JPS6244737B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a packet add/drop device that selects packets from a plurality of terminals and transmits the packets from the terminals to one subscriber line.

In a system whose purpose is to communicate with a packet switching network or packet terminals using packet terminals, when adding more packet terminals, it is necessary to add one more line to the packet switching network or to It was necessary to install a packet multiplexing device with a function of multiplexing packets from the already accommodated packet terminals and packets from the packet terminal to be added between the switching network and the switching network.

However, in the former case, in order to add a new line, it is necessary to prepare line installation equipment, line transmission modem equipment, etc. In the latter case, introducing a packet multiplexing device not only processes the frame level according to the high-level data link (HDLC) procedure between the packet switching network and the device, but also requires the addition of existing packet terminals. between the packet terminal and the packet switching network and the device.
Packet level processing in accordance with CCITT recommendation X25 is required. Moreover, packet multiplexing equipment is made more economical by accommodating a large number of packet terminals, and even small-scale equipment can accommodate between 16 and 64 terminals, making it economical to accommodate only a few terminals. It is disadvantageous for

Furthermore, when setting a line for priority processing, the former method requires the addition of a new function to the packet switching network, while the latter method requires the addition of a priority processing function to the packet multiplexing device. In either case, there are further disadvantages in addition to the above-mentioned problems.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the above-mentioned drawbacks of the prior art and to provide an apparatus for adding and dropping transmitted and received packets from a plurality of packet lines to a single line.

In order to achieve the above object, the present invention includes a priority first-come-first-served storage circuit that detects reception of packets from priority terminals, stores the packets on a first-come-first-served basis, and outputs the packets on a first-come-first-served basis; A first-come-first-served storage circuit stores multiple packets on a first-come, first-served basis and outputs them on a first-come, first-served basis.When a packet is received from a priority terminal, if the first-come-first-served storage circuit stores a certain number of packets or less, the first-come-first-served storage circuit outputs packets on a first-come, first-served basis. The packets from the priority terminal via the priority first-come-first-served storage circuit are selected in preference to the packets output from the circuit, and on the other hand, if more than a certain number of packets are stored in the first-come-first-served storage circuit, the packets from the priority terminal are selected. A packet selector having a function of queuing packets in a priority first-come-first-served storage circuit, selecting packets output from the first-come-first-served storage circuit until the number of packets in the first-come-first-served storage circuit becomes less than a certain number, and transmitting the selected packets to a line. The present invention provides a packet drop/drop insertion device provided with a circuit.

Embodiments of the present invention will be described below with reference to the drawings.

The figure shows one embodiment of the present invention.
2 is a priority first-come-first-served storage circuit; 3 is a first-come-first-served storage circuit; 4 is a packet selector circuit; 6 is a fixed number priority type packet add/drop device 1
non-priority terminals that are accommodated in and undergo non-priority processing;
7 is a line for selecting received packets from the priority terminal 5 and the non-priority terminal 6 by the packet selector circuit 4 and transmitting the packets, or for receiving the transmission packets to the priority terminal 5 and the non-priority terminal 6. (for example, a subscriber line).

In the above configuration, when a received packet from the priority terminal 5 is received and detected by the priority first-come-first-served storage circuit 2, the detection signal from the priority first-come-first-served storage circuit 2 is sent to the first-come-first-served storage circuit 3 and the packet selector circuit 4. passed to. At this time, if less than a certain number of packets are stored in the first-come-first-served storage circuit 3, the packet selector circuit 4 waits for the end of the packet output from the first-come-first-served storage circuit 3, and then connects the subscriber line 7 and the priority terminal 5. Make preferential logical connections.

On the other hand, if more than a certain number of packets are stored in the first-come, first-served storage circuit 3, the packet selector circuit 4
Even when the packets output from the first-come-first-served storage circuit 3 are finished, the subscriber line 7 and the priority terminal 5 are not logically connected, and the connection is continued until the number of packets in the first-come-first-served storage circuit 3 falls below a certain number. A preferential logical connection is made between the non-priority terminal 6 and the subscriber line 7, and packets from the priority terminal 5 are queued at the priority first-come-first-served storage circuit 2. At this time, if packet transmission is temporarily interrupted between the subscriber line 7 and the priority terminal 5 or between the subscriber line 7 and the non-priority terminal 6, which are logically connected, it means that the logical connection is not established. It becomes possible to insert packet transmission into the above logical connection between the subscriber line 7 and the non-priority terminal 6 or between the subscriber line 7 and the priority terminal 5, and the packet is stored in the storage circuit 2 or 3. Packet insertion is performed to reduce the number of packets being inserted.

Here, the priority first-come-first-served storage circuit 2 and the first-come-first-served storage circuit 3 are memory circuits capable of first-in-first-out (FIFO) input/output, and the packet selector circuit 4 is a memory circuit capable of inputting/outputting first-in-first-out (FIFO). It is a logic circuit that connects the line 7 and can be realized by a combination of a small-scale processing circuit of a microcomputer and a large-scale integrated circuit (LSI) for transmission control.

As mentioned above, when adding a new terminal to the current system, it is necessary to either install a new conventional line or install a packet multiplexer that performs packet multiplexing. Introduction costs cannot be ignored. According to the present invention, by selecting multiple packet accommodating lines, it is only necessary to prepare a simple logic for inserting and transmitting to a single line, and complex transmission control can be performed using several LSIs ( This can be realized using large-scale integrated circuits). Therefore, if the device of the present invention is introduced when a new terminal is added, the cost will be low.

Also, when there is no need to distinguish between priority and non-priority,
This is possible by changing a fixed number of values.

[Brief explanation of the drawing]

The figure shows an embodiment of a fixed number priority type packet add/drop device according to the present invention. 1... fixed number priority type packet add/drop device, 2
. . . priority first-come-first-served storage circuit, 3 . . . first-come-first-served storage circuit, 4 . . . packet selector circuit, 5 .

Claims (1)

[Claims] 1 Select and transmit a first terminal that performs priority processing, a second terminal that performs non-priority processing, and received packets from these first and second terminals, and receive packets that should be transmitted to the terminals. In the device accommodating the line, there is a first first-come-first-served storage circuit that detects reception of packets from a first terminal, stores them on a first-come-first-served basis, and outputs them on a first-come-first-served basis, and a first first-come-first-served storage circuit that stores packets from a second terminal on a first-come, first-served basis. and a second first-come-first-served storage circuit that outputs packets on a first-come, first-served basis. Packets from the first terminal via the first first-come-first-served storage circuit are selected in preference to packets output from the first-come-first-served storage circuit, while packets exceeding a certain number are sent to the second first-come-first-served storage circuit. If the packets are stored, the packets from the first terminal are queued at the first first-come-first-served storage circuit, and the packets are queued at the second first-come-first-served storage circuit until the number of packets stored in the second first-come-first-served storage circuit becomes less than a certain number. What is claimed is: 1. A constant number priority type packet add/drop device comprising a packet selector circuit having a function of selecting packets output from a forward storage circuit and transmitting the selected packets to a line.