JP3449299B2 - ATM cell transmission control device - Google Patents

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to an ATM (Asynchronous).
It relates transmit controller of nous Transfer Mode) cells, in particular, to transmit <br/> signal controller of the ATM cell for transmitting the application information preferentially that requires real time as voice.

[0002]

2. Description of the Related Art FIG. 10 shows a conventional ATM cell transmission control system. Packets to be mapped to ATM cells are divided into two types, voice and data. Voice is stored in the voice cell assembly memory 201 and data is stored in the data information memory 202. Voice cell assembly memory 20
1 is divided into a plurality of voice packets (# 1, # 2, # 3), and headers h ₁ , h ₂ , h are included in each packet.
₃ is added. Further, from the data information memory 202, a part of the stored data is taken out as a data information packet 203 under a predetermined condition. ATM cell 20
4 comprises voice packets # 1, # 2 and # 3 and a data information packet 203, and the header h _{1 of the} voice packet # _1.
, The cell header H is added before. Data information packet 203 has a variable length, is disposed after the voice packet # 3 adds a header h ₄ at the head.

As shown in FIG. 10, voice packets # 1 to # 3 for which real-time communication is required are given priority over other data and the payload of the ATM cell 204 (Payload: Payload:
Main information). Then, if no voice packet arrives within the specified ATM cell assembly time limit and an empty area occurs in the payload of the ATM cell 204, the data information is read from the data information memory 202, and the voice packet is set as the data information packet 203. # 3
Append after. As a result, the data can be multiplexed in the empty area of the payload.

FIG. 11 shows another conventional transmission control system for ATM cells. In this transmission control method, the handling of voice packets is the same, but the handling of data information is different. That is, the data information is a plurality of fixed-length data information packets 205a, 205b, 205c, 20.
It is stored as 5d. As described above, when the voice packets # 1 to # 3 are preferentially packed in the payload of the ATM cell 204 and an empty area is generated in the payload, the data information packet 205a is read from the data information memory 202 and packed in the empty area. Possible data 20
5aa is added to the ATM cell 204, and the remaining data 20
5ab is an ATM cell 206 that follows the ATM cell 204.
Is mapped so that it is arranged at the beginning of the.

[0005]

However, the conventional ATM
According to the cell transmission control method, voice packets are preferentially multiplexed into ATM cells, and when an empty area is generated in the payload, data information packets are multiplexed to fill the ATM cell payload for cell transmission. For this reason, after the cell assembly time limit is reached, the data information packet 203 is cut out from the data information memory 202 and multiplexed into the ATM cell, and if the voice packets do not arrive consecutively, they are consecutively sent. There is a problem that a transfer delay is generated by the amount of time waiting for a packet as compared with the state in which a voice packet has arrived.

Further, since the priority control buffer memory multiplexed in the ATM cell performs the packet transmission priority control by the two kinds of memories for data packet and voice data, packets of various applications arrive at the input line. Even if it did, the priority control of the application could not be performed.

It is therefore an object of the present invention reduces the transmission delay of voice packets and data packets are multiplexed into ATM cells, and transmission of ATM cells to allow the priority control of packets transmitted according to the user's application To provide a signal control device.

[0008]

The present invention SUMMARY OF THE INVENTION In order to achieve the above object, ATM multiple variable length packets from multiple user channel variable length (Asynchronous Transfer M
ode) In the ATM cell transmission control device for multiplexing and transmitting to the ATM link, voice packets and data packets input from the plurality of user channels are AA
L2 (ATM Adaptation Layer Type 2) processing is performed to generate a composite packet, and among the composite packets generated by the composite packet generation means, the voice packet is set to the first priority and the data packet is set to the first priority. Identification means for assigning the composite packet to the second priority or later and a plurality of FIFOs (First-In) for storing the composite packets assigned by the identification means
First-Out) memory means having a memory, said a read control means for reading out the composite packet the voice packet based on the control information from the identification means with priority from said FIFO memory stored, the read
An ATM cell header is added to the composite packet read by the sending control means, and an ATM cell generating / sending means for multiplexing and transmitting the ATM cell from a packet having a high priority is provided . The read control means is provided after the second priority.
For a certain time, considering the read cycle and data length
Data length of the composite packet read during
Becomes shorter as the FIFO memory with lower priority
The present invention provides an ATM cell transmission control device for reading the composite packet .

