JPH0828734B2 - Data transfer control method for slotted loop network - Google Patents

Description

TECHNICAL FIELD The present invention relates to data transfer control of a loop network in which a transmission path is divided into slots.

(Prior Art) A fixed-length ATM (Asynchronous Trunk) that divides all user information into fixed-length cells and transfers them as a communication method for uniformly handling multimedia information in a broadband network.
ansfer Mode) is attracting attention, and the IEEE802.6 committee is considering a network using a pair of unidirectional buses.

(Problems to be Solved by the Invention) However, this network has a problem in that nodes closer to both ends of the bus have unfair transmission opportunities. On the other hand, a slotted ring network is being considered as a network that does not cause unfairness. In this network, it is necessary to remove the slot signal sent to the loop from the loop. This is done by the transmitting side node or the receiving side node using the address information in the slot. Therefore, information for identifying the node is required in the header of the slot. In the fixed-length ATM currently under study, the logical channel number VCI (Vir (Vir) is used as the address information in the header information.
There is only a tual Channel Identifier). This VCI is set for each call and changes dynamically, unlike the address used on the LAN. Therefore, performing removal control from the loop by using this causes complication of processing.

Also, there are various types of address information within a slot and address information of a data frame before being divided into slots, and performing removal control using these address information means that the transfer control units are designed according to the address system. However, there is a problem that the versatility is lacking.

It is an object of the present invention to provide a slot type loop network in which removal control of a transmission slot from a transmission line can be performed without using address information in a slot or VCI, and further, address information of a data frame before being divided into slots.

(Operation) In the data transfer control method of the slot type loop network according to the present invention, the loop transmission line is divided into fixed length slots having a header section and a data transfer section, and whether or not the transmission of a signal is completed is determined by the header section. The node that has acquired the transmission right, while assigning the identification bit shown, sets the loop transmission path to the signal removal state, sets the recognition bit corresponding to the end of the transmission, and sets the recognition bit indicating the end of the transmission that makes a loop in the loop transmission path. When received, the loop transmission line is restored from the signal removed state to the signal passing state.

As described above, the address information or the like is not used for transfer control.

(Embodiment) FIG. 1 is a diagram showing a slotted signal on a loop transmission line. A VCI and an end recognition bit indicating the end of transmission are added to the header of the slot. User data is transferred using the data transfer unit. The data transfer control of the present invention relates to the removal of the transmission slot from the loop transmission line and does not depend on the transmission right acquisition method.

FIG. 2 shows a loop network in which a plurality of nodes 2, 3, 4, 5 are connected by a loop 1.

FIG. 3 is a diagram showing the function of the end identifier. Now, assume that signals of 2 slots and 3 slots are transmitted from the nodes 2 and 3, respectively. A value 1 indicating the end is set in the end identifier for the last slot transmitted. (Shown in black in the figure).

FIG. 4 shows a loop interface for transfer control of each node. The slot on the loop 1 is separated by a separation circuit 21 into a header and a data transfer unit. In the figure, only the end identifier of the header information is shown. The data transfer unit is supplied to the switch 27 and further supplied to the multiplexing circuit 22. The multiplexing circuit 22 inputs the end identifier supplied through the gates 24 and 25, reconfigures it into the original slot, and sends it to the loop 1. When the control circuit 26 performs token control by another implementation means and acquires the transmission right, the switch 27 connects the switch 27 to the transmission buffer 23 side and transmits the transmission. At the same time, the control output 26-1 is set to 0 to prohibit passage of the end identifier from the upstream, the control output 26-2 is set to 1 for the last transmission slot, and 2-62 is set to 0 for the other transmission slots. To do.
As a result, only the end identifier of the final transmission slot is set to 1. The control circuit 26 monitors the termination identifier transmitted through the separation circuit 21, and when it receives a 1 indicating the end of transmission, it connects the switch 27 to the output side of the separation circuit 27 from the next slot. As a result, the switch 27 is removed from the loop in this node for the period in which the switch 27 is connected to the transmission buffer 23, that is, until the slot having the end identifier of 1 which is first received after starting transmission.

FIG. 5 is a diagram showing the flow of removal control. In the same figure, (a), (b), (c), and (d) are node 2 respectively.
Input signal, output signal, input signal of node 3, and output signal. In the figure, the hatched slots indicate the final transmission slots. First, the node 2 transmits 3 slots. Next, the case where the node 3 acquires the transmission right and transmits four slots is shown. The node 2 performs the removal control from the transmission of the first slot in FIG. 7B to the reception of the final transmission slot shown in FIG. 7A (time T2), and restores the switch 27 from the next slot. Similarly, node 3 performs removal control during time T2. As described above, the transmission slot can be removed from the loop at the source node without using the VCI, address information, etc. in the slot. In FIG. 1, the VCI is written in the slot header, but this is to clarify that the present invention does not use the VCI. It is not limited to the network that the user has.

(Effect of the Invention) Since the address information in the slot header or the address information of the data frame before being divided into slots is not used for the transfer control, highly versatile data transfer control independent of the configuration of the slot or the data frame is performed. Can be provided.

[Brief description of drawings]

FIG. 1 shows a structure of a transmission frame of a loop network according to the present invention, FIG. 2 shows a structure of a loop network, FIG. 3 shows a signal flow on a transmission line, and FIG. 4 shows an embodiment of the present invention. FIG. 5 is a diagram showing the operation of the present invention. In the figure, 1 is a physical loop, 2, 3, 4, and 5 are nodes, 21 is a separation circuit, 22 is a multiplexing circuit, 23 is a transmission buffer,
24 and 25 are gates, and 26 is a control circuit.

Claims (1)

[Claims] 1. A loop transmission line is divided into fixed-length slots each having a header section and a data transfer section, an identification bit indicating whether or not signal transmission is completed is assigned to the header section, and a transmission right is captured. The node sets the loop transmission path to a signal removal state, sets the identification bit corresponding to the end of transmission, and removes the signal from the loop transmission path when receiving the identification bit indicating the end of transmission after making a loop in the loop transmission path. A data transfer method for a slotted loop network, which recovers from a state to a signal passing state.