JP2817094B2 - Communication control processor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication control processing apparatus which accommodates a communication line, is connected to a host computer, executes communication protocol processing, and has end and relay functions.

[0002]

2. Description of the Related Art In recent years, a host computer has been connected to a communication control processor, and a plurality of computers have been connected from the communication control processor via an ATM line. It is now possible to perform complicated processing that could not be realized by a computer. In this case, the communication control processing device is connected to another computer and has two types of forms, one for realizing an end function for mutually transferring data and the other for realizing a relay function for mutually transferring data between other computers. I am prepared to respond.

[0003]

However, such a conventional communication control processor performs control for each protocol data unit (PDU) which is a transfer unit of a protocol layer, but the PDU is divided into a plurality of ATM cells. Therefore, it is not possible to proceed to the protocol processing of the received PDU until all the cells have been received and the assembling process into the PDU has been completed. For example, when transferring 16 KB data over a line having a speed of 150 Mbps, it takes about 0.8 ms. However, whether the data is addressed to the own node or relayed, all of the data is received and assembled into a PDU. It cannot be known unless it is out of order. That is, in the case of 16 KB, it takes 0.8 ms to receive data and about 0.1 ms to perform protocol processing on the received data. Therefore, it is not 0.9 ms after data reception starts. Notification of the data and the data to the host computer of the own node or transfer to the other node did not start. For this reason,
Despite the fact that real-time processing can be performed by multiple computers, a delay on the order of milliseconds occurs and a significant time delay occurs compared to a single computer, so data transfer with other computers is processed It was an impediment to improving speed. The present invention has been made in view of such a situation, and aims to reduce a time delay when data is transferred between a plurality of computers.

[0004]

Means for Solving the Problems In order to solve such problems, the invention of claim 1, the received cell entry side virtual Cha
Depending on the channel, the received cell is assigned to a predetermined egress virtual channel.
Relay processing for relaying to
Perform termination processing to assemble the protocol data unit
ATM processing unit and, based on the first cell,
The necessity of relay processing for the receiving cell of one incoming virtual channel
An ATM processing unit, comprising:
Performs cell reception processing in response to cell reception and
The post-processing after waiting according to the expiration of the processing waiting timer
And the cell position of the received cell is
Judge and if the received cell is the first cell,
End of relay processing necessity judgment for incoming virtual channel of cell
After setting the L3 processing completed flag indicating
Notify the layer 3 processing unit that the head cell has been received, and
For a cell or last cell, its ingress virtual channel
Is referred to, and the L3 processing
If the completed flag indicates the end,
Executes relay processing or termination processing according to the virtual channel
However, when the L3 processing completed flag indicates an unfinished state,
Activating a processing wait timer corresponding to the received cell
As a post-standby process, the corresponding received cell is
Cell reception processing, and the layer 3 processing unit
In response to the notification of the reception of the head cell from the TM processing unit, the head cell
Destination address stored in the layer 3 header of the
When indicating the own device, the ingress virtual channel of the head cell
Determined that termination processing is required for cells received from
And when the destination address indicates another device,
Is the received cell from the incoming virtual channel of the head cell.
It is determined that relay processing is necessary for the
Terminates the L3 processed flag corresponding to the incoming virtual channel
Is set to . In the invention of claim 2, in the invention of claim 1, the ATM processing unit receives
ATM record based on AAL type 5 set in cell
The display information between the ear users and the reception cell
Based on whether or not the first cell received from the channel
The position of the received cell is determined .

[0005]

After receiving the first cell including the layer 3 header,
It is determined from the destination address whether it is addressed to its own node or a relay. If it is a relay, the relay display flag of the ATM processing unit is turned on. AT
The M processing unit immediately relays the subsequent cell if the relay indication flag is on, and performs an assembling process into the AAL-SDU if the relay indication flag is off.

