JPS636189B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a data drop/add device that accommodates two data terminals and multiplexes them onto one subscriber line.

Regarding the expansion of terminals accommodated in a switching network, the methods and equipment used conventionally are
(hereinafter referred to as PSN) and packet terminal (hereinafter referred to as PT)
Explain using.

The connection between PSN and PT is generally as shown in Figure 1. In Figure 1, 1 is PSN, 2 is PT,
3 is a subscriber line. Next, when adding a new PT, there are two methods. One is to newly install the subscriber line 3 shown in Figure 2, and the other is to install the packet multiplexer 4 shown in Figure 3. Introduced and multiple
Packets sent from PT are routed to one subscriber line 3.
This is a method of multiplexing. In this case, in the method shown in FIG. 2, the subscriber line 3 is newly installed, which increases the installation cost and usage fee. In addition, a packet multiplexing device 4 introduced by the method shown in FIG.
In order to multiplex packets from a plurality of PTs onto one subscriber line 3, it is necessary to have control procedures between the PSN 1 and the PT 2. This control procedure is generally defined by CCITT's International Recommendation No. . As a result, the cost of the equipment will increase, so the number of accommodated terminals will be increased (32
terminals, 64 terminals, etc.), and methods are being taken to reduce the cost per terminal. However, if the number of terminals is increased by several terminals, the cost of the packet multiplexing device 4 is high and it is not economical.

SUMMARY OF THE INVENTION An object of the present invention is to eliminate the drawbacks of the prior art described above and to provide a data drop/add device that can be economically added to each terminal. That is, the present invention provides a data branch/add device that inputs two signal lines from two terminals A and B and converts them into a single subscriber line. When data is sent from terminal B while data is being transmitted, the transmitted data is temporarily stored and a pattern indicating data abandonment is inserted to interrupt data from terminal A, giving priority to data from terminal B. When the data from terminal B is interrupted, the temporarily accumulated data of terminal A is retransmitted to the subscriber line, and if data is sent again from terminal B during retransmission, the retransmitted data of terminal A is After the transmission is completed, the above purpose is achieved by transmitting the data of terminal B to the subscriber line.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 4 shows the configuration of a packet drop/drop insert device (hereinafter referred to as PDI) according to the present invention. In Fig. 4, 5, 5A, and 5B are packet terminals A and B.
Data lines from (PTA, B) to the packet switched network (PSN) (hereinafter referred to as "upstream"), 6, 6A, 6
B is a data line from PSN to PTA, B (hereinafter referred to as "downstream"), 7, 7A, 7B are from PSN
A clock line 8 is supplied to PTA and B, a packet detection circuit 8 detects the presence or absence of a packet on the upstream data lines 5A and 5B, and 9A and 9B are data lines 5 and 5, respectively.
First-in-first-out buffer (hereinafter referred to as FIFO) for temporarily storing uplink data sent from PTA and B via A and 5B, 10
A, B, C, 14A, B, 15A, and B are AND gates, 11 is a NAND gate, 12 and 13 are OR gates, and 16 is a PDI. In FIG. 4, the downlink packet arriving from the data line 6 is branched by AND gates 15A and 15B in the PDI 16 and sent to the PTA,
The packets are sent to B at the same time, and the packet addressed to itself is selected in the PT of the user. Features of embodiments according to the invention include:
Since this involves data processing, the operation will be explained in detail below.

