JPH0748756B2 - Link layer control method - Google Patents

Description

The present invention relates to a data transmission protocol between nodes by CCITT N
o.7 Regarding data transmission that adopts a transmission method that conforms to the common line signaling method.

2. Description of the Related Art CCITT Recommendation does not stipulate the fill-in signal (FISU) transmission cycle, which is the most important feature of CCITT No.7 signaling. When there is no message signal to send, FISU should always be sent in the sense that it fills the line from the original meaning of the fill-in signal, but in the past, the capacity of the buffer memory installed on the receiving side and the processing capacity of the processor Has agreed in advance between the nodes so that they will be sent out at a certain fixed period.

Problems to be Solved by the Invention For example, when connecting CCITT No. 7 links between different systems, one side always sends FISU, and the other side assumes that transmission and reception are performed at a fixed cycle. There is a drawback that the hardware must be modified so as to increase the capacity of the buffer memory more than necessary, the processing overhead increases, and the signal processing capability significantly decreases.

The present invention has been made to solve the above-mentioned drawbacks inherent in the prior art. Therefore, the object of the present invention is to transition from the partner station verification end waiting state to the operating state at the time of state transition at link startup. When waiting for verification, the FISU reception cycle from the partner station is measured while waiting for the verification of the partner station, and subsequent FISU is measured at that cycle.
The purpose of the present invention is to provide a new link layer control method that enables connection even when connecting to different systems by transmitting, regardless of the implementation status of the other side.

Means for Solving the Problems In order to achieve the above object, the link layer control method according to the present invention makes a link layer protocol between two or more nodes conform to CCITT recommendation No. 7 signaling method. In the data transfer system performed as described above, means for detecting the reception cycle of the fill-in signal from the partner node, means for transitioning to the operating state after detecting the reception cycle, and subsequent fill-in signal transmission cycle at the same cycle as the reception cycle. And means for transmitting.

Embodiment Next, the present invention will be specifically described with reference to the drawings with respect to a preferred embodiment thereof.

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a flow chart showing the operation of the present invention.

Referring to FIG. 1, an embodiment of the present invention includes a URT circuit 12 connected to a line 11, a DMA circuit 13, and a buffer memory 14 for storing a signal (data) received from the line 11.
A processor 15 for controlling these circuits according to a microprogram stored in a ROM 16 and a processor bus 17 are connected to the processor bus 17. Further, the timer 18 is also connected to the bus 17.

Next, the operation of the present invention will be described in detail with reference to the drawings (FIGS. 1 and 2).

The signal (data) received from the line 11 is serial-parallel converted by the URT12 and output in units of 1 octet.
It is stored in the buffer memory 14 via the DMA 13. When reception of one frame is completed, the URT 12 interrupts the processor 15. The processor 15 uses the LI in the buffer memory 14
The field is checked. If LI = 0, it is determined that FISU has been received, the internal flag is turned “ON”, the timer 18 is started, and the next one frame is waited for. Then, if the next received frame is also FISU, the timing during this time is read from the timer 18.

The value is used as the timing of the subsequent FISU transmission cycle on the transmission side.

EFFECTS OF THE INVENTION As described above, according to the present invention, the FISU of the partner node
By autonomously determining the transmission cycle of the FISU in the link layer control according to the implementation status of transmission / reception, it is possible to easily face a completely different system.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG.
The figure is a flow chart when the method of the present invention is applied. 11 …… line, 12 …… URT circuit, 13 …… DMA circuit, 14 …… buffer memory, 15 …… processor, 16 …… ROM, 17 ……
Processor bus, 18 ... Timer

Claims (1)

[Claims] 1. A data transfer system for performing a link layer protocol between two or more nodes according to CCITT Recommendation No. 7 signaling system, and means for detecting a reception cycle of a fill-in signal from a partner node. A link layer control method comprising: a means for transitioning to an operating state after detecting a reception cycle; and a means for transmitting a subsequent fill-in signal transmission cycle in the same cycle as the reception cycle.