JPH08223220A - Frame relay router - Google Patents

Abstract

PURPOSE: To prevent loss of data caused by congestion in a network even when a UDP is mounted on a terminal equipment and no flow control function is provided in an application protocol. CONSTITUTION: This frame relay router is a frame relay router 23 in which data are sent between an Ethernet LAN 9 and a frame relay network 10 in terms of frame relays and a destination address(DA) of the Ethernet LAN 9 is detected by a DA detection section 100. An own station address signal 112 is generated based on the result of detection. A jam signal transmission section 200 sends a jam signal which is used to store data by the terminal equipment to the Ethernet LAN 9 through the input of the signal 112 and a signal 26 from a buffer 6 to inform that the buffer 6 is fully occupied by the data.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to LA such as Ethernet.
The present invention relates to a frame relay router for performing data transmission between N and another network such as a frame relay network by a frame relay.

[0002]

2. Description of the Related Art FIG. 7 is a block diagram showing the structure of a conventional frame relay router. Frame relay router 1
Is an Ethernet (Et
hernet) LAN (local area network) 9
Ethernet LAN transmission / reception unit 2, Ethernet LAN data link layer processing unit 3, network layer processing unit 4, route storage unit 5 connected to this network layer processing unit 4, buffer 6, frame relay data link processing unit 7 , And each of the frame relay transmission / reception units 8 connected to the frame relay network 10.

As described above, the frame relay router 1 has a role of connecting the Ethernet LAN 9 and the frame relay network 10, divides information into data units called frames, and multiplexes and transmits the data. FIG. 8 is an explanatory diagram showing a protocol configuration of a conventional frame relay router. The frame relay router protocol is IEEE (Institute of Electrical and Electronics Engineers) 802.3 Ethernet LAN.
Physical layer protocol and Ethernet LAN data link layer protocol 11, ITU-T I.S. 431 Recommendation or I.431. 430, the physical layer protocol 12 of the frame relay network 10, ITU (International Telecommunication Union) Q. 92
2 Data link layer protocol 13 of the frame relay network 10 according to the recommendation, IP1 which is a network layer protocol
4 (IP: Internet Protocol). An Internet control message protocol (ICMP) 15 is provided inside the IP 14.

The processing based on the physical layer protocol 12 is performed by the Ethernet LAN data link layer processing section 3, the processing based on the data link layer protocol 13 is performed by the frame relay data link processing section 7, and the network layer protocol. The processing based on 14 is performed by the network layer processing unit 4. FIG. 9 shows a system configuration for connecting a plurality of Ethernet LANs to a frame relay network. Frame relay routers 1a and 1b are connected between the frame relay network 10 and the Ethernet LANs 9a and 9b, respectively. The frame relay routers 1a and 1b have the configuration shown in FIG. 7, and each of the Ethernet LANs 9a and 9b has a plurality of terminal devices 16a,
16b, 16c, 16d are connected.

In such a system, for example, when the frame relay router 1a receives data from the terminal device 16a, the frame relay router 1a sends the received data to the frame relay network 10. This data is received by the frame relay router 1b, and the frame relay router 1b transfers the data to, for example, the terminal device 16c, so that the data can be exchanged between the terminal devices 16a and 16c.

FIG. 10 shows a protocol configuration of a terminal device connected to the Ethernet LAN. The protocols of the terminal devices 16 to 16d connected to the Ethernet LAN 9 are the physical layer protocol and the data link layer protocol 17 of the IEEE802.3 Ethernet LAN, the network layer protocol IP18, and the transport layer protocol such as data retransmission and flow. It is composed of a TCP (Transmission Control Protocol) 19 having a control function and an application 20 which is a protocol of a session layer, a presentation layer and an application layer.

In the frame relay network 10, a state in which the amount of data flowing into this network becomes large and approaches the upper limit of the data transfer performance of the frame relay network 10 is regarded as a congestion state. When the frame relay network 10 detects a congestion state, it notifies each of the frame relay routers 1a and 1b of this congestion state. The notified frame relay routers 1a and 1b request the frame relay network 10 to reduce the amount of data to be transmitted.

FIG. 11 is a flow chart for explaining the operation of the frame relay router when the congestion notification is received from the frame relay network. First, when the frame relay router 1 receives the congestion notification from the frame relay network 10 (step 1101), the transmission data for the frame relay network 10 is stored in the buffer 6 shown in FIG. 7 (step 1102). Then, when the buffer 6 becomes full (step 1103), the frame relay router 1 informs the terminal devices 16a to 16d, which are the data transmission source, that the frame relay network 10 is in the congestion state by the Internet control message protocol (ICMP). It is transmitted using the ICMP message issued by 15 (step 11).
04).

