JPH02192246A - Routing method and node circuit for burst data transfer - Google Patents

Abstract

PURPOSE:To minimize the abort of data due to the overflow of a buffer in a buffer in a communication processing node and to improve the communication quality by updating an effective band used through the observation of actual communication. CONSTITUTION:A traffic control means 240 introduces the band of an operating output line as to a call based on the operating band information of a terminal equipment sending a packet in the case of setting a packet call from an input line. A switching means 150, in the case of setting a packet call, transfers a packet to an output line in response to the band introduced by the traffic control means 240. Moreover, actual traffic is observed from traffic observing means (12-1)-(12-m) as to the input line to correct the residual band of the output line depending on the result of observation. Thus, the overflow of a buffer in the switching means 150 is minimized and the communication quality and the throughput of the communication processing node are improved.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a routing method and communication processing node circuit used in a packet switching system. In particular, the present invention relates to a node circuit that processes burst data transmission and a routing method applied thereto.

(Prior Art) An example of a conventional packet communication system that sucks burst data is “5 statistical switching A”.
architecture for Future 5er
vices “ISS” 84 (May 198
4). This system employs a simple communication protocol and self-routing method.

"Burst data transmission" is generally a data transmission consisting of a combination of parts in which significant information is continuously sent and parts in which no significant information is present and pauses as attributes of the data to be transmitted.

For example, in the case of transmitting a moving image, the entire image is first transmitted, and then a small amount of data representing rewritten data for the changed portion is transmitted.

These are used to improve transmission efficiency.

For example, in the case of multimedia communication consisting of audio data and image data, especially in the case of moving image transmission, such burst data transmission is often used to reduce the total amount of information to be sent. Figure 9 (a) , (b) and (c) are diagrams for explaining two different types of packet formats in burst data transmission. As shown in FIG. 9(a), a large amount of data is generated first, followed by a series of small data at intervals. If these data are transmitted in a variable length packet format, a special flag packet indicating that there is no data to be transmitted is transmitted during the interval, as shown in FIG. 9(b). . Furthermore, when such data is transmitted in a fixed-length packet format, empty packets without valid information are transmitted during the interval, as shown in FIG. 9(c) #E''. , In the figure, a packet with a half hunting portion represents a packet in which significant information is not included in the entire length of the packet.

(Problems to be Solved by the Invention) However, according to this conventional system, the system itself is nothing more than a routing device that follows address information included in packets. Therefore, since the system does not take into account the state of the transmission line or the information contained in the packet, it cannot correct errors that occur during packet transmission, nor can it compensate for lost packets due to overflow of the exchange buffer by width comparison.

In general, burst data transmission in multimedia communications has the above-mentioned special characteristics, and therefore causes buffer overflows and packet loss that degrades communication quality.

Additionally, the characteristics of a transmission path are generally determined by the maximum transmission rate, which in most cases depends on the transmission rate of the large amount of data. If the transmission path is set with the average transmission speed taken into account, a buffer overflow may occur if the average transmission speed is significantly lower than when transmitting a large amount of data initially.

However, on the one hand, there are many gaps during data transmission, so if the transmission path is configured only with the maximum speed for the initial transmission of large amounts of data in mind, then
Transmission efficiency may be wasted, or the equipment for it may become more expensive than before.

The purpose of the present invention is to observe input packet traffic,
Provides a node circuit that allows you to select the most appropriate output line,
This attempts to optimize the overall transmission efficiency.

Another object of the invention is to provide a node circuit that reduces packet loss caused by overflow of exchange buffers through a simplified routing method.

A further object of the invention is to provide a node circuit capable of absorbing multimedia communications including burst data.

(Means for Solving the Problems) According to the present invention, a node circuit is connected to a plurality of input lines and output lines and is used for packet communication. At least one of the input lines is connected to a packet terminal that handles burst data transmission.

The node circuit of the present invention is connected to an input line and an output line,
A switching network that can forward input packets to one output line based on their header information and that can store specific combinations of input and output lines, and exchange control for controlling the switching network. and a traffic control device connected to the switching control device and having the following functions.

