JP2533591B2 - Network expansion method - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a configuration control method in a communication network having a transmission right control function, and in particular, a plurality of networks are combined to form one larger network. The present invention relates to a network expansion method suitable for the case.

[Conventional technology]

As a conventional network expansion method, for example, Japanese Patent Laid-Open No.
59-50639, JP-A-60-120633, or JP-A-58.
The method described in 197940 is known. However, the methods described in these publications are aimed at detection of failure recovery in a network, and no consideration is given to, for example, connecting a normal network and expanding the scale. . That is, when a plurality of normal (meaning that the network is operating normally) networks are unconditionally combined, the data flowing in each network is destroyed. Has not been revealed in.

[Problems to be solved by the invention]

The prior art does not take into consideration the fact that a plurality of normal networks are connected, and thus there is a problem that data being transferred through the networks is destroyed at the time of connection.
In other words, if the data is combined while being transferred, the data is destroyed due to the disturbance of the signal (eg, carrier wave) resulting from the transmission path switching operation.

An object of the present invention is to prevent data from being destroyed when expanding a network, that is, combining a plurality of normal sub-networks.

[Means for solving problems]

According to the present invention, the above object is achieved by temporarily suspending the transmission right (token) flowing in each subnetwork to be combined. That is, the configuration control station located at the connection point of the plurality of sub-networks holds the token in each sub-network at the start of the connection operation. When the binding is completed, only one new token is sent to the expanded network. Stations (STs) included in each network cannot send data because the tokens are suspended. In the present invention, since the network is connected while the data transmission from the ST is suppressed, data destruction does not occur.

[Action]

A configuration control station (distributor) that joins multiple sub-networks captures the tokens in each network prior to joining. After the connection is completed, one token is sent to one extended network formed by the connection.
The ST connected to each sub-network cannot transmit unless it receives a token. On the other hand, since the distributor holds the token, no data is flowing on the network at the time of network connection. Therefore, the data sent from the ST will not be destroyed by the network connection.

〔Example〕

 Examples of the present invention will be described below.

FIG. 1 is a block diagram of a ring network in the middle of expansion, FIG. 2 is an internal block diagram of a device (distribution device) having a ring structure control function, and FIG. 3 is a switch state diagram of the distribution device before expanding the ring. , FIG. 4 and FIG. 5 show the operation flow of the distributor.

In FIG. 1, 1 (1-A, ... 1-D) is a distribution device that manages the degeneration and expansion functions of the ring, and 9 (9-A, 9-B) is a communication control mechanism (hereinafter referred to as MAC). , 30 (30−A, 30−
B) is a ring in operation. Note that the communication control mechanism (MAC) 9 includes, for example, the document "Token Ring Access Method and Physic, EE Ring Standard, 802.5, 1985 (Token Ring Access Method and Physic).
al Layer Specifications, IEEE Stndard 802.5 1985)
(ISO / DP8802 / 5) ”is added with a control mechanism that operates according to the protocol. In Fig. 1, the operating ring is 30-
It is divided into two sub-networks A and 30-B, which are states that can occur, for example, at network start-up or failure recovery.

FIG. 2 shows, for example, the first operation in the normal operation (NORMAL) state.
The state of switch 5 in distribution device 1-B in the figure is shown. In FIG. 2, 3 is a dual system transmission line consisting of transmission lines 31 and 32, 5 is a transmission line changeover switch, 8 is a configuration control mechanism, and 9
-A and 9-B are the MACs. In the following description, 31 is the first
The system transmission line and 32 are the second system transmission lines. 33 and 34, 35 and 36
Is a data line between the transmission path 3 and the MAC 9-A, 9-B, and 41 and 42, 43 and 44 are information lines between the MAC 9-A, 9-B and the configuration control mechanism 8. It is a signal line that intersects. The data input from the first transmission line 31 is output to the first transmission line 31 via the MAC 9-A. The data input from the second transmission line 32 is output to the second transmission line 32 via MAC9-B.

FIG. 3 shows a switch state in the distribution device 1-D of FIG. 1, for example, when the distribution device 1 is in the folded state (WRAP). The data input from the first transmission line 31 is output to the second transmission line 32 via the MAC 9-A. Also, the second transmission line
The data input from 32 is output to the first transmission line via MAC9-B. The data input from the first transmission line 31 is output to the second transmission line 32 via MAC9-B, and conversely, the data input from the second transmission line 32 is output to the first transmission line 31 via MAC9-A. However, in the present embodiment, it is not essential to distinguish between them, that is, which MAC the first and second transmission lines are connected to.

