JP2000165387A - Cell management processing circuit and network system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cell management processing circuit that offers simple management in spite of a small circuit scale and to provide a network system. SOLUTION: A CC cell insert circuit that manages whether or not a user cell reaches for each connection at a period of one second and inserts a CC cell to a connection to which no user cell reaches for a just preceding one second is provided with a connection management table 102 and a cell identification section 103 that identify whether or not a connection is a connection of object of management, a user cell arrival management memory 104 and a memory scan circuit 105 that manage whether or not a user cell arrives for a just preceding one second for each connection and refer to it sequentially, a CC cell generating section 106, an insertion buffer 107 and a cell insert section 108 that generate a CC cell and insert it to a connection in which no user cell arrives.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a cell management processing circuit and a network system.
Maintenance and operation (OAM: Operation a) in a network where information is transmitted in asynchronous transfer mode (OAM)
CC (Continuity), one of the nd Maintenance) functions
Check) is suitable for application to cell generation processing.

[0002]

2. Description of the Related Art ITU-T (International Telecommun
Communication Union) Recommendation I.610 states that maintenance and maintenance of the ATM layer
OAM cells for operation are defined as international standards. The CC cell is one of the OAM cells defined in I.610, and is realized by a device such as an exchange constituting an ATM network, and is used for monitoring that the connection has not been disconnected in connection units. You.

The monitoring by the OAM cell is performed by VP (Virtual
Path) connection or VC (Virtual Channe)
l) Perform connection. Further, as shown in FIG. 2, a VP segment set on the connection,
Alternatively, the VC segment can be used as a monitoring unit. The segment is set by the network administrator by arbitrarily setting an operation monitoring section. End-to-end OAM for OAM cell monitoring connection
An OAM cell having a segment as a monitoring unit is called a cell, and is called a segment OAM cell.

[0004] The method of generating a CC cell is as follows: 1) A method of transmitting a CC cell when a user cell is not transmitted for about 1 second at a terminal point on a transmission side of a connection or a segment 2) Unrelated to a user cell Specifies a method of transmitting CC cells at a period of about one second, but the method of 2) uses a wasteful band, so the method of generating 1) is more efficient. is there. The present invention aims at realization by the method 1).

[0005]

As described above, the continuity check function manages the arrival of a user cell by a device set at a connection or at an end point on the transmission side of a segment, and performs a continuity check for about one second. By providing a function of detecting that a user cell is not transmitted, it is possible to transmit a CC cell.

Here, when the continuity check function is executed simultaneously for a plurality of connections, the transmitting side manages the arrival of the user cell for each connection and waits for the next user cell after the user cell arrives. A timer function is required to determine whether one second or more has elapsed before the arrival of the vehicle.

That is, generally, whether or not a user cell has arrived is managed for each connection, and a CC cell is inserted into a connection where no user cell arrives even after a predetermined time (here, 1 second) has elapsed. Conventionally, a circuit (herein, this circuit is referred to as a “CC cell insertion circuit”) manages the arrival of cells for each connection and requires a timer function for each connection. There was a problem that the circuit was complicated and the circuit scale became large.

In the above description of the problem, the description has been made based on the process of inserting a CC cell. However, the present invention is not limited to the process of inserting a CC cell, and is not limited to a user cell. A circuit that manages the arrival and performs a predetermined process based on whether or not a cell arrival interval has passed a predetermined time or more (this circuit is referred to as a “cell management processing circuit” in this specification) is similar. Have issues.

Therefore, there has been a demand for a cell management processing circuit which is easy to manage and has a small circuit scale, and a network system having such a cell management processing circuit at a node on a network.

[0010]

According to a first aspect of the present invention, there is provided a cell for managing whether or not a cell has arrived for each connection and performing a predetermined process based on the management information. In the management processing circuit, (1) storage means having a storage area corresponding to each connection, and (2) information setting means for setting, when a cell arrives, arrival arrival information in a corresponding area of the connection of the cell in the storage means. , (3)
The storage area of the storage means is referred to at a predetermined cycle for each connection, and non-arrival information is set in the storage area referred to immediately after the reference, and this reference and setting of the non-arrival information are performed for all connections. Information reference management means; (4)
Processing means for performing a predetermined process based on arrived information or unarrived information of the storage area referred to by the information reference management means.

Further, a network system according to a second aspect of the present invention is characterized in that some or all nodes constituting the network have the cell management processing circuit according to the first aspect of the present invention.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A cell management processing circuit according to the present invention manages whether or not a user cell has arrived for each connection. An embodiment applied to a CC cell insertion circuit that inserts a symbol will be described in detail with reference to the drawings.

