JPH08237303A - Terminal adapter - Google Patents

Abstract

PURPOSE: To avoid unnecessary frame retransmission by reducing the abolition of a frame in an ISDN network. CONSTITUTION: A frame relay terminal 1 communicates with a frame relay terminal 4 through the use of the frame mode bearer service of ISDN lines 101 and 102, and a frame relay terminal 4 communicates with the frame relay terminal 1 through the use of the frame mode bearer service of ISDN lines 103 and 104. At the time of receiving a congestion information frame from an ISDN terminal 100 in utilizing the ISDN lines 101 and 103, a terminal adapter 2 calls to a terminal adapter 3 on the side of the ISDN line 104 through the use of the ISDN line 102 to add a new path between with a terminal adapter 3 and distributes transmission traffic to the ISDN lines 101 and 102.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a terminal adapter, and more particularly, to a frame relay terminal for connecting to an ISDN network (Integrated Services Digital Network) at the time of network congestion in a TA (terminal adapter) supporting FMBS (frame mode bearer service). Load balancing method

[0002]

2. Description of the Related Art Conventionally, in a system in which a frame relay terminal is connected to an ISDN network through a terminal adapter, a frame related to the congestion is transmitted to a frame relay terminal connected to the terminal adapter by using the information channel of the ISDN line at the time of network congestion. Is being sent.

When a frame relay terminal without a congestion control function is connected to this ISDN network via a terminal adapter, the ISDN network sends the IS to the frame relay terminal.
Even if a frame indicating congestion is transmitted through the information channel of the DN line and the terminal adapter, frame transmission to the ISDN network cannot be suppressed, and as a result, frame discard in the ISDN network cannot be suppressed.

Here, there is a LAN (local area network) system connected to an ISDN network via a frame relay terminal as one having a congestion control function, and this LAN system uniquely detects the congestion state of the ISDN line. It is supposed to do.

[0005]

DISCLOSURE OF THE INVENTION The conventional ISD described above
In a system connected to the N network, if a frame relay terminal without a congestion control function is connected to the ISDN network via a terminal adapter, the ISDN network notifies the frame relay terminal of the congestion by using the information channel of the ISDN line. Since the frame transmission to the ISDN network is not suppressed even if it is transmitted, a large number of frames are transmitted even though the ISDN network is in a congested state, resulting in frame discard in the ISDN network. there is a possibility.

[0006] Therefore, an object of the present invention is to solve the above problems, to provide a terminal adapter capable of reducing frame discard in the ISDN network and avoiding unnecessary frame retransmission. is there.

[0007]

A terminal adapter according to the present invention is a terminal adapter for connecting a frame relay terminal to an integrated service digital network,
First and second connections to the integrated service digital network
Line, a detecting means for detecting a congestion display frame from the integrated service digital network when the first line is connected to the integrated service digital network, and when the detecting means detects the congestion display frame. The second
And a means for making a call to the line.

Another terminal adapter according to the invention is
In addition to the above configuration, it is provided with means for distributing transmission traffic to the first and second lines when the first and second lines are connected to the integrated service digital network.

Another terminal adapter according to the present invention is
In addition to the above configuration, means for detecting that the congestion indication frame is not detected for a preset period of time when the first and second lines are connected to the integrated service digital network, and the congestion indication Means for disconnecting the second line when a frame is not detected for a preset period of time.

[0010]

[Operation] A terminal adapter for connecting the frame relay terminal to the ISDN network is connected to the ISDN network, respectively. 2
Two ISDN lines are provided, and two ISDN lines are provided when the congestion notification monitoring unit detects a congestion notification frame from the ISDN network.
A call is made to the open ISDN line of the lines, and the transmission traffic of the frame relay terminal is distributed to the two ISDN lines.

This makes it possible to suppress frame transmission per ISDN line, reduce frame discard in the ISDN network, and avoid unnecessary frame retransmission.

That is, the ISDN frame mode bearer service may guarantee the throughput per line or per DLCI (data link connection identifier), but it is necessary to perform data transfer beyond the guaranteed value. Even if the error occurs, it is possible to reduce the influence of the frame being discarded in the ISDN network by using another line that is temporarily open.