According to this method, the voice packet and the data packet input from the user channel are set to the first priority on the basis of the priority control information with respect to the composite packet generated by the AAL2 processing, and the data packet is set to the first priority. The priority is set after the second priority. The data is stored in the FIFO memory of the storage means according to this priority order, and when reading out, the voice packet is read out according to the priority order. As a result, priority control is performed for each user channel, and data transfer with a transmission quality suitable for the application and user channel becomes possible. In addition, the waiting time for payload generation can be eliminated, and the total cell delay time can be reduced. As a result, it is possible to ensure quality in the transmission of voice that requires real-time processing.

[0010]

[0011]

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a network system to which an ATM cell transmission control method and a transmission control device of the present invention are applied.

Between the ATM network terminating device (NT) 100A and the ATM network terminating device (NT) 100B as the ATM cell transmission control device of the present invention, the ATM switches 101, 1 are provided.
02 is connected. An ATM network 103 connects between the ATM exchange 101 and the ATM exchange 102. ATM network terminators 100A, 100B
Between the ATM exchanges 101 and 102 and the composite A
They are connected by the TM link 104. Also, ATM
A plurality of user channels 105 are set in the network terminators 100A and 100B, and variable-length packets are transmitted.

FIG. 2 shows an ATM network terminating device 100A (100
The detailed structure of B) is shown. ATM network terminators 100A and A
The TM network terminating device 100B has the same configuration. Therefore, only the ATM network terminating device 100A will be described here. The ATM network termination device 100A includes a variable length packet input unit 1, a composite packet generation unit 2, a composite packet priority class identification unit 3, an identification class information management unit 4, a CPU interface unit 5, and a priority class-specific FIF.
O (First-In First-Out) memory 6-1 to 6-N, FI
An FO memory read control unit 7, an ATM cell payload generation unit 8, an ATM cell header generation unit 9, an ATM cell generation / transmission unit 10, and an identification class management table 11 are provided.

The variable-length packet input unit 1 includes a composite packet generation unit 2, a composite packet priority class identification unit 3, and priority class-specific FIFO memories 6-1 to 6-N.
, ATM cell payload generator 8, ATM cell generator /
The sending unit 10 is connected in series. An identification class information management unit 4 is connected to the composite packet generation unit 2 and the composite packet priority class identification unit 3, and C is connected to the composite packet generation unit 2 and the identification class information management unit 4.
The PU interface unit 5 is connected. The FIFO memory read control unit 7 is connected to the composite packet priority class identification unit 3, the CPU interface unit 5, the priority class-specific FIFO memories 6-1 to 6-N, and the ATM cell payload generation unit 8. Further, the ATM cell header generation unit 9 is connected to the CPU interface unit 5 and the ATM cell generation / transmission unit 10.

Packets of various applications such as voice, data and images are input to the variable length packet input unit 1. Since the input packet is multiplexed with the ATM cell payload and transmitted, the composite packet generation unit 2 performs AAL2 (ATM Adaptation Layer Type 2) processing on the packet input from the variable length packet input unit 1 to form a composite cell. The composite packet generation unit 2 notifies the identification class information management unit 4 of the channel information such as the application of the packet and the channel identification number (CID). The composite packet priority class identification unit 3 has an identification class management table 11, and the identification class management table 11 is always written with the latest priority for each CID provided from the identification class information management unit 4. Based on the priority information of the identification class management table, the composite packet is assigned to the priority class FIFO
It is stored in the memories 6-1 to 6-N. FI by priority class
The composite packet stored in the FO memories 6-1 to 6-N is read by the FIFO read memory control unit 7 according to its priority. In addition, ATM cell generation /
The transmission unit 10 generates an ATM cell including the payload generated by the ATM cell payload generation unit 8 and the header generated by the ATM cell header generation unit 9. This A
The TM cell is transmitted from the ATM cell generation / transmission unit 10 to the composite ATM link 104, and is further transmitted to the ATM switch 101 via the composite ATM link 104. It should be noted that the CPU interface unit 5 centrally controls each component block.

FIG. 3 shows the structure of a composite packet. The AAL2 process is performed by the composite packet generation unit 2 to generate a composite packet (AAL-CPS) from the user packet (SSCS). A header HDR is added to the beginning of the composite packet.
The header HDR includes 8-bit SSCS entry number information (CID) as a channel identifier, 6-bit packet length information (LI) indicating the length of a user packet, and 5
It consists of bit user information (UU), 5-bit header error detection information (HEC), and user packet (UP). The CID is used for priority control.
(Channel identifier). Header H having such a configuration
The DR is incorporated in the ATM cell 12 as one packet. A plurality of AAL-CPSs are inserted in the ATM cell 12.

