JPH07312601A - Cell competition control method - Google Patents

Abstract

PURPOSE:To provide a cell competition control method for simultaneously multiplexing and transmitting plural cells consisting of one message as much as possible in ATM communication. CONSTITUTION:Each terminal outputs a desired number X [i] of cells to be transmitted to a shared cell slot 103 so as to know the number X [i] of output requesting cells of the other terminal and a terminal with transmission priority from a field 203 for competition control folded back by a folding circuit and priority display bits 203a... set inside that field. Then, the numbers of output requesting cells from the terminal with transmission priority to the present terminal are successively added, a cell transmission start position or the number of transmission enabled cells is calculated and according to the calculated result, the cells are transmitted to a shared cell slot 105.

Description

Detailed Description of the Invention

[0001]

This invention relates to asynchronous communication (AT
M; Asynchronous Transfer Mode communication), and a cell contention control method for controlling contention of a plurality of cells.

[0002]

2. Description of the Related Art Various methods are conceivable as a contention control method when cells or packets generated from a plurality of terminals or lines are multiplexed on one line. S. Tanenbaum "Computer Netw
orks "There is a bitmap protocol published in Chapter 7.1.3.

FIG. 4 is an explanatory diagram of this bitmap protocol. In this figure, 10 is a contention slot section composed of 8 bits, and 1 bit is allocated to each of 8 terminals (not shown). Further, reference numeral 11 denotes a packet part, and packets of a terminal desiring to be transmitted are transmitted one by one.

When there is a packet to be transmitted, each terminal sets the bit of the corresponding competition slot 10 to "1". Further, each terminal monitors the contention slot unit 10 and sends out the packets in the order set in the contention slot unit 10.
Then, when the packets are transmitted from all the terminals having “1” in the contention slot unit 10, each terminal issues a transmission request to the new contention slot unit 10.

For example, as shown in FIG. 4, when the terminal corresponding to bits 1, 3, and 7 of the contention slot unit 10 desires to send a packet, the bits 1, 3, and 7 are set to "1", The packets 11a, 11b, 11c are transmitted in that order. After that, when a transmission request is issued from the terminal corresponding to bits 1 and 5 of the contention slot unit 10, the packet 11
d and 11e are transmitted.

[0006]

By the way, in the above-mentioned conventional method, since the contention slot 10 is assigned to each terminal only by one bit, there is a drawback that only one packet can be sent at a time, and a plurality of packets can be sent. When sending a packet, a packet from another terminal is inserted in the meantime, so there is a drawback that a delay occurs before sending the next packet.

Particularly in the case of ATM, since the information length of a cell is limited to 48 bytes, a meaningful data string (message) is divided into a plurality of cells and transmitted. In addition, the receiving side often cannot interpret the information until it has received a message consisting of a plurality of cells, which causes a problem of delay due to the divided transmission of the cells.

The present invention has been made under such a background, and by collectively multiplexing a plurality of cells,
It is an object to provide a cell contention control method that improves communication efficiency.

[0009]

The invention according to claim 1 is
A set of an up transmission path and a down transmission path; a plurality of terminals that multiplex and transmit a cell as a first frame on the up transmission path and receive a second frame through the down transmission path; A cell contention control method of ATM communication configured by a loopback circuit provided between a transmission line and a downlink transmission line, for controlling the multiplexing of the cell,
The first frame has at least a contention control field having the same number of areas corresponding to the plurality of terminals and a shared cell slot used in common by the plurality of terminals. Each time a frame is transmitted, the number of output request cells indicating the desired number of cells to be output is output to the corresponding area of the contention control field, and the loopback circuit and the priority display bit designating the terminal to which the transmission is prioritized and the contention. A control field is inserted in the second frame, and the plurality of terminals circulate the number of output request cells arranged in the contention control field starting from the terminal designated by the priority display bit of the received second frame. And the result of the addition is compared with the maximum number of cells that can be accommodated in the shared cell slot, and the number of cells that can be transmitted is within the range of the number of output request cells of its own. And wherein the sending the shared cell slot.

According to a second aspect of the present invention, in the first aspect of the present invention, the folding circuit sets the priority display bit at the head of each area of the contention control field of the first frame, The contention control field is inserted into the second frame.

