KR970002720B1 - Aal arbitraitor unit of atm - Google Patents

Abstract

An AAL mediation device for the ATM communication type where enables to mediate in case that the confliction occures the data transmission of the AAL1 transmitter, AAL 3/4 transmitter and AAL5 transmitter in the ATM communication type.

Description

ATM communication method AAL arbitrator

1 is a block diagram illustrating an AAL layer transmitter in which a terminator according to the present invention is used.

2 is a block diagram showing an AAL arbitration apparatus according to the present invention.

3 illustrates the structure of a typical ATM cell.

(a) shows the structure of the entire ATM cell;

(b) illustrates an ATM cell header structure of a user network interface (UNI);

(c) shows the ATM cell header structure of the network node interface (NNI).

* Explanation of symbols for main parts of the drawings

1: AAL 1 Transmitter 2: AAL 3/4 Transmitter

3: AAL5 transmitter 5: arbitration device

7: ATM FIFO 10: Arbitration Request Department

12,22: D flip-flop 20: Arbitration status storage

30: Arbitration Tribunal

The present invention relates to an ATM Adaptation Layer (AAL) that matches user service information and ATMTPF format in an Asynchronous Transfer Mode (ATM) communication scheme, in particular an AAL1 transmitter according to the AAL1 protocol, AAL 3 / The present invention relates to an Arbiter that arbitrates AAL 3/4 transmitters according to 4 protocol and AAL5 transmitters according to AAL 5 protocol to simultaneously transmit them to the ATM layer.

Recently, as the means of communication is rapidly digitalized and the development of optical communication enables transmission of a wide band, a broadband ISDN (Broadband Integrated Services Digital Network) has emerged to satisfy various service requirements of users.

That is, B-ISDN is a video telephony service based on narrowband services such as remote meter reading, data terminal, telephone, facsimile, etc. It is designed to handle and deliver broadband services such as videoconferencing, high-speed data transmission, and video signal transmission in common, and is implemented based on the asynchronous transmission mode (ATM) communication method.

The ATM communication method is similar to the conventional packet communication method in that ATM cells are transmitted by cell unit by Asynchronous Time Division Multiplexing (ATDM). It handles even signal of bit rate and is standardized by international standardization organization for use in local area network as well as huge public network.

This ATM communication system communicates based on ATM cells as shown in (a) to (c) of FIG. 3, where a user's long message is divided into ATM cells and transmitted, and the received ATM cells are again one message. Is reassembled and forwarded to the parent user.

That is, as shown in (a) of FIG. 3, an ATM cell is divided into a header section of 5 bytes and a user information section of 48 bytes, and the header of 5 bytes is represented by (b) and in FIG. As shown in (c), the header structure is divided into a header structure at a user network interface (UNI) and a header structure at a network node interface (NNI), and a header at the user network interface (UNI). The structure consists of 4 bits of General Flow Control (GFC) and 4 bits of Virtual Path Identifier (VPI), and the 2nd byte consists of 4 bits of Virtual Path Identifier ( VPI) and 4-bit Virtual Channel Identifier (VCI), the third byte consists of 8-bit Virtual Channel Identifier (VCI), and the fourth byte is a 4-bit Virtual Channel Identifier (VCI). (VCI), 3-bit Payload Type (PT) and 1-bit Cell Loss Priority (CLP) Becomes luer, the fifth byte is a header error control bits of the 8: comprised of (HEC Header Error Control).

Here, the last bit of the 3-bit payload type is a user bit (AUU: ATM_USER to ATM_USER), which is usefully used in the AAL5 protocol. When the first bit is 1, the operation type is OAM (Operations, Administration, and Management). The general meaning is shown in the following table.

Table <1>

Also, when looking at the header structure at the network node interface (NNI), except that the general flow control (GFC) in the first byte of the user network interface (UNI) described above is used as the most path identification number (VPI). It can be seen that the same as the header structure of the network interface (NNI).

This ATM communication method has a hierarchical structure as shown in the following Table 2 and has standardized standards for each layer.