(al When setting up a call from the packet terminal, it receives traffic information of the input line to which it is connected, for example, the average bit rate, and calculates the amount of traffic required for the call from that traffic information, (c1 plural Select an output line with sufficient traffic capacity for the call from among the output lines of ld)
The switching control device is controlled so that the switching network stores the combination of the input line and the selected output line as a link table.

Furthermore, the present invention provides a traffic monitoring device to monitor the actual call traffic on each input line. Further, the traffic control device refers to the observation results at a predetermined period and corrects the traffic information.

According to the present invention, at the call setup stage, each node circuit can select the most suitable output line for accepting the call. Therefore, the throughput of the node circuit is improved and the load of burst data transmission is spread out. Thus, for example, the present invention can be used in a packet switching center that accommodates moving image and audio data transmission.

(Function) According to the present invention, when setting up a call for a packet from an input line, the traffic control means determines the bandwidth of the output line to be used for the call based on the usage band information of the terminal that transmitted the packet. Derive.

When setting up a packet call, the switching means transfers the packet to an output line according to the band derived by the traffic control means. Furthermore, the actual traffic on the input line is observed by the traffic observation means, and the residual bandwidth of the output line is corrected based on the observation result. This minimizes buffer overflow in the switching means and improves the communication quality and throughput of the communication processing node.

(Embodiment) FIG. 1(a) is a schematic block diagram of a preferred embodiment of the node circuit of the present invention.

1) is the control of the node circuit of this embodiment? It is a figure which shows the example of B aspect. In the figure, node circuits 100 (sending side) and 102 (receiving side) to which the present invention is applied are packet terminals 101-1.10 that perform burst data transmission, respectively.
1-2. ...101-m or 102 1.10
2-2.102-n. Although the node circuits are connected by a communication line 103, it is of course possible to install another node circuit to which the present invention is applied between them.

The present embodiment will be explained below based on FIG. 1(a).

This node circuit 100 has multiple input times*11-1, 1
1-2. 11-3. ... 11-m via traffic measuring devices 12-1...12-m. Further, these input lines are connected to a packet terminal that performs burst data transmission or another node circuit to which the present invention is applied, as shown in FIG. 1(b).

These traffic measuring devices perform bit counting in the case of a fixed-length packet format. Further, these traffic measurement devices are connected to communication lines 14-1.14-2.14- by a switching network 150 (for example, a switching module described in Japanese Patent Laid-Open No. 63-169850 published on July 13, 1988). 3. ...14-m
connected via. Hereinafter, communication lines include unidirectional and bidirectional communication lines, time-division virtual transmission lines, apology pass lines, and the like. Furthermore, this traffic measurement device is connected to a traffic control device 240 via a communication line 130.

This communication line 14-1.14-2.14-3. ...14
-m is provided to transfer input packets to the switching network, and the other communication line 130 is provided to notify the traffic control device 240 of measured traffic information.

Switching v4150 connects these communication lines 14-1...
・Receive packets from 14-m, recognize each destination information, and output them 116-1.16-2.16-3
．． ...Transfer to 16-n. Each combination of these communication lines and output lines to which packets are to be sent is controlled by the switching control device 251 (for example, the
(such as processing circuits, Mp, Ps described in )
via the communication line 255. However, the switching network itself can hold the combinations in memory. Furthermore, this exchange control device 251 is controlled by the traffic control device 240 via a communication line 245.

Further, the traffic control device 240 is connected via a communication line 230 to a terminal 220 that controls the entire node circuit. This terminal 220 is used to give various characteristics to the node circuit and to instruct the node circuit to perform functions that are not provided in the built-in software of the node circuit.

Although not shown in the drawings, all the circuits except for the traffic control device 240 and the terminal 220 may have a redundant configuration for backup purposes.

Now, before explaining the detailed configuration of the node circuit, the general function of the node circuit of the present invention will be explained as shown in FIG. 2(a).
(b), FIG. 4, and FIGS. 5(a) and (b).