According to a third aspect of the present invention, in the first or second aspect of the invention, the terminal whose priority is designated by the priority indication bit is the last one of the shared cell slots when transmitting the first frame last time. It is characterized in that it is a terminal that has transmitted a cell slot.

[0012]

According to the present invention, each terminal can determine the number of output request cells and transmission of each terminal from the contention control field returned by the loopback circuit and the priority display bit set inside or outside the field. Know the preferred terminal. Then, the number of output request cells from the terminal that is prioritized for transmission to its own terminal is sequentially added, the cell transmission start position, the number of cells that can be transmitted, etc. are calculated, and transmission is performed according to the calculation result.

As a result, it becomes possible to collectively transmit a plurality of cells forming a message, and the delay of the communication response is alleviated.

[0014]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing the configuration of the present embodiment, in which 1 is a forward highway and 2 is a backward highway, each performing unidirectional data transmission. Reference numerals 31, 32, ... Are n terminals, which are composed of, for example, digital telephones. Reference numeral 4 denotes a turnback unit, which is provided between the forward highway 1 and the backward highway 2 and another line and performs various processes. The folding unit 4 is composed of interface circuits 51 to 54 that perform synchronization adjustment between connected transmission lines and a folding circuit 41 described later.

2 (a) is a block diagram of the frame 101 transmitted to the folding unit 4 via the forward highway 1 of FIG. 1, and FIG. 2 (b) is a terminal 31 via the backward highway 2. , 32 ... Is a block diagram of a frame 201 transmitted to.

In FIG. 1A, reference numeral 102 is a synchronization time slot, which is set at the beginning of the frame 201. Reference numeral 103 is a contention field for cell contention control. For example, n areas of 8 bits are provided corresponding to each terminal 31, 32, ..., And the number of cells that the corresponding terminal desires to transmit. X [1], X [2], ...
., X [n] are set. 104 is the number of terminals (n
Individual cells area prepared only for the terminals 31, 3
Periodic information such as audio data that occurs in 2 ... Is individually set. Reference numeral 105 denotes a shared cell area shared by the terminals. For example, a maximum of m data strings such as dial information and hooking information are set for each cell.

A frame 101 is composed of the above synchronization time slot 102, contention field 103, individual cell area 104, and shared cell area 105.
Also, a synchronization time slot 20 having the same configuration as these is provided.
2, contention field 203, individual cell area 2
04 and the shared cell area 205 form a frame 201 (see FIG. 2B). However, in the contention field 203, 1 priority bit 203a, 2 is added to the head (8th bit) of n areas.
03b ... Are provided, and “1” is set to one terminal in which transmission is prioritized, and “0” is set to the other terminals.

Further, FIG. 3 is a flow chart showing the communication processing of each terminal 31, 32, .... The operation of this embodiment will be described below based on this drawing.

First, in step SP1, each terminal 3
.. (see FIG. 1) output the synchronization time slot 102 of the frame 101 (see FIG. 2A) onto the forward highway 1 and synchronize with each other. Then, in step SP2, the n terminals 31, 32, ... Send the number of cells to be output to the shared cell area 105 to the contention field 103 in each phase.

The folding circuit 41 of the folding section 4 (see FIG. 1).
Receives the contention field 103 via the interface circuit 51, and sets priority bits 203a, 203b ...
"1" is set to one of the items (see FIG. 2B) and the contention field 203 is returned to the backward highway 2. This priority bit 203
The setting of a, 203b ...
"1" is set to the terminal in which the transmission of all cells forming the message is interrupted, that is, to the terminal that has transmitted the last (mth) cell of the shared cell area 105 of the frame 101.

Then, the folding section 4 has a backward highway in the order of the synchronization time slot 202, the contention field 203, the individual cell area 204 and the shared cell area 205 supplied from another line through the interface circuit 54. The frame 201 is transmitted to the No. 2 frame. The phases of the frames 101 and 201 are adjusted by the interface circuits 51 and 52.

Each terminal 31, 32, ...
3, the synchronization is performed in the synchronization time slot 102 of the received frame 201, the corresponding area of the individual cell area 104 is received based on the synchronization, and further, the terminal number included in each slot of the shared cell area 105, etc. To identify the terminal to which the slot was sent, and receive the corresponding slot.

