JP2844331B2 - ATM filter method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an ATM (Asyn)
The present invention relates to an ATM filter system capable of media scaling in a relay node in a (chronous transfer mode) communication system.

[0002]

2. Description of the Related Art A conventional method of media scaling in a relay node of this type is described in a paper "Quality Assurance Type" published by Mr. Sebayashi et al. ATM multicast communication system ". This paper introduces two communication schemes.
These two systems are both systems in which the transfer information is divided into a plurality of sub-streams so that even if only one of them is received, it becomes meaningful information according to its priority. For example, the spatial resolution and the temporal resolution in moving image transfer can be adjusted by the number of substreams. The first of the above two methods is a one-bit cell loss priority indication (CLP: Cell Loss Prio) of all cells.
The second method is a method of allocating a VC (Virtual Channel; virtual channel) to each of the divided substreams.

[0003]

However, in the case of the first system in which the substream is divided by the cell loss priority display, the display field can only be divided into two because of one bit, and furthermore, the information is discarded. There is a problem that it is caused not by the convenience of the terminal but by the congestion of the relay node. Also,
In the case of the second method in which VCs are assigned to each substream, the problem of synchronization between VCs becomes serious, especially when information to be transferred is continuous media such as moving images. The present invention has been made in view of the above-described problems, and an object of the present invention is to divide transfer information into substreams in one VC, and to separate substreams independently of congestion of relay nodes. An object of the present invention is to provide a removable ATM filter system.

[0004]

In order to solve such a problem, the present invention divides transfer information into sub-streams at a transmitting terminal, and adds a sub-stream identification information at the head of each information frame of the sub-stream. Cell is assigned, 1
A means for transferring data by one VC is provided to identify a substream. As a result, it is possible to divide a single VC into a number of substreams that can be represented by a field length allowed for a cell for identifying a transfer information substream. In addition, synchronization problems caused when different substreams are assigned to different VCs can be solved. Also, the relay node is provided with a means for holding a table (second table) for registering a combination of the address of the called terminal and the substream list to be discarded, and the substream is discarded based on the table. The substream to be transferred to is restricted. As a result, unnecessary information for the called terminal does not need to be sent on the line from the relay node to the called terminal, so that useless use of the band of the line can be prevented.
Further, the relay node has means for holding a judgment table (decision table; first table) for discarding substreams, and registers a substream to be discarded by a message from a terminal. As a result, a substream to be discarded can be specified by a message from the terminal. Further, a means for holding a judgment table for discarding substreams is provided, and a substream to be discarded is registered by a maintenance command. As a result, a substream to be discarded by the maintenance command of the relay node can be specified. Further, a means for holding a table for registering a combination of the address of the receiving terminal managed in the relay node and a substream list to be discarded is provided, and information is registered by a message from the terminal,
The sub-stream to be discarded is registered in a decision table for discarding the sub-stream at the time of call setting. As a result, a substream to be discarded by a message from the terminal can be specified. In addition, a means is provided for holding a table for registering a combination of an address of a terminating terminal managed in the relay node and a substream list to be discarded, information is registered by a maintenance command, and a judgment for discarding the substream at the time of call setting is provided. A substream to be discarded is registered in a table. As a result, a substream to be discarded by the maintenance command of the relay node can be specified.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing a configuration of an ATM network to which the present invention is applied. In the figure, 1
Is an originating terminal, 2 is an ATM filtering switch in the ATM network, and 3 and 4 are incoming terminals.

FIG. 2 is an explanatory diagram showing how the sub-streams are discarded in the filtering switch 2 shown in FIG. In the figure, 5 is the input side VC, 15,
Reference numeral 18 denotes a delivery VC. 6 and 9 are information frames of substream # 1, and 11 and 14 are substreams # 1
Information frames 6 and 9 of the substream # 1 transferred through the output VC # 1 (15) through the ATM filtering switch 2, and 16 and 17 are information frames 6 and 9 of the substream # 1. This is an information frame of the substream # 1 transferred to the output VC # 2 (18) through the switch 2.

[0007] Also, 7 is an information frame of substream # 3, and 12 is an information frame 7 of substream # 3.
Outgoing VC # 1 through TM filtering switch 2
The information frame of the substream # 3 transferred to (15), 8 is the information frame of the substream # 2, and 13 is the information frame 8 of the substream # 2 passing through the ATM filtering switch 2 to the outgoing VC # 1 (15 ) Is the information frame of the substream # 2 transferred.

Next, FIG. 3 is a table for deciding the substream management managed by the ATM filtering switch 2 shown in FIG. In the figure, reference numerals 19 and 22 denote incoming VCs.
Outgoing VCs 21 and 24 registered corresponding to the outgoing VCs
It is a list of discarded substream numbers registered corresponding to Nos. 19 and 22, respectively. Here, 20 and 23 are control flags.