Table <2>

As shown in Table 2, the ATM communication method is divided into vertical structures such as a physical layer, an ATM layer, an ATM adaptation layer (AAL), and a higher protocol layer. Segmentation And Reassembly sublayer (SAR) and Convergence Sublayer (CS) sublayers are divided again, and the physical layer is further subdivided into Physical Media (PM) and Transmission Convergence (TC) sublayers.

In addition, according to the service of the user, that is, the characteristics of the source in the ATM communication method can be separated as shown in the following Table.

Table <3>

As shown in Table 3 above, the types of services in B-ISDN are classified into Classes A through D according to the nature of the source. The Class A services are real-time, identity bit rate, and connectivity services. It is a service of sex, variable bit rate, and connectivity, and class C service is a non-real time, variable bit rate, and a non-connectivity service, and a class D service is a non-real time, variable bit rate, and a connectionless service. Representative examples of such services include identity rate video signal, variable rate video signal, connectivity data transmission, and connectionless data transmission.

On the other hand, the AAL protocol corresponding to the above service is divided into AAL1 ~ AAL5 as shown in the following table <4>, conventionally divided into AAL1 ~ AAL4, but AAL3 and AAL4 have many similarities, combined with AAL3 / 4, high-speed data AAL5 has been proposed, which reduces overhead for communication.

Table <4>

As shown in Table 4, the AAL layer is divided horizontally as AAL1, AAL2, AAL3 / 4, AAL5 in order to efficiently process the corresponding service according to the type of service. It is suitable for high speed data communication by reducing overhead of AAL3 / 4 layer that carries data of Class C and Class D service, and transparent service data unit (U-SDC) from service user. Make a ATM cell by transferring data of variable length received from Convergence Layer (CS) and Convergence Layer (CS) to detect transmission error, identify and buffer information, and transfer it to ATM layer. In addition, the ATM cell is divided into a truncation and re-determination sublayer (SAR) that receives an ATM cell from the ATM layer, reassembles it, and recovers a CS-PDU (CS-Protocol Data Unit). In addition, the convergence (CS) sublayer includes a common part convergence sublayer (CPCS) that performs functions common to the connected and disconnected services, and a service-specific convergence sublayer (CPCS) for providing a specific AAL user service. SSCS: Service Specific Convergence Layer.

Details of this AAL layer have been proposed in ITU-T Recommendations "1.362" and "1.363", and by Craig Partridge, "Gigabit Networking; Craig Partridge; 1994; Addison Wesley; pp 61-87. ) And two other co-authors, "Co-Band Information Communications (pp 314-327)".

As described above, in implementing the respective transmitters supporting the AAL1, AAL3 / 4, and AAL5 protocols together to provide various services in the AAL layer, each mediation is performed when contention occurs between the transmitters. In the related art, each transmitter supporting one protocol is individually implemented or implemented in software, resulting in slow data processing speed and inconvenience. In particular, the conventional low speed AAL 1 transmitter has a problem that the bottleneck caused by the low speed preemption FIFO.

Accordingly, the present invention provides an AAL mediation apparatus that can efficiently mediate when there is contention in the data transmission between the AAL1 transmitter, AAL 3/4 transmitter, and AAL5 transmitter in an ATM communication scheme to solve the above problems. The purpose is to provide.

In the arbitration apparatus of the present invention for achieving the above object, as a result of the logical multiplication of the flag signal (flag [2..0]) and the count end signal (1_end, 3_end, 5_end), the count start signal (1_start, 3_start, 5_start) and an arbitration request unit for outputting an arbitration request signal by ORing the queue signal temp [2..0]; An arbitration state storage unit which stores previous arbitration results; The flag signal flag [2..0], the queue signal temp [2..0], and the arbitration signal are determined according to the output and priority of the arbitration state storage unit at the request of the arbitration request unit. 1_count_en, 3_count_en, 5_count_en) having an arbitration plate end to mediate data transmission of the AAL1 transmitter, AAL3 / 4 transmitter, and AAL5 transmitter.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

1 is a schematic diagram illustrating transmitters of an AAL layer to which the present invention is applied, and data contention between the transmitters and a plurality of transmitters (1, 2, 3) supporting an appropriate protocol according to characteristics of a source from a higher layer. If this occurs, it is composed of an arbitration device 5 which arbitrates and sends it to the ATM layer.

