JP2003273915A - Shaping circuit and method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a shaping circuit and a method capable of transmitting pieces of burst data by smoothing them even when a data stream consisting of pieces of data with infinite length, the packet length of which is not constant as an IP packet is received in burst. <P>SOLUTION: A transmission interval value between an IP packet transmitted immediately before and an IP packet to be transmitted next is preset according to the packet length, the transmission interval value and the packet length are recorded in a transmission interval value table 7 before receiving the IP packets. The transmission interval value according to the packet length of the received IP packet is compared with count CNT inputted from a counter and when the transmission interval value is in a prescribed state, the IP packet to be transmitted next, which is recorded in a buffer memory 3 is read and transmitted from a transmission terminal 12 after elapse of the transmission interval value. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a shaping circuit and a method for shaping a received packet and transmitting it, and more particularly to a shaping circuit and a method for shaping an IP packet received in burst and transmitting it.

[0002]

2. Description of the Related Art Recently, a plurality of IPs (Internet Protoco
l) Packets are transmitted and these plural IPs are transmitted
A service for time-division-multiplexing packets with one multiplexer and delivering the generated signal to a network is under study. For example, video data read from a disc or the like is transmitted as a plurality of IP packets, and the plurality of transmitted IP packets are time-division multiplexed by one multiplexer, and a large number of video sources are time-division multiplexed. A study is underway on a service for generating such a signal and delivering it to the network.

A signal read from a disk or the like as described above and transmitted is often bursty. In a multi-channel multiplexer that multiplexes multiple channels for such signals, data must be discarded if bursty signals from multiple channels are concentrated unless an extremely large capacity buffer memory is prepared. There was a problem that it would end up. In order to avoid this problem, it is necessary to smooth the bursty data of each channel input to the multi-channel multiplexer to eliminate the burstiness.

As a method for smoothing bursty data, ATM (Asynchronous Transfer) has been used conventionally.
Mode) ATM cell shaping (ce)
ll shaping) method has been put to practical use. But ATM
Since the cell (packet) has a fixed length of 53 bytes, I
There is a problem in that the ATM cell shaping method cannot be applied to a data stream composed of data of an indefinite length whose packet length is not constant like P packets.

[0005]

Therefore, the object of the present invention is to solve the above problems.
A shaping circuit and method capable of smoothing and transmitting bursty data even when receiving a data stream composed of data of indefinite length whose packet length is not constant like P packets. To provide.

[0006]

A shaping circuit according to the present invention is a shaping circuit for shaping a received packet and transmitting it, and a transmission interval value between a packet transmitted immediately before and a packet transmitted next. A setting circuit for setting the transmission interval value according to the length of the packet transmitted immediately before, and the transmission interval value set by the setting circuit and the length of the packet corresponding to the transmission interval value are recorded in the transmission interval value table. A table recording circuit, a counter that is reset each time a packet is transmitted and starts counting from a predetermined value, a packet length detection circuit that detects the length of a received packet, and a length that is detected by the packet length detection circuit. A buffer memory in which the packets are recorded in the order in which the packets are received, and a transmission time based on the packet length detected by the packet length detection circuit. A table reading circuit that reads out the transmission interval value according to the length of the packet from the value table and records the transmission interval value in the transmission interval value memory in the order of reception of the packet; and a table reading circuit immediately before inputting from the transmission interval value memory. A comparison circuit that compares the transmission interval value according to the transmitted packet with the count input from the counter and issues a transmission instruction for the packet to be transmitted next in the case of a predetermined state, and the comparison circuit. When the transmission instruction of the packet to be transmitted next is issued, the packet to be transmitted next recorded in the buffer memory is transmitted, the counter is reset to a predetermined value, and the length of the packet transmitted immediately before is transmitted. And a packet transmission processing circuit for inputting a transmission interval value corresponding to the transmission interval value from the transmission interval value memory to the comparison circuit. Counting up, the predetermined state in the comparison circuit is that the transmission interval value corresponding to the packet transmitted immediately before input from the transmission interval value memory and the count input from the counter are equal. Characterize.