FIG. 12 is a flowchart showing the operation of the terminal device which has received the ICMP message. First, when the terminal device 16 receives an ICMP message from the frame relay router 1 (step 1201), it starts control to stop transmission data by TCP19 which is a transport layer protocol (step 1202). FIG. 13 is an explanatory diagram showing a state in which congestion is generated in the frame relay network and flow control is started in the terminal device. A congestion notification 21 is sent from the frame relay network 10 to the frame relay router 1, and an ICMP message 22 is sent from the frame relay router 1 to the terminal device 16.
After receiving the congestion notification 21 from the frame relay network 10, the frame relay router 1 executes the processing shown in FIG. In addition, in the terminal device 16, after receiving the ICMP message 22 from the frame relay router 1,
The process shown in is executed.

FIG. 14 shows a UDP (User Datagram Prot) that does not have a data retransmission or flow control function in place of TCP.
col: user datagram protocol) is a flowchart showing the operation of the terminal device. First, when receiving the ICMP message 22 from the frame relay router 1 (step 1401), it is determined whether or not the application 20 has a flow control function (step 1402). If there is a flow control function, flow control in the terminal device 16 is started (step 1403). If it is determined in step 1402 that there is no flow control function, the process ends without performing flow control in the terminal device 16 (step 1404).

FIG. 15 is a flowchart showing the operation of the conventional frame relay router after issuing the ICMP message. First, the frame relay router 1 issues an ICMP message 22 to the terminal device 16 (step 1501). Then, it is determined whether or not the flow control is activated in the terminal device 16 (step 1
502). When the operation of the flow control is confirmed, the data received from the terminal device 16 is lost, the buffer 6 is not overwritten, and the data disappearance due to the overwriting does not occur (step 1503). On the other hand, when it is determined in step 1502 that the flow control is inoperative, the received data from the terminal device 16 is not lost and the buffer 6 is overwritten, and the previous data is erased by this overwriting (step 1504).

[0012]

However, in the above-mentioned conventional technique, the terminal device is replaced with TCP, UDP which does not have a data retransmission or flow control function is mounted, and the flow control function is provided in the application protocol. Otherwise, if congestion occurs in the frame relay network, the data will be lost in the frame relay router, and the terminal device does not have the data retransmission function.Therefore, the data lost in the frame relay router will be lost in either the terminal device or the frame relay router. However, there is a problem that the quality of communication is deteriorated because it cannot be reproduced.

Therefore, an object of the present invention is to make the terminal device UD.
An object of the present invention is to provide a frame relay router that implements P and that can prevent the disappearance of data due to network congestion even if the application protocol does not have a flow control function.

[0014]

In order to achieve the above object, the present invention is a frame relay router for transmitting data between a LAN and another network by a frame relay, and detecting a received signal from the LAN and a carrier wave. A jam signal is generated based on an address detection unit that detects a destination address of the data frame from the LAN based on the signal, and a destination address output from the address detection unit and a signal indicating that the buffer is full. And a jam signal sending unit for generating the jam signal.

In this case, the jam signal is sent from the terminal device connected to the LAN to the data addressed to the frame relay router after the congestion notification is received from the other network and the data cannot be stored in the buffer. Is received, the message is transmitted to the LAN.

[0016]

According to the above-mentioned means, the address detecting unit detects the destination address of the LAN, generates the own station address signal based on the detection result, and confirms that this signal and the buffer are full of data. Signal 2
Is input, the jam signal sending unit
A jam signal is sent to N. As a result, the terminal device can store the data to be transmitted to the frame relay router in the Internet protocol, prevent the data from being lost by overwriting the buffer, and improve the communication quality.

The jam signal causes the terminal device to stop the data transmission to the frame relay router and stores the data to be transmitted in the device until the buffer in the frame relay router becomes empty. This prevents the buffer on the frame relay router side from being overwritten,
Data disappearance can be avoided.

[0018]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a block diagram showing an embodiment of a frame relay router according to the present invention. 2 shows a detailed configuration of the destination address detecting unit shown in FIG. 1, and FIG. 3 is a block diagram showing a detailed configuration of the jam signal transmitting unit. In addition,
In FIG. 1, since the same reference numerals are used for the same members as those in FIG. 7, duplicated description will be omitted below.