(A) Description of the outline The OAM function of the ATM network is described in ITU-
Specified in T Recommendation I.610. The continuity check function, which is one of the OAM functions, tests the continuity of the connection by inputting a CC cell from one end point of a connection or a segment and detecting the CC cell at the other end point. FIG. 3 shows a case where a test is performed in a segment section. The CC cell inserted at one end point of the segment is detected at the receiving end point. The termination point on the receiving side monitors the arrival of the CC cell and the user cell, and when no cell arrives for a certain period of time, LOC (Loss Loss) is determined for the connection.
of Continuity) state. In this state, it is one of the failure states, and AIS (AlarmIndi
cation signal) cell.

In the present embodiment, the same function is realized by monitoring the arrival time of the user cells for each connection at once, instead of monitoring the arrival time of the user cells for each connection in the CC cell insertion circuit at the terminal of the connection or the transmission side of the segment. It will be realized.

(B) Description of Configuration FIG. 1 is a block diagram showing the configuration of the CC cell insertion circuit of this embodiment. 1, the CC cell insertion circuit includes a VPI / VCI conversion unit 101, a connection management table 102, a cell identification unit 103, a user cell arrival management memory 104, and a memory scan circuit 105.
, CC cell generation unit 106, insertion buffer 107
And a cell insert 108.

The VPI / VCI converter 101 converts the VPI and / or VCI of the input ATM cell into a connection number used inside the CC cell insertion circuit. However, if the device can support all VPIs and / or VCIs of the incoming ATM cells,
There is no particular need for conversion, and this VPI / VCI conversion unit 10
1 does not have to be provided.

In the connection management table 102, setting information on the continuity check function of each connection is registered with the connection number as an address. When the converted connection number is given from the VPI / VCI conversion unit 101, The connection setting information is provided to the cell identification unit 103. For example, FIG. 4 is an image diagram showing the registration status of the connection management table 102. In this example, information indicating whether the continuity check function is in service (item indicated by “SON” in the figure) and information indicating whether the connection is a continuity check target (see FIG. Are registered, and SON = 1 indicates that the service is being serviced, and CCON = 1 indicates that the connection is a continuity check target connection.

When an ATM cell is given from the VPI / VCI conversion unit 101, the cell identification unit 103 identifies whether the ATM cell is a user cell, and as a result of the identification, the cell is a user cell. When the setting information from SON = CCON = 1, “1” is written in the corresponding connection number position of the user cell arrival management memory 104, and the ATM cell is transmitted on the output side via the cell insertion unit 108. Output to the road.

The user cell arrival management memory 104 stores the VP
When the converted connection number is given from the I / VCI conversion unit 101 and a write signal of “1” is given from the cell identification unit 103, “1” is placed at the connection number position.
Is set. In addition, the memory scan circuit 10
The setting value of each connection number is scanned at a predetermined interval from 5 and a write enable signal is output to the insertion buffer 107 when the scanned setting value is “0”, and when the set value is “1”, Outputs a write disable signal. Here, when the setting value of each connection number is scanned by the memory scan circuit 105, immediately after that, referring to the connection management table 102, the connection number of SON = CCON = 1 is “0”, and the other values are “0”. The connection number is cleared to "1".

Although not shown, the memory scan circuit 105 includes a one-second counter that counts one second based on an input trigger signal given each time an ATM cell is input to the VPI / VCI conversion unit 101, and a trigger signal. , An access interval control counter that counts the timing of scanning (accessing) the user cell arrival management memory 104 based on the above, and a CC cell generation counter that counts this access. Here, in this embodiment, scanning is performed in the order of connection numbers.
The count value of the C cell generation counter indicates the connection number, and outputs the count value of the CC cell generation counter to the user cell arrival management memory 104 at the timing counted by the access interval control counter. Processing will be performed on the connection number. When the one-second counter counts one second, all the counters are reset.

The CC cell generator 106 generates a CC cell having the connection number output from the memory scan circuit 105 and supplies the CC cell to the insertion buffer 107.

When a write enable signal is supplied from the user cell arrival management memory 104, the insertion buffer 107 buffers the CC cell from the CC cell generation unit 106 and supplies the buffered cell to the cell insertion unit 108. When a write disable signal is given from the user cell arrival management memory 104, the CC insertion unit 1 discards the CC cell from the CC cell generation unit 106 without buffering it.
08 is not given.

