JPH08237293A - Frame relay router - Google Patents

Abstract

PURPOSE: To attain a frame relay router in which no annihilation of data due to superscription occurs by confirming the free capacity of the maximum frame portion of the Ethernet in a buffer, and transmitting a jam signal to an Ethernet LAN. CONSTITUTION: In the frame relay router which is interposed between the Ethernet LAN 17 and a frame relay network 18, and accumulates receiving data from the Ethernet LAN 17 in the buffer 19 when the frame relay network 18 is in a congestive state, when the buffer 19 becomes full, it is judged whether there is a free capacity of the maximum frame portion of the Ethernet LAN in the buffer 19 or not. Also, a jam signal transitting part 93 which judges whether the rate or the quantity of the receive data is the rate or the quantity to meet the acknowledgement information rate CIR of the frame relay network 18 or not, and transits the jam signal to the Ethernet LAN 17 is provided.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a frame relay router for interconnecting a plurality of LAN segments via a frame relay network, and even if the free space of the buffer is less than the amount of received data, data disappears by overwriting. Not about frame relay routers.

[0002]

2. Description of the Related Art FIG. 7 shows the configuration of a conventional frame relay router. The frame relay router 10 includes an Ethernet LAN transmitter / receiver 13 connected to an Ethernet LAN 17 and an Ethernet LAN data link layer processor 12
A network layer processing unit 11, a route storage unit 14,
A buffer 19, a frame relay data link layer processing unit 15, a frame relay transmission / reception unit 16 connected to a frame relay network, and a DA for detecting a destination address (DA) of a data frame received from the Ethernet LAN 17.
It is composed of a detection unit 20 and a jam signal transmission unit 21.

FIG. 8 shows a detailed structure of the DA detection section 20. The DA detection unit 20 includes gate circuits 203 and 209,
Memories 204 and 210 and match determination circuits 206 and 212
A counter circuit 208, a start delimiter holding circuit 205, and an own station address holding circuit 211. The gate circuit 203 is the Ethernet LAN transmission / reception unit 1
3 detects the carrier wave detection signal 202, passes the received signal 201 from the Ethernet LAN transmitter / receiver 13 only when there is a carrier wave, and the coincidence determination circuit 206 causes the memory 20
4 and the contents of the start delimiter holding circuit 205 match, and if they match, the counter circuit 20
8 to the enable signal 214. Counter circuit 2
08 receives the enable signal 214 and then receives and reproduces the clock 207 from the Ethernet LAN transmitter / receiver 13.
Allows the signal 215 to be sent for the same length of time as the destination address.
Is output. The gate circuit 209 can be passed only while the signal 215 is being output. The coincidence determination circuit 212 determines whether or not the contents of the memory 210 and the self-station address holding circuit 211 match, and outputs the self-station address detection signal 213 if they match.

FIG. 9 shows a detailed structure of the jam signal transmitting section 21. The jam signal transmission unit 21 includes a jam signal generation circuit 215 that generates a jam signal, a determination circuit 218, and a gate circuit 216. Gate circuit 21
6 is a signal 21 indicating that the buffer 19 is full
When both 9 and the own station address detection signal 213 are input, the passage is possible. When the gate circuit 216 can pass, the jam signal 217 is output to the Ethernet LAN transmitting / receiving unit 13.

FIG. 10 shows a protocol configuration of the frame relay router. The frame relay router protocol is I
EEE802.3 Ethernet LAN physical layer protocol and data link layer protocol 41, and I.T.I. of ITU-T which is a physical layer protocol of a frame relay network. 431
Recommendation 44 and Q.2 of ITU-T which is a data link layer protocol of a frame relay network. 922 Recommendation 43 and IP42 which is a network layer protocol.
The IP 42 includes an internet control message protocol (ICMP) 45.

