IVCI under the control of the call processor,
A code tag for specifying the exit highway # 1out to # (N + 1) out and a VCI or an internal identifier are registered. Therefore, when x copy cells are output from the copy server 43 ₁ , the header converters 44 _{1 to} 44 _(x-1) output the copy cells using the internal identifier as a key.
The code tag for routing to #Nout and the regular VCI are obtained from the routing table. Then,
The header converters 44 _{1 to} 44 _(x-1) add the code tag to the copy cell, replace the internal identifier with a regular VCI, and input it to the switch unit 42. The switch part 42 is (x
-1) Each copy cell is routed to the output highway designated by the code tag, the code tag is removed, and the copy cell is transmitted.
As described above, (x-1) copy cells are transmitted from the predetermined (x-1) output highways.

On the other hand, the header converter 44x, when the number of remaining copies to be multicast is (x + 1) or more,
From the routine table of the header converter 44x, the AT
A code tag for routing the M cell to the exit highway # (N + 1) out and another internal identifier are obtained. The header converter 44x adds the code tag to the copy cell, replaces the internal identifier with a new internal identifier, and inputs it to the switch unit 42. The switch unit 42 routes the copy cell to the output highway # (N + 1) out designated by the code tag. Copy server 43 ₁ is out highway # (N + 1) ou
When ATM cells (copy cells) are input from t, x copy cells are generated again and sent to x output links.

The header converters 44 _{1 to} 44 _(x-1) and 44 _x repeat the above-mentioned processing, and thereafter, the copy cells are recursed to the copy server 43 ₁ until the required number of copy cells are multicast to the output highway. Then, the above operation is repeated. When the number of remaining copy cells to be multicast is c (≦ x−1), the copy server outputs the copy cells to c output links. Header copy cell is input transducer 44 ₁ ～44C the prescribed outgoing highway c present the c-number of copies cells through the switch unit 42 performs the aforementioned operation # 1
Send out to #Nout to complete the multicast operation.

The remaining copy sessions to be multicast are also
If the number of rules is c (= x), the copy server has x
Output copy cells to all output links. Each header converter
44 ₁~ 44x uses the internal identifier of the copy cell as a key,
Route the copy cell to exit highway # 1out to #Nout.
Route the code tag and the regular VCI for
Obtain from the teaching table. Next, each header converter 4
4₁~ 44x is the same as adding a code tag to a copy cell.
In addition, replace the internal identifier with a regular VCI and switch
Enter in 42. The switch unit 42 has x copy cells.
X outbound highways instructed by code tags
Routing, remove code tag and send. more than
Then, the multicast operation is completed. In this case, the last
If the number of copy cells output to is c (c ≦ x)
Copy from the consecutive c output links of the copy server.
-Output cells. And after that, another multicast
For a call, a predetermined number of copies are continuously sent from the next output link.
-Output cells recursively. If you do this, copy
The number of copy cells output from each output link of the server is averaged.
The load on the exchange can be made uniform. Also,
Peer server's xth output link is used for recursion
It was also used as a routing function for Yahoo, but it should be used only for recursion.
Can be.

Further, in the above description, when the number of copy cells to be finally output is c (c≤x), the copy cells are output to the predetermined c output links and are connected to the output links. The copy cell is routed to a predetermined output highway through the c header converters and the switch section. However, the copy server may always send the copy cells to all x output links, and the header converter may discard unnecessary copy cells. FIG. 15 is a diagram for explaining the operation of the ATM switch when discarding such unnecessary copy cells. When ATM cell of the multicast call is inputted from the incoming highway # 1in header converting unit (VCC1) 41 to _1, code tag E the header converting unit VCC1 is corresponding to the VCI of the ATM cell inputted from the routine table with internal identifier IVCI (e.g. Find a).

