JP3538018B2 - Communication network - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is applied to a communication network in which the bandwidth allocated to another line is changed in conjunction with the state change processing (setting, release, band correction, etc.) of one line and the fluctuation of the information transfer rate. I do. The present invention relates to an ATM (Asynchr
onous Transfer Mode) network (IP)
col) It is suitable for use in a communication network in which a line different from a line normally used in a specific section is set as required, such as in a form for realizing communication.

[0002]

2. Description of the Related Art First, the Internet and Internet Protocol (IP)
rnet Protocol) will be described with reference to FIG. FIG.
FIG. 3 is a diagram for explaining an outline of IP communication. United States IS
Internet Protocol standardized by OC
l (IP) is a packet transfer protocol used between many communication devices. Communication by IP (IP communication)
The information is stored in a packet called an IP packet, and as shown in FIG.
Is transferred by a network (IP routing network) configured by connecting devices called “IP routing network”. In the IP packet, an address indicating a destination terminal called a destination IP address is written, and the IP router a understands the destination IP address (A → B) of the IP packet received from the terminal A, and if possible, the destination terminal B. If this is not possible, select an appropriate IP router b or d from the connected IP routers b or d as the next-stage IP router (in this case, select IP router b). (IP routing processing). By increasing the number of connected IP routers, a wide area communication network is configured,
Remote communication in which a packet passes through a plurality of IP routers becomes possible.

[0003] Today, there is an IP router network constructed on a worldwide scale called the "Internet", and is widely used as a public IP communication network as a means for realizing communication between terminals of unknown users. From the viewpoint of a terminal, a terminal can communicate with any terminal in the world if a line for transmitting and receiving IP packets is secured with a certain IP router.

[0004] For example, in the case of a telephone or a facsimile, a communication partner is notified to a network in advance to send information to the communication partner, and a line (connection) is set. This communication form is called connection-oriented communication (CO communication). On the other hand, IP communication does not require prior connection setting, and can immediately start sending information to any terminal. This communication mode is called connectionless communication (CL communication).

Next, ATM (Asynchronous Transfer Mod)
e: asynchronous transfer mode) will be described with reference to FIG. FIG. 9 is a diagram for explaining the outline of the ATM communication. On the other hand, there is an ATM technology as an information transfer technology for constructing a high-speed data transfer network.
It has already been standardized by ATM forums and the like. A
In the communication by TM, as shown in FIG. 9, a network is formed by connecting switching devices called ATM switches. The information is stored in a 53-byte packet called a cell and transferred in the network. A label called VPI / VCI is written in the cell.

An ATM switch has a plurality of ports for connecting physical lines. When a cell is input to a switch from a certain port and is output from a certain port, the port to which the cell is input is called an input port. The port that is used is called an output port. The label value of the cell at the time of input is called an input label, and the label value at the time of output is called an output label.

The ATM switch has means (routing table) for storing and managing the relationship between input ports, input labels and output ports, and output labels (hereinafter referred to as "routing table entries") in cell transfer processing. When a cell arrives, the routing table is searched by the input port and input label of the cell to determine the output port and output label, the cell is transferred to the output port, and the label value is replaced with the output value and output (cell transfer processing) ).

When ATM switches SW1 to SW4 in the network are set such that a cell transmitted from a certain terminal (terminal A) with a certain label value is transferred to another terminal (terminal B), terminal A Assume that the terminal B has a logical line. This logical line is called a VC (Virtual Connection).

FIG. 10 is a diagram for explaining the concept of a VP. As shown in FIG. 10, a VP (Virtual Path) is a unit indicating a cell transfer path (path), and the VP is a control unit for grouping a plurality of VCs that partially share the same transfer path. V across ATM switch
When P is set, the ATM switch performs routing using only the VPI for cells transferred on the VP, and the VCI uses the value at the time of input as the output value as it is.

[0010] The ATM network is operated on the premise of the CO communication, and the routing table entry is generated simultaneously with the generation of the VC, and is deleted simultaneously with the release of the VC. As one of the VC setting methods, there is a form in which the state of the ATM switch is updated through a management interface (an interface for maintenance and operation) of the ATM switch, and this form is called a PVC method (Permanent Virtual Connection). Another setting method is SVC (Switched Virtua
l Connection) system, in which a terminal and an ATM switch exchange messages for controlling (setting, releasing, and changing the bandwidth) VC. This message procedure is called signaling, the terminal requesting the VC setting is called the calling terminal, and the terminal designated as the communication partner is called the called terminal.