Here, in the shaping circuit of the present invention, the comparison circuit issues a transmission instruction of a packet to be transmitted next when the count input from the counter is in a predetermined state, and the packet transmission processing circuit When the comparison circuit instructs to transmit the packet to be transmitted next, the packet to be transmitted next recorded in the buffer memory is transmitted, and the counter is reset to a predetermined value and transmitted immediately before. A transmission interval value according to the length of the packet transmitted from the transmission interval value memory to the counter, the counter counting down from the transmission interval value input from the transmission interval value memory, The predetermined state in can be a state in which the count input from the counter becomes zero.

In the shaping circuit of the present invention, the transmission interval value C (count) is the length of the packet to be transmitted next, L (Byte), the frequency of the counter is f (Hz), and the shaping rate. Is set to D (bits / sec),

[0009]

[Equation 1]

It can be the smallest integer that satisfies.

The shaping method of the present invention is a shaping method for shaping a received packet and transmitting it, wherein a transmission interval value between a packet transmitted immediately before and a packet transmitted next is transmitted immediately before. The transmission interval value and the length of the packet to be transmitted next are recorded in advance in the transmission interval value table, the length of the received packet is detected, and Is recorded in the buffer memory in the order of reception of the packet, and the transmission interval value corresponding to the length of the packet is read from the transmission interval value table based on the length of the detected packet, and the transmission is performed in the order of reception of the packet. The interval value is recorded in the transmission interval value memory, and the transmission interval value corresponding to the packet transmitted immediately before input from the transmission interval value memory and the packet Is reset every signal by comparing the count input from the counter to start counting from a predetermined value, when a predetermined state, said buffer
It is characterized in that the packet to be transmitted next recorded in the memory is transmitted.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, each embodiment of the present invention will be described in detail with reference to the drawings.

Embodiment 1. FIG. 1 illustrates a block diagram of a shaping circuit according to a first embodiment of the present invention. In FIG. 1, reference numeral 20 is the entire shaping circuit, reference numeral 1 is a receiving terminal for receiving an IP packet Pi (for example, i is 1 to an appropriate integer n), and 12 is a transmission for transmitting the shaped IP packet Pi. Terminal, 2
Is a packet length detection circuit for detecting the length (hereinafter, referred to as “packet length”) Li of the IP packet Pi received at the receiving terminal 1. The IP packet Pi has a payload part which is a field for transmitting actual data, a header part including the packet length Li of the IP packet Pi and a destination address or a source address, and a trailer part mainly used for error detection. The packet length detection circuit 2 can detect the packet length Li of the IP packet Pi from the header part.

Next, reference numeral 3 is a packet length detection circuit 2.
Receives the IP packet Pi that has detected the packet length Li.
Shinshun (eg P₁, P_Two,. ． ． ) Recorded buffer
-It is a memory. The buffer memory 3 is, for example, the first-in first-out destination.
Uses a first-in-first-out (FIFO) memory
Can be The buffer memory 3 stores the packet Pi
While sequentially storing the packet transmission processing circuit described later.
Sequential acquisition of stored packets Pi according to instructions from 11
Send out. The code 5 is transmitted from the transmission terminal 12 immediately before.
IP packet Pi and I to be transmitted next from the transmission terminal 12
P packet P_{i +1}Transmission interval value (or shape
IP packet P transmitted immediately before Ci.
A setting circuit for setting the packet length Li of i, 6 is a setting circuit
The transmission interval value Ci set by the constant circuit 5 and this transmission interval value
The packet length Li of the IP packet Pi corresponding to Ci
A table recording circuit for recording in the transmission interval value table 7.
It Here, the transmission interval value table 7 is the IP packet Pi.
Address addr uniquely corresponding to the packet length Li of
(Li) is the transmission interval value corresponding to the packet length Li
Ci is expanded (recorded) in a table format. Reference numeral 4 is a
Packet of the IP packet Pi detected by the packet length detection circuit 2.
Of the transmission interval value table 7 that uniquely corresponds to the packet length Li.
An address addr (Li) is generated and this address ad
Transmission interval value C according to packet length Li from dr (Li)
i is read, and the reception order of IP packets Pi (for example,
P₁, P_Two,. ． ． ) In the transmission interval value Ci
It is a table reading circuit for recording in the value memory 8. here
In the transmission interval value memory 8, the reception order of IP packets Pi
(Eg P₁, P_Two,. ． ． ) Corresponding to the transmission interval value
(Eg C ₁, C_Two,. ． ． ) Is recorded.