FIG. 11 shows the system configuration. 10a and 1
0b is a frame relay router, 18 is a frame relay network, 31a and 31b are terminals connected to the Ethernet LAN 17a, 31c and 31d are Ethernet LAN 17b.
Is a terminal connected to. Conventional frame relay router 1
0a and 10b interconnect two Ethernet LANs 17a and 17b via the frame relay network 18. For example, the frame relay router 10a sends the data received from the terminal 31a to the frame relay network 18, and the frame relay router 10b uses the frame relay network. Net 1
By passing the data received from the terminal 8 to the terminal 31b, the data can be exchanged between the terminals 31a and 31b.

FIG. 12 shows a protocol configuration of an Ethernet LAN terminal connected to the Ethernet LAN. The protocol of the Ethernet LAN terminal is IEEE802.3.
It is composed of a physical layer protocol and a data link layer protocol 41 of the Ethernet LAN, an IP 60 which is a network layer protocol, a transport layer protocol 61, and an application 62 which is a session layer, a presentation layer and an application layer protocol.

Now, in the frame relay network 18,
The amount of data flowing into the frame relay network 18 increases,
A state in which the upper limit of the transfer performance of the frame relay network 18 is approached is called a congestion state. When the frame relay network 18 detects a congestion condition, the frame relay network 10
a, 10b, etc., and the frame relay router 10a,
10b or the like requests the frame relay network 18 to reduce the amount of data to be transmitted.

The operation when the conventional frame relay router receives the congestion notification from the frame relay network will be described with reference to FIG. When the congestion notification is received from the frame relay network 18, the conventional frame relay router 10 first transfers the data transmitted to the frame relay network 18 to the buffer 1
9, when the buffer 19 becomes full, the fact that the frame relay network 18 is in a congested state with respect to the Ethernet LAN terminal 31 which is the data transmission source is included in the IP 42.
(MP) 45 issues and sends an ICMP message. After that, it is checked from the Ethernet LAN terminal 31 whether there is data addressed to the conventional frame relay router 10, and if there is data addressed to the frame relay router 10, a jam signal is sent to the Ethernet LAN 17.

FIG. 14 shows the system operation when congestion occurs. Congestion occurs in the frame relay network 18 and the buffer 1
When the Ethernet LAN terminal 31 has data destined for the conventional frame relay router 10 after 9 is full, a data frame 70 destined for the frame relay router 10 and a jam signal 72 are transmitted on the Ethernet LAN 17.

FIG. 15 shows a processing flow of the Ethernet LAN terminal. The Ethernet LAN terminal 31 is not a TCP having a data resending or flow control function as a transport layer protocol 61, but a UDP not having a data resending or flow control function is mounted, and a flow is applied to an application layer protocol 62. There is no control function. Even if the Ethernet LAN terminal 31 starts data transmission to the frame relay router 10, if the buffer 19 of the frame relay router 10 is full, the Ethernet LAN terminal 31 detects the jam signal 72 issued by the frame relay router 10 and therefore transmits data. Determines that it is unsuccessful, and stores the transmission data inside the IP60 which is a network layer protocol.

[0012]

In the above-mentioned conventional frame relay router 10, when the frame relay network 18 becomes congested and the buffer 19 becomes full, ICMP
A message is issued. On the other hand, Ethernet L
If the AN terminal 31 has TCP as a transport layer protocol 61 having data retransmission and a flow control function, or if the application layer protocol 62 has a flow control function, Ethernet is used when the frame relay network 18 is in a congestion state. The flow control function of the LAN terminal 31 operates.

In the conventional frame relay router 10 described above, the frame relay network 18 becomes congested, the buffer 19 becomes full, and an ICMP message is issued. When the data addressed to the router 10 is received, the frame relay router 10 sends a jam signal 72 onto the Ethernet LAN 17. Therefore, only when the buffer 19 is full, the Ethernet LAN terminal 31
Even if the transport layer protocol 61 is not TCP which has a data retransmission or flow control function but UDP which does not have a data retransmission or flow control function, and the application layer protocol 62 does not have a flow control function. The data is not erased by overwriting the buffer 19.