The cell insertion unit 108 outputs the ATM cell from the cell identification unit 103 to the transmission line on the output side. When a CC cell is supplied from the insertion buffer 107, the cell is inserted into the ATM cell. It is inserted between cells and output to the transmission path.

(C) Description of Operation Next, the operation of the CC cell insertion circuit having the above configuration will be described with reference to FIG. 1 and FIGS. 5 is an explanatory diagram of the operation of the memory scan circuit 105, FIG. 6 is an explanatory diagram of the operation of the CC cell generator 106, and FIG. 7 is an explanatory diagram of the operation of the user arrival management memory 104.

VPI and / or V of the input ATM cell
The CI is converted by the VPI / VCI conversion unit 101 into a connection number inside the device. It is assumed that the device operates within this connection number. However, if all VPI and / or VCI can be supported inside the device,
No conversion is required.

Here, the ATM cell converted by the VPI / VCI conversion unit 101 is given to the cell identification unit 103, and the converted connection number is stored in the connection management table 102 and the user cell arrival management memory 104.
, And an input trigger signal is supplied to the memory scan circuit 105 every time the conversion is performed.

The connection management table 102 and the cell identification unit 103 identify whether a given ATM cell is to be managed.

In the connection management table 102, as shown in FIG.
Information of each connection is registered in advance. In the example shown in this figure, SON and CCON are registered. SON = 1 indicates that the service is being performed. Also, CCON = 1 indicates a connection subject to continuity check. For the input user cell, this is a connection in service (SON = 1) and a connection subject to continuity check (CCON =
In the case of 1), the arrival of this user cell is detected by writing "1" in the corresponding connection number position of the user cell arrival management memory 104.

The cell identification section 103 identifies a user cell by identifying a cell header. As a result of the identification, when the cell is a user cell and the output of the connection management table 102 is SON = CCON = 1, “1” is written in the corresponding connection number position of the user cell arrival management memory 104. This operation is shown in FIG.
Shown in

FIG. 5 shows an operation example of the memory scan circuit 105.
Shown in As described above, the memory scan circuit 105 includes the one-second counter, the access interval control counter, and the CC cell generation counter. The one-second counter and the access interval control counter count cells in the main signal cell flow. It works by.

The one-second counter is set to 1 according to the transmission speed.
One second is detected by counting the number of ATM cells transferred per second. As an example, when the cell length in the apparatus is 54 bytes, counting 360,000 cells corresponds to one second at a transfer rate of 156 Mbit / s (n = 360,000 in the figure). When this counter makes one cycle, the other counters are also reset.

The access interval control counter is a counter for controlling the minimum interval between occurrences of CC cells, and controls the interval between occurrences of CC cells according to the value of j shown in FIG. j
Is large, the generation interval of CC cells is widened as shown in FIG. 6A, and if the value of j is small, the generation interval of CC cells is small as shown in FIG. 6B. The value of the CC cell generation interval j is determined as follows: the output of the CC cell for all connections supported by the device is completed within 1 second, and if the interval is too short, the burstiness of the CC cell becomes strong, and The setting is made in consideration of, for example, not overloading.

The CC cell generation counter counts up when the value of the access interval control counter reaches the set value j. The CC cell occurrence counter counts connection numbers serviced by the device. FIG. 5 shows a case where the number of connections is k.

By combining these counters, all connection numbers supported by the circuit are generated in one second as shown in FIG. By accessing the user cell arrival management memory 104 using this connection number, a bit ("1" or "0") at a location corresponding to a certain connection number is read.
By performing read & clear, this memory can detect, for each connection, whether a user cell has arrived within one second from the previous read.

FIG. 7B shows a user cell arrival management memory 1.
A procedure for reading out the data 04 and generating a CC cell from the result will be described.

The memory scan circuit 105 accesses the user cell arrival management memory 104 according to the connection numbers sequentially output, and sets the bit at the corresponding position to "
0 ”, it is determined that the user cell has not arrived, and C
Assemble the C cell. As the CC cell generated at this time, a CC cell having the same value as the connection number accessing the user cell arrival management memory 104 is generated.

(D) Description of Effects As described above, according to this embodiment, the connection management table 102 and the cell identification unit 103 identify whether or not the connection is a management target connection. At 104 and the memory scan circuit 105, whether or not the user cell has arrived in the immediately preceding one second is sequentially managed and referred to for each connection, and the CC cell generation unit 106, insertion buffer 107 and cell insertion unit 108 Since the CC cell of the connection is generated and inserted for the connection that is not performed, the arrival of the user cell can be collectively managed for all the connections in service at a cycle of about one second. Since it is not necessary to prepare a one-second period timer for each time, the management is simple and the circuit scale is small.

