JPH05199226A - Communication system - Google Patents

Abstract

PURPOSE:To enable communication by using a group address at a terminal housed in a branched LAN by merging the address of a received packet with the information part of an individual address retrieved from a table when it is the group address, and transmitting the packet to the terminal at the destination. CONSTITUTION:The packet from the terminal is received by a node. When this packet is received, a branched LAN interface(IF) part 9 of the node informs it of a temporary storage control part 7. When a storage part 13 enables storage, the control part 7 informs this state of the IF 9. The IF 9 separates the received packet into a header part and the information part and stores them in the storage part 13. An operation part 11 receives receiving information from the control part 7, reads the header part, informs the group address(GA) of a processor 1 and requests the presentation of information. The processor 1 retrieves the individual addresses of nodes on a trunk line LAN corresponding to this GA and the total number of them from a table 3, transmits them to the operation part 11 and copies the header. Then, the individual address is added to this packet, the packet is transmitted to the other node, converted to the original GA and transmitted to the terminal at the destination.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication system such as a local area network (LAN).

[0002]

2. Description of the Related Art Generally, a high-speed LAN (Local Area Network)
The work local area network) rarely directly accommodates and operates terminals, and has a hierarchical structure in which a plurality of medium and low speed LANs are accommodated and the medium and low speed LANs accommodate terminals.

In such a LAN, when each terminal communicates with an individual address (an address designating one node by one address), the address accommodates the terminal or the terminal at any stage of the hierarchical structure. Uniquely indicates the node to be used. There are also national / international organizations that manage addresses.

In such a LAN, terminals are group addresses (addresses that specify multiple nodes with one address)
When communicating using, it is difficult to guarantee normal communication,
Since there is no management organization such as an individual address, problems such as duplication of addresses and erroneous allocation are likely to occur, making detection difficult.

FIG. 4 shows a schematic configuration of such a LAN. In the trunk LAN 100, nodes ND1 and ND are provided.
2, ... NDn are connected by a transmission line t. A branch line LAN is connected to each node. For example, the branch line LAN 131 is connected to the node ND3. The terminals T311, T312, ... T31i are connected to the branch LAN 131.

In such a LAN, a branch line LAN
The terminal T312 accommodated in 131 is the branch line LAN1.
When a packet in which the group address to which the terminals T411 and T412 accommodated in No. 41 belong is designated as the destination, on the trunk LAN 100, the trunk LAN 10
The individual address from the node ND3 on node 0 to the node ND4 may be designated. However, the terminal T312 is connected to the terminal T411 and the terminal Tn accommodated in the branch line LAN1n1.
When a packet in which the group address to which 11 belongs is designated as the destination is transmitted, there is no method for designating the group address of the branch LAN on the trunk LAN 100 as the address of the node of the trunk LAN 100, so the branch LAN
Prohibit the use of group addresses on the main LAN1
In reality, the broadcast address of 00 (an address that specifies all nodes by one address) must be transmitted to all the nodes on the trunk line.

The group address of the branch line LAN is the main line LA
The problem with the method realized by the broadcast address of N is that in the above-mentioned example, a packet which only the nodes ND4 and NDn on the trunk LAN need to receive is received by a node such as the node ND1 which is not originally required to receive. Is to end up.
As described above, in a system in which the terminal communicates using the group address and the trunk LAN corresponds to the broadcast address, the number of broadcast packets on the trunk LAN increases, and a node such as the node ND1 discards the received packet. Since the processing is frequently performed, there is a high possibility of causing a substantial decrease in communication traffic, the occurrence of packets exceeding the processing capability, a phenomenon called a broadcast storm, and the like.

[0008]

As described above, the branch line LA is
In order to replace the packet using the N group address as the destination with the packet using the broadcast address as the destination,
There is a problem in that the occurrence of a failure is induced due to an increase in the number of packets that use broadcast addresses on the trunk LAN.

Further, when transmitting from the terminal, it is necessary to limit the use of the group address, there is a difference in address form such as a difference in address length between the branch LAN and the trunk LAN, or there is already allocation in the trunk LAN. There is also a problem that the terminal may use the same address as the group address.

