KR970007252B1 - Connection control system of atm - Google Patents

Abstract

The apparatus relates to an ATM interface control. The B-ISDN on the basis of the ATM transfers the various service cells and the ATM sends the data via a packet. The method saves the searching time by storing the 24bit connection information of the 53 octet cell header containing the VPI/VCI (Virtual Path Identifier/Virtual Channel Identifier) field format in the routing table by using CAM(Content Addressable Memory). The method comprises the steps of: (a)receiving the address provided by an external CPU, generating the status information from the received control signal, and sending it; (b)searching the CAM in the routing table within one search cycle; (c)generating the control signal to control the routing table; and (d)extracting the VPI/VCI from the cell header and sending the information to the routing table. The apparatus includes: the address decoder, the control register, the status register, the buffers, and an ATM interface control device.

Description

Asynchronous Transfer Mode (ATM) Connection Control Unit

1 is a block diagram of an asynchronous transmission mode (ATM) connection control apparatus according to the present invention,

2 is a detailed configuration diagram of an asynchronous transmission mode (ATM) connection control apparatus according to the present invention,

3 is a state transition diagram of a routing table controller,

4 is a timing diagram of an asynchronous transfer mode (ATM) connection control device.

* Explanation of symbols for main parts of the drawings

1: CPU connection part 2: routing table control part

3: routing table 4: ATM layer functional module connection

The present invention relates to an asynchronous transmission mode (hereinafter referred to as ATM) connection control device.

Today's interest in telecommunications networks is not only to provide integrated services such as telephone and data, but also to provide a wide range of bandwidth services ranging from data communications to CATV (Common Antenna TeleVision) and HDTV (High Definition TeleVision). It is concentrated in the broadband integrated information network (B-ISDN) that can be provided through the interface.

Broadband Telecommunication Network (B-ISDN) uses Asynchronous Transfer Mode (ATM) to transfer service information. The main feature of this Asynchronous Transfer Mode (ATM) is that the packet is suitable for real-time information transfer. It is also possible to support high-speed services such as narrowband and broadband. Here, all information of the B-ISDN is transmitted through a virtual channel providing continuity of information transmission using a virtual path / virtual channel (VP / VC).

First, when there is a service request for the purpose of providing an ATM cell path to provide an ATM upper layer service, connection-related information is determined by negotiation between the call control and signaling function processing unit, and this information is transferred to the ATM layer by the ATM layer management function processing unit. Is transmitted by sending a message, and the ATM layer establishes and releases an ATM connection according to this command. After this process is performed at the ATM layer management and ATM layer by peer-to-peer and link-by-link, the cell is transmitted and received between the upper layer and the ATM management plane and the physical layer. Will be provided.

In B-ISDN, the transmission of various service cells begins with ATM layer management and connection establishment / release of ATM layer, and the function of managing them. Since the information required for connection control is provided within one cell time, the processing delay related to the cell's connection path should be minimized in the B-ISDN system to maximize the transmission efficiency, performance, and management capability of the network. have. Therefore, the higher the service speed that the B-ISDN system can provide, the more difficult processing for connection control becomes.

Accordingly, the present invention provides a routing table using CAM (Content Addressable Memory) for connection information of 24-bit length transmitted in the form of VPI / VCI (Virtual path Identifier / Virtual Cannel Identifier) field in a 53 octet long cell header. It is an object of the present invention to provide an Asynchronous Transfer Mode (ATM) connection control device which minimizes the searching time by performing a related table search during one search cycle regardless of the number of stored lists.

In addition, another object of the present invention is to improve the utilization of the ATM layer function by searching for features and additional information on VPI / VCI, and in particular, the central processing unit (CPU) function is dedicated to the initialization process of the routing table. Asynchronous transfer mode (ATM) connection control, which reduces the hardware load and increases the CPU layer's freedom of control at the ATM table, by allowing CPU access time for the routing table appearing in I / O arbitration of the routing table at any time other than searching for the input cell. To provide a device.

On the other hand, another object of the present invention is to provide an asynchronous transfer mode (ATM) connection control apparatus for arbitrating to use the CAM used in software in routers or bridges as a routing table of the ATM protocol. There is this.

In order to achieve the above object, the present invention receives an address provided from an external central processing unit (CPU), generates and transmits a selection signal, and receives control information from the central processing unit (CPU) according to the control information. CPU connection means for transmitting status information; A routing table configured with a content addressable memory (CAM) to store routing information to perform related table searches during one search cycle regardless of the number of stored lists; Receives control information from the CPU through the CPU connection means, generates a control signal for controlling the routing table to the routing table, and receives a selection signal from the CPU connection means to generate the routing table. Routing table control means for retrieving and transmitting status information to the CPU connection means, receiving header information, searching the routing table, and transmitting the result; And extracting a virtual path identifier / virtual channel identifier (VPI / VCI) in a cell header from a valid cell flow inputted from an ATM layer function connected to the routing table control means and transmitting the extracted virtual path identifier / virtual channel identifier (VPI / VCI) to the routing table control means. ATM layer function module access means for receiving the result of searching the routing table by a virtual channel identifier (VPI / VCI) from the routing table control means and delivering the result to the ATM layer function.