That is, as described in Tables <3> and <4>, the ATM communication method supports data transmission using an appropriate protocol according to the characteristics of the source in order to treat various sources in the same manner. The source transmits data to the ATM layer through the AAL1 transmitter (1) supporting the AAL1 protocol, and the source with variable or no connectivity variable bit rate through the AAL3 / 4 transmitter (2) supporting the AAL 3/4 protocol. Data is transmitted to the ATM layer, and a source requiring fast data transmission transmits the data to the ATM layer through the AAL5 transmitter 3 supporting the AAL5 protocol.

At this time, when the AAL1 transmitter 1, the AAL3 / 4 transmitter 2, and the AAL5 transmitter 3 transmit data to the ATM layer, the AAL1 transmitter 1 completes writing data to the FIFO to mediate contention of data transmission, and then counts a signal related thereto. (complete) to cause the ATM layer to read the data. That is, the AAL1 transmitter 1 records 48 bytes of cell data in the FIFO according to the AAL1 protocol, and then outputs a count related signal (type1_complete) to the arbitrator 5, and the AAL3 / 4 transmitter 2 transmits the AAL3 / 4 protocol. After recording 48 bytes of cell data in the FIFO and outputting the count-related signal (type3_complete) to the arbitrator 5, the AAL5 transmitter 3 records 48 bytes of cell data in the FIFO according to the AAL5 protocol and then counts it. The signal type5_complete is outputted to the arbitration apparatus 5.

The arbitration apparatus 5 inputs these count related signals to determine whether the ATM layer is ready to receive according to the arbitration priority and selects a transmitter to transmit to the ATM layer. Typically, since the AAL1 transmitter 1 is real-time data, the AAL1 transmitter 1 preferentially selects other transmitters to transmit data.

FIG. 2 is a block diagram illustrating an arbitration apparatus according to the present invention. As a result of performing an AND operation on a flag signal flag [2..0] and a count end signal 1_end, 3_end, 5_end, the count start signal 1_start, 3_start A mediation request unit 10 for outputting an arbitration request signal by ORing the queue signal temp [2..0]; Arbitration state storage unit 20 for storing the previous arbitration results: and according to the output of the arbitration state storage unit 20 and the arbitration priority by the request of the arbitration request unit 10 to determine the flag signal ( AAL transmitter 1, AAL3 including an arbitration judging unit 30 for generating flag [2..0]), queue signal temp [2..0] and arbitration signals 1_count_en, 3_count_en, 5_count_en. / 4 Transmitter (2), AAL5 transmitter (3) to mediate the data transmission.

In addition, the arbitration request unit 10 logically multiplies the flag signal flag [2..0] by the count end signals 1_end, 3_end, and 5_end to request mediation at the end of the count. , AND3); A plurality of OR gates OR1, OR2, OR3 for ORing the output of the AND gate, the queue signal temp [2..0], and the count start signal 1_start, 3_start, 5_start; And a plurality of deflip-flops 12 for storing the output of the oragate, and the arbitration decision unit 30 is implemented as a programmable logic array.

That is, the count start signal 1_start is set to "1" or the count start signal 1_start is set to "1" in order to start counting the AAL1 transmitter 1 after the data is written to the FIFO and the cell data is read from the ATM layer. Even if it is set as "1", if the priority is low and it is not selected, or if the count start signal (1_ start) was previously selected as "1" and the count signal (1_end) was ended when the flag signal (flag [0]) is "1", The ORA outputs "1" to request arbitration by outputting "1" to the arbitration decision unit 3 through the type [0] flip-flop, and the AAL3 / 4 transmitter 2 sends data to the FIFO. Even if the count start signal (3_start) is set to "1" or the count start signal (3_start) is set to "1" in order to start counting the cell data to be read by the ATM layer, the priority is not selected because of low priority. Previously, the count start signal 3_start was selected with " 1 " so that the flag signal flag [1] was set to " 1 ". If the count is terminated (3_end), the ORA outputs "1" and outputs "1" to the arbitration decision unit 3 through the type [1] flip-flop to request mediation, and then the AAL5 transmitter ( Even if the count start signal (5_start) is set to "1" or the count start signal (5_start) is set to "1" in order to start counting to read the cell data from the ATM layer after 3) runs out of data in the FIFO, If the ranking is not selected because it is not selected or if the count signal (5_start) was previously selected by setting the count start signal (5_start) to "1" and the flag signal (flag [2]) is "1", the ORA (OR3) It outputs "1" and requests "mediation" by outputting "1" to the arbitration judgment part 3 through the type [2] flip-flop.