[0006]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, and FIG. 2 is an example of a network configuration for explaining setting information of various controls in FIG. Here, a communication control device that realizes up to the protocol layer 3 will be described. In FIG. 1A, a communication control device 1 accommodates an ATM line 2 via a DSU 3 and is connected to a host computer 4. The communication control device 1 includes an ATM processing unit 11, a layer 3 processing unit 12, a host interface unit 13, and a buffer 14. Here, in the ATM network, a connection provided to an end user is called a virtual channel (VC), and each VC is a virtual path identifier (VP).
I) and a virtual channel identifier (VCI) are uniquely identified.
Let's call it C number.

The ATM processing unit 11 has a configuration shown in FIG. 1C. The AL processing unit 111 realizes an ATM adaptation layer (AAL) function for disassembling and assembling user data in units of cells. Processing unit 112 that realizes an ATM layer function for performing transmission and reception, etc., DSU
Processing unit 113 for realizing a physical layer function for performing electrical matching between the communication control device 3 and the communication control device 1, a FIFO type cell FIFO capable of temporarily storing a plurality of transmission and reception ATM cells
An O-buffer 114 and a relay control unit 115 that performs relay control. The relay control unit 115 indicates that each item of the relay display flag, the L3 processed flag, the outgoing VC number, and the buffer cell address pointer for AAL-SDU assembly is associated with the incoming VC number and represents one entry. Each of the specifications corresponding to the VC number is written in the form of a relay control table. As shown in FIG. 1B, the layer 3 processing unit 12 performs an L3 control processing unit 121 that processes a packet in accordance with the protocol of the protocol layer 3, and outputs a destination address corresponding outgoing route (outgoing VC number) in a table format. There is a path control unit 122 for writing. The host interface unit 13 performs electrical matching with the host computer 4.

In the following, the AAL type is AAL type 5 suitable for high-speed data communication, and the layer 3 protocol is TCP.
The description will be made on the assumption that the IP of the / IP system is used, and that the VC between the nodes is already set as shown in FIG. FIG.
Is the relationship between ATM cells and PDU configuration in AAL type 5,
4 and 5 are flowcharts showing the operation of the ATM processing unit 11, and FIGS. 6 and 7 are flowcharts showing the operation of the layer 3 processing unit 12. In FIG. 2,
A, B, C, and D are node addresses, and 10, 20,
Reference numeral 30 denotes a VC number, a bold line indicates a layer 3 packet flow, and a pipe-shaped route surrounding the bold line indicates VC. In the device configured as described above, the relay operation will be described first. In this case, the communication control device 1 performs two operations of the relay operation and the end operation.
Although various types of operations are possible, the relay operation will be described on the assumption that the relay is performed via the communication control device 1 from the terminal A to the terminal D in FIG.

When the terminal A attempts to communicate with the terminal D, it creates a PDU including a destination address and the like, decomposes it into ATM cells, and sends it to the communication control device 1 via the ATM network. The communication control device 1 converts this cell into a D in FIG.
The data is taken into the ATM processing unit 11 from the ATM line 2 via the SU 3. The ATM processing unit 11 is the AL processing unit 1 shown in FIG.
Since the cell 11 receives the head cell, the AL processing unit 111 notifies the AM processing unit 112 of the cell reception. Thereby, AM processing section 112 determines that the activation type in step 100 in FIG. 4 is cell reception.

Next, the AM processing unit 112 shown in FIG. 1C stores the received cell in the cell FIFO buffer 114.
And the process of step 102 of extracting the VC number from the cell header. Then, the AM processing unit 112 determines whether the cell is the top, middle, last, or single from the information of the ATM layer user display in the header. The display between the ATM layer users is set to "0" when the cell is at the beginning and middle, and "1" when the cell is at the end and solely. Is determined.