Next, FIG. 4 is a flowchart of a filter cycle in the ATM filtering switch 2 shown in FIG. In FIG. 4, "Y" means "YES" (affirmation).
"N" means "NO" (negative). The operation of the main part of the present invention will be described mainly with reference to the explanatory diagram of FIG. 2 while referring to the flow of FIG. In FIG. 2, three substreams are flowing into the ATM filtering switch 2 from the incoming VC 5. Here, VC # 1 on the output side (FIG. 2)
15), all substreams are transferred, and the outgoing VC # 2 (reference numeral 18 in FIG.
Only 1 has been transferred.

Such a state is caused by the output VC # 1 (reference numeral 15 in FIG. 2) and the output VC # 2 (reference numeral 15 in FIG. 2) corresponding to the input VC (reference numeral 5 in FIG. 2). 2) is registered, and is not registered in the substream list 21 corresponding to VC # 1.
This is achieved by registering the substream # 2 and the substream # 3 in the substream list 24 corresponding to the sub stream # 2.

In FIG. 2, when the information frame 9 of the substream # 1 arrives at the input port of the ATM filtering switch 2, a cell is taken out from the input port (step S1 in FIG. 4) and the input VC is referred to (step S1 in FIG. 4). Along with step S2 in FIG. 4, the sub-stream discard decision table is indexed from the input VC (step S3 in FIG. 4), and a list of discarded sub-stream numbers corresponding to the output VCs (19 and 22 in FIG. 3) (FIG. 3 are extracted (step S4 in FIG. 4).

In this case, each time one cell is taken out from the input VC, it is determined whether or not to send the cell to the egress VC (steps S6 to S13 in FIG. 4). That is, first, it is determined whether or not the cell is a substream identification cell (step S7 in FIG. 4). If the cell is a substream identification cell, whether or not there is a substream indicated by the cell information in the discarded substream list Is determined (step S9 in FIG. 4).
If the determination in step S9 is "Y", the control flag in the entry of the substree number indicated by the cell in the substreet determination table of FIG. 3, that is, VC # 1 (15) in FIG. ) Is added to the control flag FLG # 1 indicated by reference numeral 20 in FIG.
For # 2 (18), YES is set to the control flag FLG # 2 indicated by reference numeral 23 in FIG. 3 (step S11 in FIG. 4). If the determination in step S9 of FIG. 4 is “N”, the control flag is set to NO (FIG.
Step S10), and sends the cell to the egress VC (step S12 in FIG. 4).

Subsequently, the next input cell is taken out and it is similarly determined whether or not the cell is a substream identification cell (step S7 in FIG. 4). If the cell is a substream identification cell, the same processing as described above is performed. If it is not a substream identification cell, it is determined whether or not the corresponding flag is set to YES or NO with reference to the control flag extracted in step S4 in FIG. 4 (step S8 in FIG. 4). And
If the control flag is set to NO, the cell
C (step 12 in FIG. 4), and if YES is set, the next VC process is performed without any processing (step S13 in FIG. 4). Here, the information frame (reference numeral 9 in FIG. 2) is the substream # 1 and is not registered in the entry (reference numerals 21 and 24 in FIG. 3) of the substream discard decision table in FIG. Is VC # 1 in FIG.
(15) and VC # 2 (18) to form information frames 14 and 17, respectively.

The information frame 8 in FIG. 2 is a sub-stream # 2, and is not registered in the entry 21 of the sub-stream discarding decision table in FIG. The information frame 13 is sent to # 1 (15) to form the information frame 13, but is transmitted to VC # 2 (18).
Will not be sent to The information frame 7 in FIG. 2 is a substream # 3, which is not registered in the entry 21 of the substream discarding decision table in FIG.
Sent to (15) to compose the information frame 12,
It is not sent to C # 2 (18). Further, since the information frame 6 in FIG. 2 is the substream # 1 and is not registered in the entries 21 and 24 of the substream discarding decision table in FIG. 3, all the cells constituting the information frame are the same as those in FIG. VC # 1 (15) and VC # 2 (18)
To form information frames 11 and 16, respectively.

Next, FIG. 5 is a table for registering combinations of addresses of the receiving terminals 3 and 4 managed by the ATM filtering switch 2 and substreams to be discarded. In the figure, reference numeral 25 denotes a list of discarded substream numbers indexed from the address of the called terminal (called terminal).

FIG. 6 shows the setting status of information in the substream discarding decision table or the setting of information in the table for registering a combination of the destination terminal address and the substream list to be discarded, based on the maintenance command and the message from the communication terminal. It is an explanatory view for explaining a situation. In the figure, reference numeral 27 denotes a maintenance terminal; 28, a database provided with a sub-stream discarding determination table shown in FIG. 3 and a table for registering combinations of destination terminal addresses and discarded sub-streams shown in FIG. 5; Is a communication terminal for registering information in.

The operation of setting information in the database 28 will be described with reference to FIGS. 3 and 5, focusing on the explanatory diagram of FIG. In response to a maintenance command from the maintenance terminal 27, information is set in the substream discarding decision table shown in FIG. 3 in the database 28 or the table shown in FIG. Further, the communication terminals 29 and 30 send the information to the table for determining the substream discarding shown in FIG. 3 in the database 28 or the table for registering the combination of the destination terminal address and the substream list to be discarded shown in FIG. Set.