An example of a time chart of upstream packet processing is shown in FIG. In FIG. 5, T5A and T5B
T5 is a time chart showing the flow of packets from PTA and PTB, and T5 is a time chart showing the flow of packets toward PSN. In PDI16,
When there is no packet from the PTB, the clock is switched to the clock lines 7A and 7 under the control of the packet detection circuit 8.
The data is sent to the PTA and B via B, and the upstream data line 5A from the PTA is connected to the upstream data line 5 heading toward the PSN. Therefore, as shown in FIG. 5, the packet _a0 sent from the PTA is sent to the PSN without any time delay and at the same time is temporarily stored in the FIFO 9A connected to the upstream data line 5A from the PTA. When a packet _b0 is sent from the PTB via the data line 5B, the packet is detected by the packet detection circuit 8, and when a packet _a1 is sent from the PTA, it is sent via the upstream data line 5A. The packet detection circuit 8 inserts an abandonment pattern indicating midway abandonment into the packet sent to the PSN via the OR gate 12, and after the packet from the PTA is midway abandoned, the packet from the PTB is sent to the upstream data line 5.
Send to PSN via. Note that processing time is required for inserting a discard pattern to discard packets from the PTA until the packets from the PTB are detected by the packet detection circuit 8 and sent to the PSN via the uplink data line 5. packets are temporary
Connected to upstream data line 5B from PTB
Stored in FIFO9B. Also, when a break in the packet from the PTA is detected while the packet from the PTB is being sent to the PSN, the packet detection circuit 8 controls
Interrupts the clock sent to the PTA and prevents the next packet from being sent. Then P.T.B.
When the packet detection circuit 8 detects that the packet from the PSN is interrupted, the uplink data line 5 between the FIFO 9A connected to the data line 5A from the PTA and the PSN is
is connected, and packet _a1 stored in FIFO 9A is retransmitted. Furthermore, while PTA packet _a1 is being retransmitted from FIFO9A, packet bn+1 from PTB is being retransmitted.
Stored in FIFO9B. When the transmission of the retransmission packet is completed and the packet from the PTB is interrupted, the clock transmission to the PTA is restarted under the control of the packet detection circuit 8, making it possible to transmit the next packet _a2 .

In the present invention, the purpose of inserting an abandonment pattern indicating midway abandonment into the data is to enable the receiving side to be instructed to discard the immediately preceding data using the abandonment pattern.

In other words, in the present invention, in order to transmit the data on the priority side, it is necessary to interrupt the data on the non-priority side, so the receiving side (PSN) is instructed to discard some of the data that has already been sent on the non-priority side. This is to insert an abandonment pattern for the purpose.

As is clear from the embodiments described above, in the present invention, one terminal can be added by inserting a drop-and-drop device into the subscriber line between the existing terminal and the switching network. Therefore, it is possible to economically increase the number of terminals by up to several terminals without installing a new subscriber line or introducing a large-scale packet multiplexing device, which has been done in the past.

[Brief explanation of the drawing]

Figure 1 is a diagram showing the connection between a packet switching network and packet terminals, Figure 2 is a diagram showing the addition of packet terminals by adding subscriber lines, and Figure 3 is a diagram showing the connection of packet switching networks and packet terminals by introducing a packet multiplexing device. FIG. 4 is a block diagram showing a data add/drop device according to an embodiment of the present invention, and FIG. 5 is a time chart showing the operation of the data add/drop device according to the present invention. 1...Packet switched network (PSN), 2...Packet terminal (PT), 3...Subscriber line, 4...Packet multiplexer, 5...Uplink data line, 6...Downlink data line, 7... ...Clock line, 8...Packet detection circuit, 9...First-in-first-out buffer (FIFO), 10, 14, 15...AND gate, 11...NAND gate, 12, 13...OR gate, 16... Packet drop-insert device (PDI).

Claims (1)

[Claims] 1. In a data add/drop device that accommodates two data terminal devices and multiplexes them onto one subscriber line,
When data is sent from a second data terminal device on the priority side while data is being sent to the subscriber line from the first data terminal device on the non-priority side, the data from the second data terminal device is detected. The data sent from the first data terminal device is temporarily stored, and at the same time, an abandonment pattern indicating mid-term abandonment of data is inserted into the data sent from the first data terminal device on the non-priority side. , the data sent from the first data terminal device is interrupted, the data sent from the second data terminal device is preferentially sent to the subscriber line, and the data sent from the second data terminal device is When the data is interrupted, the temporarily stored data from the first data terminal device is retransmitted, and if data is sent again from the second data terminal device during this retransmission, the data from the first data terminal device is retransmitted.
1. An abandoned data retransmission type data branching/insertion device, characterized in that after transmission of retransmission data from said second data terminal device is completed, data from said second data terminal device is sent to a subscriber line.