In this case, the cell that arrives first is A
Since the display between TM layer users is “0”, it is determined that the cell is the first cell. If this is not the first but "0", the middle cell, if "1", the last cell, the first "1"
Is determined as a single cell. Therefore, the AM processing unit 11
No. 2 determines that the received cell is the first from the header of the first cell, so that it is determined in step 103 in FIG. 4 that the position of the cell is the first. Next, the AM processing unit 112 performs a process of setting the L3 processing completion flag = 0 of the relay control unit 115 shown in step 105. In this case, as shown in FIG. 2, it is assumed that the incoming VC number is previously set at 30, so that the relay control unit 115 shown in FIG.
, The L3 processing completion flag corresponding to the entry side VC number 30 is first set to “0” and cleared. Thereafter, as shown in step 106 of FIG. 4, a notification that the head cell has been received is sent to the layer 3 processing unit 12, and the ATM processing unit 11 ends the processing at this stage.

[0012] Based on the first cell reception report received earlier, that is, the notification of step 106, the layer 3 processing unit 12
The L3 control processing unit 121 in FIG.
00 is determined as the first cell, and the cell FIFO
Step 201 from the cells stored in the buffer 114
Of the layer 3 shown in FIG. Then, it is determined from the read header whether the destination address of step 202 is addressed to itself or a relay. In this case, since the relay is assumed, the L3 control processing unit 121
As shown in the figure, the exit side VC is determined by the route control unit 122,
The outgoing VC number of the relay control unit 115 is set, and the relay display flag is set to “1”. In this case,
Since it is assumed that the VC between each node has already been set,
The set VC corresponds to the route control unit 12 shown in FIG.
2 is written. That is, as shown in FIG. 2, the VC is determined to be 30 for terminal A, 10 for terminal B, and 20 for terminal D. Therefore, the VC is written in the route control unit 122 for the destination address.

Therefore, in step 203 of FIG. 6, when the communication control device 1 relays from the terminal D in response to the request from the terminal A from the route control unit 122, the VC numbers 30 and 2
0 is connected, and the outgoing VC number 20 is set for the incoming VC number 30 of the relay control unit 115,
The relay display flag is set to “1”. Then, in step 204, the transmission of this head cell is instructed to the AM processing unit 112 of the ATM processing unit 11. Therefore, step 100 in FIG. 4 is determined to be a cell transmission request, and the ATM cell transmission processing shown in step 119 is performed.

Next, as shown in step 205 of FIG.
The L3 processing completion flag is set from “0” to “1”. At this point, the L3 processing completion flag changes from “0” to “1” in the relay control unit 115 of FIG.
When the AL processing unit 111 of the ATM processing unit 11 receives an intermediate cell, step 100 in FIG. 4 determines that the cell has been received, and stores the cell in the cell FIFO buffer 114 in step 101. The VC number shown in step 102 Is performed, and in step 103, the position of the cell is determined to be intermediate.

Since the relay operation is performed at this time, the L3 processing completed flag is set to "1" in step 205. However, the layer 3 processing unit is configured to process not only the line described here but also a plurality of lines simultaneously. For this reason, if the processing of another line is congested, the L3 processing completed flag may not be able to be set to “1” immediately after receiving the head cell of the line described here. In this case, since the L3 processing completion flag shown in step 110 of FIG. 4 remains “0”, the processing of waiting for a certain time shown in step 118 is performed, and the communication control device 1 shown in FIG.
Of the timer management unit (not shown) is started. This timer is set in consideration of the time during which the L3 processing completion flag can be turned on even when the layer 3 processing unit 12 is under time division control.

Therefore, when the time of the intermediate cell timer expires, this is notified from the timer management unit to the ATM processing unit 1.
Since the first AM processing unit 112 is notified,
At 0, it is determined that the activation type is the timeout of the intermediate cell, and the L3 processing completed flag is determined again at step 110. At this point, since the L3 processing completed flag has already been set to “1”, it is determined whether or not the relay display flag shown in the next step 111 is “1”. Since this flag is also set to "1" in step 203, the process of reading the value of the outgoing VC number of the relay control unit 115 shown in step 112 and setting it in the VC number field of the ATM cell is performed. And transmits the received ATM cell to the terminal D indicated by the outgoing VC number.

