JPH0276340A - Node equipment for back bone lan - Google Patents

Abstract

PURPOSE:To miniaturize a table and to shorten retrieval time by providing only address information of a terminal equipment connecting to its own branch line LAN to a node equipment in the node equipment of a back bone LAN where branch line LANs are coupled with the back bone LAN. CONSTITUTION:A node equipment 6 buffers and fetches all frames sent from terminal equipments in its own branch lines. Then a filtering table 7 is retrieved and when the destination of the frame is within its own branch line, the frame is aborted. If not, the frame is sent to the back bone LAN as it is. Moreover, all frames sent by other nodes on the back bone LAN 2 are buffered and fetched. Then the filtering table 7 is retrieved and when the destination of the frame is other than its own branch line, the frame is aborted. If the destination is addressed to its own branch line, the frame is sent to its own branch LAN as it is.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a backbone LAN node device having address filtering information.

[Conventional technology]

FIG. 3 shows an example of a conventional system configuration of this type. In the figure, (1) is a branch LAN, (2) is a backbone LAN for connecting branch LANs to expand the scale, and (3) is a backbone LAN for connecting branch LANs to expand the scale.
) connects the branch line L A N (1) to the backbone L A N
(2) is a node device coupled to, (4) is a filtering table, and (5) is a terminal.

The terminal (5) connected to the above branch line LAN (1) can also communicate with terminals within the same branch line LAN, and can also communicate with terminals connected to other branch line LANs via the backbone LAN (2). Can be done. However, node device (3)
buffers and imports frames on the branch LAN (1), and transfers them to the backbone LAN (2).
Regarding the frames above, only those addressed to the station are taken in, and control is performed so that only necessary frames flow on the backbone L A N (2). Also, at this time, the filtering table (4) is necessary for this operation, and all terminals in the system are connected to which branch line LA.
It holds information on whether it is connected to N. In addition, Fig. 4 (a) and (b) show the branch line L A N (1)
and the frame format flowing through the backbone L A N (2), and all frames must have this format. In the figure, (DAb) is the destination address field of the terminal, (SAb) is the source address field of the node device, (CRCb), (CRC,)
is the error check code for each frame.

Next, an example of the operation of the node device (3) based on the above configuration will be described with reference to FIGS. 5(a) and 5(b). Figure 5(a)
is an operation when receiving a branch line frame, and the node device (3) buffers and captures all frames transmitted by terminals within its own branch line (551). Next, the filtering table is searched (552), and if the destination of the frame is within the own branch line, it is discarded (S53.554). If not, check to which node device the frame should be sent and create the format shown in FIG. 4(b) (S53.555). This frame is the backbone LA
N (556).

Further, FIG. 5(b) shows the operation when receiving a frame on the backbone LAN, and the node device (3)
Destination address field (DA,) of frames on the AN
If the frame is addressed to the local station, it is buffered internally and fetched (S57), and then the frame is transferred to the frame shown in Figure 4 (S57).
a) Convert it into the format shown in (SSa) and send it to your own branch line LAN (559).

In this way, communication between terminals across branch LANs becomes possible, and only necessary frames are sent to the backbone LAN.
It starts to flow over N.

(Problem to be solved by the invention) Since the conventional node device is configured as described above,
As filtering information, a table that corresponds the addresses of all the terminals in the system with the addresses of the node devices is required, which requires a huge number of tables, and it also takes a long time to search, leading to problems such as decreased performance. was there.

The present invention has been made to solve the above-mentioned problems, and an object of the present invention is to obtain a backbone LAN node device that can reduce the amount of table filtering information as much as possible.