Next, the header converter (VCC1) 41 ₁
Attaches the code tag E to the ATM cell and
To the internal identifier IVCI (= a) and switch unit 4
Enter 2. The switch unit 42 routes the ATM cell to the output highway (# (N + 1) out) based on the code tag E. Copy server 43 ₁ is out highway # (N + 1) out
When more ATM cells are input, x copy cells are generated and sent to x output links. Header converter (VC
C2) The routing table of 44 ₁ contains the internal identifier I
Corresponding to VCI (= a), exit highway # 1out
Code tag A that identifies the
CI (= 5) is registered, the routing table of the header converter 44 _2, corresponding to the internal identifier IVCI (= a), and code tag B to identify the output highway # 2out, is a normal call identifier VCI (= 2) is registered, the routing table below Similarly header converter _{44 3 ~44 (x-1)} , respectively in correspondence to the internal identifier IVCI (= a), identifying a prescribed outgoing highway A code tag and a VCI that is a regular call identifier are registered. Further, in the routing table of the header converter 44x, a code tag E for identifying the output highway # (N + 1) out and another internal identifier (= b) are associated with the internal identifier IVCI (= a). It is registered.

As a result, VC is set on the output highway # 1out.
Copy cell with I = 5, VC on output highway # 2out
The copy cells of I = 2 are ... Further, the copy cell having the internal identifier = b is routed to the output highway # (N + 1) out, and the copy server 43 ₁ is recursed from the output highway. When an ATM cell (copy cell) is input from the output highway # (N + 1) out, the copy server 43 ₁ again generates x copy cells and sends them to x output links. The number of remaining copy cells is 2. In the routing table of the header converter (VCC2) 44 ₁ , a code tag C that identifies the outgoing highway # 3out and a VCI (= 4) that is a regular call identifier are associated with the internal identifier IVCI (= b). is registered, the routing table of the header converter 44 _2, corresponding to the internal identifier IVCI (= b), and code tag D which specifies the output highway #Nout, VCI is a call identifier of the normal (= 3) is It is registered, the remaining header converter 44 ₃ ~44x routing table, discarding in association with internal identifier IVCI (= b) is registered.

As a result, VC is set on the output highway # 3out.
Copy cell with I = 4, VC on output highway #Nout
The copy cells of I = 3 are respectively routed and transmitted, and the multicast operation ends. In the above, the internal identifier of the recursive copy cell is changed. However, the internal identifier is not changed as in FIG. 10, and the recursion count (count) m is added to the copy cell instead, and the internal identifier and the recursion count m are added. Can be considered as a new internal identifier. That is, the copy server 43 ₁ monitors and updates the recursion count m. When the recursion count m ≠ 0, the recursion count m is added to the copy cells and output to all x output links. If it is 0, the multicast is terminated. When m ≠ 0 and copy cells are output to all output links, the header converters 44 _{1 to} 44 (1-x) connected to the first to (x−1) th output links are Tag information for routing the copy cell to a predetermined output highway and a regular VCI based on the internal identifier and the number of recursion.
Ask for. Then, the header converters 44 _{1 to} 44 _(1-x) add the tag information and the regular VCI to the copy cells and input them to the switch unit 42. Also, the header converter 44x connected to the xth output link does not change the internal identifier of the copy cell and adds the tag information for routing the copy cell to the copy server and inputs it to the switch unit 42. After that, the above process is repeated.

(D) Fourth Embodiment (d-1) Configuration FIG. 16 is a configuration diagram of a fourth embodiment of the present invention, which is a configuration diagram of an ATM exchange by a time copy trunk system.
In the figure, # 1in to #Nin are incoming highways, and # 1out to #No.
ut is an output highway, 51 _{1 to} 51 _N are header converters (VCC1) provided on each input highway, 52 is a switch unit, 53 ₁ is x (N ≧ x ≧≧) from one ATM cell at a predetermined time during multicast. 3) Copy server (1: x copy server) that generates and outputs the number of copy cells, 5
Reference numerals 4 _{11 to} 54 ₁ x are header converters (VCC2) provided on x output links of the copy server, and 55 is a call processor. When there are many multicast calls, the copy servers 53 ₁ , m (≧ 2) or more, as shown by the dotted line,
... The provided 53m, header converting section 54 ₁₁ through 54 ₁ x the output link for each copy server can be configured to provide a ··· 54m ₁ ~54mx.

