JP2962903B2 - New station invitation system in LAN - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a new station invitation system in a LAN.

[0002]

2. Description of the Related Art As an access control method in a LAN, a CSMA method, a token passing method and the like are known. The token passing method is an access control method in which transmission right information called a token is cyclically delivered to each station, and only the station that has received the token can obtain the right to transmit data. Note that there are a method of delivering tokens to a lower station in the transmission direction in order, a method of determining the order of delivery in advance in consideration of a priority order, and the like.

FIG. 5 shows a token-passing LAN.
FIG. 4 is an explanatory diagram of a conventional new station invitation system in FIG. here,
Stations 0, 2, 4, and 6 are link stations that have already joined the logical ring, and stations 1, 3, 5, and 7 are new stations that have not joined the logical ring. The solid arrows in FIG. 5 indicate the token transfer direction. In this example, the tokens are sequentially transferred from the lower stations in the transmission direction, for example, from station 0 to station 2 and from station 2 to station 4.

In FIG. 5, in the token holding station, the station number of the new station is such that the station number of the token holding station <the station number of the new station <the station number of the following station or the station number of the token holding station> the station number of the new station> the station number of the following station In such a case, it is determined that a new station exists between the own station and the succeeding station, and a new station is invited.

The timing at which each link station starts the solicitation operation is determined by a solicitation counter (not shown) of each link station.
Is controlled by A random initial value is set in the invitation counter at the time of initializing, and the value of the invitation counter is decremented every time the link station receives a token. Then, when the value of the invitation counter becomes “0”, an invitation operation for a new station is performed in the corresponding link station. Further, each link station performs a solicitation operation when the value of the counter becomes “0”, and then sets a random initial value again in the solicitation counter.

[0006]

In the above-mentioned method, each link station performs a solicitation operation at a random token period, that is, each time the value of the solicitation counter of its own station becomes "0", so that the token makes one cycle. There is a possibility that a plurality of link stations perform the solicitation operation in the meantime.

Since it takes a certain processing time to invite a link station to a new station and to respond to the invitation by the new station, a certain processing time is required.
If a solicitation operation is performed at a plurality of link stations during one cycle of the token, the token circulation time becomes longer. Therefore, in a system in which it is necessary to secure an accurate data refresh cycle, a delay in the token circulation time becomes a problem.

SUMMARY OF THE INVENTION It is an object of the present invention to reduce the delay of the token circulation time and to enable each link station to uniformly invite a new station.

[0009]

FIG. 1 is a diagram illustrating the principle of the first invention. In the figure, the determination means 1 determines whether or not the token has made one or more rounds of the logical ring after performing a solicitation operation for a new station to which the local station intends to join the logical ring.

When the determining means 1 determines that the token has completed one or more rounds, the soliciting station designating means 2 adds solicitation right holding station information for designating a subsequent station as the next solicitation right holding station to the token frame and sends it out. I do. The token frame includes, for example, a token pass destination station number indicating a destination station number to which a token is to be transferred, a source station number, and invitation right holding station information indicating the next invitation right holding station number.

In the second invention, after the solicitation operation, the solicitation right holding station information for designating the preceding station from which the token is transmitted as the next solicitation right holding station is added to the token frame, and the solicitation right is given to the preceding station. hand over.

[0012]

According to the first aspect, the station designated by the invitation right holding station information of the token frame obtains the invitation right, and only the station which has obtained the invitation right performs the operation of soliciting a new station. Then, after performing the solicitation operation, the station that has obtained the solicitation right passes the solicitation right to the next station when the token makes one or more rounds of the logical ring.

Further, in the second invention, after the solicitation operation is performed, the solicitation right is passed to the preceding station of the token transmission source. Not done.

Therefore, in the first invention, the number of stations performing the solicitation operation during the cycle of the token is limited to one station, and in the second invention, the number of stations performing the solicitation operation during the cycle of the token is maximum. Since the number of stations is limited to two, the token circulation time does not become longer than an expected fixed time, and no problem occurs even when it is necessary to guarantee an accurate data refresh cycle. Also, since the solicitation right is sequentially passed to the succeeding station or the preceding station, the solicitation right can be equally given to each station.