According to the virtual call process used in general packet communication, first, at the stage of making a call from a packet terminal, a call request (call Raque) including a destination address is sent.
ST (hereinafter referred to as CR) packet is sent to the destination packet terminal, and in the next step, call reception (call Ackn) is sent to the destination packet terminal.
A packet (hereinafter referred to as CA) is sent from the receiving terminal back to the calling terminal as an acknowledgment of data transmission. During these packet transmissions, each node circuit (or switching center) on the transmission path stores in link memory the input and output line combinations used for the transmission.

According to the present invention, instead of the conventional "CR" packet, a small number of (1) destination addresses, e.g.
, 164, which includes information on (2) maximum transmission bit rate and (3) average transmission bit rate, is used when setting the transmission route.

These pieces of information can be easily calculated using conventional techniques, for example, within the packet terminal that performs the burst data transmission. For example, set the maximum throughput of the terminal to the maximum bit rate, and set an appropriate coefficient Q (0<Q<1)
The average bit rate may be determined by multiplying by .

FIGS. 2(a) and 2(b) are diagrams for explaining how the node circuit of the present invention handles the above information in the memory of the traffic control device 240. In the first step, as shown in FIG. 2(a), the calling node circuit receives the maximum bit rate and looks up the maximum bit rate table to determine the address of the next effective bit rate table. This address is stored at an address spaced from the top address of the maximum bit rate table by an address distance corresponding to the maximum bit rate.

These maximum bit rate tables are provided for each input line. Of course, a common large-scale table can be provided for shared use by each line.

The effective bit rate to be determined is located at an address spaced from the top address of the effective bit rate table by the same address distance as the value of the average bit rate received together with the maximum bit rate. Note that in the initial settings, the average via rate may be set as the effective bit rate.

Generally, the effective bit rate is set as a compromise between the maximum bit rate and the average bit rate. This means that if the maximum bit rate is too large and the subsequent data is relatively small, the average bit rate becomes too low and the communication path bumper may overflow during the first data transmission, and long slow intermittent In the case of data transmission, the average bit rate and the effective bit rate are approximately equal. In order to cover such cases, the effective bit rate is almost always located between the maximum bit rate and the average bit rate.

Next, as shown in FIG. 2), the node circuit analyzes the destination address and refers to the destination table.

The contents of this destination table store the top address of a characteristic table representing the characteristics of each valid output line.

Generally, a plurality of output lines for the same destination are prepared to prevent width comparison or for emergencies, and are given a predetermined priority.

In the specific table, A″ represents the maximum bit rate of a certain output line (line number #C#), and both A and C are unique values. #B″ represents the transmission currently being used by that output line “C#”. This value is rewritten as follows.

First, the node circuit calculates the difference between #A'' and #B# for each output line, and searches for the first output line for which this difference is greater than the effective bit rate determined in the previous step. If it is found, The node circuit stores the combination of the input line number for sending the packet and the obtained output line number #C# in its link memory, and further stores the above #B# as
Replace with the sum of #B# and the effective bit rate.

It should be noted that all of the above-mentioned tables can be loaded by appropriate software provided in the traffic control device, or can be input from the terminal 220 if necessary.

In this way, the most suitable output line with the most suitable transmission rate is selected. Further, subsequent data transmission is performed like a normal virtual call (based on the contents of the link memory).

This situation will be explained in detail below after explaining the packet format applied to the present invention.

The node circuit of the present invention can be applied to either variable length or fixed length formats. FIG. 3 (al and bl) are diagrams for explaining applicable packets.

Figure 3 (al is an example of the structure of a fixed-length packet based on the CCITT recommendation draft. In the figure, GFC is a general flow control
ntro1), and VPI stands for Virtual Bus Identification (Virtual Path
YCI stands for Virtual Channel Identification.
ual Channel Identification
n), PT is the payload type (Payload type).
HEC is an abbreviation for leader error control (treader error control 1), and IIIES is an abbreviation for reserved. This packet structure consists of 5 octets (1 octet - 8 bits) of header information and 48 octets of data information. In the case of an empty packet, VCI (1
2 bits) #0#, and the information in the data field is discarded in the node circuit without any consideration.