However, the jam signal 72 is transmitted to the buffer 19
Is sent only when is full, so the case shown in FIG. 16 occurs. That is, if the buffer 19 is not full, but the capacity Y of the free area 19-2 is smaller than the amount X of the data 80 received from the Ethernet LAN terminal 31, the used area 19-1 of the buffer 19 is used.
The data inside is erased by the amount of XY. When data is lost in the frame relay router in this way, communication quality is degraded.

Therefore, an object of the present invention is to solve the above problems and to provide a frame relay router in which data disappearance due to overwriting does not occur even if the free space of the buffer is smaller than the received data amount.

[0016]

In order to achieve the above object, the present invention intervenes between an Ethernet LAN and a frame relay network, and buffers data received from the Ethernet LAN when the frame relay network is in a congestion state. In a frame relay router that accumulates and sends a jam signal to the Ethernet LAN when the buffer is full, when there is received data from the Ethernet LAN after the buffer is full, the maximum number of Ethernet frames in the buffer A jam signal sending unit that sends a jam signal to the Ethernet LAN by judging whether there is a free space and whether or not the speed or quantity of the received data corresponds to the certified information speed CIR of the frame relay network. It is provided.

A buffer free space detector is provided for counting the amount of data transmitted to the frame relay network after the buffer is full and detecting whether or not the free space of the buffer has reached the maximum Ethernet frame. May be.

In advance, the maximum frame of Ethernet is CIR
The data frame interval time is set based on the time that can be transmitted by the Ethernet L within this data frame interval time.
A received data amount detection unit may be provided for detecting that the received data amount is an amount commensurate with the CIR depending on whether the received data is received from the AN.

[0019]

With the above configuration, if the buffer has a free space corresponding to the maximum Ethernet frame, the received data is stored in the buffer. Further, even if the buffer does not have the free space for the maximum Ethernet frame, it is sufficient that the received data has the free space. Therefore, the speed or amount of the received data corresponds to the certified information speed CIR of the frame relay network. Or if it is a quantity, the received data is stored in the buffer.

By counting the amount of data sent to the frame relay network after the buffer is full,
It reliably detects whether the buffer has reached the maximum Ethernet frame capacity.

Since the data frame interval time is set based on the time at which the maximum Ethernet frame can be transmitted by CIR, even if all the received data that is received is the maximum frame, only the amount of received data that matches the CIR is received. A jam signal is reliably sent to the received data that is stored in the buffer and exceeds this.

[0022]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

The operation when the frame relay router of the present invention receives a congestion notification from the frame relay network will be described with reference to FIG. When the congestion notification is received from the frame relay network, the frame relay router of the present invention first starts to store the transmission data to the frame relay network in the buffer according to step 1, and when the buffer is full, it is the data transmission source according to step 2. I indicate that the frame relay network is congested with respect to the Ethernet LAN terminal.
The ICMP message issued by the Internet control message protocol (ICMP) included in P is issued and transmitted. Then, it is checked whether there is data addressed to the frame relay router of the present invention from the Ethernet LAN terminal. If there is data destined for the frame relay router of the present invention, it is checked in step 3 whether or not the buffer is empty for the maximum number of Ethernet frames. It is checked whether the amount of data is less than the amount of data that can be transmitted at the minimum data transmission rate CIR that can be transmitted even at the time of congestion. If the amount of data is less than the amount of data that can be transmitted, the data addressed to the frame relay router of the present invention is received from the Ethernet LAN terminal. If the buffer is not empty for the maximum number of Ethernet frames and if the received data amount is not less than the CIR transmittable data amount, a jam signal is sent to the Ethernet LAN.

FIG. 2 shows the configuration of the frame relay router of the present invention. The frame relay router 90 includes an Ethernet LAN transmitting / receiving unit 13 connected to the Ethernet LAN 17 and an Ethernet LAN data link layer processing unit 12.
A network layer processing unit 11, a route storage unit 14,
A buffer 19, a frame relay data link layer processing unit 15, a frame relay transmission / reception unit 16 connected to a frame relay network, and a DA for detecting a destination address (DA) of a data frame received from the Ethernet LAN 17.
The detector 20 includes a jam signal transmitter 93, a buffer free space detector 91, and a received data amount detector 92. Descriptions of the same reference numerals as those in FIG. 6 are omitted, and the buffer free space detection unit 91, the received data amount detection unit 92, and the jam signal transmission unit 93 according to the present invention will be described in detail.

