JPH09168032A - Connection method between communication networks - Google Patents

Abstract

(57) Abstract: A congestion occurring in a frame relay network is recovered early by reducing the throughput of bidirectional data frames. SOLUTION: A bruta 1 connected to each LAN 1 and 2.
In the inter-communication network connection method for transmitting frame format data by connecting 1 and 21 via a logical connection identifier of the communication network 10, the receiving side brouter 21
When the communication network recognizes that the communication network is normal, when it receives a data frame including the forward explicit congestion notification, it transmits the data frame in the reverse direction to the congestion to the transmitting brouter 21 at least once with normal throughput. The data is transmitted to notify the congestion, and thereafter, the throughput of the data frame in the direction opposite to the congestion is suppressed to CIR or less, and the throughput of the data frame is controlled in both transmission and reception.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a communication network connection method for connecting communication networks forming a LAN via a frame relay network.

[0002]

2. Description of the Related Art Conventionally, in this type of connection method between communication networks, when a frame relay network is in a congestion state when data is transmitted and received between LANs, a data frame in the same direction as the congestion direction is transferred to the network. Forward Explicit Congestion Notifica
bit (hereinafter, referred to as "FECN") is set to "1", and the LAN connection device on the receiving side has detected that the network is in a congested state by FECN in the data frame.

A data frame in the reverse direction of the congestion direction is transmitted by the above network to the backward explicit congestion notification (Backward Explici).
The bit of t Congestion Notification (hereinafter referred to as “BECN”) is set to “1”, and the transmission side inter-LAN connecting device has detected that the network is in a congested state by BECN in the data frame. When the frame relay network is not in a congestion state and is normal, both the FECN and BECN bits are set to "0".

Further, in the case of no packet in the reverse direction, that is, when BECN cannot be detected, the LAN connection device on the transmitting side has a function of consolidating link layer by the autonomous function of the network.
It was equipped with a mechanism that can detect congestion by a control message (t, hereinafter referred to as "CLLM").

[0005]

However, in the above method, since the congestion is recovered by only decreasing the throughput of the data frame in the same direction as the congestion direction, it takes a considerable time to recover the congestion. There was a problem to do. Therefore, for example, the transmission side LAN-to-LAN connecting device determines the above throughput by the committed information rate (Committed Information Ra
te, hereinafter referred to as “CIR”), but there is also a problem such as discarding data frames in the frame relay network when congestion is not recovered even with such suppression. .

The present invention has been made in view of the above problems, and provides a communication network connection method capable of recovering congestion occurring in a frame relay network at an early stage by reducing the throughput of bidirectional data frames. With the goal.

[0007]

In order to achieve the above object, according to the present invention, a connection device connected to each LAN is connected to a logical connection identifier (data link In the inter-communication network connection method for transmitting data in frame format by connecting via the connection identifier), the receiving-side inter-LAN connecting device, when it recognizes that the frame relay network is normal, forward direction When a data frame including an explicit congestion notification is received, a data frame in the reverse direction of the congestion is sent to the transmission side LAN connecting device at least once at normal throughput to notify the congestion, and thereafter, the data frame in the reverse direction of the congestion is notified. A communication network that suppresses the throughput of data frames to CIR or less and controls the throughput of the data frames in both transmitting and receiving directions. Over click connecting method is provided.

According to a third aspect of the present invention, when the LAN connection device on the receiving side receives the forward explicit congestion notification when the communication network recognizes that the communication network is in the congestion state, the data in the reverse direction to the congestion data is received. A frame is sent at a predetermined throughput and the throughput is controlled to recover congestion early. In claim 4, when the receiving side inter-LAN connecting device receives the recovery notification of the forward explicit congestion when it recognizes that the communication network is in a congestion state, the data frame in the reverse direction of the congestion is received. Is sent at the throughput of the normal state to restore the normal condition after the congestion recovery.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A LAN connection method according to the present invention will be described with reference to the drawings of FIGS. FIG. 1 is a block diagram showing a configuration of a data communication system using a method for connecting LANs according to the present invention. In the figure, in this embodiment, a frame relay (hereinafter referred to as "FR") network 10 is used.
A plurality of connecting devices (hereinafter, referred to as “Bruta”) 11 and 21 having the functions of a bridge and a router are connected via the.