When the next cell is received, step 10
0 is determined to be a cell reception, and the cell FI shown in step 101
The process of storing in the FO buffer and the VC number extraction process of step 102 are performed, and the determination of the cell position in step 103 is performed. At this time, if it is an intermediate cell again, the above-described processing is performed. If it is the last cell, it is determined whether or not the L3 processing completion flag of step 140 shown in FIG. 5 is “1”.

If there are three or more cells, the last cell is determined in step 103 as the last cell. In this case, the L3 processing completion flag is determined in step 140 of FIG. 5. At this point, the L3 processing completion flag is "1" since the processing of the first cell has been completed. Then, the relay flag is determined in step 141, but in the case of the relay operation, since it is set to "1", the value of the outgoing VC number of the relay control unit 115 shown in step 142 is set to AT
Processing for setting the VC number field of the M cell, processing for transmitting the ATM cell shown in step 143, step 14
The process of clearing the entry of the relay control unit shown in FIG. 4 is performed, and the relay process ends.

If the cell is composed of two cells, step 103 in FIG. 4 determines that the second cell is the last cell, so that the L3 processing completed flag in step 140 in FIG. It is determined whether or not there is. Here, as described above, when the processing of the first cell is not completed in the layer 3 processing unit 12, the L3 processing completed flag is "0", so the timer for the last cell shown in step 165 is started. , A process of waiting for a certain time is performed. Then, in step 100, the AM processing unit 1 of the ATM processing unit 11
12, the timeout of the timer for the last cell is determined, and the processing completion flag of step 140L3 in FIG. 5 is determined. Here, since the timer has expired, it is determined that the L3 processing completed flag is set to “1”. Therefore, it is determined in step 141 that the relay flag is “1”, and in step 142, the relay control is performed. The processing of setting the value of the outgoing VC number of the unit 115 in the VC number field of the ATM cell is performed, the processing of transmitting the ATM cell in step 143 is performed, and the relay control unit 115 of step 144 is performed.
Is performed, and the relay process ends.

Thus, each time one cell is received,
Since it relays to the destination, for example, 150Mbps
Even in the case of relaying 16 KB data over a line, the conventional one that waits for PDU assembly and performs the next processing is 0.8
Since the relay operation cannot be determined unless the time is after ms, the relay operation is performed each time one cell is received by applying this method. Therefore, the relay operation is performed with a time delay of about 12 μs. Can be started, and the next action can be quickly moved to. In the case of the relay operation, in the conventional method, it takes 0.8 ms to receive, for example, 16 KB data, and it takes about 0.1 ms to analyze the data and perform the relay operation. 0.
Since it takes 8 ms, it takes about 1.7 ms in total. On the other hand, when the method of the present invention is adopted, 12
The head cell containing the layer 3 header necessary for performing the relay operation in about μs is received, and about 0.1 ms is required for the relay operation processing based on the header cell, and it takes 0.8 ms to reach the destination.
ms, so that the data reaches the destination in about 0.91 ms. Therefore, the time is reduced to about half of the conventional time.

The above description is based on the assumption that a plurality of ATM cells shown in FIG.
This is a description of a case where a DU is configured. When the information field is short, data from the information field of the CS-PDU of FIG. 3 to the trailer is configured in one cell.
In this case, step 103 in FIG. 4 determines that the position of the cell is sole, and performs the process of setting the L3 process completion flag of the relay control unit 115 to “0” shown in step 130 of FIG. A CRC check of the indicated CS-PDU is performed. The CRC code is accommodated in the trailer section of the CS-PDU in FIG. 3, and is checked. If the CRC code is normal, a single cell reception is notified to the layer 3 processing section in step 132.
Thereafter, the same processing as described above is performed, and the relay of the single cell is performed. If it is determined in step 131 that the received data is abnormal, the received data is discarded and the process ends.

Then, it is determined that the activation type in step FIG. 6 is single cell reception, and it is determined in step 221 in FIG.
In step S223, the outgoing VC is determined by the route control unit shown in FIG. 2, and the process of setting the outgoing VC number of the relay control unit and setting the relay display flag to "1" is performed.
A request is sent to the processing unit for cell transmission, and the processing is terminated.