FIG. 3 shows a detailed structure of the buffer free space detecting section 91. The buffer free space detector 91 uses the OR
It is composed of a gate 131, a flip-flop 132, a gate circuit 134, and a count circuit 135. O
A signal 133 indicating that the buffer 19 is full is input to the R gate 131, and when the buffer 19 is full, the gate circuit 134 can pass through. Gate circuit 1
The transmission data 136 to the frame relay network 18 is input to 34, and if the gate circuit 134 can pass, the amount of transmission data to the frame relay network 18 can be counted by the counting circuit 135. The counting circuit 135 outputs the signal 137 when counting up to the maximum Ethernet frame size. Therefore, when the data of the maximum frame size of Ethernet is transmitted to the frame relay network 18 after the buffer 19 is full, the signal 137 = “1” is output as the output of the buffer free space detection unit 91.
Is output, which means that the free capacity of the buffer 19 has reached the maximum Ethernet frame.

FIG. 4 shows the detailed structure of the received data amount detecting section 92. The reception data amount detection unit 92 uses the OR gate 1
41, 148, 157, flip-flops 142, 14
9, 158, exclusive OR gate 147, gate circuit 1
50, 153, 1-bit memory 151, 154, 15
5, a timer 152, and an AND gate (no reference sign). “1” is written as fixed data in the 1-bit memory 151, and the 1-bit memory 154
"0" is written as fixed data in the
Data is rewritten in the bit memory 155, but "0" is written as an initial value. The timer 152 can set the time to be measured, and the flip-flop 1
It is started by a signal from 49 and outputs an output when a set time has elapsed. Among the signals in each section, the signal 143 indicates that the buffer 19 is full, the signal 144 indicates that the congestion state of the frame relay network 18 has been released, and the signal 145 indicates the Ethernet LAN.
It shows that the data received from 17 is addressed to its own station,
A signal 146 indicates that the data received from the Ethernet LAN 17 after the buffer 19 is full is addressed to itself, a signal 156 is an output of the received data amount detection unit 92, and a signal 159 is one Ethernet data frame. Signal 160 indicates the end of reception of the
The signal 161 indicates that the set time has elapsed in the timer 152.

Here, the set time T1 of the timer 152 is set so as to satisfy 1518 / T1 <CIR (1). This is because the maximum frame size of Ethernet is 1518 bytes, and even if all received frames are assumed to have the maximum frame size, the left side of Expression (1) does not exceed CIR. Yes, it is used as the data frame interval time. If the CIR is 64 kbps, T1 is about 0.19s. By setting the data frame interval time, it is checked whether the amount of data received from the Ethernet LAN 17 and stored in the buffer 19 exceeds the amount of data extracted from the buffer 19 and transmitted to the frame relay network 18. It The signal 156 = “1” output from the reception data amount detection unit 92 indicates that the reception data amount from the Ethernet LAN 17 is equal to or less than the transmission data amount at the minimum data transmission rate CIR which can be transmitted even in the congestion state in the frame relay network 18. Indicates that there is.

FIG. 5 shows a detailed configuration of the jam signal transmitting section 93. The jam signal transmission unit 93 includes a jam signal generation circuit 215, a determination circuit 218, a gate circuit 216,
And an OR gate 170. Signal 219 indicates that buffer 19 is full. A signal 137 is an output of the buffer free space detection unit 91, and when it is "1", indicates that the free space of the buffer 19 has reached the maximum Ethernet frame. The signal 156 is the output of the received data amount detection unit 92, and when it is “1”, the Ethernet LA
The data transmission rate CI at which the amount of data received from N17 can be transmitted at the minimum in the congestion state in the frame relay network 18.
It indicates that the amount of data transmitted in R is less than or equal to the amount. Signal 213
Is a local station address detection signal output from the DA detection unit 20. The signal 217 output from the jam signal transmission unit 93 is a jam signal. The jam signal transmission unit 93 receives the local station address detection signal 213 = “1”, and
When the R gate 170 outputs “1”, the gate circuit 216 is allowed to pass and the jam signal 217 is output to the Ethernet LAN transmitting / receiving unit 13.