FIG. 17 is a block diagram of the copy server 53 _1. BFR is a buffer for storing ATM cells to be multicast, CNA is a copy number adding unit CNA for adding a copy number m to the ATM cells, and CCO is a copy number m. A copy cell output unit for copying x number of ATM cells to which x has been added and transmitting the copy cells to all x output links at a predetermined time; The CEM is a copy completion monitoring unit that compares the command copy number M and the copy number m, and
= M, the copying is completed, and when m <M, the copy number m is input to the copy number adding section CNA to add the copy number m to the ATM cell. In the third embodiment, the copy cells are recurred to the copy server a required number of times, and each time (x-1) copy cells are multicast, the multicast operation is terminated when the number of recursion reaches the set number. However, in the fourth embodiment, the copy cell is not recursed one by one, but multicast A is used.
The TM cells are stored in the copy server, the copy cells are multicast by the set number x times, and the multicast operation is terminated when the recursion number reaches the set number.

(D-2) Operation Routine table RTBL of the header converters 51 _{1 to} 51 _N
(Not shown) includes tag information (code tag) that identifies the destination of the input cell in correspondence with the VCI of the input cell under the control of the call processor when a call is made, and only within the VCI or ATM switch. A valid internal identifier IVCI is registered at. That is, in the case of a multicast call, a code tag that specifies the outgoing highway # (N + 1) out to the copy server 53 ₁ in association with the VCI of the input cell,
The internal identifier IVCI is registered. If the call is not a multicast call, the VCI of the input cell should be associated with
A new VCI and a code tag that identifies one of the outgoing highways # 1out to #Nout are registered.

When a normal ATM cell other than a multicast call arrives, the header converters 51 _{1 to} 51 _N send a code tag for routing the ATM cell to the output highway # 1out to #Nout and a new VCI from the routing table. V code as well as adding the code tag to the ATM cell
The CI is replaced with a new VCI and input to the switch unit 52. The switch unit 52 routes the ATM cell to the output highway designated by the code tag and sends it. on the other hand,
When an ATM cell of a multicast call arrives, the header converters 51 _{1 to} 51 _N add a code tag for routing to the copy server 53 ₁ to the ATM cell, and VC
I is replaced with the internal identifier IVCI and input to the switch unit 52. The switch unit 52 routes the ATM cell to the output highway # (N + 1) out indicated by the code tag.
Copy server 53 ₁ is AT from output highway # (N + 1) out
When M cells are input, they are stored in the built-in buffer. Then, the copy number m = 1 is added to the ATM cell, x ATM cells to which the copy number has been added are copied, and the copy cells are sent to all x output links.

In the routing tables of the header converters 54 _{1 to} 54 x, the internal identifier IVCI and the copy number m (m = m
Corresponding to the combination 1) (corresponding to a new internal identifier), a code tag that identifies one outgoing highway among outgoing highways # 1out to #Nout and a VCI that is a regular call identifier are registered. . Therefore, when x copy cells are output from the copy server 53 ₁ , the header converters 54 _{1 to} 54 x output the copy cells using the combination of the internal identifier and the number of copies m as a key.
The code tag for routing to #Nout and the regular VCI are obtained from the routing table. Then,
The header converters 54 _{1 to} 54 x add the code tag to the copy cell, replace the internal identifier with a regular VCI, and input it to the switch unit 52. The switch unit 52 routes each x copy cells to the output highway designated by the code tag, removes the code tag, and sends it. As described above, x copy cells are transmitted from the predetermined x output highways.

After a predetermined time, the copy server 53 ₁ checks whether the number of times of copying m is equal to the number of times of setting M, and if not equal, the number of times of copying m is counted up, and m = 2 is set to ATM.
Append to cell. Then, x number of ATM cells to which the copy number m (= 2) is added are copied, and the copy cells are transmitted to all x output links. Header converter 54 _{1 to} 54x
Repeats the above operation, and thereafter repeats the above operation until the required number of copy cells are multicast to the output highway (until m = M). When the number of copy cells to be finally output is c (≦ x), the copy server outputs the copy cells to c output links. The header converters 54 _{1 to} 54 c to which the copy cells have been input perform the above-described operation to send c copy cells to the c predetermined output highways # 1out to #Nout via the switch unit 52 to perform a multicast operation. To complete.

(D-3) Modified Example Modified Example 1 When the number of copy cells to be finally output is c, the copy server 53 ₁ outputs the copy cells to arbitrary c output links and outputs the desired output highway. Multicast to. However, in such a case, the number of copy cells of each output link is not uniform. Therefore, when the number of copies is c (c ≦ x), the copy server 23 ₁ outputs the copy cells from the continuous c output links, and thereafter, the copy cells 23 ₁ continue from the next output link to another multicast call. To output a predetermined number of copy cells. By doing so, the number of copy cells sent from each output link of the copy server becomes uniform, and the load in the exchange can be equalized.