As shown in FIG. 1, the frame relay router 23 according to the present invention comprises an Ethernet LAN transceiver 2,
In contrast to the configuration of FIG. 7 including the Ethernet LAN data link layer processing unit 3, the network layer processing unit 4, the route storage unit 5, the buffer 6, the frame relay data link processing unit 7 and the frame relay transmission / reception unit 8, the DA detection unit 100 ( The address detection unit) and the jam signal transmission unit 200 are added.

The DA detector 100 is an Ethernet LAN
It is connected to the path between the transmission / reception unit 2 and the Ethernet LAN data link layer processing unit 3 and serves to detect the destination address (DA) of the data frame received from the Ethernet LAN 9. Further, the jam signal sending unit 200 is connected to each of the buffer 6 and the Ethernet LAN transmitting / receiving unit 2, and operates based on the detection result of the DA address detecting unit 200.

As shown in FIG. 2, the DA detector 100 is
A gate circuit 101 that receives the reception signal 24 and the carrier wave detection signal 25, a memory 102 that stores the output signal,
A match determination circuit 104 that is connected to each of the start delimiter holding circuit 103, the memory 102, and the start delimiter holding circuit 103 and outputs an enable signal 105, and a counter circuit 108 that outputs a signal 107 using the enable signal 105 and the received reproduction clock 106 as inputs. , Signal 1
07 and the output signal of the gate circuit 101, the gate circuit 109, the memory 110 in which the output signal of the gate circuit 109 is stored, the own station address holding circuit 111, the outputs of the own station address holding circuit 111 and the memory 110 Each of the coincidence determination circuits 113 that receives the signal and outputs the local address signal 112 is provided.

Next, the operation of the DA detector 100 will be described. The gate circuit 101 monitors the carrier wave detection signal 25 from the Ethernet LAN transmission / reception unit 2 and passes the reception signal 24 from the Ethernet LAN transmission / reception unit 2 only when there is a carrier wave. The received signal 24 is stored in the memory 102. The read output of the memory 102 and the content of the start delimiter holding circuit 103 are compared by the coincidence determination circuit 104, and when they match each other, the enable signal 105 is sent to the counter circuit 108.

The counter circuit 108 has an enable signal 10
After receiving 5, the signal 107 is output for the same length of time as the destination address (DA) by the reception reproduction clock 106 from the Ethernet LAN transmitting / receiving unit 2. This signal 1
The gate circuit 109 allows the output signal of the gate circuit 101 to pass while 07 is at the “H” level. This passing signal is stored in the memory 110. The match determination circuit 113 compares the read output signal of the memory 110 with the contents of the own station address holding circuit 111, and outputs the own station address signal 112 when they match.

Further, as shown in FIG. 3, the jam signal sending unit 200 receives the signal 26 issued when the buffer 6 is full and the own station address signal 112 as input, and a jam signal generating circuit. 202, each of the jam signal generation circuit 202 and the gate circuit 204 connected to the determination circuit 201. In the jam signal transmitting unit 200, the output signal of the determination circuit 201 becomes "H" level when both the signal 26 and the local station address signal 112 are "H" level. The gate circuit 204 keeps the jam signal generating circuit 2 only while this state continues.
The output signal of 02 is output as the jam signal 203.

The frame relay router 2 having the above configuration
The operation of No. 3 will be described with reference to the flowchart of FIG. First, when the frame relay router 23 receives a congestion notification from the frame relay network 10 (step 40
1) Then, the transmission data to the frame relay network 10 is started to be stored in the buffer 6 (step 402). When it is determined that the buffer 6 is full of data (step 403), the frame relay router 23 sends the frame relay network 10 to the terminal device that is the data source.
Is transmitted by outputting an ICMP message issued by the Internet Control Message Protocol (ICMP) 15 (step 404). afterwards,
It is checked whether or not there is data to be transmitted from the terminal device 16 side to the frame relay router 23 (step 405). If there is data destined for the frame relay router 23 (step 406), the jam signal sending unit 200 sends the jam signal 203 to the Ethernet LAN 9 (step 407).

FIG. 5 is an explanatory diagram showing a signal transmission relationship between the frame relay router and the terminal device when there is data addressed to the frame relay router of the present invention from the terminal device after congestion occurs in the frame relay network. . Data frame 2 from the terminal device 16 to the frame relay router 23
7 is sent, and the jam signal 28 is sent from the frame relay router 23 to the terminal device 16.