When the arbitration request is received, the arbitration decision unit 30 arbitrates as shown in the following table, taking into account the previous arbitration result, priority, and pending transmitter.

Table <5>

In Table 5, type [0], which is an input for arbitration judgment, is the result of logically multiplying 1_end and flag [0] by the logical result of 1_start and temp [0], and type [1] is 3_end and flag. [1] is the result of logical OR of 3_start and temp [1], type [2] is the result of AND of 5_end and flag [2] and of OR of 5_start and temp [2].

Thus, if type [0] is "1", it indicates that the AAL1 transmitter has requested arbitration; if type [1] is "1", it indicates that the AAL3 / 4 transmitter has requested arbitration, and type [2] is "1" If it is, it indicates that the AAL5 transmitter has requested termination.

In addition, the flag data (flag [2..0]) is a semaphore that indicates the currently selected transmitter to prevent other transmitters from accessing it. The temp data (temp [2..0]) of the arbitration decision unit 30 is A queue indicating the transmitter currently waiting for arbitration for transmission, so if flag [0] is "1", it indicates that AAL1 transmitter 1 has been selected and is transmitting, and if flag [1] is "1", AAL3 / 4 Transmitter 2 is selected to be transmitted as a result of arbitration, and if flag [2] is " 1 ", AAL5 transmitter 3 is selected to be transmitted and is being transmitted, and if temp [0] is " 1 " The transmitter 1 has requested mediation but the priority is low and it is not selected this time, so it is waiting for the next turn. If temp [1] is "1", the AAL3 / 4 transmitter 2 has requested mediation but the priority is low. Failed to indicate the next turn, and if temp [2] is "1", A The AL5 transmitter 3 requested mediation, but the priority was low, indicating that it was not selected this time and waiting for the next turn, where the AAL1 transmitter 1 handled the real-time data and had the highest priority, so temp [0] was "1." "Doesn't really happen.

The operation of the arbitration device 5 based on the data used in the arbitration device of the present invention as described above will be described in detail with reference to Table 5 above.

If the input data is &quot; 100000 &quot; as shown in Table &lt; 5 &gt;, then the AAL5 transmitter 3 is requesting the FIFO to read 48 bytes of cell data from the ATM layer after completing the writing. 100 "to indicate that the AAL5 transmitter is transmitting data to the ATM layer and to enable the AAL5 transmitter 3 by applying" High (VCC) "to the 5_count_en signal.

In addition, when the input data is "110000", since the AAL5 transmitter 3 and the AAL3 / 4 transmitter 2 have requested the arbitration, the arbitration apparatus 5 outputs "10100" so that the AAL5 transmitter 3 having a high priority is output. Then select temp [1] as "1" to indicate that the AAL3 / 4 transmitter 2 is waiting for arbitration, and flag [2] as "1" to indicate that the AAL5 transmitter is transmitting data to the ATM layer. And A &lt; 5 &gt; _en signal to &quot; high (VCC) &quot; to enable the AAL5 transmitter 3.

In addition, when the input data is "111000", since the AAL5 transmitter 3, the AAL3 / 4 transmitter 2, and the AAL1 transmitter 1 have requested mediation, the arbitration apparatus 5 outputs "110001" to give priority. After selecting the highest AAL1 transmitter (1), set temp [2] and temp [1] to "1" to indicate that AAL5 transmitter (3) and AAL3 / 4 transmitter (2) are waiting for arbitration, and flag [0] Is set to "1" to indicate that the AAL1 transmitter 1 is transmitting data to the ATM layer, and "ALC" is applied to the 1_count_en signal to enable the AAL1 transmitter 1.