The present invention has been made in view of the above problems, and an object thereof is to use a group address by a terminal accommodated in a branch line LAN without using a packet using a broadcast address. It is to provide a communication system capable of performing communication by performing the communication.

[0011]

In order to achieve the above-mentioned object, the present invention provides a trunk LAN in which a plurality of nodes are connected by a transmission line, and a branch line LAN having a plurality of terminals and connected to the node. In the communication system including, the node separates a table showing correspondence between a group address on the branch LAN and an individual address of a trunk node, and a packet transmitted from the terminal into a header part having the address and an information part. Means, when the address is the group address, a corresponding individual address is searched from the table, the individual address and the information section are combined and transmitted, and the individual address obtained by converting the group address is used. When it receives a packet sent from another node, it converts it to the original group address, adds an information section, and Means for sending a communication system including a.

[0012]

According to the present invention, when a node receives a packet transmitted from a certain terminal and the address is a group address, the corresponding individual address is searched from the table, and this individual address and the information section are combined. When the packet is sent to the destination node, and the destination node receives the transmitted packet with the group address converted individual address, it converts it to a group address and adds the information part to this group address Send to the terminal.

[0013]

Embodiments of the present invention will now be described in detail with reference to the drawings.

The structure of the LAN according to this embodiment is similar to that shown in FIG.

FIG. 1 is a block diagram showing a schematic configuration of a node (eg, node ND1) in FIG.

The node processor and the peripheral circuit 1 are composed of a node processor for controlling a node and a peripheral circuit for controlling an interrupt and the like.

The address correspondence table 3 shows the relationship between the group address on the branch line LAN and the individual address on the trunk line LAN.

FIG. 2 shows this address correspondence table. For example, when the group address on the branch LAN is “11001010”, this indicates ND4 and NDn as individual addresses on the trunk LAN.

The trunk line LAN interface section 5 includes a trunk line L.
It has a transmitting / receiving unit for transmitting / receiving packets to / from the AN, a sorting unit for separating a frame into a header unit and an information unit, a circuit for transferring data with the temporary storage control unit 7, and the like.

The temporary storage control unit 7 includes a trunk LAN and a branch line L.
An arbitration circuit that arbitrates contention when the AN, the header operation unit 11, and the node processor 1 access the packet holding temporary storage unit 13, generation of an address to the packet holding temporary storage unit 13, and generation of a write / read signal. It has a circuit and so on.

The branch line LAN interface section 9 has a branch line L.
It has a transmission / reception section for transmitting / receiving packets to / from the AN, a sorting section for separating the frame into a header section and an information section, a circuit for transferring data between the temporary storage control section 7, and the like.

The header operation unit 11 detects whether or not the packet uses a group address, and in the case of a packet using a group address, transfers information to and from the node processor 1 and, according to the information, stores the header section. Copy,
Rewrite the address. The packet holding temporary storage unit 13 has a packet holding memory and the like. Code 15
Indicates a data bus.

Next, the operation of this embodiment will be described.
Here, the terminal T31 accommodated in the branch line LAN 131
2 to terminal T421 accommodated in branch line LAN 142
Then, consider a case where a packet is transmitted using a group address including the terminal Tn11 accommodated in the branch line LAN1n1 as a destination address. This group address is, for example, "11001010".

When the packet is transmitted from the terminal T312, the node ND3 receives the packet. Node N
Upon receiving this packet, the branch LAN interface unit 9 of D3 notifies the temporary storage control unit 7 that the packet will be received in the temporary storage unit 13 for holding packets. The temporary storage control unit 7 checks that there is a receivable area in the packet holding temporary storage unit 13, and if possible, notifies the branch line LAN interface unit 9 of this.

The branch line LAN interface unit 9 stores the received packet in the packet holding temporary storage unit 13 as shown in FIG.
As shown in (3), the header section 301 and the information section 302 are separated and stored separately. After that, the branch line LAN interface unit 9 notifies the node processor 1 of reception.

The header operating unit 11 also receives the received information from the temporary storage control unit 7, reads the header portion of the frame, and confirms whether or not it is a group address. In this case, since "11001010" is the group address, the node processor 1 is notified and requested to provide information.