FIG. 4 shows the operation of the ATM cell transmission control system of the present invention. In FIG. 4, A1 to A4 and B1 to B
2, C1 to C5, and D1 are composite packets that have been AAL2 processed by the composite packet generation unit 2. A1 to A4 are composite packets of user A, B1 to B2 of user B, C1 to C5 of user C, and D1 of user D. The composite packet is given a CID (channel identifier) to the header portion of the composite packet for each user by the composite packet generation unit 2. Further, the composite packet generation unit 2 notifies the identification class information generation unit 4 of the CID information of each composite packet and the channel information such as the application of each packet, and generates the identification class management table 11. The composite packet priority class identification unit 3 writes the composite packet in the priority class-specific FIFO memories 6-1 to 6-N according to the priority of the composite packet designated by the identification class information management unit 4. The identification class information management unit 4 determines the priority of writing based on the priority order of the channel of the identification class management table 11. In FIG. 4, user B
The user D information is registered as a first priority packet, the user A information is registered as a second priority packet, and the user C information is registered as a fourth priority packet in the identification class management table 11.

Next, the operation from the writing to the memory for each priority class to the generation of the ATM cell will be described. As shown in FIG. 2, the FIFO memory 6 for each priority class
-1 to 6-N and the FIFO memory read control unit 7 are connected by a control line 13. Therefore, the packet presence / absence information in each FIFO memory is notified from the priority class FIFO memories 6-1 to 6-N to the FIFO memory read control unit 7, and the FIFO memory read control unit 7 gives priority to the packet presence / absence information and the FIFO memory. The composite packet (AAL-CPS) is read out based on the class. When the composite packet is stored in the FIFO memory 6-1 for each priority class, the composite packet read operation is immediately performed as in "multiplex operation 1" shown in FIG. FIFO memory by priority class 6
When there is no composite packet in -1, the packet is read from the priority class-specific FIFO memory 6-2 by "multiplex operation 2".

"Multiple operation 2" means a priority class-specific FIF
The priorities of the O memories 6-1 to 6-N are weighted according to the reading cycle and the data length of the composite packet, and the data length of the composite packet read at a fixed time is controlled to be shorter in the FIFO with lower priority. Say the method. In the FIFO memory read control unit 7 that performs this control, the composite packet priority class identification unit 3 writes the write information including the composite packet length to each of the priority FIFO memories 6-1 to 6-n and each priority FIFO.
By managing the read information from the O memories 6-1 to 6-n, the above-mentioned "multiplex operation 1" and "multiplex operation 2" can be realized. After the multiplexing operation of the composite packet is performed on the ATM payload based on the priority class, the ATM cell generation / transmission is performed by the header information generated by the ATM cell header generation unit 9 and the payload generated by the ATM cell payload generation unit 8. An ATM cell is generated by the unit 10 and the ATM cell 12-1 to 12 is sent to the ATM switch 101.
-4 is transmitted.

As described above, the priority control of packets according to the application can be performed for each input channel. At the same time, if there is no input data on all channels,
It is possible to efficiently transmit data with no empty area in the ATM cell payload.

Next, an example in which the present invention is applied to a wireless transmission system will be described. FIG. 5 shows an interface portion with a user in a wireless transmission system in which the effect of multiplexing composite packets on ATM cells is remarkable. In this wireless transmission system, four wireless channels (used by users A, B, C, D) are connected to the network terminating device 100. Then, the users A and B are the PDC (Persona
l DigitalCellular) voice data is transmitted to the network terminating device 100 via the wireless station 105, the user C transmits PDC packet data to the network terminating device 100, and the user D transmits PDC FAX data to the network terminating device 100. Shall be transmitted. A1, A2, A3, A4 are user A's composite packets, B1, B2, B3 are user B's composite packets, C1, C2 are user C's composite packets, and D1, D2, D3 are user D's. Is a composite packet of.