Next, reference numeral 9a is a counter that operates at a predetermined frequency f (Hz) to control the transmission interval for transmitting the IP packet Pi from the transmission terminal 12. The counter 9a is reset by the packet transmission processing circuit 11 described later each time the IP packet Pi is transmitted from the transmission terminal 12, and starts counting CNT from a predetermined value. Count C
NT counts up from 0, for example. Count CN
T can be used as a timer indicating the time elapsed since the IP packet P _i-1 was transmitted immediately before. Code 1
For 0, the transmission interval value Ci corresponding to the IP packet Pi transmitted immediately before input from the transmission interval value memory 8 and the count CNT input from the counter 9a are compared, and a predetermined state, for example, both are equal. In this case, the signal SD is sent to the packet transmission processing circuit 11 which will be described later, and I is transmitted next.
It is a comparison circuit for instructing the transmission of the P packet P _{i + 1} .
Reference numeral 11 indicates that when the signal SD is transmitted from the comparison circuit 10 and the transmission instruction of the IP packet P _{i + 1} to be transmitted next is performed, the signal Send is transmitted to the buffer memory 3 and is transmitted next after being recorded in the buffer memory 3. IP packet P _{i +1}
Is a packet transmission processing circuit for transmitting from the transmission terminal 12. The packet transmission processing circuit 11 then moves to the counter 9a.
To reset the count CNT to a predetermined value, for example 0. Along with this, the packet transmission processing circuit 11 sends a signal Request to the transmission interval value memory 8 and sends the transmission interval value Ci corresponding to the length Li of the IP packet Pi transmitted immediately before from the transmission interval value memory 8 to the comparison circuit 10. Input.

Hereinafter, the shaping pin according to the first embodiment
The operation of the circuit 20 will be described with reference to FIG. IP packet
Setting circuit 5 immediately before receiving the transmission terminal 1
2 and the next transmission terminal 12
IP packet P sent from _{i + 1}Transmission interval value C between
i is set according to the packet length Li of the IP packet Pi.
Keep it. The table recording circuit 6 is set by the setting circuit 5.
The transmission interval value Ci and the IP corresponding to this transmission interval value Ci
The packet length Li of the packet Pi and the transmission interval value table
Record at 7.

When the IP packet Pi is received from the receiving terminal 1, the packet length detection circuit 2 detects the packet length Li of the IP packet Pi from the header part of the IP packet Pi. The IP packet Pi whose packet length Li is detected by the packet length detection circuit 2 is received in the buffer memory 3 in the order of reception.
To record. The packet length Li of the IP packet Pi detected by the packet length detection circuit 2 is sent to the table reading circuit 4.

The table read circuit 4 has a packet length Li of the IP packet Pi sent from the packet length detection circuit 2.
Address of the transmission interval value table 7 that uniquely corresponds to
Generates dr (Li). The table reading circuit 4 reads the transmission interval value Ci corresponding to the packet length Li from the address addr (Li) of the transmission interval value table 7 and outputs the IP
The transmission interval value Ci is recorded in the transmission interval value memory 8 in the order in which the packets Pi are received.

After the packet Pi is transmitted from the transmission terminal 12, the counter 9a is reset by the packet transmission processing circuit 11 to count from a predetermined value (for example, 0) CNT.
To start. This count CNT is sent to the comparison circuit 10. Along with this, the packet transmission processing circuit 11 causes the transmission interval value Ci corresponding to the length Li of the transmitted IP packet Pi.
Is input to the comparison circuit 10 from the transmission interval value memory 8.
The comparison circuit 10 compares the count CNT input from the counter 9a with the transmission interval value Ci input from the transmission interval value memory 8 and sends a signal to the packet transmission processing circuit 11 in a predetermined state, for example when both are equal. SD is sent and an instruction to send the IP packet P _{i + 1} to be sent next is issued. The packet transmission processing circuit 11 sends a signal Se to the buffer memory 3.
nd is sent, and the IP packet P _{i + 1} to be transmitted next recorded in the buffer memory 3 is transmitted from the transmission terminal 12.