Modified Example 2 In the above description, when the number of copy cells to be finally output is c, the copy server 53 ₁ sends the copy cells to predetermined c output links. It can also be configured to. That is, copy number is c
When (c ≦ x), the copy server 53 ₁ sends copy cells to all x output links. Copy server 53 ₁ x number provided on the output side header converter 54 ₁
Out of 54x, (x-c) header converters discard (x-c) cells that do not need to be routed, and only c header converters route ATM cells to the outgoing highway. Whether to discard or not is to be discarded when, for example, the code tag has a specific value.

(E) Other Embodiments (e-1) Priority In the third embodiment, when the recursive copy cell is discarded, the multicast cannot be realized. Therefore, the priority of the recursive copy cell is set to be high.
For example, the cell loss priority included in the header of the ATM cell is set to high (= "1"). FIG. 18 is a block diagram of an ATM cell, where HD is a header and PLD is a 48-byte payload. Generic flow control GFC, VPI, VCI, payload type PTI, 1-bit cell loss priority CL in header HD
There are P and header error correction codes HEC. Therefore,
In the header converter that causes the copy cell to recurse to the copy server, the cell loss priority CLP of the copy cell
To high. In this way, even if the switch unit discards cells, cells with low cell loss priority are discarded, and recursive cells are not discarded.

(E-2) Output order of copy cells to output highway When sending copy cells to the output highway of the switch unit,
The order of outgoing highways for outputting cells is made constant, the order of outgoing highways for outputting cells is made random for each cell, or the order of outgoing highways for outputting cells is rotated for each cell. ,, the QOS (delay time, cell loss rate) and the like can be kept uniform. Although the present invention has been described above with reference to the embodiments, the present invention can be variously modified according to the gist of the present invention described in the claims, and the present invention does not exclude these.

[0071]

As described above, according to the present invention, various types of ATM exchanges having a multicast function, that is, an internal copy type ATM exchange, a space copy type ATM exchange, and a recursive copy type AT are used.
It is possible to provide an M switch and an ATM switch of a time copy type trunk system. Also, according to the present invention, an ATM
By using a unique internal identifier within the switch,
Calls can be identified without using the input highway number. Further, according to the present invention, since the copy server is externally attached to the switch unit, it is possible to provide an ATM switch having a multicast function without making the switch unit large in size. Further, according to the present invention, since the number of copy cells input from the copy server to the switch unit is made uniform in each output link, the load in the exchange can be made uniform. Further, since the copy cells are evenly output to the output highway of the switch unit, QOS (Quarity of
Service) etc. can be held uniformly.

[Brief description of drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a configuration diagram of a first embodiment (internal copy method) of the present invention.

FIG. 3 is an operation explanatory diagram of the first embodiment.

FIG. 4 is a configuration diagram of a second embodiment (spatial copy type trunk system) of the present invention.

FIG. 5 is an operation explanatory diagram of the second embodiment.

FIG. 6 is a configuration diagram of a modified example of the second embodiment.

FIG. 7 is a configuration diagram of another modification of the second embodiment.

FIG. 8 is a configuration diagram of a third embodiment (recursive copy type trunk system) of the present invention.

FIG. 9 is an operation explanatory diagram of the third embodiment.

FIG. 10 is an operation explanatory diagram of the third embodiment when the number of recursion times m is added to a cell.

FIG. 11 is a block diagram of an incoming highway header converter.

FIG. 12 is a configuration diagram of a copy server.

FIG. 13 is a configuration diagram of a header converter provided on the output side of the copy server.

FIG. 14 is a modification of the third embodiment (recursive copy type trunk system).

FIG. 15 is an operation explanatory diagram of a modified example of the recursive copy type trunk system.

FIG. 16 is a configuration diagram of a fourth embodiment (time copying trunk system) of the present invention.

FIG. 17 is a configuration diagram of a copy server.

FIG. 18 is a block diagram of an ATM cell having cell loss priority.

FIG. 19 is a block diagram of an ATM cell.