FIG. 6 shows the structure of a composite packet generated by AAL2 processing packets on a plurality of input channels. Further, FIG. 7 shows an identification class management table corresponding to the operation of FIG. 5, and stores identification information for performing priority read control from the priority class FIFO. Here, two audio channels (corresponding to data A and B) are used for the first priority FIFO, a first data channel (corresponding to data C) is used for the second priority FIFO, and a second data channel (corresponding to data D). ) Is stored in the third priority FIFO, the identification class management table is generated. Packets are A1, B1, C1, D1, A2, D2, B
It is transmitted in an array of 2, A3, C2, D3, A4, B3. C for user A's composite packets A1 to A4
ID = 1A is set, CID = 21 is set in the composite packets B1 to B3 of the user B, CID = 58 is set in the composite packets C1 and C2 of the user C, and composite packets D1 to D3 of the user D are set. Is C
Set ID = 9B.

FIG. 8 shows the structure of the priority class-specific FIFO and ATM cell payload. In the FIFO, the composite packets of each user are sorted according to their priority. Here, the priority is set to three levels, and the first priority FIFO (A1, B1, A2, B2, A3, A4, B
3), second priority FIFO (C1, C2), third priority FI
Three FOs (composite packets D1 to D3 of user D) are set.

FIG. 9 shows the structure of an ATM cell using the composite packet generated in FIG.

Next, the operation of the ATM cell transmission control system according to the present invention will be described with reference to FIGS. 2 and 5 to 9. First, as shown in FIG. 6, the packets of the respective channels of users A to D are sequentially subjected to AAL2 processing by the composite packet generation unit 2 in the order of packet arrival, and the composite packet header has an 8-bit channel for each user (channel). An identifier (CID) is given. at the same time,
The composite packet generation unit 2 notifies the identification class information management unit 4 of channel information such as CID information of each packet and application (voice, packet data, FAX data) information, etc., and the identification class management table 4 shown in FIG. Update. Here, the applications (for audio) such as users A and B, which require real-time performance, are positioned as the first priority, and the users C and D are set as the second priority and the third priority in the identification class management table. Is going. This setting can be arbitrarily performed under the control of the CPU interface unit 5.

Next, the packet composited by the composite packet generation unit 2 is processed by the composite packet priority class identification unit 3 according to the instruction of the identification class information management unit 4 based on the information of the "identification class management table", as shown in FIG. As shown in FIG. 5, the priority class-based FIFO memories 6-1 to 6-N are sorted and stored. When the packet is written to the priority class FIFO memories 6-1 to 6-N, the flag information indicating that the packet is written is notified to the FIFO memory read control unit 7. The FIFO memory read control unit 7 performs read control of the composite packet stored in the first priority FIFO, and sequentially transmits the composite packet to the ATM cell payload generation unit 8 to obtain a FIFO for each priority class.
When all the composite packets for the first priority are read from the memories 6-1 to 6-N, the corresponding FI for each priority class
The FO memory 6 notifies the FIFO memory read control unit 7 of an empty flag. Then,
The FIFO memory read control unit 7 assigns packets of the second and third priorities to the FIFO memories 6-1 to 6 for each priority class.
-N (not including the FIFO memory storing the first priority packet) is read and sequentially transmitted to the payload generation unit 8. Here, since the composite packet C2 exceeds the cell assembly time limit, the composite packet C2 is divided into C2 ′ that is within the cell assembly time limit and C2 ″ that enters the next cell. Similarly, the composite packet D3 is also D.
3'and D3 ".

Here, when the composite packet is being read from the FIFO memory 6 of the second priority and thereafter, a new packet is stored in the first priority FIFO memory 6 and the flag information indicating the writing is stored in the FIFO memory. The case of being sent to the read control unit 7 will be described.
In this case, the FIFO memory read control unit 7 completes the reading of the composite packet currently being read, and then shifts to the read operation of the first priority FIFO memory 6. The composite packet transmitted to the ATM cell payload generation unit 8 is sequentially multiplexed into the payload, and when the payload is filled with packets, the composite packet shown in FIG. 9 is obtained based on the ATM header and the payload generated by the ATM cell header generation unit 9. As described above, the ATM cell generation / transmission unit 10 generates the ATM cell 106,
It is sent to the ATM switch 101 connected to the ATM network 103 via the M link 104.