After the transmission of the packet P _{i + 1} is completed, the packet transmission processing circuit 11 sends a signal Reset to the counter 9a.
To reset the count CNT to a predetermined value, for example 0. Along with this, the IP packet P transmitted immediately before
_The transmission interval value C _{i + 1} according to the length L _{i + 1} of _{i + 1} is input from the transmission interval value memory 8 to the comparison circuit 10. Hereinafter, in the same manner as described above, the comparison circuit 10 causes the counter circuit 9a to operate.
From the transmission interval value memory 8 and the transmission interval value C _{i + 1} input from the transmission interval value memory 8 are compared. As a result of the comparison, when a predetermined state, for example, when both are equal, the packet transmission processing circuit 11 sends a signal Send to the buffer memory 3 and transmits the IP packet P _{i + 2} recorded in the buffer memory 3 to be transmitted next to the transmission terminal 12 To send from.

The above-mentioned transmission interval value Ci (count value) is
The length Li (Byt of the IP packet Pi transmitted immediately before
e), when the frequency of the counter 9a is f (Hz) and the shaping rate is D (bits / sec),

[0022]

[Equation 2]

It can be the smallest integer that satisfies.
Here, it is assumed that the count CNT of the counter 9a is incremented from 0. When the frequency f is increased, the transmission interval value Ci is also increased, and the shaping rate can be set finely. Since the maximum packet length Li is 1500 Bytes, the size of the transmission interval value table 7 for one channel only needs to be about 1500 Bytes.

2A and 2B are timing charts of the shaping circuit 20 according to the first embodiment of the present invention. 2A shows the received IP packet Pi (i = 0 to 5) at the receiving terminal 1, and FIG. 2B shows the corresponding transmission packet Pi (i = 0 to 0) at the transmitting terminal 12.
5) is shown. In FIGS. 2A and 2B, Li (i = 0 to 0)
5) is the packet length recorded in the header portion of each IP packet Pi (i = 0 to 5). Ci (i = 1 to 4) is the transmission interval value (count value) represented by the above equation (1). As shown in FIG. 2 (A), for example, IP packet _{P 1} is an IP packet _{P 2} is received at time _{t i n1} is received at time _{t in2.} As shown in FIG. 2 (B), the IP packet P ₁ is transmitted at time t _out1 ,
The IP packet P ₂ has the transmission interval value C ₁ from the time t _out1.
Only after the time t _out2 (= t _out1 +
C ₁ ). The same applies to the other packets Pi.

As described above, according to the first embodiment, before receiving the IP packet Pi, the setting circuit 5 transmits between the IP packet Pi transmitted immediately before and the IP packet P _{i +1} to be transmitted next. The interval value Ci is set according to the packet length Li of the IP packet Pi, and the transmission interval value Ci and the packet length Li are recorded in the transmission interval value table 7. The packet length detection circuit 2 receives the received IP packet Pi
The packet length Li of the packet is detected and the IP packet Pi is recorded in the buffer memory 3 in the order of reception. The table reading circuit 4 reads the transmission interval value Ci corresponding to the packet length Li from the transmission interval value table 7 based on the detected packet length Li, and the transmission interval value Ci in the reception interval of the IP packet Pi in the transmission interval value memory 8 Record it in. The counter 9a is reset each time the IP packet Pi is transmitted and starts counting from a predetermined value. The comparison circuit 10 compares the transmission interval value Ci corresponding to the IP packet Pi transmitted immediately before input from the transmission interval value memory 8 with the count CNT input from the counter 9a, and is in a predetermined state. In this case, the packet transmission processing circuit 11 is instructed to transmit the IP packet P _{i + 1} to be transmitted next recorded in the buffer memory 3. As a result, the packet transmission processing circuit 11 can transmit the IP packet P _{i + 1} to be transmitted next recorded in the buffer memory 3 after the transmission interval value Ci has passed from the read transmission terminal 12. As described above, even when the data stream Pi (i = 1 to n), which is composed of data of an indefinite length in which the packet length Li is not constant like the IP packet Pi, is received, these burst-like data are transmitted. Data can be smoothed and transmitted.

Embodiment 2. In the first embodiment, the shaping 20 using the counter 9a that counts up is described. In the second embodiment, the shaping circuit 21 in the case of using the counter 9b for down counting will be described.