[0013]

Next, an embodiment of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing the system configuration of an embodiment of the present invention. In the figure, frame relay (FR) terminals 1 and 4 are connected to the ISDN network 100 via frame mode bearer service compatible terminal adapters (FMBS compatible TA) (hereinafter, terminal adapters) 2 and 3 and ISDN lines 101 to 104, respectively. It is supposed to be connected.

That is, the frame relay terminal 1 uses the ISD
The frame mode bearer service of the N lines 101 and 102 is used to communicate with the frame relay terminal 4, and the frame relay terminal 4 is used to communicate with the frame relay terminal 1 using the frame mode bearer service of the ISDN lines 103 and 104. .

The terminal adapter 2 is composed of two ISDN lines 101, 1 corresponding to the frame mode bearer service.
02, and the terminal adapter 3 uses two ISDN lines 10 compatible with the frame mode bearer service.
It is connected to 3,104.

The terminal adapter 2 is an ISDN line 10
When a congestion notification frame is received from the ISDN network 100 while using 1, 103, a call is made to the terminal adapter 3 on the ISDN line 104 side using the ISDN line 102, and a new call is made between the terminal adapter 3 and the terminal adapter 3. Add a path.

As a result, the terminal adapter 2 is I
By distributing the transmission traffic to the SDN lines 101 and 102, the ISDN line 10 is used in the terminal adapter 3.
Communication can be received via 3, 104. Therefore, since the frame transmission per ISDN line is suppressed, it is possible to suppress the frame discard in the ISDN network 100.

When the frame indicating the congestion on the ISDN line 101 is not received for a certain period of time, the terminal adapter 2 disconnects the call on the ISDN line 102 and concentrates the transmission traffic on the ISDN line 101.

FIG. 2 is a block diagram showing the configuration of the terminal adapter 2 shown in FIG. In the figure, the terminal adapter 2 includes a terminal-side control unit 21 and a multilink processing unit 22.
And ISDN line control units 23 and 24, and a congestion notification monitoring unit 25.

The terminal side control unit 21 is the frame relay terminal 1
Is an interface for connecting to. Since the multi-link processing unit 22 distributes the signal from the frame relay terminal 1 to a plurality of lines, it controls the sequence and changes the DLCI (data link connection identifier) corresponding to the ISDN line side frame mode bearer service.

The ISDN line control unit 23 uses the ISDN line 1
01 call control is performed to set the signal from the multilink processing unit 22 to the information channel of the ISDN line 101. I
The SDN line control unit 24 calls the ISDN line 102,
A new path is set for the terminal adapter 3 on the partner side.

The congestion notification monitoring unit 25 uses the ISDN line 101.
When the information channel is monitored and a frame indicating congestion is received from the ISDN network 100, the fact is notified to the multilink processing unit 22 and the ISDN line control unit 24.

Upon receiving the notification from the congestion notification monitoring unit 25, the multi-link processing unit 22 transmits, to the ISDN line control unit 24, a frame out of the signals from the terminal side line control unit 21 that exceeds a preset specified value. . Upon receiving the notification from the congestion notification monitoring unit 25, the ISDN line control unit 24 sets the signal to the information channel of the ISDN line 102.

Also, the congestion notification monitoring unit 25, after the ISDN line control unit 24 sets up the call on the ISDN line 102,
When no frame indicating congestion is detected on the ISDN line 101 for a certain period of time, the fact is notified to the multilink processing unit 22 and the ISDN line 24.

Upon receiving the notification from the congestion notification monitoring unit 25, the multilink processing unit 22 concentrates the transmission traffic, that is, the signal from the terminal side line control unit 21 on the ISDN line control unit 23. Upon receiving the notification from the congestion notification monitoring unit 25, the ISDN line control unit 24 disconnects the call to the ISDN line 102. When the ISDN line control unit 24 first performs call control and the ISDN line control unit 23 sets a new path, the operation is the same as above.

On the other hand, the multi-link processing unit 22 uses the ISDN
ISDN lines 101, 1 through the line control units 23, 24
When receiving a signal from 02, two ISDN lines 1
The signals from 01 and 102 are subjected to sequence control to be edited into one DLCI and transmitted to the frame relay terminal 1 through the terminal side control unit 21.

