JPH01212140A - Multi-address response control system in local area network - Google Patents

Abstract

PURPOSE:To decrease the collision of responses from respective receiving terminals by selecting the response starting time of the respective receiving terminals in a multi- address frame at random with use of the transmitting time of the multi-address frame and the number of broadcasting addresses. CONSTITUTION:For the respective receiving terminals, a maximum transmission delay time Tsend of the multi-address frame, a maximum transmission delay time Ta of one response and an all responses delay maximum allowing time Tack are supplied in advance. At first, a response startable time t1 is set from the maximum transmission delay time Tsend of the multi-address frame and a multi-address frame transmitting time ts in a multi-address frame header 1. Next, an all receiving terminals responding time Tn is obtained from the maximum transmission delay time Ta for the response of one receiving terminal and the number (n) of the multi-addresses and equally divided into the number (n) of the multi-addresses and t2, t3...,tn are set. A time tx is selected at random out of the t1-tn and a response is returned at the random time tx. Thus, since a time to be needed for the responses of all the receiving terminals is forecasted in each receiving terminal and each receiving terminal executes the response at a random time in the forecasted time, the colliding proportion of the respective responses can be decreased.

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Technical field to which the invention pertains The present invention relates to a ti11m system for responding to broadcast communications, and in particular to a system for local area networks in which responses are efficiently performed without concentrating on transmission paths. This relates to the broadcast response mW method.

(2) Prior Art In local area networks, a broadcast transmission medium is sometimes used to transmit data by broadcast communication. The response to the broadcast communication is the same as the response to one-to-one communication, and each receiving terminal responds immediately after receiving the coaxial data.
When a contention method such as the A/CD method is used, responses are concentrated on the transmission path, resulting in collisions between responses.

There is a problem in that retransmissions due to collisions and furthermore their repetitions occur. Furthermore, there is a C3MA/CD system with ACK that has a response means in the medium access control section.

In this method, when a terminal receives data, it immediately returns a response.

Other terminals delay their own data transmission, but in this case as well, there is a problem that collisions occur between responses to broadcast communication. Therefore.

Under the C5MA/CD system with ACK, no response is made to broadcast communication.

(3) Purpose of the Invention The present invention aims to solve the problem of the above-mentioned prior art, which is the frequent occurrence of collisions due to the concentration of responses to broadcast communication on the transmission path. The purpose of this invention is to provide a broadcast response control method that predicts a time, causes each receiving terminal to respond at a random time within that time, and reduces the probability of collision between responses.

(4) Examples An embodiment will be described in detail with reference to the drawings.

FIG. 1 shows an explanatory diagram of the principle of the present invention, and FIG. 2 shows a broadcast frame header in an embodiment of the present invention. Folder 1 is for the broadcast frame.

In addition to the broadcast address field 2 and the source address field 3, it includes a timestamp field 4 indicating the broadcast frame transmission time and a destination number field 5 indicating the number of broadcast destinations.

As shown in FIG. 1, each receiving terminal is given in advance the maximum transmission delay time Tsend of a broadcast frame, the maximum transmission delay time Ta of one response, and the maximum allowable delay time Tack of all responses. First, the maximum transmission delay time Tsend of the broadcast frame and the response start possible time t1 from the broadcast frame transmission time ts in ladder 1 to the broadcast frame are set. Next, - the maximum transmission delay time Ta of the response of the receiving terminal
Then, find the response time Tn of all receiving terminals from the number n of broadcast destinations,
Equally divided into the number of broadcast destinations n, t2. t3. ......,t
Set n. Then, a time tx is randomly selected from t1 to tn, and a response is sent back at the random time tx. When a collision occurs between responses, retransmission is performed for the maximum allowable total response delay time T ack. The retransmission procedure is performed using the same method as in the case of a collision in Ethernet.

Next, the details of the operation of this embodiment will be described. FIG. 3 shows an explanatory diagram of the operation of an embodiment of the present invention. Prior to communication, each terminal performs initial processing when the system starts up. Then, the event becomes awaited■. The event referred to here is the reception of a single broadcast frame. Upon receiving the broadcast frame, each receiving terminal transmits Tn
, calculate tl~tn, ■ Tn timer from time tl,
Start the Tack timer and further t 1 % t
■ Select time tx randomly from n. Then, when the second time tx arrives, it sends a response (■).If there is no collision with another optical receiving terminal response, it waits until the Tack timeout and returns to waiting for an event (■). If there is a conflict with another receiving terminal response ■,
The response retransmission process is performed after waiting until Tn and timeout and before Tack timeout. If there is another collision,
Repeat response retransmission process until Tack timeout,
However, for response retransmission processing.

Uses collision retransmission processing in Ethernet.

(5) As described in detail of the invention, according to the present invention, the response start time of each receiving terminal of the 9th broadcast frame is randomly selected using the 1st broadcast frame transmission time and the 1st broadcast destination number, so each receiving terminal It is possible to sufficiently reduce collisions between responses from . Therefore, by applying the present invention to the prior art, it is possible to reduce the probability of collision of responses from each receiving terminal, which is a problem with the prior art, and to efficiently respond to broadcast communication. Furthermore, even when the present invention is applied to the C3MA/CD system with ACK, it is possible to respond not only to one-to-one communication (
, responses to broadcast communications can also be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram illustrating the principle of the present invention, FIG. 2 is a diagram illustrating a broadcast frame header according to an embodiment of the present invention, and FIG. 3 is a diagram illustrating the operation of an embodiment of the present invention. In the figure, 1 represents a broadcast frame header, 4 represents a timestamp field, and 5 represents a destination number field. :Just 44+' Response return Figure 1: Explanation of the principle of the present invention Figure 1: Broadcast frame header of the embodiment Figure 2: Explanation of operation of the embodiment

Claims (1)

[Claims] In a local area network in which a plurality of terminals are connected to a simultaneous broadcast medium and perform broadcast communication, a timestamp field and a broadcast destination number field are provided in a broadcast frame, and each reception The terminal has a function to extract the broadcast frame transmission time in the timestamp field and the number of broadcast destinations in the number of broadcast destinations field, and estimates the time required for responses from all receiving terminals based on the extracted information. A broadcast response control method in a local area network, characterized by having a function of determining a random time within the above period, and a function of responding at the random time.