JPH0537558A - Packet exchange line - Google Patents

Abstract

PURPOSE:To improve the transmission efficiency by reducing the quantity of data to be sent again on the occurrence of a transmission error. CONSTITUTION:Suppose that a bit error rakes place on a physical line 5, the re-transmission request is made in compliance with the international recommendations X.25, since the data is sent again in the unit of frames, only the data shared to each of SLP control sections 3a-3d are sent. Thus, it is enough to send data again being nearly 1/4 in comparison with re-transmission of data in the unit of frames inputted in an MLP control section 2 in a conventional system.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a packet switching line, and more particularly to International Recommendation X.264. 25 relates to a packet switching line for performing a packet switching service.

[0002]

2. Description of the Related Art International Recommendation X. In the case of the packet switching service to which No. 25 is applied, the transmission procedure applying the asynchronous balanced mode in the high level data link procedure called LAPB is used as the link layer control between the packet switch and the packet terminal.

In the error control method in this transmission procedure,
A frame check sequence error is checked for the received frame, the frame in which the error is detected is discarded, and the next frame is received. Then, since an error in the reception sequence number is detected, a resend request is made by the REJ command and the error is recovered by receiving again from the discarded frame.

[0004]

In the above-mentioned conventional packet switching line, all the frames in which an error has occurred must be retransmitted, and particularly in a high-speed line, all the data left on the line is retransmitted. However, there is a problem that the transmission efficiency is lowered because it is necessary to do so.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a packet switching line capable of improving the transmission efficiency by reducing the amount of retransmitted data when a transmission error occurs. ..

[0006]

In order to achieve the above object, the invention according to claim 1 is a multilink protocol control unit for transmitting / receiving data to / from a host device in a connection path between a packet switching device and a packet terminal. And a plurality of single link protocol control units for transmitting and receiving data to and from the multi-link protocol control unit, and a concentrating unit for concentrating the plurality of single link protocol control units on a single line.

[0007]

In the invention according to claim 1 configured as described above, in the connection path between the packet switching device and the packet terminal, the host device transmits and receives data through the multilink protocol control unit. The multi-link protocol control unit transmits / receives data via the plurality of single-link protocol control units. The concentrator concentrates the plurality of single link protocol controllers on a single line.

That is, the multilink procedure is applied between the host device and the line. Therefore, when an error occurs, data is retransmitted for one virtual circuit distributed by multilink.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram of a packet switching line according to an embodiment of the present invention. In the figure, the host device 1
Is connected to a multi-link protocol control unit (hereinafter referred to as MLP control unit) 2 and performs packet communication with the MLP control unit 2. The MLP control unit 2 includes a plurality of single link protocol control units (hereinafter referred to as SLP control units) 3.
a-3d, and the respective SLP control units 3a-3
packet communication with d.

Each of the SLP control units 3a to 3d is connected to the concentrating unit 4, and the concentrating unit 4 concentrates each line and connects them to one physical line 5.

Next, the operation of this embodiment having the above configuration will be described. The data sent from the higher-level device 1 is distributed to a plurality of lines by the MLP control unit 2 and transmitted to each of the SLP control units 3a to 3d. Each SLP control unit 3a to 3d
Performs link layer control to transmit the data to the concentrator 4, and the concentrator 4 sends the data transmitted from each of the SLP controllers 3a to 3d to the physical line 5.

At this time, the concentrator 4 uses the upper 4 bits that are not used in the address part of the frame for each S
A unique value is assigned to each LP control unit 3 and sent to the physical line 5. Further, at the time of reception, the concentrator 4 identifies the upper 4 bits of the address part of the frame in the data input from the physical line 5, and the SLP controller 3 first
Each SLP control unit 3a as assigned to each
~ 3d.

Then, each of the SLP control units 3a to 3d outputs M
When input to the LP control unit 2, the MLP control unit 2
Performs the link level control and then causes the host device 1 to input.

If a bit error occurs on the physical line 5 in such a state, International Recommendation X. A resend request conforming to 25 is made. However, since the frame is retransmitted, only the data distributed to the SLP control units 3a to 3d is retransmitted. Therefore, in the conventional case, ML
As compared with the case where the data in frame units input to the P control unit 2 is retransmitted, it is sufficient to retransmit approximately ¼ of the data.

[0015]

As described above, according to the present invention, since the multi-link procedure is adopted between the host device and the line,
When an error occurs, only part of the data distributed by the multilink procedure is retransmitted, and it is necessary to provide a packet-switched line that can reduce the amount of data retransmission and improve transmission efficiency. You can

[Brief description of drawings]

FIG. 1 is a block diagram of a packet switching line according to an embodiment of the present invention.

[Explanation of symbols]

 1 ... Host device 2 ... Multilink protocol control unit 3 ... Single link protocol control unit 4 ... Concentrator 5 ... Physical line

Claims (1)

Claim: What is claimed is: 1. A multi-link protocol control unit for transmitting and receiving data to and from a host device, and a multi-link protocol control unit for transmitting and receiving data, in a connection path between a packet switching device and a packet terminal. A packet switching line comprising: a plurality of single-link protocol control units that perform the operations; and a concentrator that concentrates the plurality of single-link protocol control units on a single line.