As described above, according to the embodiment of the present invention, by providing a plurality of FIFO memories for each priority class, an input packet is stored in each FIFO memory for each channel, and the FIFO having the highest priority is used for the composite. The packet is read. Further, the FIFOs of the second priority and later
When reading from the memory, the read control is performed in consideration of the read interval and the read data length, and the FIFO memory 6 for each priority class in which the composite packet is input.
The composite packet is read from 1 to 6-N by priority control to generate an ATM cell payload. Therefore, until all the FIFO memories are empty, composite packets are always read from any one of the FIFO memories without waiting time, and therefore ATM cells multiplexed with valid composite packets can be transmitted without interruption. You can In other words, while performing priority control of packets of various applications arriving on a channel-by-channel basis, it is possible to prevent useless empty areas in the ATM cell payload and to perform ATM cell generation processing with less delay. In particular, it is effective in terms of quality assurance in voice transmission that requires real-time processing. In this way, the priority class-specific FIFO memories 6-1 to 6-1 ...
As long as the composite packet is stored in any of 6-N, it is possible to effectively use the bandwidth of the ATM link without waste.

[0030]

As described above, the ATM cell of the present invention
According to transmission of signal control device, the input packet into a plurality of FIFO memories stored in accordance with the priority to the channel unit of a storage unit, since the read out high composite packet priority from the storage means previously, Data can be transferred with a transmission quality suitable for the application and user channel. Also, since the waiting time for unnecessary payload generation can be eliminated, it becomes possible to reduce the total cell delay time, and in voice transmission that requires real-time processing, quality assurance and transmission efficiency improvement. Will be possible. Furthermore, by using the FIFO memory, it is possible to simplify the configuration of the transmission control device, reduce power consumption, improve maintainability, improve reliability, and the like.

[Brief description of drawings]

FIG. 1 is a block diagram showing a schematic configuration of a network system to which an ATM cell transmission control system and a transmission control device of the present invention are applied.

2 is a block diagram showing a detailed configuration of an ATM network terminating device of FIG.

FIG. 3 is a configuration diagram showing a configuration of a composite packet handled by the present invention.

FIG. 4 is an explanatory diagram showing an operation of an ATM cell transmission control system of the present invention.

FIG. 5 is a schematic configuration diagram showing an interface portion with a user in the wireless transmission system.

FIG. 6 is a configuration diagram showing a configuration of a composite packet obtained by processing packets on a plurality of input channels by AAL2.

FIG. 7 is a configuration diagram showing an identification class management table corresponding to the operation of FIG.

FIG. 8 is an explanatory diagram showing a configuration of a priority class FIFO and an ATM cell payload.

9 is a configuration diagram showing a configuration of an ATM cell by the composite packet generated in FIG.

FIG. 10 is an operation explanatory view showing a first example of a conventional ATM cell transmission control system.

FIG. 11 is an operation explanatory diagram showing a second example of a conventional ATM cell transmission control system.

[Explanation of symbols]

1 Variable length packet input section 2 Composite packet generator 3 Composite packet priority class identifier 4 Identification class information management section 5 CPU interface section 6-1 to 6-N priority class FIFO memory 7 FIFO memory read controller 8 ATM cell payload generator 9 ATM cell header generator 10 ATM cell generation / transmission unit 11 Identification class management table 100A, 100B ATM network terminator (NT) 101,102 ATM switch 103 ATM network 104 Composite ATM Link 105 user channels

Continuation of front page (58) Fields surveyed (Int.Cl. ⁷ , DB name) H04L 12/28

Claims (2)

(57) [Claims] 1. A plurality of variable length packets from a plurality of variable length user channels are transferred to an ATM (Asynchronous Transfer M).
In an ATM cell transmission control device for multiplexing and transmitting to an ATM link, voice packets and data packets input from the plurality of user channels are AAL2 (ATM Adaptation Lay).
er Type 2) composite packet generating means for processing to generate a composite packet; and, of the composite packets generated by the composite packet generating means, the voice packet has a first priority and the data packet has a second priority. Identification means for setting the composite packets to be assigned thereafter, storage means having a plurality of first-in first-out (FIFO) memories for storing the composite packets assigned by the identification means, and control from the identification means high and read control means for reading the composite packets with priority from said FIFO memory to said voice packet is stored, the priority by adding an ATM cell header to the read composite packets by said read control means based on the information From packet An ATM cell generation / transmission means for multiplexing and transmitting the ATM cells is provided , and the read control means is provided for the second priority and thereafter.
Read at a fixed time considering the read cycle and data length.
The data length of the composite packet to be output is the priority order
The lower the FIFO memory, the shorter
An ATM cell transmission control device for reading a composite packet . 2. The composite packet generating means,
2. The AT according to claim 1, wherein individual channel information for each channel is added to the composite packet after the AAL2 processing, and the priority of the composite packet is determined based on the channel information.
Transmission control apparatus of the M cell.