[0011] In the connection setting procedure, the calling terminal sets the ATM switch accommodating the calling terminal to the SETU.
Send a message called P. Then, the control message is transferred between the ATM switches, the necessary state of the ATM switch is updated, and the ATM containing the called terminal is updated.
When the control message arrives at the switch, the ATM switch sends a SETUP message to the called terminal.
The called terminal determines whether or not to accept the call based on the contents of the SETUP message (determination of whether or not to accept the call). When accepting the call, it sends a message called CONNECT to the ATM switch as a response, and when rejecting the call, A message called RELEASE COMPLETE is sent to the ATM switch.

Since it is only necessary to store the routing information for the existing VC, the number of entries to be stored in the routing table is small, and the cell transfer process can be realized by hardware. Thus, the ATM has an advantage that high-speed information transfer is possible.

In the ATM communication, it is possible to define an assigned band (cell rate) for each VP or VC, and the ATM switch monitors the flow rate of input cells for each VP or VC, and receives an input at a rate higher than the assigned cell rate. Discard the used cell. As a result, it is possible to prevent the quality of another connection from deteriorating due to a certain connection, and at the same time, to secure a certain bandwidth for each connection. The user terminal ensures that, for each VC, the cell transmission rate does not exceed the assigned rate, and for each VP, the sum of the cell transmission rates of the VCs belonging to that VP exceeds the rate assigned to the VP. Need not be.

In order to guarantee a certain band or more for each VC, a band on a transmission line is allocated in conjunction with the setting of the VC,
During the continuation of the VC, it is necessary to continue to reserve the band for the VC. For this reason, in the future, in an ATM public network having an assumed SVC function, it is considered that the user is charged based on the setting and the duration of the VC. VC
There are the following two methods for defining or changing the cell rate with respect to.

Method by signaling: Defines and changes the bandwidth allocated to the VC by means of a signaling message.

RM cell system: VC already set
Is a method of changing the allocated bandwidth of the
A cell called an RM cell (resource management cell) is transferred above, and the allocated band is changed.

Of the above, the aspects of VC important for the description of the present invention are summarized as follows. (1) VC indicates connection between terminals, and high-speed communication using high-speed data transfer of an ATM network can be performed between terminals connected by the VC. (2) VC is the minimum unit of band control, and the network can guarantee a transfer rate of a certain value or more for each VC, or limit the transfer rate to a certain value or less. Also VC
The allocation and release of the transmission band are performed in conjunction with the setting and release of the transmission band. (3) VC is also one element in the billing process, and ATM
It is considered that a billing process is performed in a public network according to the setting and the duration of a VC.

Next, a description will be given, with reference to FIG. 11, of a mode of realizing a typical IP communication using ATM. FIG. 11 is a diagram for explaining a typical use form of ATM in IP communication. In a typical mode for realizing IP communication using ATM, as shown in FIG.
VCs are set between P routers a and c and between adjacent IP routers a to c. Terminals A and B are IP
The VC held between the routers a and c is called the default VC of the terminal. In this mode, the following problem occurs.

Problem 1 (IP router congestion problem): IP
Since the line connecting the router and the terminal has become ATM, IP packets arrive at a high transfer rate.
Congestion may occur at the P router.

As a method for avoiding this, there is a method of setting a VC between terminals (or between adjacent IP routers) and transmitting and receiving IP packets when communication that continues for a long time occurs. This method is called a cut-through method, and a VC set between terminals set by this method is called a cut-through VC. There are the following two forms of the cut-through VC generation method. (1) A mode in which a terminal activates cut-through VC generation In this method, a terminal generates a cut-through VC by signaling by designating an address of a partner terminal as an incoming call address. FIG. 12 shows a cut-through VC by starting the terminal.
FIG. 6 is a diagram for explaining a mode of generating a. As shown in FIG. 12, a protocol called NHRP is defined as a procedure in which the terminal A acquires the ATM address of the partner terminal B. (2) A form in which the IP-ATM integrated router activates cut-through VC generation An IP router configured by adding an IP routing processing module to an ATM switch is called an IP-ATM integrated router. The IP-ATM integrated router has the ability to change the state of the built-in ATM switch in conjunction with the IP routing process. FIG. 13 is a diagram for explaining a mode in which a cut-through VC is generated by activating the IP-ATM integrated router RA (in FIG. 13, the IP-ATM integrated router RA is used).
To RC are simply shown as routers RA to RC). Upon detecting that the IP packet for the same destination terminal B continues to flow for a long time, the IP-ATM integrated router RA
As shown in FIG. 13, the routing table of the built-in ATM switch is changed to generate the routing table entry for the cut-through VC, and
Send a message prompting the ATM integrated router RB to generate a cut-through VC. Then, the IP-ATM integrated router RA transmits the cut-through VC generated for the terminal A.
(VPI, VCI) are transmitted.