FIG. 4 shows an operation flow of the distribution device when expanding the network (ring), particularly the distribution device in the WRAP state,
For example, an operation flow of the configuration control mechanism 8 in 1-A and 1-D in FIG. 1 is shown.

The configuration control mechanism 8 includes a plurality of operation rings, for example, a first operation ring.
When combining 30-A and 30-B in the figure, a timer T _TKN for instructing each MAC 9-A and 9-B to hold the token (step 100) and monitoring the maximum ring 1 round time of the token
Is activated (step 110). Check whether the token hold of each MAC is completed (step 120) or T _TKN has timed out (step 130), and if either condition is satisfied, switch 5 is switched to NORMAL state, ring 30- Connect (expand) A and 30-B (step 14)
0). Next, the token hold state of each MAC is released (step 150), and a new token is sent (step 160).
T _TKN is effective when the token disappears from the ring. The disappearance of the token occurs when noise is generated in the transmission line due to a temporary failure, or when the token is held by the other distributor first because the multiple distributors are operating independently and asynchronously. . If the token cannot be received during the T _TKN period, it can be judged that there is no token in the ring.

Normally, only one token is needed for one ring network. Therefore, when a new token is generated, it is necessary to devise so that there is one token per ring. When a plurality of distribution devices independently and asynchronously perform the above-described control for ring expansion, there is a possibility that a plurality of tokens generated by the plurality of distribution devices will circulate on the same ring. As a countermeasure against this, for example, the token may be transmitted only to the distribution device including the MAC having the maximum address value on the expanded ring. However, various other methods can be applied as to how to determine the only station that performs the token management described above in the network. The point is that after the ring expansion, the token may be sent to a specific station.

FIG. 5 is an operation flowchart of each MAC 9-A, 9-B. According to an instruction from the configuration control mechanism 8, it is checked whether or not the token is in the token holding state (step 200). If the receipt of the token is detected in the token holding state (step 210), the token is held (step 2).
20). Whether the token suspension is released by the T _TKN timeout in the configuration control mechanism 8 (step 200) or the token is released by the token suspension (step 200), the token is received, and the token is suspended. This operation is continued until (step 220).

FIG. 6 shows another embodiment of the present invention. In this example,
The network is composed of distribution devices 1-E to 1-H, and each distribution device is basically the same as that shown in FIG. 2 and the like except that the number of MACs is different. The switch 5 and the configuration control mechanism 8 are omitted for simplifying the drawing. When connecting two or more rings 30-C, 30-D and 30-E, the same procedure as described above may be performed. The distributor located at the joining point of the plurality of rings temporarily holds the tokens flowing through each ring, and then joins the plurality of rings. Expanded 1
Only one token is sent for each ring. Although FIG. 1 shows a dual ring network, the present invention can be applied to networks of other configurations.

In the above embodiments, the ring-shaped network has been described as an example, but the network to which the present invention can be applied does not have to be a ring-shaped network, but may be a bus-shaped network, a star network, or a tree network. In short, any network that operates under the control of the transmission right (corresponding to the token) may be used.

〔The invention's effect〕

As is apparent from the above description, according to the present invention, when a plurality of networks that perform communication by transmission right (token) control are combined, the transmission rights of the networks are temporarily held and then combined. , Data transmission from communication terminals connected to the network is suppressed,
Therefore, there is an effect that the network can be expanded without destroying data.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a network in the middle of expansion to which the present invention is applied, FIGS. 2 and 3 are normal states,
And a diagram showing the state of the switch of the distribution device in the folded state, FIGS. 4 and 5 are flowcharts for explaining the operation of the distribution device when the network is expanded, and FIG. 6 is another network to which the present invention can be applied. It is a figure which shows the structural example. Explanation of reference numerals 1 (1-A to 1-H): distributor, 30: ring transmission line,
5: Switch, 8: Configuration control mechanism, 9 (9-A to 9-B): M
AC

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hiroyuki Wada 1 Horiyamashita, Hadano-shi, Kanagawa Hitachi Ltd. Kanagawa factory (72) Inventor Yoshinori Toji, 1 Horiyamashita, Hadano, Kanagawa Hitachi, Ltd. Kanagawa factory (56) Reference JP-A-62-24747 (JP, A) JP-A-62-8639 (JP, A) JP-B 7-36560 (JP, B2)

Claims (1)

(57) [Claims] 1. A network system in which each sub-network has a plurality of communication stations, and the data transmission of each communication station is performed by transmission right (token) control, which is located at a connection point of the plurality of sub-networks. The control station temporarily holds a token on each network to be combined, and combines a plurality of subnetworks in a state where no token exists on each network to form one extended network. And network expansion method.