Furthermore, when a certain packet is used for signal control according to the present invention, the sequence of vcIs within the packet follows a predetermined pattern.

Figure 3(b) shows a high-level data link (HighLe
This is an example of a variable length format packet based on the velData Link (hereinafter referred to as DLC) standard. In this structure, #F# is an 8-bit sequence '0111111
0' and is used as a delimiter between packets.

Further, #A# is an 8-bit destination address, and "C" is an 8-bit control field.

pcs is a frame check sequence (Frame C
HeckSequence) is used to correct errors in transferred data.

Note that the maximum length of a packet is 4096 octefts.

When there is no data to be transmitted, only said flag sequence is transmitted at predetermined intervals for the purpose of maintaining communication. Therefore, packets containing only flag sequences are discarded without being measured.

Furthermore, in the present invention, when a certain packet is used for signal control, the LC in #1# frame for information transfer is
GN (4 bits), LCN (8 bits) (VCI mentioned above)
) has a predetermined pattern.

4 and 5+8) are diagrams for explaining the present invention in detail.

FIG. 4 is an explanatory diagram when the calling side packet terminal 260 sets a call to the called side packet terminal 290.

For generalization, in the following description, it is assumed that a signal packet is identified by its header information.

Of course, if the header information is in fixed length packet format, the VC! has the specific pattern mentioned above! It may be information, or in the case of a variable length packet format, it may be an LCGN or LCN with a predetermined pattern.

First, when the packet terminal 260 on the calling side wants to originate a call involving burst data transmission, the packet terminal 260
A signal packet having header information Sl indicating a call request from the packet terminal to the node circuit is sent to the switching network 150 of the first node circuit 100 via the communication line 265.

In the switching network 150, the header information is translated and recognized as a signaling packet.

This signal packet contains the above-mentioned traffic information for selecting the output line, that is, (1) destination address, (2)
The packet includes maximum transmission bit rate information and (3) average transmission bit rate information, and the switching network 150 sends this packet to the traffic control device 240 via the exchange control device 251.

The traffic control device 240 executes the process of selecting the most appropriate output line described above, and the traffic control device 240 controls the switching control device 251 so that the switching network 150 stores the input line and output line combination in memory. control to do so. For example, assume that the link table is stored as Ll:(11;12). Furthermore, the traffic control device 240 rewrites the header of the packet to S2 representing a signal packet for between node circuits, and sends the packet to the output line obtained by the switching control device 251 and the switching 1i1150.
Output via.

To explain in detail, the link table corresponding to each input line is a virtual table as shown in FIG. 5(b). As mentioned above, each call is assigned a VCI (or LCGN for variable length packets).

LCN). Furthermore, this link table manages all calls on the corresponding input line, and is placed at the address position of the corresponding input line in the switching network.

As shown in this figure, calls on the next output line, numbers 10, .
8 is converted one-to-one.

Generally, switching control equipment automatically assigns unused, vacant call numbers to calls on output lines.

The next node circuit 100A is connected to the node circuit 100 via a communication line 275, and receives the above-mentioned radar information S2.
Receive a packet with . This node circuit 100A
Inside, the same processing as that performed in the previous node circuit 100 is performed on the switching network 150A, exchange control device 251A,
) is done by the rough controller 240A, and yet another link table L2: (12;13) is set in the switching m150A. Further, the traffic control device 240A rewrites the header information of the packet to S3, which means a signal packet from the node circuit to the packet terminal, and transfers this packet to the output line from the switching control device 251A and switching! ii Output via 150A.

A packet terminal 290 on the called side is connected to the node circuit 100A via a communication line 285. This packet terminal 290 receives the packet with header information S3 and returns another packet with the same header information S3 and with the packet terminal 290's traffic information.

In this way, on the return trip, the link table Ll(11;
12) and link table L4:(12;13) are set in switching W4150 and 150A, respectively.