Hereinafter, with reference to the accompanying drawings will be described another embodiment of the present invention;

1 is a block diagram of an asynchronous transmission mode (ATM) connection control apparatus according to the present invention.

The present invention connects to a central processing unit (CPU), receives an address provided from the central processing unit (CPU), transmits a selection signal to the routing table control unit 2, and receives control information from the central processing unit (CPU). To control the routing table by receiving control information from the CPU through the CPU connection unit 1 and the CPU connection unit 1, which transmits status information according to the control information to the CPU. Generates a signal to the routing table 3, receives a selection signal from the CPU connection unit 1, retrieves the routing table 3, and transmits status information to the CPU connection unit 1, and from the ATM layer function module connection unit 4 Routing Table Control Unit (RTCU) (2) and Routing Table Control Unit (2) for receiving the header information, searching the routing table (3), and transmitting the result to the ATM layer function module connection unit (4). Receive The VPI / VCI in the cell header is extracted from the valid cell flow input from the ATM layer function connected to the routing table 3 and the routing table controller 2 storing the routing information, and transmitted to the routing table controller 2. An ATM layer function module connection unit 4 which receives the result of searching the routing table 3 by the extracted VPI / VCI from the routing table control unit 2 and delivers the result to the ATM layer function is provided.

2 is a detailed block diagram of an asynchronous transmission mode (ATM) connection control apparatus according to the present invention.

The CPU connection unit 1 receives the address from the CPU function unit, generates a selection signal for the ATM connection control device, and transmits the address decoder 5 for transmitting to the routing table control unit 2 and control information for connection control from the CPU. A control register unit 6 which receives and transmits to the routing table control unit 2, reports the operation state of the routing table control unit 2 to the CPU function unit, and delivers the search results to the CPU function unit in the case of connection confirmation. And a command buffer 8 having a depth of 6 in 16-bit units for storing connection control data and routing table drive command codes. This is because the maximum number of command codes is required to drive the CAM with 16 bits by using the CAM for transmitting and receiving data and command codes with 16 bits.

The routing table control unit 2 mainly generates control signals E ^* , W ^* , EC ^* , CM * 15 for controlling the routing table 3, and the instruction buffer (1) of the CPU connection unit 1 is generated. 8) and the control signals and command codes from the ATM layer functional module connection unit 4 are arbitrated (multiplexed) to drive the routing table 3.

In addition, the ATM layer function module connection unit 4 generates the routing table 4 by the VPI / VCI extraction unit 12 and the extracted VPI / VCI, which are in charge of extracting the VPI / VCI in the cell header from subsequent valid cell flows. It is composed of a connection function connection unit 13 for transmitting the search result to the ATM layer function.

In the arbitration method of the routing table control unit 2, the command of connection establishment / release / confirmation during the period in which the connection with the ATM layer function is invalid is executed by the command control signals E ^* , W ^* , EC ^* , CM *) (14) and command codes are driven directly from the CPU into the routing table (4), and when the connection with the ATM layer function is enabled (that is, a valid cell is input), the connection is established / released from the CPU. The command control signal 14 of the confirmation / confirmation is stored in the command buffer and executed by transferring the command to the routing table 4 at any time except between searchers of the routing table 4 by the valid cell.

The state transition diagram of the routing table control unit 2 for driving the routing table is specifically shown in FIG. 3 and the timing diagram in FIG.

In FIG. 3, when the reset signal 24 is received at any moment of power-on or operation, the routing table is initialized 21. If one of the signals of the connection establishment (Est) / disconnection (Rel) / connection confirmation (Rd) is input (25) while the connection with the ATM layer function is not valid (25), the ATM connection establishment / release / confirmation state (22). In this case, the CPU function unit directly inputs the command code and data into the routing table 4 to drive the same. At this time, the control signal of the routing table 4 is a signal generated by the mapped memory input and output.

During this operation, when the connection to the ATM layer function module connection unit 4 becomes valid 26 and a valid cell starts to be input, the control signal of the routing table 4 is inputted to the ATM layer function module connection unit 4. It is generated by a combination of a clock, a cell synchronization clock, and an effective cell signal (20 in FIG. 2), and the instruction buffer 8 has already been received from the CPU at a time except for the searching time of the routing table 4 for the effective cell in synchronization with this control signal. The routing table 4 is operated by reading and inputting the corresponding command code and data stored in the " Here, since the operation of the CPU (connection establishment / release / confirmation) and the ATM layer function operate independently, the instruction buffer write operation for connection establishment / release / confirmation function is performed irrespective of the operation of the routing table control unit 2. . When the search is completed (27), regardless of the validity of the connection (28) in accordance with the command at the CPU connection (1) receives the command from the instruction buffer 8, ATM connection establishment / release / confirmation (22) is performed.