FIG. 6 is a flow chart showing an operation in the case where the terminal device is mounted with UDP which does not have the function of retransmitting data or flow control, instead of TCP, and the application protocol has no flow control function. First,
Data is transmitted from the terminal device 16 to the frame relay router 23 (step 601). When the terminal device 16 receives the jam signal 28 in response to this data transmission, the terminal device 16 recognizes the unsuccessful data transmission (step 603), and transmits the transmission data to the IP 18 which is a network layer protocol built in the terminal device 16. Store.

As described above, when the buffer 6 is full and the ICMP message is issued and the data addressed to the frame relay router is received from the terminal device on the Ethernet LAN, the jam signal 203 is sent to the Ethernet LAN. However, the means of the present invention for storing data in the terminal device is not limited to the above system, and is also applied to a router other than the frame relay router for connecting the communication network that depends on the terminal for congestion control and the Ethernet LAN. It is possible.

Further, although the LAN is Ethernet in the above description, the present invention is not limited to this, and any LAN may be used. Similarly, the frame relay network 10 may be another network.

[0030]

As described above, according to the present invention, the LAN
A frame relay router for transmitting data between a network and another network by a frame relay, wherein the LAN
Address detecting section for detecting the destination address of the data frame from, and a jam signal transmitting section for generating a jam signal based on the destination address output from the address detecting section and the signal indicating that the buffer is full Since the terminal is provided, the terminal device can save the data to be transmitted to the frame relay router on the terminal side, prevent the data from being lost by overwriting the buffer, and improve the communication quality.

In addition, the jam signal is sent from the terminal device connected to the LAN to the data addressed to the frame relay router after the congestion notification is received from the other network and the data cannot be stored in the buffer. Since it is performed toward the LAN when the data is received, it is possible to prevent the buffer on the frame relay router side from being overwritten and to prevent the disappearance of data.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a frame relay router according to the present invention.

FIG. 2 is a block diagram showing a detailed configuration of a destination address detection unit shown in FIG.

FIG. 3 is a block diagram showing a detailed configuration of a jam signal transmission unit in FIG.

FIG. 4 is a flowchart showing the operation of the frame relay router according to the present invention.

FIG. 5 is an explanatory diagram showing a signal transmission relationship between the frame relay router and the terminal device when there is data addressed to the frame relay router of the present invention from the terminal device after congestion occurs in the frame relay network.

FIG. 6 is a flowchart showing an operation in the case where a terminal device is equipped with UDP without a data retransmission or flow control function instead of TCP and the application protocol does not have a flow control function.

FIG. 7 is a block diagram showing a configuration of a conventional frame relay router.

FIG. 8 is an explanatory diagram showing a protocol configuration of a conventional frame relay router.

FIG. 9 is a connection diagram showing a system configuration in which a plurality of Ethernet LANs are connected to a frame relay network.

FIG. 10 is an explanatory diagram showing a protocol configuration of a terminal device connected to an Ethernet LAN.

FIG. 11 is a flowchart illustrating an operation of a frame relay router when a congestion notification is received from the frame relay network.

FIG. 12 is a flowchart showing an operation in the terminal device that has received the ICMP message.

FIG. 13 is an explanatory diagram showing a state in which congestion has occurred in the frame relay network and flow control is started in the terminal device.

FIG. 14 is a flowchart showing the operation of a terminal device that implements UDP without data retransmission or flow control functions instead of TCP.

FIG. 15 is a flowchart showing the operation of a conventional frame relay router after issuing an ICMP message.

[Explanation of symbols]

 2 Ethernet LAN transmitter / receiver 6 Buffer 9 Ethernet LAN 10 Frame relay network 14, 18 IP 15 Internet control message protocol 23 Frame relay router 100 DA detector 200 Jam signal transmitter

Claims (2)

[Claims] 1. A frame relay router for performing data transmission between a LAN and another network by a frame relay, wherein a destination address of a data frame from the LAN is detected based on a received signal from the LAN and a carrier wave detection signal. A frame relay comprising: an address detection unit; and a jam signal transmission unit that generates a jam signal based on a destination address output from the address detection unit and a signal indicating that the buffer is full. Router. 2. The jam signal is sent from a terminal device connected to the LAN to a frame relay router after receiving a congestion notification from the other network and storing data in the buffer. The frame relay router according to claim 1, wherein when received, the frame relay router is directed to the LAN.