FIG. 5fa) is a diagram showing the state when data is transmitted using these link tables. - Once link tables are set up on a communication path, they do not need to be rewritten until the next call occurs. These switching control devices 251.degree. 251A and traffic control devices 240.24OA are therefore freed from processing during subsequent data transmissions.

During data transmission, switching FM 150.15OA
automatically creates the obtained link table Ll, L2゜L3
．． According to L4, the header information is rewritten into address information from the calling side to the called side. For example, as shown in FIG. 5(a), the calling side packet terminal 26 having address information 1
0 sends out a data packet with header information 11. This header information is automatically rewritten on the communication path. Finally, this packet is received by the packet terminal 290 on the called side as a packet having header information 13.

In this way, the optimal output line is selected by the above process,
Since the exchange control device and the traffic control device are freed from processing during data transmission, high-speed data transmission corresponding to high-speed data burst data transmission in multimedia communication can be realized.

The detailed configuration and functions of the embodiment of the present invention will be described below with reference to FIGS. 6(a), 6(b), 7, and 8.

When there is not much difference between the above-mentioned effective bit rate and the actual bit rate, it is also possible to fix the effective bit rate at the average bit rate determined in advance by the calling packet terminal.

However, when there is a large difference between the effective bit rate and the actual bit rate, it is necessary to adjust the effective bit rate to prevent overflow due to calculation errors and waste of communication efficiency due to underestimation.

To solve this situation, the node circuit of the present invention is equipped with a traffic measurement circuit that measures the actual input traffic and adjusts the effective traffic of subsequent calls.

Also, since there are two different packet formats, two different traffic measurement devices are expected.

FIG. 7 shows an example of a traffic measuring device compatible with a fixed-length packet format, and FIG. 8 shows an example of a traffic measuring device compatible with a variable-length packet format.

In FIG. 7, the communication line 435 corresponds to one of the input ports 111-1 to 11-m shown in FIG. 1 (al).

Shift register 430 holds the bit string input from communication line 435 and transfers it to comparator 440.

Note that before that, several packet patterns have been written into memory 450 (RAM) by CPU 470.

In the comparator 440, the input bit string is assembled into a packet format and compared with the pattern previously written in the RAM 450. This is because there are not only empty packets but also other packets in the node and node circuits that should be discarded without being counted.

When comparator 440 detects a packet to be counted,
Comparator 440 controls counter memory 460 to add one to its value. This measurement is performed for all calls identified by the VCI, and a plurality of measurement results are stored in counter memory 460.

The control memory 480 is composed of a normal ROM and RAM that is combined with the CPt 1470, and stores control software for the traffic measuring device and necessary data, such as countable packet patterns.

In this embodiment, control memory 480 further stores unit time information for packet measurement.

The CPU 470 reads the contents of the counter memory 460 and the unit time information in the memory 480 at a predetermined period, and calculates the number of packets received in the unit time for each call. CPt 1470 sends this number of packets to traffic controller 240 for each call.

FIG. 6(a) is a block diagram of the traffic control device 240. This traffic control device 240 includes a central control device (hereinafter referred to as CPU) 340, a read only memory (hereinafter referred to as ROM) 350, a random access memory (hereinafter referred to as RAM) 360, and a traffic measurement device 1.
Input/output interfaces 370, 380 for 2-1 to 12-m, input/output interfaces 370, 380 for exchange control device 251;
It consists of output interfaces 390, 400, input/output interfaces 410, 420 for terminal 220. The above processing is executed in RAM 360 based on control software in ROM 350.

The traffic control device 240 receives a signal packet from the exchange control device 251 via the input interface 390, processes it in the CPU 340, and stores the result in the RAM.
360. When the CPt 1340 receives and processes a signal packet, the CPU 340 prepares in memory an adjustment table as shown in FIG. 6, and stores the input line number and the obtained effective bit rate. Further, the CPU 340 receives the aforementioned number of packets per unit time, and calculates the actual bit rate and an adjustment coefficient for matching the two. This adjustment factor is, for example, AP
, (0<AF<1) to reduce the effective bit rate.