Having described the relay function, the function as the end will now be described. When the first cell is received, cell reception is determined in step 100 of FIG.
In step 101, the received cell is stored in the cell FIFO buffer 114, the VC number is extracted in step 102, the cell position is determined to be the first cell in step 103, and the L3 processing completion flag of the relay control unit 115 is determined in step 105. Is set to “0”, and step 10 is performed.
In step S6, the head cell reception is notified to the layer 3 processing unit. In step S200 of FIG. 6, it is determined that the activation type is the head cell reception. This is similar to the operation when a cell is received.

Next, in step 202, the destination address is checked. If the address is addressed to the own node, the AAL-SDU is checked in step 210.
(CS-PDU) The buffer cell for assembling is acquired, and the contents of the cell information field in the cell FIFO buffer 114 are stored in this buffer. Then, as shown in step 211, the relay display flag of the relay control unit 115 is set to “0”, and the buffer cell address of the relay control unit 115 is set. Finally, the L3 processing completed flag of the relay control unit 115 is set to “1”. In the example of FIG. 2, the VC number 10 is addressed to the own node, so the relay control unit 115 of FIG.
, The L3 processing completion flag of the portion corresponding to the VC number 10 is set to “1”, the relay display flag is set to “0”, and the buffer address is set to aaa.

When the second cell is received, the activation type is determined to be cell reception in step 100 of FIG.
01 is stored in the cell FIFO buffer, the VC number is extracted in step 102, and
At 03, it is determined that the cell position is intermediate. Then, in step 110, it is determined whether or not the L3 processing completion flag is “1”. At this time, if the layer 3 processing unit is processing another line as described above, the layer 3 , The L3 processing completed flag may not yet be "1".

At that time, a timer for an intermediate cell (not shown) in the communication control device 1 is started, and a wait for a fixed time shown in step 118 is performed. When the timer times out, the activation type in step 100 determines that the intermediate cell has timed out. By then, the L3 processing completed flag is set to “1”. Therefore, step 110 determines that the L3 processing completed flag is “1”. Then, the relay display flag is checked in step 111. Since the end function is now being implemented, the relay display flag is set to "0", so that the cell data is assembled into the AAL-SDU in step 115, and the buffer cell indicated by the buffer address is received. The received data is stored after the completed data part.

When the last cell is received, step 1 is executed.
03 determines that it has received the last cell,
At 0, it is determined that the L3 processing completed flag is "1". At step 141, it is determined that the relay display flag is "0". At step 146, the assembling process of the cell data into the AAL-SDU is performed. The data of the last cell is stored after the received data portion of the received buffer cell indicated by the address.

Next, a CRC check of the trailer portion of the CS-PDU shown in step 147 is performed. If the result is normal, as shown in step 148, the L3 control processor 121 is notified of the end of the reception of a plurality of cells, the entry of the relay controller 115 shown in step 149 is cleared, and the new CS-P
Prepare for DU reception processing. However, if the CRC check in step 147 is abnormal, the buffer cell is released as shown in step 160, and the received data is discarded. Then, as shown in step 161, the relay control unit 11
5 is cleared.

When the CRC check is normal, it is determined that the activation type in step 200 in FIG. 6 is reception of a plurality of cells, and a request is made to the host interface unit 13 to transfer the received data to the host computer 4 shown in step 215. I do.
As a result, the data received and stored in the buffer cell is transferred to the host computer 4. When the end function is realized, when two cells are received, the cell arriving later is determined to be the last cell, and when it waits for a fixed time in step 165, the last cell timer The operation is the same as that described above except that is driven.

Step 1 when the received cell is single
03 is determined to be alone, and step 13 in FIG.
At 0, the process of setting the L3 process completion flag of the relay control unit 115 to “0” is performed, and the CRC check shown at step 131 is performed. If this check is normal, the single cell reception is notified to the layer 3 processing unit as shown in step 132. Then, according to the notification, step 20 in FIG.
In step S221, it is determined that the activation type is single cell reception, the layer 3 header is read out in step 220 of FIG. 7, and it is determined in step 221 that the destination address is addressed to the own node. As a result, AA shown in step 225
The assembling buffer cell of the L-SDU is obtained, and the received data is stored in the obtained buffer.
Is performed to request the host interface unit 13 to transfer the received data to the host computer shown in FIG. As a result, the data stored in the buffer is transferred to the host computer 4.