The LAN 1 includes a brouter 11 and a terminal device 1.
2 and a transmission line 13 to which the brouter 11 and the terminal device 12 are connected. LAN2 is Bruta 2
1 and the terminal device 22, and a transmission path 23 to which the brouter 21 and the terminal device 22 are connected. In order to perform route control, each brouter 11 and 21 stores a routing address that stores a destination address that indicates the network-side address of the transmission destination and a relay-destination bruta address that indicates the network-side address of the relay-destination bruta corresponding to this destination address. Holding a table. In order to perform FR control, each of the brouters 11 and 21 corresponds to a hardware address (data link connection identifier, hereinafter referred to as “DLCI”) indicating the information on the logical channel of the FR network 10 and this DLCI. An address resolution protocol (hereinafter referred to as “AR”) in which an IP address (LAN interface address (LIFA)) indicating the network side address of the relay brouter is stored.
Table).

Upon receipt of the LAN transmission frame from the same terminal devices 12 and 22 as the own device, the transmission side bruta among the brutas 11 and 21 uses the addresses in the routing table and the ARP table as shown in FIG. The relay data frame shown is created and transmitted to the FR network 10. The data frame shown in FIG. 2 includes a start flag indicating the start of a frame, an address field storing various addresses, an information field storing predetermined information such as addresses of a source terminal device and a destination terminal device, and a frame check sequence. And an end flag indicating the end of the frame. The address field consists of a 2-octet field, and in the 1st octet the higher address of DLCI and arbitrary bit N /
A (transparently transferred to the network) and an address field extension bit EA (fixed to "0") are stored, and the lower address of the DLCI is stored in the second octet.
The FECN and BECN for notifying the congestion state, the discardable indication bit DE indicating whether or not the data frame can be discarded, and the address field extension bit EA
(Fixed to "1") are stored.

The FR network 10 uses the DLC in the data frame.
Based on the I information, the transmission side brouter and the relay destination brouter corresponding to the DLCI are connected to enable transmission of the data frame (see arrow). FR network 10
Is in a state in which no congestion occurs, the throughput of the data frame transmitted from the brouter 11 on the transmitting side to the brouter 21 on the receiving side is, for example, FR in the FR network 10.
Throughput that matches the line speed of the network 10 is obtained.
Similarly, a data frame transmitted in the opposite direction is also F
Throughput that matches the line speed of the R network 10 is obtained.

FIG. 3 is a block diagram of a system configuration for explaining the recovery processing operation of this embodiment when congestion occurs in the FR network 10. In the present embodiment, the case of data transmission from the terminal device 12 to the terminal device 21 will be described. In FIG. 3, the transmission side brouter 11 existing on the same LAN 1 as the terminal device 12 performs data transmission to the reception side brouter 21 by the FR network 10. The reception-side brouter 21 sends data to the terminal device 22 existing on the same LAN 2, thereby establishing data transmission from the terminal device 12 to the terminal device 22. And Bruta 11 and 21
Performs data transmission using the logically set DLCI.

First, when the transmitting brouter 11 recognizes that the FR network 10 is normal, the FECN bit and BEC
When congestion occurs in the forward direction from the transmission side to the reception side in the FR network 10 when the data frame 30 in which both N bits include “0” is transmitted, the FR network 10 causes the data frame 30 to be transmitted.
The FECN bit stored in is rewritten to "1" and sent to the brouter 21 on the receiving side. At this time, the throughput of the data frame 30 in the network has obtained the line speed.

When the reception side brouter 21 receives the data frame 30 including the FECN bit of "1" when the FR network 10 recognizes that it is normal, it detects that congestion has occurred in the forward direction and immediately The data frame 31 in which both the FECN bit and the BECN bit include "0" is returned to the transmitting side brouter 11 with normal throughput. The data frame 31 is forcibly transmitted when congestion is detected even when the normal receiving brouter 21 does not need to return the frame.

In the data frame 31, the BECN bit is rewritten by the FR network 10 to "1", and the data frame 31 is sent to the transmitting side brouter 11. Sender side bruta 11
Is a data frame 31 whose BECN bit contains "1".
, The congestion is detected from the BECN bit in the frame 31, and the data transmission rate is suppressed so that the throughput of the data frame 32 to be sent to the receiving side brouter 21 thereafter becomes equal to or lower than the CIR value.
Send to

When the brouter 21 on the receiving side receives the data frame 32 including the FECN bit of "1" while recognizing the congestion in the FR network 10, that is, the FECN bit of "1" is continuously received twice. When the data frame including the data frame is received, the data transmission rate is suppressed so that the throughput of the data frame 33 becomes equal to or lower than the CIR value, and the data frame 33 is transmitted to the transmission side brouter 11. This data frame 33 is also F
The BECN is rewritten to “1” in the R network 10 and sent to the transmission side brouter 11.