Although not shown, the terminal adapter 3 has the same structure as the terminal adapter 2, and its operation is also the same as the processing operation of the terminal adapter 2 described above.

3 and 4 are flow charts showing the operation of one embodiment of the present invention. 1 to 4, when the frame relay terminal 1 transmits to the frame relay terminal 4 using the frame mode bearer service of the ISDN line 101, and when the frame relay terminal 1 is an IS
The operation of one embodiment of the present invention in the case of receiving the communication from the frame relay terminal 4 using the frame mode bearer service of the DN line 101 will be described.

The frame relay terminal 1 uses the ISDN line 10
When transmitting to the frame relay terminal 4 using the frame mode bearer service of No. 1, first, the multilink processing unit 22 of the terminal adapter 2 starts operation, and then whether the processing is transmission or reception by the ISDN lines 101 and 102 is performed. A judgment is made (step S1 in FIG. 3). In this case, since the frame relay terminal 1 communicates with the frame relay terminal 4 using the frame mode bearer service of the ISDN line 101, it is judged as transmission and the ISDN line control unit 23
Call control of the ISDN line 101 through the ISDN
Connect to the line 101 (step S2 in FIG. 3).

The multi-link processing unit 22 uses the ISDN line 1
When connected to 01, the signal transmitted from the frame relay terminal 1 through the terminal side line control unit 21 is transmitted to the frame relay terminal 4 through the ISDN line 101, the ISDN network 100, the ISDN line 103 and the terminal adapter 3 (Fig. 3 step S3). Multilink processing unit 2
2 transmits all the signals sent from the frame relay terminal 1 to the frame relay terminal 4 (step S in FIG. 3).
4), the process ends.

Further, when all the signals transmitted from the frame relay terminal 1 are not transmitted to the frame relay terminal 4 (step S4 in FIG. 3), when the multilink processing unit 22 continues the transmission processing, the congestion notification monitoring unit 25 ISDN
When it is notified that the congestion notification frame is detected on the line 101 (step S5 in FIG. 3), the ISDN line control unit 24
Calls the ISDN line 102 and sets a new path for the terminal adapter 3 on the other side (step S6 in FIG. 3).

When the multi-link processing unit 22 receives the notification from the congestion notification monitoring unit 25, it sends to the ISDN line control unit 24 a frame out of the signals from the terminal side line control unit 21 that exceeds a preset specified value. (Fig. 3 Step S
7). The ISDN line control unit 24 sets the signal to the information channel of the ISDN line 102.

When the congestion notification monitoring unit 25 does not detect a congestion notification frame on the ISDN line 101 for a certain period of time after the ISDN line control unit 24 sets up the call on the ISDN line 102 (step S8 in FIG. 3), this is indicated. Is notified to the multilink processing unit 22 and the ISDN line 24.

Upon receiving the notification from the congestion notification monitoring unit 25, the ISDN line control unit 24 disconnects the call to the ISDN line 102 (step S9 in FIG. 3), and the multilink processing unit 22 notifies from the congestion notification monitoring unit 25. When receiving, the transmission traffic, that is, the signal from the terminal side line control unit 21 is concentrated in the ISDN line control unit 23.

Next, when the frame relay terminal 1 receives the communication from the frame relay terminal 4 using the frame mode bearer service of the ISDN line 101, first, the multilink processing unit 22 of the terminal adapter 2 starts operation. , It is determined whether the processing is transmission or reception by the ISDN lines 101 and 102 (step S in FIG. 3).
1). In this case, since the frame relay terminal 1 receives the communication from the frame relay terminal 4 using the frame mode bearer service of the ISDN line 101, it is judged as the reception and the ISDN line 1 is passed through the ISDN line control unit 23.
01 (step S10 in FIG. 4).

The multi-link processing unit 22 uses the ISDN line 1
When it is connected to 01, the signal from the ISDN line 101 is subjected to sequence control to be edited into one DLCI and transmitted to the frame relay terminal 1 through the terminal side control unit 21 (step S11 in FIG. 4). When the multi-link processing unit 22 transmits all the signals transmitted from the frame relay terminal 4 to the frame relay terminal 1 (step S1 in FIG. 4).
2), the process ends.