Next, the operation of the embodiment will be described.

In FIG. 2, when the frame relay network 18 is in a congestion state, the frame relay network 18 notifies the frame relay router 90 of congestion so as to reduce the amount of transmission data. Frame relay router 90 that received the congestion notification
Starts accumulating the received data from the Ethernet LAN 17 in the buffer 19 and limits the speed of transmitting the contents of the buffer 19 to the frame relay network 18 to the certified information speed CIR. Certified information rate CIR is the frame relay network 1
Reference numeral 8 indicates the minimum data transmission rate that can be transmitted even during congestion. After the buffer 19 is full, the buffer free space detector 91, the received data amount detector 92, and the jam signal transmitter 93 perform the following operations, respectively.

When the signal 133 indicating that the buffer 19 is full is input to the buffer free space detector 91 of FIG. 3, the count circuit 135 causes the frame relay network 18 to operate.
When the data for the maximum Ethernet frame size is transmitted to the frame relay network 18, a signal 137 = "1" is output. As a result, the jam signal transmitting unit 93 is notified that the free space of the buffer 19 has reached the maximum Ethernet frame.

In the received data amount detection unit 92 of FIG. 4, when the data received from the Ethernet LAN 17 is addressed to itself after the buffer 19 is full, the signal 146 becomes "1". This signal 146 and 1-bit memory 155
When the output 160 of the signal 160 is calculated by the exclusive OR gate 147 and the result is "1", the output Q of the flip-flop 149 becomes "1".
50 can be passed, and "1" is written in the 1-bit memory 155. When the set time T1 in the timer 152 elapses after "1" is written in the 1-bit memory 155,
Since the signal 161 is output, the gate circuit 153 can pass through and "0" is written in the 1-bit memory 155. Therefore, the signal 160, which is the output of the 1-bit memory 155, keeps "1" until the set time T1 elapses, and during that time, the signal 146 becomes "1" because the data received from the Ethernet LAN 17 is addressed to itself. However, the output of the exclusive OR gate 147 is "0".

If the signal 156 output from the received data amount detection unit 92 is "1", the received data amount from the Ethernet LAN 17 is at the minimum data transmission rate CIR that can be transmitted even in the congestion state in the frame relay network 18. Indicates that it is less than or equal to the amount of data to be transmitted. On the contrary, if the signal 156 is "0", it indicates that the amount of data received from the Ethernet LAN 17 exceeds the amount of data to be transmitted at the minimum data transmission rate CIR that can be transmitted even in the congestion state in the frame relay network 18. .

In the jam signal sending unit 93 of FIG. 5, a signal 219 indicating that the buffer 19 is full and a signal 137 = "0" indicating that the free capacity of the buffer 19 is not equal to the maximum Ethernet frame. And a signal 156 = "0" indicating that the amount of received data from the Ethernet LAN 17 exceeds the amount of transmitted data at the minimum data transmission rate CIR that can be transmitted even in the congestion state in the frame relay network 18. Logically ORed at 170. On the other hand, if the frame arriving at the Ethernet LAN transmission / reception unit 13 is addressed to the frame relay router 90, the DA detection unit 20 outputs the local station address detection signal 213. At this time, if the output of the OR gate 170 is “1”, the jam signal 217 is output to the Ethernet LAN transmitting / receiving unit 13.