FIG. 20 is a schematic explanatory diagram of an ATM network.

FIG. 21 is a block diagram of a self-routing ATM switch.

FIG. 22 is a configuration diagram of a self-routing module (switch unit).

[Explanation of symbols]

# 1in to #Nin ··· Input highway # 1out to #Nout ··· Output highway 11 _{1 to} 11 _N · · Header converter provided on the input highway 12 · · Switch section 13 _{1 to} 13 _N · · Provided on the output highway Header converters 31 _{1 to} 31 _{N ···} header converters provided on the input highway 32 · · switch unit 33 ₁ · copy server 34 _{1 to} 34x · · header converter provided on the output link of the copy server 51 _{1 to} 51 _{N ···} Header converter provided on the incoming highway 52 · · Switch section 53 ₁ · Copy server 53a · Buffer 54 _{1 to} 54x · · Header converter provided on the output link of the copy server

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tsuguo Kato 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa, Fujitsu Limited (72) Inventor Toshio Somiya 1015, Kamiodanaka, Nakahara-ku, Kawasaki, Kanagawa Prefecture, Fujitsu Limited (72) Inventor Koji Amano 1-4-4 Hakataekimae, Hakata-ku, Fukuoka City, Fukuoka Prefecture, Fujitsu Kyushu Communication Systems Co., Ltd. (72) Inventor, Koji Nakamichi, Kawara-shi, Kanagawa 1015, Uedota Naka, Fujitsu Limited

Claims (17)