The adjustment factor obtained is used in the next call setup step. For example, at the next call setup stage, the traffic control device 240
The adjustment table may be referred to in correspondence with the input line number, and the obtained effective bit rate in the effective bit rate table may be multiplied by the adjustment coefficient in the adjustment table.

Also, observe the actual bit rate of the packet with the VCI to be observed, and update the effective bit rate of Pig, 2 (al) with the observed value.By doing this, the same characteristics (maximum value, average value) It is possible to increase the accuracy of effective bit rate estimation for data traffic with

FIG. 8 is a block diagram of the traffic measuring device,
This corresponds to variable length packet format. In FIG. 8, the communication line 485 is the input line all-1 in FIG.
11-m. The input cover sofa 490 takes in the bit string from the communication line 485 and the CPU 500 receives the bit string from the communication line 485.
Transfer to.

In this case, since the format of the discarded packet that is applied is only a flag sequence, there is no need for a memory for storing a predetermined pattern or a comparator for comparing and detecting the predetermined pattern. Therefore, the CPt 1500 can easily identify flag sequences and, in turn, can easily identify packets to be counted.

On the other hand, since the packet length is variable up to 4096 octets, it is necessary to count the packet length to accurately measure traffic.

When the CPU 500 recognizes a packet to be counted, it adds #l'' to the counter memory 510 and starts measuring the octet length of the packet. When the CPU 500 finishes measuring the octet length, it similarly stores the value in the counter memory 510. Similar to the traffic measuring device shown in FIG. 7, unit time information is stored in the control memory 520. Also, in order to identify each call, the CPU 500 extracts the LCGN and LCN from the packet. .

At predetermined intervals, the CPU 500 reads out the packet number, octet length, and unit time information, and calculates the actual bit rate for each call.

The CPU 500 sends the result to the traffic control device 24.
Send to 0. Thereafter, the traffic control device 240 performs the same operation as that described with respect to the traffic measurement device shown in FIG. 7 above.

The present invention is not particularly limited to data transmission using a virtual call method, but can also be applied to a permanent virtual call method.

For example, maximum bit rate information and average bit rate information of a specific subscriber can be transmitted from the terminal 220 to the traffic measuring device 2.
It is also possible to input it into the memory of 40.

Furthermore, it is also possible to introduce other units to represent traffic. For example, the actual number of packets per unit time can be used instead of the bit rate.

Furthermore, it is also possible to use packets in other formats and packets in different locations to transmit traffic information. For example, in the case of a fixed-length packet format, CR packets can be given specific data and used as signal packets. Good too.

Furthermore, in the case of a variable length packet format, a packet having a control field #C'' having a specific value may be used as a signal packet.

Furthermore, if necessary, the traffic control device 2 of the present invention
40 may be installed at a location separate from the main body of the node circuit 100, and remote control may be performed via a communication line.

(Effects of the Invention) As described above, according to the present invention, the following effects are expected by observing actual communication and updating the effective band to be used. First, data discard due to buffer overflow within communication processing nodes is minimized, providing high quality communication. Further, since it is avoided to set a band with an excessive margin for actual communication, the efficiency of use of the output line is increased. Therefore, throughput at the communication processing node is improved.

[Brief explanation of the drawing]

FIG. 1(a) is a schematic block diagram of a node circuit according to an embodiment of the present invention, FIG. 1('b) is a diagram for explaining the connection mode of the node circuit of this embodiment, and FIG. 2(a) , (b) is a diagram for explaining how the routing method of the present invention handles traffic information in the node circuit;
Figures (al and b) are diagrams for explaining the packet format applicable to the present invention, Figure 4 is a diagram for explaining how the present invention determines the communication route, and Figure 5 (
a) is a diagram for explaining how the node circuit of the present invention handles packets during communication, FIG. 5 (bl is a link table created in the present invention, and FIG. A block diagram of the applied traffic control device,
6(b) is an adjustment table stored in the traffic control device of FIG. 6(a), FIG. 7 is a traffic measuring device of the present invention used for fixed-length packet format, and FIG. 8 is a variable-length packet format. Traffic measuring device of the present invention used in packet format, FIGS. 9(a), (b), (c1 is a diagram for explaining burst data transmission. 12; Traffic measuring device, 100.102; Node circuit , 150; switching network, 240; traffic control device, 251; switching control device.