FIG. 3 is a block diagram of a shaping circuit according to the second embodiment of the present invention. In FIG. 3, the parts denoted by the same reference numerals as those in FIG. The shaping circuit 21 of the second embodiment differs from the shaping circuit 20 of the first embodiment in that the counter 9b performs down-counting.

The transmission interval value memory 8 according to the second embodiment is
When the signal Request is transmitted from the packet transmission processing circuit 11, the transmission interval value Ci corresponding to the length Li of the IP packet Pi transmitted immediately before is transmitted to the counter 9b. Counter 9
When the Reset signal is sent from the packet transmission processing circuit 11, b is the transmission interval value Ci sent from the transmission interval value memory 8.
Start down counting from. The comparator circuit 10 is configured such that the count CNT input from the counter 9b is in a predetermined state,
For example, when it is 0, the IP packet P to be transmitted next is
The transmission instruction of _{i + 1} is sent to the packet transmission processing circuit 11.
When the comparison circuit 10 instructs the packet transmission processing circuit 11 to transmit the IP packet P _{i + 1} to be transmitted next, the packet transmission processing circuit 11 records the IP to be transmitted next recorded in the buffer memory 3.
The packet P _{i +1} is transmitted, the counter 9b is reset to a predetermined value, and the transmission interval value C corresponding to the packet length L _{i + 1} of the IP packet P _{i + 1} transmitted immediately before is transmitted.
_{i + 1} is input from the transmission interval value memory 8 to the counter 9b.

The timing chart of the shaping circuit 21 of the second embodiment is similar to the timing chart of the shaping circuit 20 of the first embodiment shown in FIG. The shaping circuit 20 shown in FIG.
While the transmission interval value Ci shown in FIG. 2 is up-counted from 0 (to Ci), the shaping circuit 21 shown in FIG.
The transmission interval value Ci shown in 1 is down-counted to 0.

As described above, according to the second embodiment, even when the counter 9a in the shaping circuit 20 of the first embodiment is replaced with the counter 9b for down counting, the same as in the first embodiment. Even when a data stream Pi (i = 1 to n) composed of data of indefinite length whose packet length Li is not constant is received, these burst-like data can be smoothed and transmitted. .

[0031]

As described above, according to the shaping circuit and method 1 of the present invention, before receiving the IP packet, the setting circuit 5 previously transmits the IP packet Pi transmitted immediately before and the IP packet transmitted next. The transmission interval value Ci between the packet P _{i + 1} and the packet P _{i + 1} can be set according to the packet length Li of the IP packet Pi, and the transmission interval value Ci and the packet length Li can be recorded in the transmission interval value table 7. The packet length detection circuit 2 detects the packet length Li of the received IP packet Pi and records this IP packet Pi in the buffer memory 3 in the order of reception. Table reading circuit 4
Reads out the transmission interval value Ci corresponding to the packet length Li from the transmission interval value table 7 based on the detected packet length Li, and transmits the transmission interval value Ci in the order of reception of the IP packets Pi.
Is recorded in the transmission interval value memory 8. The counter 9a is reset each time the IP packet Pi is transmitted and starts counting from a predetermined value. The comparison circuit 10 receives the IP packet P transmitted immediately before being input from the transmission interval value memory 8.
The transmission interval value Ci corresponding to i is compared with the count CNT input from the counter 9a, and if it is in a predetermined state, the next transmission I recorded in the buffer memory 3 is transmitted.
An instruction to transmit the P packet P _{i + 1} is sent to the packet transmission processing circuit 11. As a result, the packet transmission processing circuit 1
1 is recorded in the buffer memory 3 and then transmitted I
The P packet P _{i + 1} can be transmitted after the transmission interval value Ci has passed from the read transmission terminal 12. As described above, even when the data stream Pi (i = 1 to n) composed of data of indefinite length whose packet length Li is not constant like the IP packet Pi is received,
These bursty data can be smoothed and transmitted.

[Brief description of drawings]

FIG. 1 is a block diagram of a shaping circuit according to a first embodiment of the present invention.

FIG. 2 is a shaping circuit 2 according to the first embodiment of the present invention.
It is a figure which shows the timing chart of 0.