Further, when all the signals sent from the frame relay terminal 4 are not transmitted to the frame relay terminal 1 (step S12 in FIG. 4), when a call request for the ISDN line 102 from the terminal adapter 3 is received (step in FIG. 4). S13), the multilink processing unit 22 uses the ISD
The N line control unit 24 connects to the ISDN line 102 (step S14 in FIG. 4).

When the multi-link processing unit 22 is connected to the ISDN line 102 by the ISDN line control unit 24,
ISD received through the ISDN line control units 23 and 24
The signals from the N lines 101 and 102 are sequence-controlled to be edited into one DLCI and transmitted to the frame relay terminal 1 through the terminal-side control unit 21 (step S15 in FIG. 4).

If there is no signal on the ISDN line 102 connected afterwards for a certain period of time, the ISDN line control unit 24 (see FIG. 4).
In step S16), the call is disconnected from the ISDN line 102 (step S17 in FIG. 4). After this, the multi-link processing unit 22 returns to step S11, and the ISDN line 10
One DL by performing order control on the signal from 1
The CI is edited and transmitted to the frame relay terminal 1 through the terminal-side control unit 21.

In this way, the two ISDs connected to the ISDN network 100 are respectively connected to the terminal adapters 2 and 3 for connecting the frame relay terminals 1 and 4 to the ISDN network 100.
The N lines 101 to 104 are provided, and the congestion notification monitoring unit 25
When the congestion notification frame from the SDN network 100 is detected, the open ISDN line of the two ISDN lines is called to suppress the frame transmission per ISDN line. Therefore, it is possible to reduce frame discard within the ISDN network 100 and avoid unnecessary frame retransmission.

That is, the ISDN frame mode bearer service may guarantee the throughput per line or per DLCI, but even if it is necessary to transfer data beyond the guaranteed value,
By temporarily using another open line, ISD
It is possible to reduce the influence of discarding frames in the N network 100.

Further, the transmission traffics of the frame relay terminals 1 and 4 are distributed to the two ISDN lines, and when the congestion notification frame is not detected for a certain period of time, the ISDN line connected later is disconnected and one transmission traffic is transmitted. Of I
By concentrating on the SDN line, the ISDN network 100
ISDN line 101-
104 can be effectively used.

[0044]

As described above, according to the present invention, the terminal adapter for connecting the frame relay terminal to the integrated service digital network is provided with the first and second lines for connecting to the integrated service digital network. , ISDN by calling the second line when the congestion indication frame from the integrated services digital network is detected while the first line is connected to the integrated services digital network.
It is possible to reduce frame discard in the network and avoid unnecessary frame retransmission.

[Brief description of drawings]

FIG. 1 is a block diagram illustrating a system configuration according to an embodiment of the present invention.

FIG. 2 is a block diagram showing the configuration of the terminal adapter of FIG.

FIG. 3 is a flowchart showing the operation of one embodiment of the present invention.

FIG. 4 is a flowchart showing the operation of the embodiment of the present invention.

[Explanation of symbols]

1,4 Frame relay terminal 2,3 Frame mode bearer service compatible terminal adapter 21 Terminal side line control unit 22 Multilink processing unit 23,24 ISDN line control unit 25 Congestion notification monitoring unit 100 ISDN network 101 to 104 ISDN line

Claims (3)

[Claims] 1. A terminal adapter for connecting a frame relay terminal to an integrated service digital network, wherein the first and second lines connected to the integrated service digital network and the first line are integrated into the integrated service. And a means for detecting a congestion display frame from the integrated service digital network when connected to the digital network, and a means for calling the second line when the detection means detects the congestion display frame. A terminal adapter characterized in that 2. The first and second lines when the first and second lines are connected to the integrated service digital network.
2. The terminal adapter according to claim 1, including means for distributing transmission traffic to the line. 3. A means for detecting that the congestion display frame is not detected for a preset period of time when the first and second lines are connected to the integrated service digital network, and the congestion display frame is 3. The terminal adapter according to claim 1 or 2, further comprising means for disconnecting the second line when a predetermined period of time has not been detected.