[0015]

Embodiments of the present invention will be described below with reference to the drawings. The following embodiment shows a case where the new station invitation system of the present invention is applied to a token passing LAN.

FIG. 2 is a frame format diagram of a token frame based on the new station invitation system of the present invention. FIG.
As shown in (1), the token frame includes a token pass destination station number indicating the next token holding station, a source station number, and invitation right holding station information designating the next invitation right holding station.

Next, the new station invitation system according to the first embodiment of the present invention, in which the preceding station passes the invitation right together with the token to the succeeding station, is shown in FIG.
This will be described with reference to FIG. Now, when the stations 1, 2, 4, and 5 have joined the logical ring, the station 2 to which the invitation has been granted exists between the own station and the subsequent station 4. An operation for inviting the deaf station 3 to join a logical ring (link) will be described.

The station 2 analyzes the token pass destination station number and the invitation right holding station information of the token frame 1 transmitted from the station 1 (arrow in FIG. 3) and determines that the own station serves as the token holding station and the invitation right holding station. If it recognizes that it is designated, if there is data that needs to be transmitted, the data is sent out to the network, and the new station 3 that may exist between the own station and the succeeding station 4 is sent to the new station 3. A solicitation operation is performed (arrow in FIG. 3). Further, the station 2 stores that the invitation operation has been performed once.

As a result of the invitation operation, if there is no new station that wants to newly join the logical ring, the station 2 designates the succeeding station 4 as the token holding station, and further sets itself as the invitation right holding station. The invitation right holding station information designating the station is added to the token frame 2, and the token frame 2 is transmitted to the subsequent station 4 (arrow in FIG. 3).

The station 4 analyzes the token pass destination station number and the invitation right holding station information of the token frame 2 received from the station 2, and designates itself as a token holding station and another station as an invitation right holding station. If it is recognized that there is data to be transmitted, the data is transmitted to the network, and the same information as the received invitation right holding station information is set in the token frame without performing the invitation operation. Further, the station number of the succeeding station 5 is set to the token pass destination station number of the token frame and transmitted to the station 5 (arrow 'in FIG. 3).

Similarly, the stations 5 and 1 analyze the token frame received from the preceding station (in this case, the station 4 or the station 5), specify their own station as the token station, and hold the invitation right holding station. , The same information as the received invitation right holding station information is set in the token frame without performing the invitation operation, and the token is passed to the subsequent station.

In this way, if the station 1 receives the invitation right holding station information designating the own station, that is, the station 2 as the invitation right holding station, the station 2 has already performed the invitation operation. It is determined that the token has made one round between the link stations subscribing to the logical ring. In this case, the station 2 does not perform the invitation operation, sets the station number of the succeeding station 4 in the invitation right holding station information of the token frame 3, and passes the invitation right and the token to the succeeding station 4 (see FIG. 3). Arrow).

In this embodiment, the station which has received the solicitation right from the preceding station performs the solicitation operation, stores that the solicitation operation has been performed once, and stores the token number in which its own station number is set as the solicitation right holding station information. Send the frame to the subsequent station. Then, when receiving the token frame designating the own station as the invitation right holding station again, the invitation station passes the invitation right to the succeeding station.

Therefore, in the present system, the number of stations that invite a token during one round is limited to one station, so that a plurality of stations randomly perform an invite operation as in the prior art, and the token circulation time becomes longer. There is nothing. Therefore, even in a system that needs to refresh data at regular time intervals, a new station can be invited without any trouble by the new station invitation method of the present embodiment.

Although FIG. 3 shows a LAN having a ring configuration, it may be a bus or star LAN. Next, a second embodiment of the present invention for transferring an invitation right to a preceding station will be described with reference to FIG. The format of the token frame of the second embodiment is the same as the format shown in FIG.