In addition, when the input data is "111010", the AAL5 transmitter 3, the AAL3 / 4 transmitter 2, and the AAL1 transmitter 1 request a lot, and since the AAL3 / 4 transmitter 2 has previously transmitted, The device 5 outputs "100001" to select the highest priority AAL1 transmitter 1, then sets temp [2] to "1" to indicate that the AAL5 transmitter 3 is waiting for arbitration and flag [0] Denotes that data is being transmitted to the AAL1 transmitter 1 ATM layer by setting " 1 " to enable the AAL1 transmitter 1 by applying "High (VCC)" to the 1_count_en signal.

In addition, when the input data is "111001", the AAL5 transmitter 3, the AAL3 / 4 transmitter 2, and the AAL1 transmitter 1 request arbitration, and since the AAL1 transmitter 2 has previously transmitted, the arbitration apparatus ( 5) outputs "10100" to select the second highest priority AAL5 transmitter 3, wherein temp [1] is set to "1" to indicate that the AAL3 / 4 transmitter 2 is waiting for arbitration; , flag [2] is set to "1" to indicate that the AAL5 transmitter 3 is transmitting data to the ATM layer, and the AAL5 transmitter 3 is enabled by applying "High (VCC)" to the 5_count_en signal. From the above description, it can be seen that when the AAL1 transmitter 1, the AAL3 / 4 transmitter 2 and the AAL5 transmitter 3 simultaneously request arbitration, the arbitration priority is AAL1> AAL5> AAL3 / 4.

On the other hand, if the input data is "1001", the AAL1 transmitter 1 requests arbitration, and since the AAL1 transmitter 1 has previously transmitted, the arbitration apparatus 5 outputs "0" to display flag [0]. By setting "0", it indicates that the AAL1 transmitter 1 has completed the transmission and disables the AAL1 transmitter 1 by applying "GND" to the 1_count_en signal.

As described above, the AAL arbitration apparatus according to the present invention implements each transmitter supporting the AAL1, AAL 3/4, and AAL 5 protocols together, and then mediates the contention when data contention occurs between the transmitters. Implemented in hardware, it can provide various services quickly. Especially, by writing data to the FIFO and requiring arbitration, the bottleneck does not occur even when the low-speed AAL1 transmitter preempts the FIFO.

Claims (3)

In a device for arbitrating data transmission of an AAL1 transmitter according to AAL1 protocol of ATM communication method, AAL3 / 4 transmitter according to AAL 3/4 protocol, and AAL5 transmitter according to AAL5 protocol, a flag signal (flag [2..0]) And an arbitration request for outputting an arbitration request signal by ORing the count end signals 1_end, 3_end, and 5_end by the OR, and counting the signal start signals 1_start, 3_start, 5_start and the queue signal temp [2..0]. Section 10; An arbitration state storage unit 20 which stores previous arbitration results; The flag signal flag [2..0] and the queue signal temp [2] are determined according to the output of the arbitration state storage unit 20 and the arbitration priority level at the request of the arbitration request unit 10. .. 0]) and the AAL arbitration apparatus of the ATM communication method, characterized in that it comprises an arbitration decision unit 30 for generating the arbitration signals (1_count_en, 3_count_en, 5_count_en). 2. The apparatus of claim 1, wherein the arbitration requesting unit (10) comprises: a plurality of AND gates (AND1, AND2, AND3) for requesting arbitration upon completion of counting by multiplying the flag signal and the count end signal; A plurality of OR gates OR1, OR2, OR3 for ORing the output of the AND gate, the queue signal and the count start signal; And a plurality of deflip-flops (12) for storing the outputs of the oragates. 2. The AAL arbitration apparatus of claim 1, wherein the arbitration decision unit (30) is implemented by a programmable logic array.