In parallel with this reception, the terminals 31, 32 ...
In step SP4, ... Calculates the number of actually transmittable slots from the received contention field 203. Here, if an area in which the priority bit of "1" is set is j, the number of cells shown in the area is X [j], the corresponding terminal is terminal j, and the terminal that performs the calculation is terminal i, i is the number of cells X [1], X
Of [2], ..., X [n], the sum of the number of cells from area j whose priority bit is “1” to its own area i is cyclically calculated according to the following formula. y1 = X [j] + ... + X [i-1] (1) y2 = y1 + X [i] (2)

Then, in step SP5, the calculation result y2 is set to the maximum value m of the number of cell slots in the shared area 105.
If y2 is equal to or less than m, the process proceeds to step SP6, and X (i) cell slots from the (y1 + 1) th cell slot of the shared cell area 105, that is, all cells desired to be transmitted are transmitted.

Further, in step SP5, y2 is m
If it exceeds, branch to step SP7 and (y1 +
1) From the cell slot, the cells are transmitted by the number of cells that can be output, that is, from the last m slot.

Then, the processing returns to step SP1 and the above processing is repeated. The terminal that could not send out all the desired cells in the previous transmission is again X-framed in the next frame 101.
Issue [i] to try to send the cell.

By such an algorithm, allocation control of access to each cell slot of the shared cell area 105 is performed. According to the above-described embodiment, the cells desired by a certain terminal can be concentrated and transmitted for a maximum of m slots, so that the receiving side can collectively interpret the cells.

[0028] For example, one message is usually divided into a plurality of cells to be sent. Therefore, if cells for one message can be sent in a concentrated manner, the receiving side can immediately receive it as a message. Then you can move on to the next action.

[0029]

As described above, according to the present invention,
Since ATM cells can be sent in a batch, when one message is composed of multiple cells, cells for one message can be sent in a batch. The effect is that the delay can be improved and therefore the transmission efficiency is improved.

[Brief description of drawings]

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

FIG. 2 is a diagram showing a frame configuration (a) and a backward highway frame configuration (b) transmitted on the forward highway 1 of FIG.

3 is a flowchart showing a process of terminals 31, 32, ... Of FIG.

FIG. 4 is an explanatory diagram of a bitmap protocol which is a conventional technique.

[Explanation of symbols]

1 Forward Highway 2 Backward Highway 4 Folding Unit 41 Folding Circuit 31, 32 ... Terminals 51-54
Interface section 101 Forward highway frame 201 Backward highway frame 102, 202 Synchronization time slot 103, 203 Cell contention control contention field 104, 204 Terminal proprietary cell area 105, 205 Shared cell area

Claims (3)

[Claims] 1. A set of upstream transmission lines and downstream transmission lines,
A loopback provided between a plurality of terminals that multiplex cells to be transmitted as the first frame on the uplink transmission path and transmit the second frame via the downlink transmission path, and the uplink transmission path and the downlink transmission path. And a circuit,
In the cell contention control method of ATM communication for controlling the cell multiplexing, the first frame is commonly used by a plurality of terminals and a contention control field having the same number of areas corresponding to the plurality of terminals. At least a cell slot, and the plurality of terminals outputs an output request cell number indicating a desired output cell number for each transmission of the first frame to a corresponding region of the contention control field, and the loopback circuit. The priority indication bit designating the terminal to which the transmission is prioritized and the contention control field,
The plurality of terminals cyclically add the number of output request cells arranged in the contention control field starting from the terminal designated by the priority indication bit of the received second frame, and the addition result And a maximum number of cells that can be accommodated in the shared cell slot are compared, and the number of cells that can be transmitted is transmitted to the shared cell slot within the range of the number of output request cells of its own. . 2. The folding circuit sets the priority display bit at the head of each area of the contention control field of the first frame, and sets the contention control field to the second section.
The cell contention control method according to claim 1, wherein the cell contention control method is to insert it into a frame. 3. The terminal whose priority is designated by the priority indication bit is the terminal which has transmitted the last cell slot of the shared cell slot at the time of the first transmission of the previous first frame. The described cell contention control method.