The reception side bruta 21 is connected to the FR network 1.
When the congestion at 0 is recognized and the recovery of the congestion at the FR network 10 is detected, the data transmission rate is controlled so that the throughput becomes a normal value, and the data frame is forcibly transmitted by the transmitting side. Send to bruta 11. This allows
The transmission side brouter 11 controls the data transmission rate so that the recovery of the congestion is detected by the data frame including the BECN bit of "0" and the normal recovery is immediately performed, and the throughput of the data frame becomes a normal value. Then, the data is transmitted to the brouter 21 on the receiving side.

Therefore, in this embodiment, when the reception side brouter receives a data frame containing the FECN bit of "1" while the FR network recognizes that the data frame is normal, the reception side brute force the data frame to the normal throughput. In order to notify the occurrence of congestion by sending to the brouter on the sending side, and thereafter, the recovery process is performed to reduce the data frame throughput bidirectionally by suppressing the data transmission rate so that the throughput becomes the CIR value or less. It is possible to quickly recover the congestion that occurred in.

Further, in this embodiment, the receiving side brouter is
When a data frame containing FECN bits of "0" is received while recognizing congestion on the FR network, the data frame is forcibly returned to the transmitting bruta at the throughput in the normal state to notify the congestion recovery. Since the processing is performed, the normal recovery after the recovery of the congestion occurring in the FR network becomes quick.

[0021]

As described above, in the present invention, each L
In a connection method between communication networks in which a connection device connected to an AN is connected via a logical connection identifier of a frame relay network to transmit frame format data, the connection device is configured so that the frame relay network is normal. If the forward explicit congestion notification is received, the data frame in the reverse direction of the congestion is sent out at least once at the normal throughput, and thereafter, the data frame in the reverse direction of the congestion is transmitted. Since the throughput is suppressed below the certified information rate and the throughput of the data frame is controlled bidirectionally, the congestion generated in the frame relay network can be recovered early by lowering the throughput of the bidirectional data frame.

According to a third aspect of the present invention, when the connection device recognizes that the communication network is in a congestion state and receives the forward direction explicit congestion notification, a predetermined data frame in the reverse direction of the congestion is received. Since the data is transmitted at the throughput, the throughput can be quickly reduced and the congestion generated in the frame relay network can be recovered early. In claim 4, when the connection device receives the recovery notification of the forward explicit congestion when the communication network recognizes that the communication network is in the congestion state, the connection device sets the data frame in the reverse direction to the congestion in the normal state. Since the data is transmitted at the throughput, the normal recovery after the congestion recovery that occurred in the frame relay network is prompt.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of a data communication system using an inter-LAN connection method according to the present invention.

2 is a configuration diagram showing a format of a relay data frame used in the system of FIG.

FIG. 3 is a block diagram of a system configuration similar to that of FIG. 1 for explaining a recovery processing operation of the present embodiment when congestion occurs in a frame relay network.

[Explanation of symbols]

 1, 2 LAN 10 Frame relay network 11, 21 Bruter (inter-LAN connection device) 12, 22 Terminal device 13, 23 Transmission line 30-33 Relay data frame

Claims (5)

[Claims] 1. An inter-communication network connection method for transmitting frame format data by connecting a connection device connected to each communication network via a logical connection identifier of a communication network, wherein the connection device comprises: A method for connecting between communication networks, characterized in that when a data frame including a congestion notification is received, the throughput of the data frame is bidirectionally controlled. 2. The connection device, when recognizing that the communication network is normal, receives a forward explicit congestion notification and transmits a data frame in the reverse direction to the congestion at least once at a normal throughput. 2. The communication network connection method according to claim 1, wherein, after the transmission, the data frame in the direction opposite to the congestion is transmitted at a throughput not higher than the authorized information rate. 3. The connection device, when receiving the forward direction explicit congestion notification when the connection device recognizes that the communication network is in a congestion state, transmits a data frame in the reverse direction to the congestion information speed equal to or lower than the authorized information rate. 3. The communication network connection method according to claim 1, wherein the communication network is transmitted at a throughput of. 4. When the connection device recognizes that the communication network is in a congestion state and receives the recovery notification of the forward explicit congestion, the connection device sets the data frame in the reverse direction to the congestion normal state. 4. The communication network connection method according to claim 1, wherein the communication network is transmitted at a throughput of. 5. The method according to claim 1, wherein the communication network is a local area network, and the communication network is a frame relay network.