JPS636190B2 - - 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 the 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. In this method, packets transmitted from multiple PTs are multiplexed onto one subscriber line 3. 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, the packet multiplexing device 4 introduced by the method shown in FIG. Must have. This control procedure is generally
What is specified in CCITT's International Recommendation No. As a result, the cost of the device increases, so measures are taken to increase the number of accommodated terminals (32 terminals, 64 terminals, etc.) and reduce the cost per terminal. However, when adding up to a few 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.

For this reason, the present invention provides a data branch/add device that inputs two signal lines from two terminals A and B and converts them into one subscriber line. When data is sent from terminal B while data is being transmitted, data from terminal A is discarded, data from terminal B is sent to the subscriber line, and data from terminal A is queued until data from terminal B is interrupted. , which achieves the above objectives.

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 connected to the packet switching network (PSN) from packet terminals A and B (PTA, B).
(hereinafter referred to as "up") data line, 6, 6
A, 6B are data lines from PSN to PTA, B (hereinafter referred to as "downstream"), 7, 7A, 7B are PSN
8 is a packet detection circuit for detecting the presence or absence of packets on uplink data lines 5A and 5B, and 9 is for temporarily storing uplink data sent from PTB via data line 5B. First-in-first-out buffer (hereinafter referred to as FIFO), 10A, 10B, 14A,
14B, 15A, 15B are AND gates, 11 is NAND gates, 12, 13 are OR gates, 16 is
It is PDI. In FIG. 4, a downstream packet arriving from data line 6 is branched by AND gates 15A and 15B in PDI 16, and then sent to data lines 6A and 6.
Simultaneously sent to PTA and B via B, and each PT
Select the packet addressed to you. Since the feature of the embodiment according to the present invention lies in 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 Figure 5, T5A is a time chart showing the flow of packets from PTA;
B is a time chart showing the flow of packets from the PTB, and T5 is a time chart showing the flow of packets toward the PSN. In the PDI 16, when there is no packet from the PTB, the clock is sent to the PTA, B via the clock lines 7A, 7B under the control of the packet detection circuit 8, and the uplink data line 5 from the PTA is sent.
A is connected to the upstream data line 5 going to the PSN. Therefore, as shown in FIG. 5, the packet _a0 sent from the PTA is sent to the PSN without any time delay. P.T.B.
When a packet _b0 is sent from the PTA via the data line 5B, the packet is detected by the packet detection circuit 8, and if a packet _a1 is sent from the PTA, it is sent via the upstream data line 5A. The packet detection circuit 8 inserts a discard pattern indicating mid-term discard into the packet being sent to the PSN via the OR gate 12, and after discarding the packet from the PTA, the packet is sent up the data line 5 from the PTB. Send to PSN via. Note that processing time is required for inserting a discard pattern to discard the packet from the PTA until the packet is detected by the packet detection circuit 8 and sent to the PSN via the uplink data line 5. is temporary
Stored in FIFO9. 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 the
Interrupts the clock sent to the PTA and prevents the next packet from being sent. After that, the packet detection circuit 8 detects that the packet from the PTB is interrupted.
When detected, the uplink data line 5 between PTA and PSN
Connect A and 5, send the clock to PTA,
Enables PTA to send the next packet.

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: Upstream data line, 6: Downstream data line, 7:
Clock line, 8: Packet detection circuit, 9: First-in-first-out buffer (FIFO), 1
0, 14, 15: AND gate, 11: NAND gate, 12, 13: OR gate, 16: Packet drop-insertion 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. and inserts an abandonment pattern indicating midway abandonment of data into the data being sent out from the first data terminal device on the non-priority side, interrupting the data being sent out from the first data terminal device, and An abandon pattern insertion type data branching/insertion device characterized in that data sent from a data terminal device No. 2 is sent preferentially to a subscriber line.