If the invitation right holding station information of the token frame 1 (token frame 1 in FIG. 4) transmitted from the preceding station 1 matches the station number of the own station (station 2), the station 2 becomes the own station. New station 3 that will exist between the new station and the subsequent station 4
(The arrow in FIG. 4).

If there is no new station between the own station and the succeeding station 4, the subsequent station 4 is set as the token pass destination station number.
Of the preceding station as the next invitation right holding station.
Is set in the invitation right holding station information of the token frame 2 and transmitted to the succeeding station 4 (arrow in FIG. 4).

When the station 4 receives the token frame 2 from the station 2, the station 4 analyzes the token pass destination station number and the invitation right holding station information in the token frame 2, and the token station is the station itself and holds the invitation right. If the station recognizes that it is not its own station, it sends the data to the network if there is data to be transmitted, and does not perform the invitation operation of the new station, but transmits the same information as the received invitation right holding station information. Set in the token frame. Further, the station number of the succeeding station 5 is set as the token pass destination station number and transmitted to the station 5.

In the same manner, in the station 5, the same information as the received invitation right holding station information is set in the token frame and transmitted to the station 1. When receiving the token frame from the station 5, the station 1 analyzes the invitation right holding station information of the token frame, and if the invitation right holding station information matches the station number of the own station, performs an operation of soliciting a new station. At this time, if there is no new station between the own station and the station 2, the station number of the succeeding station 2 is set as the token pass destination station number of the token frame 3, and
The station number of the station 5 which is the preceding station of the station 1 is set as the invitation right holding station information and transmitted to the station 2 which is the succeeding station (arrow in FIG. 4).

Thereafter, the above operation is repeated at each link station. In this case, since the station 5 is designated as the invitation right holding station, the stations 2 and 4 do not perform the invitation operation, and the station 5 does not perform the invitation operation.
The solicitation operation is performed only when the token is passed to.

In the second embodiment, the station having the token passes the token to the succeeding station, and the station having the invitation right designates the preceding station as the next invitation right holding station. 2 stations that perform solicitation during
It can be restricted to stations below.

Therefore, unlike the related art, many stations do not perform an invitation operation while the token makes one round, and it is possible to prevent the token rounding time from becoming longer than a certain time. Also,
Since the solicitation right is sequentially given to the preceding stations, each station can perform the solicitation operation equally.

The new station invitation system of the present invention is not limited to the token passing LAN, but may be applied to other access LANs as long as at least the invitation right is cyclically transferred to each link station.

[0034]

According to the present invention, it is possible to limit the number of soliciting stations to one or two while the token makes one round.
The token patrol time can be kept within a certain time. In addition, each station can be given an opportunity to perform a solicitation operation equally.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating the principle of the present invention.

FIG. 2 is a format diagram of a token frame according to the embodiment.

FIG. 3 is an explanatory diagram of a new station invitation method according to the first embodiment.

FIG. 4 is an explanatory diagram of a new station invitation system according to a second embodiment.

FIG. 5 is an explanatory diagram of a conventional new station invitation system.

[Explanation of symbols]

 1 Judgment means 2 Solicitation station designation means

Claims (2)

(57) [Claims] 1. A station which has already subscribed to a LAN logical ring performs a solicitation operation for a station to be newly subscribed.
In the AN, a determination unit (1) that determines whether or not the token has made one or more rounds of the logical ring after performing a solicitation operation for a new station that the local station intends to join the logical ring; When it is determined in 1) that the token has completed one or more rounds, there is provided a solicitation station designating means (2) for adding solicitation right holding station information for designating a succeeding station as the next invitation right holding station to the token frame and sending it out. LAN characterized by
New station recruitment method in. 2. A station which has already subscribed to a LAN logical ring performs an invitation operation to a station to be newly subscribed.
In the AN, after the station granted the solicitation right performs an invitation operation to a new station that intends to join the logical ring, the solicitation that designates the preceding station that is the token transmission source as the next invitation right holding station in the token frame. A new station solicitation method in a LAN, characterized by adding rights holding station information and passing an invitation right to a preceding station.