When comparing the above (1) and (2),
In (1), the user terminal activates the generation of the cut-through VC, and in (2), the IP-ATM integrated router in the network activates the generation of the cut-through VC.

[0022]

However, the following problems arise in the method in which the user terminal activates the generation of the cut-through VC as in the above (1).

Problem 2 (problem of burden of charges related to cut-through VC): The user's terminal originally holds a default VC as a means for communicating with an arbitrary terminal, and for the user, the generation of the cut-through VC It is an important background that newly added value is small.

If a user who executes communication using cut-through VCs bears the charge for cut-through VCs, many users may set their terminals so as not to start generating cut-through VCs. Easy to predict. As a result, it becomes impossible to solve the congestion of the IP router using the cut-through VC.

Conversely, if the user is not charged for the cut-through VC with the charge of the cut-through VC as the burden of the network operator, the user can use more cut-through VCs than necessary. It can be easily anticipated that the terminal will be set so that it is set, and the generated cut-through VC is held for a long time. As a result, a long-time band is secured for the cut-through VC for which communication has been completed, and there is a possibility that the band of the ATM network becomes insufficient.

When the IP-ATM integrated router is cut-through V
In the method of activating C generation, since the network controls generation and release of cut-through VCs, there is a problem that the network operator bears the cost of cut-through VCs, but there is a shortage of ATM network bandwidth. There is no. However, this method has the following problems.

Problem 3 (Degradation of service fairness due to generation of cut-through VC): A terminal using cut-through VC can use both cut-through VC and default VC. On the other hand, a terminal that does not use the cut-through VC can use only the default VC.
This means that, while a transmission band of a plurality of VCs is reserved for a certain terminal, a transmission band of one VC is reserved for another terminal. It will be.

Therefore, the present invention solves problem 1 without causing problems 2 and 3, that is, does not perform charging processing for the user with respect to cut-through VC, and at the same time congestion and bandwidth in the ATM network. The purpose is to prevent shortage and lower service fairness.
As described above, the present invention provides a communication network capable of changing the bandwidth allocated to another line in conjunction with the state change processing (setting, release, band correction, etc.) of one line and the fluctuation of the information transfer rate. The purpose is to do.

[0029]

Here, the exchange device is A
It includes a device that performs switching processing such as a TM switch and a device that performs routing processing such as an IP router. Also,
A line is a line that is physically set in a circuit switching network such as a telephone network, a packet switching network, a frame relay network, an AT.
Includes lines that are logically set in an M network or the like. Here, for the sake of simplicity, the description will focus on ATM switches and IP routers, but the scope of the present invention is not limited thereto.

The basic guideline for solving the problem is that the network takes measures to reduce the bandwidth allocated to the default VC for communication terminals using cut-through VC. According to this guideline, the present invention changes the bandwidth allocated to another line in conjunction with the status change processing (setting, release, band correction, etc.) of one line and the fluctuation of the information transfer rate observed on the line. A communication network capable of That is, the features of the present invention are as follows. (Means 1) A communication network according to the present invention provides a bandwidth allocated to another line in conjunction with a state change processing (setting, release, band correction, etc.) of a certain line and a change in an information transfer rate observed on the line. Is changed.

Further, the switching apparatus according to the present invention has a function of changing the band allocated to another line in conjunction with the state change processing of one line and the fluctuation of the information transfer rate observed on the line. The present invention is characterized in that it has a means for storing the width of the change of the allocated band of another line performed in conjunction with the generation of the line and the securing of the band with respect to the line being controlled and controlled. (Means 2) A terminal according to the present invention changes a bandwidth allocated to another line in conjunction with a line state change process or a change in an information transfer rate observed on the line in a control message for performing a line state change process. A means for writing information indicating that the operation is permitted.

