JPS6121649A - Line exchange type loop network - Google Patents

Abstract

PURPOSE:To reduce restricting items when a data is transmitted via a network by including a bit string representing the synchronizing state of a terminal data to each channel, allowing a sender node station to detect the lead/lag state of the data inputted from a terminal equipment, and allowing a transmission destination node station to detect the lead/lag of data outputted to the terminal equipment. CONSTITUTION:A timing signal ST inputted from a terminal equipment is fetched to a terminal data input circuit 33 and also to a lead/lag detection circuit 31. The ST is sampled by a network synchronizing clock 32 obtained from a high speed transmission clock on a loop to detect the lead or lag state. The state of the timing signal from the terminal equipment is coded as ''01'' for lead state, ''10'' for lag state and ''11'' for synchronizing state, and transmitted to the loop in a channel 41 together with the information bit. A reception node station on the loop receives the channel and uses a clock for network synchronization the same as the sender clock to execute the entirely inverse operation depending on the lead/lag state of the preceding timing signal and transmits the result to the terminal equipment.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a transmission system for a circuit-switched loop network, and particularly to a synchronization system for terminal data in a loop network.

[Prior Art 1] In recent years, loop networks to which optical transmission lines can be easily applied have been attracting attention among so-called local area networks.

This loop network can be roughly divided into two types: packet switching type and circuit switching type (channel multiplex transmission type).

The present invention relates to the latter circuit-switched loop network, and conventionally this type of transmission has been performed by a method not shown in FIG.

The transmission frame 11 is assigned a fixed length channel number,
If the node stations 21a to 21d are divided into 1, NO, 2, etc. and connected by a loop transmission path 22, for example, as shown in FIG.
Data to be transmitted from the terminal device @23a of the node station 21C to the terminal device 23c of the node station 21C was transmitted by being assigned to the third channel.

By the way, in circuit-switched loop networks,
It is completely unconcerned with the content of the data sent from the terminal, and is normally sent to the network bit by bit.

By doing this, transmission is possible without being influenced by complicated transmission protocols between terminals, and the amount of contraception within the network is constant, making it suitable for transmitting voice, telephone, etc. .

However, as a condition at this time, in order to determine the period of data between the terminals, both the transmitting side and the receiving side had to use a clock consisting of the same signal source supplied from the network.

Typically this clock is taken from the data going around the loop.

[Problems to be solved by the invention] However, as the usage of networks becomes more sophisticated and complex, it has become necessary to communicate between networks or to transmit only one line over a long distance via a modem in the network. could not be connected due to the conditions described above.

That is, when connecting circuit-switched networks, it is necessary for each network to import data using the clock of its own network, but it has been impossible for both networks to satisfy this condition.

Means for Solving the Problems The purpose of the present invention is to eliminate the drawbacks of the prior art described above and to provide a synchronization method for terminal data that uses an external clock for transmission. is a loop network in which each node station that performs data input/output control with a terminal device is sequentially connected with a transmission line to form a ring, and a fixed frame that circulates around the loop at a constant speed is composed of multiple channels. Each channel includes at least a bit string of -1 to 1 or more bits indicating the synchronization state of the data of the terminal connected to the source node station, and the source node station indicates the advance or delay status of the data input from the terminal. It is a circuit-switched loop network characterized by detecting the data and controlling the advance and delay of data output to the terminal at the destination node station.

[Operation] The present invention includes a bit string indicating the synchronization state of terminal data in each channel of a fixed frame, detects the synchronization state of terminal data using this bit string, and performs transmission by adjusting to this synchronization state. be.

[Embodiments] Next, specific embodiments of the present invention will be further described with reference to the accompanying drawings.

FIG. 1 shows a terminal interface section of one node station in a loop network. A timing signal ST input from a terminal is taken into a terminal data input circuit 33, and at the same time, a timing signal ST inputted from a terminal is inputted into a lead/lag detection circuit 3.
1 is input.

The ST is sampled by a network synchronization clock 32 obtained from a high-speed transmission lock on the loop to detect a lead or lag state.

At this time, the 'advanced' and 'delayed' states mean, for example, that when the network clock and the data timing ST from the terminal are synchronized, the network synchronization clock 32 samples the data 16 times, and 15 When it comes to times, it's a ``delayed state'',
When the number of times is 17, it is assumed to be an "advanced state".

The states of the timing signal from the terminal obtained in this way are '01''' in the leading state and 111Q I in the delayed state.
+, the synchronization status is encoded as '11' and sent out on the loop along with the information bit in channel 41 as shown in FIG.

The receiving node station on the loop receives this 11 channel, and depending on the lead or lag state of the previous timing signal, it operates in the completely opposite way (in the synchronized state, 1 bit counts 16 times) using the same network synchronization clock as the transmitter. , in the advanced state, 1 bit counts 17) and sends it to the terminal.

[Effects of the Invention] According to the present invention as described above, data based on timing signals supplied from outside the loop network can be transmitted, thereby making it possible to connect between loop networks, and also facilitating modem connection. Therefore, restrictions on transmission via a network are reduced, and it can be used more generally, and its industrial value is extremely large.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram showing a specific embodiment of the present invention, Fig. 2 is an explanatory diagram showing the state of channels used in the present invention, and Fig. 3 is an explanatory diagram showing the frame structure of a circuit switched loop network. FIG. 4 is an explanatory diagram showing the state of data transmission in the line-switched Lube network. 11: Transmission frames 21a to 21d: Node station 22: Loop transmission path 23a to 23d: Terminal device 31:
Lead/lag detection circuit 32: Network synchronization clock 33: Terminal data input circuit 34: Channel generation circuit 41: Channel light

Claims (1)

[Claims] (1) In a loop network in which each node station that performs data input/output control with a terminal device is sequentially connected with a transmission line to form a ring, a fixed frame that goes around the loop at a constant speed is composed of multiple channels. ,
Each channel includes a bit string of at least one bit indicating the synchronization state of data of a terminal connected to the source node station, and the source node station detects the advance or lag status of data input from the terminal. In addition, a circuit-switched loop network is characterized in that a destination node station controls the advance and delay of data output to a terminal.