Next, FIG. 7 shows the registration status in the substream discard decision table when the corresponding destination address is registered in the table for registering the combination of the destination terminal address and the substream list to be discarded at the time of call setting. It is a flow shown. That is, at the time of call setting, the ATM filtering switch 2 shown in FIG. 5 first determines the VC identification number corresponding to the terminating terminal by normal call processing (step S14 in FIG. 7). Next, referring to the table for registering the combination of the destination terminal address and the substream list to be discarded shown in FIG. 5, it is determined whether or not the corresponding destination terminal address is registered (step S15 in FIG. 7). . If there is a registration at the address of the corresponding called terminal, the sub-stream list is registered in the sub-stream discarding decision table shown in FIG. 3 (step S16 in FIG. 7).

[0019]

As described above, according to the present invention, the transmitting terminal divides the transfer information into substreams, adds a cell for identifying the substream to the head of each information frame of the substream, and A means for transferring with one VC is provided to identify the sub-stream. Therefore, within one VC, the number of sub-streams that can be expressed by the field length allowed for the cell for identifying the transfer information sub-stream is determined. Division becomes possible. Also, different VC
The synchronization problem caused when different sub-streams are assigned to the sub-stream can be solved. Also, the relay node is provided with a means for discarding substreams and limiting the substream to be transferred for each destination terminal, so that information unnecessary for the destination terminal is not transmitted on the line from the relay node to the destination terminal. Thus, it is possible to prevent useless use of the line bandwidth. Also, a means for holding a judgment table for discarding substreams is provided in the relay node, and a substream to be discarded by a message from the terminal is registered, so that a substream to be discarded can be designated by a message from the terminal. . Also, a means for holding a judgment table for discarding substreams is provided, and a substream to be discarded is registered by a maintenance command, so that a substream to be discarded can be designated by a maintenance command of a relay node. Further, a means is provided for holding a table for registering a combination of an address of a terminating terminal managed in the ATM filtering switch (relay node) and a substream list to be discarded, and information is registered by a message from the terminal. Since the substream to be discarded is registered in the judgment table for discarding the stream, the substream to be discarded can be specified by a message from the terminal. In addition, there is provided means for holding a table for registering a combination of an address of a called terminal managed by the ATM filtering switch (relay node) and a substream list to be discarded, registering information by a maintenance command, and In the judgment table for disposal,
Since the substream to be discarded is registered, the substream to be discarded can be specified by the maintenance command of the relay node.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an ATM network to which the present invention is applied.

FIG. 2 is an explanatory diagram showing how a substream is discarded in an ATM filtering switch in an ATM network.

FIG. 3 is a diagram showing a substream discarding decision table managed in the ATM filtering switch.

FIG. 4 is a flowchart showing a cycle operation of a filter in the ATM filtering switch.

FIG. 5 is a diagram showing a table for registering a combination of an address of a receiving terminal managed by the ATM filtering switch and a substream list to be discarded.

FIG. 6 is an explanatory diagram showing how information is set in a substream discarding decision table or a table for registering a combination of an address of a called terminal and a substream list to be discarded, based on a maintenance command and a message from a communication terminal. .

FIG. 7 is a flowchart showing a registration status in a substream discard determination table when a corresponding destination address is present in a table for registering a combination of an address of a called terminal and a substream list to be discarded at the time of call setting.

[Explanation of symbols]

1. Calling terminal, 2 ... ATM filtering switch,
3, 4 ... incoming terminal, 5 ... incoming VC, 6, 9, 11, 1
4, 16, 17 ... information frame of substream # 1,
7, 12,... Information frame of substream # 3, 8, 1
3 ... information frames of substream # 2, 15, 18 ...
Outgoing VC, 27: maintenance terminal, 28: database, 2
9, 30 ... Communication terminal.

Claims (6)

(57) [Claims] 1. In an ATM communication in which a transmitting terminal and a receiving terminal communicate with each other via an ATM network including a relay node, transfer information is divided into sub-streams by a transmitting terminal, and at the beginning of each information frame of the sub-stream. A cell for sub-stream identification is added and transferred on the same VC, and a first node for discarding the sub-stream at the relay node.
An ATM filter system, wherein the table is held and sub-streams are discarded based on the first table. 2. The ATM filter method according to claim 1, wherein the relay node holds a second table for registering a combination of a destination terminal address and a substream list to be discarded. 3. The ATM filter method according to claim 1, wherein a substream to be discarded is registered in the first table by a message from an arbitrary terminal. 4. The ATM filter method according to claim 2, wherein a combination of an address of the called terminal and a substream list to be discarded is registered in a second table by a message from an arbitrary terminal. 5. The method according to claim 3, wherein the substream to be discarded is stored in the first stream by a maintenance command.
An ATM filter method characterized by registering in an ATM table. 6. The ATM filter method according to claim 4, wherein a combination of a destination terminal address and a substream list to be discarded is registered in the second table by a maintenance command.