FIG. 6 shows the buffer free capacity and the amount of received data over time. Ethernet LAN1
Each terminal connected to 7 transmits a data frame by sharing the transmission rate defined by the transmission path. After the buffer is full, the frame relay router determines whether or not to send a jam signal for these data frames based on the data frame interval time when the buffer does not have the free space for the maximum Ethernet frame. That is,
If a data frame arrives within the data frame interval time, a jam signal is transmitted. As a result, the transmission speed of the received data is adjusted. That is, as shown in FIG. 6, from the time point 601 when the buffer is full to the time point 602 when the buffer has a free space corresponding to the maximum Ethernet frame, the buffer free space has a slope straight line 603 equal to the certified information rate CIR. Change along. Further, after the time 602 when the free space for the maximum Ethernet frame is formed in the buffer, the received data amount changes along a straight line 604 having an inclination equal to the certified information rate CIR even at the maximum. Therefore, the Ethernet LAN terminal 31
Even if the transport layer protocol 61 is not TCP which has a data retransmission or flow control function but UDP which does not have a data retransmission or flow control function, and the application layer protocol 62 does not have a flow control function. Since the frame relay router accepts data according to the free space of the buffer, the disappearance of data is prevented.

Although the present invention uses the frame relay router connected to the frame relay network as an embodiment, the present invention is applicable not only to the frame relay network but also to a router connecting an Ethernet LAN to a communication network that depends on terminals for congestion control. .

[0037]

The present invention exhibits the following excellent effects.

(1) Since no data disappears due to overwriting, communication quality does not deteriorate.

[Brief description of drawings]

FIG. 1 is an operation flow chart of a frame relay router showing an embodiment of the present invention.

FIG. 2 is an internal configuration diagram of a frame relay router of the present invention.

FIG. 3 is a circuit diagram of a buffer free space detection unit of the present invention.

FIG. 4 is a circuit diagram of a received data amount detection unit of the present invention.

FIG. 5 is a circuit diagram of a jam signal transmission unit of the present invention.

FIG. 6 is a diagram showing the elapsed time of the buffer free capacity and the amount of received data in the frame relay router of the present invention.

FIG. 7 is an internal configuration diagram of a conventional frame relay router.

FIG. 8 is a circuit diagram of a DA detection unit.

FIG. 9 is a circuit diagram of a conventional jam signal transmission unit.

FIG. 10 is a protocol configuration diagram showing a protocol configuration of a frame relay router.

FIG. 11 is a system configuration diagram using a frame relay router.

FIG. 12 is a protocol configuration diagram showing a protocol configuration of an Ethernet LAN terminal.

FIG. 13 is an operational flowchart of a conventional frame relay router.

FIG. 14 is a system configuration diagram showing a system operation when congestion occurs.

FIG. 15 is a flowchart of processing of the Ethernet LAN terminal.

FIG. 16 is a diagram showing a conventional buffer and received data.

[Explanation of symbols]

 17 Ethernet LAN 18 Frame Relay Network 19 Buffer 91 Buffer Free Space Detection Unit 92 Received Data Amount Detection Unit 93 Jam Signal Transmission Unit

Claims (3)

[Claims] 1. An intermediary between an Ethernet LAN and a frame relay network for accumulating received data from the Ethernet LAN in a buffer when the frame relay network is in a congested state, and for jamming to the Ethernet LAN when the buffer is full. When there is received data from the Ethernet LAN after the above buffer is full in the frame relay router that sends out, whether or not there is free space for the maximum Ethernet frame in the above buffer, and the speed or amount of received data. Is provided with a jam signal sending unit for sending a jam signal to the Ethernet LAN by determining whether or not the speed or the amount is suitable for the certified information speed CIR of the frame relay network. 2. A buffer free space detection unit that counts the amount of data transmitted to the frame relay network after the buffer is full and detects whether the free space in the buffer has reached the maximum Ethernet frame. The frame relay router according to claim 1, further comprising: 3. The CI maximum Ethernet frame is set in advance.
A data frame interval time based on the time that can be transmitted by R is set, and it is detected whether the received data amount is an amount commensurate with CIR depending on whether or not the received data is received from the Ethernet LAN within this data frame interval time. The frame relay router according to claim 1, further comprising a received data amount detection unit.