The node processor 1 searches the address correspondence table 3 for the individual address of the node on the trunk LAN corresponding to this group address and the total number thereof, and notifies the header operation unit 11 of it. In this case, since the group address is "11001010", ND4, NDn and the total number "2" of them are read from the address correspondence table 3 as individual addresses.

The header operating unit 11 is the node processor 1
From the total number of data sent from (in this case, "2"),
Copy the header part for the total number. That is, FIG. 3 (b)
As shown in (2), two separated header sections 301a and 302b are copied in the packet holding temporary storage section 13. In this case, the information section is not copied. Since the information part is not copied and only a plurality of header parts are copied, it is possible to suppress an increase in memory capacity. Incidentally, FIG. 3B shows a case where n header parts are copied.

Further, information on the individual address sent from the node processor 1 (in this case, ND1 and NDn)
Is added to the header part, and if necessary, information indicating that the packet uses a group address,
Information for regrouping is added to the group address.

After the operation is completed, the header operation section 11 notifies the node processor 1 of the completion. Upon receiving this notification, the node processor 1 issues a transmission request signal to the trunk LAN interface unit 5. Upon receiving the transmission request signal, the trunk LAN interface unit 5 receives the transmission data, and thus makes an access request to the packet holding temporary storage unit 13. That is, the header part and the information part are sequentially read, assembled into packets, and transmitted to the trunk LAN. In this case, the first header section 301a and the information section 302 are combined and assembled into a packet, and the second header section 301b and the information section 302 are combined and assembled into a packet and transmitted.

Node NDn which is one of the receiving nodes
Then, the packet using the individual address is received from the trunk LAN interface unit 5 and expanded in the packet holding temporary storage unit 13. After that, if you read the information indicating that the packet used the group address,
The node processor 1 and the header operation unit 11 use the procedure for reassembling into a group address in the reverse procedure of the node on the transmission side, and based on the information for reassembling to a group address, a packet using an individual address of the trunk LAN is used to determine a group address of the branch LAN. The used packet is reassembled and the transmission request processing is performed on the branch LAN interface unit 9.

The branch LAN interface unit 9 is
The reassembled packet is transmitted to the branch line LAN 1n1, and this packet is received by the terminal Tn11.

Similarly, the packet is received also at the node ND4 which is one of the receiving side nodes, transmitted to the branch line LAN 142 by the same procedure, and received at the terminal T421.

Thus, according to the present embodiment, it is possible to perform communication using the group address from the terminal accommodated in the branch line LAN without using the broadcast address. Further, it is possible to perform packet communication using the group address of the trunk LAN without considering the duplication with the group address of the branch LAN.

In this embodiment, the node processor 1 and the header operating unit 11 are different, but the header operating unit 1
1 function can be achieved by the software of the node processor 1.

[0036]

As described in detail above, according to the present invention, a terminal accommodated in a branch LAN can communicate using a group address without using a packet using a broadcast address. it can.

[Brief description of drawings]

FIG. 1 is a block diagram showing the configuration of a node

FIG. 2 is a diagram showing an address correspondence table.

FIG. 3 is a diagram showing storage of data in a packet storage temporary storage unit 13.

FIG. 4 is a diagram showing a schematic configuration of a LAN.

[Explanation of symbols]

 1 ... Node processor and peripheral circuit 3 ... Address correspondence table 5 ... Main line LAN interface 7 ... Temporary storage controller 9 ... Branch line LAN interface 11 ... Header operation unit 13 ... ... Temporary storage for packet storage

Claims (1)

[Claims] 1. A trunk LAN in which a plurality of nodes are connected by a transmission line, and a branch LAN having a plurality of terminals and connected to the node
In the communication system having :, the node has a table showing a correspondence between a group address on the branch LAN and an individual address of a trunk node, and a packet sent from the terminal in a header part having an address and an information part. Means for separating, means for searching the corresponding individual address from the table when the address is the group address, means for combining the individual address and the information part and transmitting, and an individual address for which the group address is converted When the packet transmitted from another node is received, the means for converting the original group address, adding the information part and transmitting the packet to the terminal.