FIG. 3 is a block diagram of a shaping circuit according to a second embodiment of the present invention.

[Explanation of symbols]

1 reception terminal, 2 packet length detection circuit, 3 buffer memory, 4 table read circuit, 5 setting circuit, 6 table recording circuit, 7 transmission interval value table, 9a, 9b counter, 10 comparison circuit, 1
1 packet transmission processing circuit, 12 transmission terminals, 2
0,21 shaping circuit.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Eiko Sone             12-12 Dogenzaka, Shibuya-ku, Tokyo Shibuya             Mark City Entiti Electronic             Cos Co., Ltd. (72) Inventor Reiji Furuya             12-12 Dogenzaka, Shibuya-ku, Tokyo Shibuya             Mark City Entiti Electronic             Cos Co., Ltd. F-term (reference) 5K030 HA08 KA03 LC02 MB11 MB12

Claims (4)

[Claims] 1. A shaping circuit for shaping and transmitting a received packet, wherein a transmission interval value between a packet transmitted immediately before and a packet to be transmitted next is a length of the packet transmitted immediately before. A setting circuit for setting the transmission interval value set by the setting circuit and a packet length corresponding to the transmission interval value in a transmission interval value table, and a reset circuit for each packet transmission A counter that starts counting from a predetermined value, a packet length detection circuit that detects the length of the received packet, and a buffer that records the packets whose length has been detected by the packet length detection circuit in the order of reception of the packet. A memory and a transmission corresponding to the length of the packet from the transmission interval value table based on the length of the packet detected by the packet length detection circuit A table reading circuit for reading the transmission interval value and recording the transmission interval value in the transmission interval value memory in the order of reception of the packet; and a transmission interval value corresponding to the packet transmitted immediately before input from the transmission interval value memory. A comparison circuit that compares the count input from the counter and issues a transmission instruction for the packet to be transmitted next when in a predetermined state, and a transmission instruction for the packet to be transmitted next by the comparison circuit. In this case, the packet to be transmitted next recorded in the buffer memory is transmitted, the counter is reset to a predetermined value, and the transmission interval value according to the length of the packet transmitted immediately before is set to the transmission interval. A packet transmission processing circuit for inputting from a value memory to the comparison circuit, wherein the counter counts up from a predetermined value, Constant state, shaping circuit, characterized in that the counting said inputted transmission interval value corresponding to the transmitted packets immediately before is input from the transmission interval value memory and from said counter is equal state. 2. The shaping circuit according to claim 1, wherein the comparison circuit issues a transmission instruction of a packet to be transmitted next when the count input from the counter is in a predetermined state, and the packet transmission processing circuit. When the comparison circuit issues a transmission instruction for the packet to be transmitted next, causes the packet to be transmitted next recorded in the buffer memory to be transmitted, resets the counter to a predetermined value, and immediately before A transmission interval value according to the length of a transmitted packet is input from the transmission interval value memory to the counter, the counter counting down from the transmission interval value input from the transmission interval value memory, and the comparison The predetermined state in the circuit is a state in which the count input from the counter is zero. Vaping circuit. 3. The shaping circuit according to claim 1, wherein the transmission interval value C (count) is a length of a packet to be transmitted next is L (Byte), a frequency of the counter is f (Hz), Set the shaping rate to D (bits / se
c), the shaping circuit is a minimum integer that satisfies C ≧ 8 × L × f / D. 4. A shaping method for shaping and transmitting a received packet, wherein a transmission interval value between a packet transmitted immediately before and a packet transmitted next is a length of a packet transmitted immediately before. The transmission interval value and the length of the packet transmitted immediately before are recorded in advance in the transmission interval value table, the length of the received packet is detected, and the packet is While recording in the buffer memory in the order of reception,
The transmission interval value corresponding to the length of the packet is read from the transmission interval value table based on the detected packet length, and the transmission interval value is recorded in the transmission interval value memory in the order of reception of the packet. The transmission interval value corresponding to the packet transmitted immediately before input from the transmission interval value memory is compared with the count input from the counter that is reset every time the packet is transmitted and starts counting from a predetermined value, A shaping method, wherein the packet to be transmitted next recorded in the buffer memory is transmitted when the packet is in a predetermined state.