(E) Other Embodiment In the above embodiment, the CC which is one of the OAM cells defined for the operation / maintenance of the ATM network is used.
Although the present invention is applied to the cell insertion circuit, if the cell arrival / non-arrival is periodically managed and a predetermined process is performed based on the arrival / non-arrival, the cell insertion circuit can be used for inserting a CC cell. The present invention can be similarly applied without limitation.

In the above embodiment, the cell to be managed is a user cell, and only the user cell of the connection to be managed is managed. However, the processing of this circuit is applied to the insertion of a CC cell. If there is no limitation, the cell to be managed may not be identified. In this case, the connection management table 102 and the cell identification unit 103 need not be provided.

Further, in the above-described embodiment, the access to the user cell arrival management memory is performed in the order of the connection numbers. However, the access order is not limited to the number as long as all the connection numbers are sequentially accessed.

[0041]

As described above, according to the first and second aspects of the present invention, (1) storage means having a storage area corresponding to each connection, and (2) when a cell arrives, An information setting means for setting arrival information in an area corresponding to the connection of the cell; and (3) a storage area of the storage means is referred to at a predetermined cycle for each connection, and the storage area referred to immediately after the reference is not stored in the storage area. Information reference management means for setting arrival information and setting this reference and non-arrival information for all connections; and (4) based on arrived information or non-arrival information of a storage area referred to by the information reference management means. And a processing means for performing a predetermined process, so that the arrival of cells for all connections can be managed collectively at a predetermined cycle, and a timer (for counting a predetermined cycle for each connection) Because there is no need to provide a counter),
Easy management and small circuit size.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a CC cell insertion circuit according to an embodiment.

FIG. 2 is an explanatory diagram of connections and segments.

FIG. 3 is an explanatory diagram of an outline of an embodiment.

FIG. 4 is an image diagram of a registration status of a connection management table 102;

FIG. 5 is an explanatory diagram of an operation of the memory scan circuit 105.

FIG. 6 is an explanatory diagram of the operation of the CC cell generator 106.

FIG. 7 is an explanatory diagram of the operation of the user cell arrival management memory 104.

[Explanation of symbols]

102: connection management table, 103: cell identification unit, 104: user cell arrival management memory, 105: memory scan circuit, 106: CC cell generation unit, 107: insertion buffer, 108: cell insertion unit.

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[Procedure amendment]

[Submission date] December 7, 1998 (1998.12.
7)

[Procedure amendment 1]

[Document name to be amended] Drawing

[Correction target item name] All figures

[Correction method] Change

[Correction contents]

FIG.

FIG. 2

FIG. 3

FIG. 4

FIG. 5

FIG. 6

FIG. 7

Claims (5)

[Claims] 1. A cell management processing circuit for managing whether or not a cell has arrived for each connection, and performing a predetermined process based on the management information, comprising: storage means having a storage area corresponding to each connection; When a cell arrives, information setting means for setting arrival information in a corresponding area of the connection of the cell in the storage means, and a storage area of the storage means is referred to at a predetermined cycle for each connection, and the reference Information reference management means for setting the non-arrival information in the storage area referred to immediately thereafter and performing this reference and setting of the non-arrival information for all connections; and Processing means for performing predetermined processing based on the non-arrival information. 2. The information reference management means includes: a first counter that counts a predetermined period; and a second counter that counts the timing of sequentially referring to all connections during the predetermined period. The cell management processing circuit according to claim 1, further comprising: a counter for counting the number of the connection to be sequentially referred to during the predetermined period. 3. The method according to claim 1, wherein the cell is a user cell, and the predetermined processing includes, for a connection of a cell that has not arrived during a immediately preceding predetermined period, generating a connection normality check cell for the connection. 3. The cell management processing circuit according to claim 1, wherein the cell management processing circuit inserts the data into a transmission path. 4. A management table for storing information on whether or not to receive a service for generating and inserting a connection normality check cell for each connection, wherein the information setting means refers to the management table, The received information is set for the connection receiving the service, and the information reference management means refers to the management table,
4. The cell management processing circuit according to claim 3, wherein reference and non-arrival information are set for a connection receiving a service. 5. A network system comprising the cell management processing circuit according to claim 1 in some or all nodes constituting a network.