(Means for Solving the Problems) A backbone LAN node device according to the present invention is a backbone LAN node device that connects a branch line LAN to the backbone LAN. It incorporates all frames sent by terminals on the branch LAN, refers to the above filtering table, and discards the frame if the destination of the frame is a terminal within the own branch LAN, and if not, sends it to the backbone LAN.
A branch line frame reception function that transmits the above frames as they are to the N, and a branch line frame reception function that internally takes in all frames sent on the backbone LAN and determines whether the destination of the frame is the own branch line LAN by referring to the above filtering table.
It has a backbone reception function that transmits the frame as is if it is a terminal within the network, and discards the frame if it is not.

(Operation) The backbone LAN node device in this invention has the following features:
All frames on the backbone LAN are received and examined, and the frame is sent onto the own branch LAN only if the destination of the frame is a terminal on the own branch LAN.

(Example) Hereinafter, an example of the present invention will be explained using the drawings.
In the figure, (6) is a node device according to the present invention, and (7) is a node device according to the present invention.
) indicates a filtering table that holds only the addresses on the own branch LAN, and the node device (6) is equipped with the filtering table (7) and is connected to the branch LAN as shown in FIGS. 2(a) and 2(b). Incorporates all frames sent by the terminal above and refers to the filtering table above to determine if the destination of the frame is the own branch LAN.
If it is a terminal within the network, it will be discarded, and if not, it will be sent to the backbone LAN as is.The branch frame reception function will internally capture all frames sent to the backbone LAN and use the filtering table described above. Check that the destination of that frame is local branch line L.
If it is a terminal within the AN, it has a backbone reception function that transmits the frame as is, and otherwise discards it. Other numbers are the same as those in FIG.

Further, the frame format according to the present invention is the same on the backbone LAN as on the branch LAN, as shown in FIG. 4(a).

Next, the operation related to the above configuration will be explained based on FIG. 2.

FIG. 2 shows an example of the operation of the node device (6) according to the present invention, and FIG. 2(a) shows an example of the operation when receiving a branch line frame.
, the node device (6) buffers and captures all frames transmitted by terminals within its own branch line (521). Next, the filtering table (7) is searched (522), and if the destination of the frame is within the own branch line, it is discarded (S23.524). If not, this frame is sent as is to the backbone LAN (S23.525).

Also, the second section shows an example of operation when receiving a backbone frame.
In figure (b), the node device (6) is the backbone L
A N (2) Buffers and captures all frames sent by other nodes on the top (526), then searches the filtering table (7) (527) to determine if the destination of the frame is other than the white line. If it is, discard it (528.529), and if it is addressed to the white line, S send this frame as is to the own branch line LAN (52
8.530).

(Effects of the Invention) Therefore, as described above, according to the present invention, the node device only needs to have the address information of the terminals connected to its own branch line LAN, so the table can be small and the search time can be shortened. There is an effect that can be avoided.

[Brief explanation of the drawing]

FIG. 1 is a system configuration diagram according to an embodiment of the present invention, FIGS. 2(a) and 2(b) are flow diagrams showing an example of the operation of the node device of the present invention, and FIG. 3 is a conventional system configuration diagram. Figures 4 (a) and (b) are frame format diagrams, Figure 5 (a)
) and (b) are flow diagrams showing the operation of a conventional node device. (1)...Branch line LAN (2)...Backbone LAN (5)...Terminal (6)...Node device (7)...Filtering table Note that in each figure, the same reference numerals are the same or A considerable portion is shown.

Claims (1)

[Claims] A backbone LAN node device that connects a branch LAN to the backbone LAN is equipped with a filtering table containing only address information of terminals within its own branch LAN, and internally captures all frames transmitted by terminals on the branch LAN. Referring to the above filtering table, if the destination of the frame is a terminal within the own branch LAN, it is discarded, and if not, it is discarded.
A branch line frame reception function that transmits the above frames to the AN as they are, and a function that internally captures all frames sent on the backbone LAN and determines whether the destination of the frame is the own branch line LA by referring to the filtering table above.
A backbone LAN node device characterized in that it has a backbone reception operation function that transmits the frame as it is if it is a terminal within N, and discards it if it is not.