[Claims] 1. An ATM switch having a multicast function for copying one ATM cell to a plurality of designated outgoing highways and routing the VC of the input ATM cell provided in each incoming highway.
It is provided with a table storing tag information for identifying a plurality of outgoing highways to which the ATM cell is to be transmitted corresponding to I and an internal identifier unique in the exchange, and adding the tag information to the input ATM cell. With VCI
With the internal identifier, and a header converter for outputting the ATM cells; a switch unit for routing the ATM cells to a plurality of output highways based on the tag information of the input ATM cells; ATM switch having a multicast function, which is provided with a header converter that converts the internal identifier of the above into a regular VCI and sends it out. 2. An ATM switch having a multicast function for copying one ATM cell to a plurality of designated output highways and routing the same, and outputs one input ATM cell by copying an arbitrary number of N or less. A copy server, a first header converter provided in each of the input highways, which adds the tag information for routing to the input ATM cells to the copy server or a predetermined output highway, and outputs the copy information. A second header converter provided on each of the output links and adding tag information for routing to a predetermined output highway to the copy cells output from the copy server; and first and second header converters. Based on the cell tag information input by the cell, the cell is routed to a predetermined output highway or a copy server. ATM exchange having a multicast function, characterized in that a switch unit. 3. The copy server sets the copy number to c (c ≦
3. An ATM switch having a multicast function according to claim 2, wherein, in the case of N), the copy cells are output from arbitrary consecutive c output links. 4. The copy server sets the number of copies to c (c ≦ c
N), copy cells are output to N outputs of the copy server, and the second header converter provided on the output side of the copy server does not need to be routed (N-
The ATM switch having a multicast function according to claim 2, wherein c) cells are discarded. 5. The output link of the copy server and the output highway of the switch are made to correspond to each other in a 1: 1 relationship, and the copy server outputs copy cells to predetermined c output links to route to the output highway. An ATM switch having a multicast function according to claim 2. 6. An ATM switch having a multicast function for copying one ATM cell to a plurality of designated output highways and routing the same, and outputting one input ATM cell by copying x cells (x ≧ 2). Of the copy server, and a first header converter provided in each of the input highways, which adds tag information for routing to the input ATM cells to the copy server or a predetermined output highway, and outputs the copy. x number of output links,
(x-1) Add tag information for routing to a predetermined output highway to each copy cell from the output link,
A second header converter for adding tag information for routing to the copy server to the copy cell from the output link, and a predetermined output highway for the ATM cell based on the tag information of the ATM cell input from each header converter. Alternatively, an ATM switch equipped with a switch function for routing to a copy server and recursively routing copy cells to the copy server until the required number of copies is reached. 7. An ATM switch having a multicast function for copying one ATM cell to a plurality of designated output highways and routing the same, and outputting one input ATM cell by copying x cells (x ≧ 2). Copy server, and a header exchange provided in each of the input highways, which adds tag information for routing to the input ATM cells to the copy server or a predetermined output highway, and outputs x copies of the copy server. Attached to the link, tag information for routing the copy cell to a predetermined exit highway or copy server is added,
A second header exchange that discards cells that do not need to be routed and a switch that routes the ATM cells to a predetermined output highway or a copy server based on the tag information of the ATM cells input from each header exchange. An ATM switch equipped with a multicast function, which is equipped with a recursive routing of one or more copy cells to a copy server until a required copy number is reached. 8. The copy server outputs x copy cells each time the copy cells are recursed, and the header converter provided on the output side of the copy server discards cells that do not need to be routed. An ATM switch having a multicast function according to claim 6. 9. When recursively outputting the copy cells until the required number of copies is reached, when the number of copy cells output at the end is c (c ≦ x), the copy server has an arbitrary number of consecutive c cells. 7. An ATM switch having a multicast function according to claim 6, wherein the copy cell is output from the output link of the above. 10. An input ATM cell to be routed to a copy server, the first header converter adds tag information to the ATM cell and outputs the VCI by replacing the VCI with an internal identifier, and the copy server inputs the ATM cell. The second header converters connected to the first to (x-1) th output links of the copy server are routed to a predetermined output highway to the copy cells based on the internal identifier. Tag information for updating the internal identifier and replacing the internal identifier with a regular VCI, and the second header converter connected to the xth output link of the copy server replaces the internal identifier of the copy cell with another internal identifier. 7. The AT having the multicast function according to claim 6, wherein the AT is routed to a copy server.
M switch. 11. The copy server monitors the recursion count,
Each second header converter connected to the first to (x-1) th output links of the copy server adds the data indicating the number of recursion to the copy cell and outputs the copy cell based on the number of recursion. Of the tag information and the regular VCI for routing the data to a predetermined exit highway, add the tag information and the regular VCI to the copy cell, input them to the switch unit, and connect them to the xth output link of the copy server. 7. The ATM switch having a multicast function according to claim 6, wherein the header converter of No. 2 adds tag information for routing the copy cell to the copy server and inputs the tag information to the switch unit. 12. An ATM switch having a multicast function according to claim 6, wherein a cell loss priority of a copy cell recursively routed to the copy server is increased. 13. When routing a copy cell to an output highway of a switch unit, the order of output highways outputting cells is made constant, or the order of output highways outputting cells is made random for each cell, or 7. An ATM switch having a multicast function according to claim 6, wherein the order of the outgoing highway for outputting is output for each cell. 14. An ATM switch having a multicast function for copying one ATM cell to a plurality of designated output highways and routing it, after storing one input ATM cell, copies the copied cell of the ATM cell to x. A copy server that generates and outputs the copy cells, and then outputs x copy cells at a predetermined time until the designated copy number is reached, and a copy server or a copy server that is provided in each input highway and is provided in each input highway. A first header converter that adds tag information for routing to a predetermined output highway and outputs, and x copy output links of the copy server, and copy cells from each output link are respectively output to the predetermined output highway. A second header converter that adds tag information for routing to ATM tags of ATM cells input from each header converter. ATM exchange having a multicast function, characterized in that a switch unit for routing the ATM cell to the prescribed outgoing highway or copy server based on the distribution. 15. The multicast function according to claim 14, wherein the copy server outputs x copy cells at a time, and the header converter provided on the output side of the copy server discards cells that do not need to be routed. AT with
M switch. 16. When repeatedly outputting x copy cells by x until the required copy number is reached, when the number of copy cells output last is c (c ≦ x), from consecutive c output links. The copy cell is output, and thereafter, for a different multicast call, a predetermined number of copy cells are repeatedly output continuously from the next output link.
An ATM exchange equipped with the multicast function described in 4. 17. A copy server monitors the number of times of repetition, adds data indicating the number of times of repetition to a copy cell and outputs the data, and each second header converter connected to each output link of the copy server comprises: The tag information for routing the copy cell to a predetermined output highway and the regular VCI are obtained based on the number of repetitions, and the tag information and the regular VCI are added to the copy cell and output to the switch unit. An ATM switch having the multicast function according to Item 14.