The processing for clearing the relay control unit 115 in steps 144, 149, and 161 can be omitted.

[0032]

As described above, according to the present invention, it is determined whether the relay function or the end function is required from the information of the head cell, and the arriving cell is transferred for each cell according to the determination result. Therefore, it becomes possible to recognize the processing type of the succeeding cell only by receiving the first cell, and to determine after receiving the first cell what could not be determined until after the completion of PDU assembly as in the prior art. In addition, the processing time in the communication control processing device is shortened, and when real-time processing is performed in distributed processing, there is an effect that response is improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a network configuration.

FIG. 3 is a diagram showing a relationship between an ATM cell and a PDU configuration.

FIG. 4 is a flowchart illustrating an operation of an ATM processing unit.

FIG. 5 is a flowchart showing an operation leading to FIG. 4;

FIG. 6 is a flowchart illustrating an operation of a layer 3 processing unit.

FIG. 7 is a flowchart showing an operation leading to FIG. 6;

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Communication control device, 2 ... ATM line, 3 ... DSU, 4 ...
Host computer, 11: ATM processing unit, 12: Layer 3 processing unit, 13: Host interface unit, 14: Buffer, 111: AL processing unit, 112: AM processing unit, 113
... PH processing unit, 114 cell FIFO buffer, 115
... Relay control unit, 121 ... L3 control processing unit, 122 ... Route control unit.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁶ , DB name) H04L 12/28 H04L 12/56

Claims (2)

(57) [Claims] 1. A transfer processing unit in a predetermined protocol layer
To store protocol data units that are
Received via the ATM line and the contents of the received cell
Relay the received cell to another node based on the
Assemble the original protocol data unit from the
In the communication control processing device for transferring to the host computer connected to the host , the received cell is transferred according to the incoming virtual channel of the received cell.
Relay processing to relay to a predetermined egress virtual channel or before
A predetermined protocol data unit is formed by the received cell.
An ATM processing unit for performing a terminating process, and an incoming virtual channel identical to the head cell based on the head cell.
To determine whether or not relay processing is necessary for received cells
The ATM processing unit performs a cell reception process in response to the cell reception,
Executes post-waiting processing according to the expiration of the processing waiting timer.
In the cell reception process, the cell position of the reception cell is determined,
If the source cell is the first cell, the entry side of the first cell
L indicating the end of the relay process necessity determination for the virtual channel
(3) After setting the processed flag to incomplete, receive the first cell
Is notified to the layer 3 processing unit, and the received cell is an intermediate cell or
For the last cell, it corresponds to the incoming virtual channel
Referring to the L3 processed flag, this L3 processed flag
Indicates the end, the incoming virtual channel of the received cell
Relay processing or termination processing in accordance with the
If the processed flag indicates incomplete, the received cell
The processing wait timer shall be started in response to the
The layer 3 processing unit performs a reception process, and in response to the notification of the reception of the head cell from the ATM processing unit,
Destination address stored in the cell's Layer 3 header
Indicates the own device, the incoming virtual channel of the head cell
If termination processing is required for cells received from channels
And if the destination address indicates another device,
In this case, the reception cell from the ingress virtual channel of the first cell
It is determined that relay processing is necessary for the first cell, and L3 processing corresponding to the incoming virtual channel of the head cell has been completed.
A communication control processing device, wherein a communication flag is set to end . 2. The communication control processing device according to claim 1, wherein
The ATM processing unit performs AT based on AAL type 5 set in the received cell.
M layer user-to-user display information and the received cell is
Based on whether or not this is the first cell received from the virtual channel
A communication control processing device for determining a cell position of the reception cell .