4 is a timing diagram of the routing table control unit when the connection to the ATM layer function module connection is made valid and a valid cell starts to be input. Here, the header [7: 0] (29) inputs header data for the 8-bit wide valid cell that reaches the ATM layer function connection unit (4). [Routing Table (RT) input [15: 0] (30), RT Outputs [15: 0] (31) display 16-bit long command codes and connection related data to and from the routing table (3). HEN (32) is a signal indicating the search time of the header and is valid up to l / 2 cell times (27th byte clock), and when a valid cell signal (CEN) is input, the 1/2 cell cycle is a routing table by the ATM layer function. If it is assigned in the search period (3) and there is no valid cell signal (CEN), the entire cell cycle is allocated to the CPU operation (connection setting / release / confirmation).

The E ^* signal in the routing table is a combination of the byte clock BCLK, cell synchronization clock CCLK, and valid cell signal CEN inputted from the ATM layer function module connection 4 as described above. It is generated in a cycle (36). (38) shows an instruction buffer write part operating in synchronization with the CPU clock of (33) regardless of HEN, and (39) shows an area where connection establishment / release / verification is performed. It is shown that the connection control is actually performed from an arbitrary moment after the last information is transmitted.

Accordingly, the present invention, which is configured and operated as described above, provides a broadband synthesis for operation of ATM functions (ATM routing function, VPI / VCI conversion function, traffic control function, multiplexing / demultiplexing, etc.) for providing transparent transmission of ATM information cells. The ATM layer of the information communication network (B-ISDN) performs an essential ATM connection control function and efficiently operates and manages a routing table that stores connection control information. The routing table can be searched for any length within a maximum of 64 bits in one cell time for the cells that arrive without delay and lossless processing for ATM cells transmitted at high speed. The function of establishing / releasing / verifying the connection to the table is possible at any time other than the searchers, thereby increasing the degree of freedom of the ATM layer management unit and minimizing the delay of the overall ATM protocol execution speed. Therefore, the present invention can be effectively used in any broadband integrated information network (B-ISDN) system in which connection control functions are involved in an ATM protocol performed at high speed, and furthermore, a byte clock (BCLK), a cell synchronization clock (CCLK), and an effective cell. If there is a signal input corresponding to the signal CEN, the device can be used as a device for performing address translation at high speed.

Claims (2)

CPU connection means for receiving an address provided from an external central processing unit (CPU), generating and transmitting a selection signal, receiving control information from the central processing unit (CPU), and transmitting status information according to the control information; A routing table configured with a content addressable memory (CAM) to store routing information to perform related table searches during one search cycle regardless of the number of stored lists; Receiving control information from the CPU through the CPU connection means, generating a control signal for controlling the routing table to the routing table, and receiving a selection signal from the CPU connection means. Routing table control means for searching and transmitting status information to the CPU access means, receiving header information, searching the routing table, and transmitting the result; And extracting a virtual path identifier / virtual channel identifier (VPI / VCI) in a cell header from a valid cell flow inputted from an ATM layer function connected to the routing table control means and transmitting the extracted virtual path identifier / virtual channel identifier (VPI / VCI) to the routing table control means. Asynchronous connection mode (ATM) connection control including an ATM layer function module access means for receiving the result of searching the routing table by a virtual channel identifier (VPI / VCl) from the routing table control means and transferring the result to the ATM layer function. Device. 2. The apparatus of claim 1, wherein the CPU connection means comprises: an address decoder which receives an address from the central processing unit, generates a selection signal for an asynchronous transfer mode (ATM) connection control device, and transmits the selection signal to the routing table control means; A control register for receiving control information on the connection control from the central processing unit and transferring the control information to the routing table control means; A connection status register which reports an operation state of the routing table control means to the central processing unit, and transmits a search result to the central processing unit in the case of connection confirmation; And a buffer for storing connection control data and routing table driving command codes, wherein the routing table control means generates control signals E ^* , W ^* , EC ^* , CM * for controlling the routing table; Mediating (multiplexing) control signals and command codes from the buffer of the CPU access means and the ATM layer function module access means to drive the routing table, and establishing a connection for a period in which a connection with the ATM layer function is invalid. The command of release / confirmation is driven by inputting command control signals CE ^* , CW ^* , CEC ^* , CCM *) and command codes directly from the central processing unit to the routing table by mapped memory input / output. When the connection with the connection is valid (i.e., when a valid cell is input), the command control signal of connection establishment / release / confirmation from the CPU is stored in the command buffer. Multi- valid by transmitting a command to the routing table at any time except between the searchers of the routing table by the effective cell, wherein the ATM layer function module access means is arranged in a cell header from a valid cell flow continuing from the ATM layer function. Means for extracting a virtual path identifier / virtual channel identifier (VPI / VCI) which is responsible for extracting a virtual path identifier / virtual channel identifier (VPI / VCI); And connection function access means for transferring the result of searching the routing table by the extracted virtual path identifier / virtual channel identifier (VPI / VCI) to the ATM layer function. Device.