Claims (1)

[Scope of Claims] 1. In a node circuit connected to a plurality of input lines and output lines and used for packet communication, a) a switching network that stores combinations of the input lines and output lines as a link table; a) a switching network including means for connecting an input line and an output line of the combination based on header information of a packet; then, calculates the traffic capacity required for the call based on the traffic information of the input line, and selects an output line from the plurality of output lines that has sufficient traffic capacity to transmit the call based on the result. and further comprising means for instructing the switching network to store a combination of the input line and the selected output line. 2. In the node circuit according to claim 1, the traffic information is a signal packet, and includes destination address information,
A node circuit comprising estimated maximum bit rate information and estimated average bit rate information. 3. In a node circuit connected to a plurality of input lines and output lines and used for packet communication, a) a switching network that stores a combination of the input lines and output lines as a link table; a) a switching network including means for connecting input lines and output lines of the combination based on header information; b) packet observation means connected to said input line to observe actual traffic on said input line; c) connected to the switching network and the traffic observation means; (c1) recognizing the estimated traffic of the call when the first call arrives on one input line; calculating and storing in a memory a first value representing a required traffic capacity for the call; (c3) select one of the output lines with sufficient traffic capacity for the call based on the traffic information; and (c3) send the combination of the input line and the selected output line to the switching network. (c4) Subsequently, based on the stored actual traffic, when a call arrives on that input line with the same estimated traffic, the first value is changed to a second value; A node circuit comprising: means having an adjustment function; 4. In a routing method for sending packets from a calling terminal to a called terminal from an input line to an output line in a packet switching network, the following steps (a) Estimating the traffic of the call to be sent. (b) receives the call on an input line of the node circuit; and (c) transmits data representing the required traffic capacity for the call on its lead circuit. (d) selecting an output line from a plurality of output lines leading to the called terminal having sufficient traffic capacity to transmit the call based on the calculation; (e ) A routing method comprising: storing the combination of the input line and the selected output line as a link table; and (f) connecting the combination of the input line and output line based on the stored link table. 5. In the routing method according to claim 4, step (a) includes the following steps (5a) including in the call an estimate representing the traffic capacity required for the call; and (5b) transmitting the call to the node. A routing method consisting of transmitting to a circuit. 6. The routing method according to claim 5, wherein the call includes a burst data transmission following a signaling packet;
The estimated traffic is the estimated average bit rate and maximum bit rate of the routing method. 7. The routing method of claim 6, further comprising the following steps: (7a) observing the actual traffic during the burst data transmission; (7b) based on the observed traffic within the node circuit during the next call; , calculating the required traffic capacity for the next call. 8. The routing method according to claim 6, further comprising: (8a) providing a maximum bit rate table having a first address at an address corresponding to the value of the maximum bit rate; (8b) providing the first address; an effective bit rate table storing the estimated average bit rate and the corresponding effective bit rate; (8c) accessing the maximum bit rate table from the estimated maximum bit rate in the signal packet to obtain the first bit rate; Find the address, (8d) access the corresponding effective bit rate table using the address, find the corresponding effective bit rate using the estimated average bit rate in the signal bucket, and (8e) calculate the found effective bit rate. A routing method comprising: using the required traffic capacity as a first value. 9. The routing method according to claim 8, wherein the selection step includes the following step (9a): A characteristic table is provided for each called terminal, and in the table, the maximum bit rate of the output line to each terminal, the maximum bit rate in use, The bit rate and line identifier are stored in the corresponding memory address, (9b) a destination table is provided in which the address of each characteristic table can be accessed by the destination, and (9c) it is determined which terminal the call is destined for. Recognize,
accesses the destination table to obtain the address of the characteristic table; (9f) thereby accesses the characteristic table and determines that the difference between the stored maximum bit rate and the currently used bit rate is greater than or equal to the determined effective bit rate; 1. A routing method, comprising: determining an output line of a certain type.