The switching apparatus according to the present invention interlocks with the state change processing of the line in the control message for requesting the state change processing of the line received from the terminal and the fluctuation of the information transfer rate observed on the line to perform other processing. Means for recognizing information indicating whether or not changing the assigned bandwidth of a line is permitted and determining whether or not to change the assigned bandwidth of another line in conjunction with the state change process of the requested line It is characterized by having. (Means 3) The terminal according to the present invention, in response to a control message requesting a line state change process (setting, release, band change, etc.), interlocks with the line state change process and the fluctuation of the information transfer rate observed on the line. And means for writing information (band-linked line group indicator) indicating a line for which the allocated band is changed.

The switching apparatus according to the present invention has a function of determining a line whose band is to be changed by the band-linked line group designator included in the control message for performing the line state changing process in the band-linked line group management table. It is characterized by the following. (Means 4) The switching device according to the present invention has a certain line (line A)
When changing the bandwidth allocated to another line in conjunction with the state change processing for the network, a control message (a bandwidth change permission / inhibition inquiry message) for asking the switching device or terminal involved in the line for which the allocated bandwidth is to be changed whether the change is possible is transmitted. Means for determining whether or not to perform a state change process on the line A in accordance with the presence or absence of a response message to the bandwidth change permission / inquiry message and the content of the response message.

The terminal according to the present invention sends a response message in response to the bandwidth change permission / inquiry message, and determines whether or not to permit changing the allocated bandwidth of the line by changing the state of another line or changing the transfer rate. Characterized by having means for indicating (Means 5) The switching device according to the present invention is involved in a line whose bandwidth is to be changed when another assigned band is changed in conjunction with a state change process of a certain line or a change in an information transfer rate observed on the line. It is characterized by having a means for sending a control message indicating a change in the allocated bandwidth to the switching device or terminal.

As a method of collectively controlling the bandwidths of a plurality of different lines, in an ATM network, there is a means for defining a bandwidth allocated to a VP and restricting the sum of cell rates of VCs belonging to the same VP. This method uses a new V
Even if C is set or the bandwidth allocated to a certain VC is changed, the bandwidth allocated to another VC is not changed. The present invention is different from the first embodiment in that when a new VC is set or a band allocated to a certain VC is changed, another VC is set.
The point is that the bandwidth allocated to C is changed. In addition, according to the present invention, it is not necessary that the VC groups whose bands are linked belong to the same VP.

The operation generated by the means 1 is as follows. Even if the terminal does not charge the cut-through VC in the form in which the terminal generates the cut-through VC, if the cut-through VC is generated and the band of the default VC is reduced, the user is no longer necessary. The cut-through VC is no longer held for a long time, and the probability that band shortage occurs can be suppressed to an extremely low level.
Further, when a packet destined for a specific terminal occupies a large area of the default VC, it is more efficient to generate a cut-through VC.
Is considered to be generated. As described above, according to the present invention, it is possible to realize a communication network that reduces the congestion probability of the switching device while generating a cut-through VC without causing a band shortage.

Further, as an exchange device, an I / O device in which an exchange device and a routing device are integrated into one.
In a mode in which a switching device called a P-ATM integrated router starts generation of a cut-through VC, the cut-through V
If the bandwidth of the default VC is reduced for the user holding C, the difference between the users regarding the total bandwidth that can be secured on the communication network is reduced. That is,
According to the present invention, service fairness can be improved for communication using cut-through VC generation.

Also, as in the means 1, the switching device has a band-linked line group management table, so that when a state change process is performed on a certain line, the switching device determines the line whose band should be changed in conjunction with the state change processing. can do.

By means 2, the terminal is cut-through VC
Regarding generation and band change, whether to change the band of the default VC or charge is selectable every time the cut-through VC is generated or the band is changed.

By means 3, when a terminal already holds a plurality of VCs for some reason, a VC whose bandwidth is to be changed in conjunction is designated every time a cut-through VC is generated or a band is changed. Becomes possible.

Before generating the cut-through VC or changing the band, the means 4 inquires of a terminal or an exchange device relating to the VC whose band is to be changed whether or not the band change to another VC can be performed in conjunction therewith. Becomes possible. For example, by setting up to what value the terminal holding the default VC is allowed to reduce the band of the default VC, it is possible to keep the band of the default VC at a certain value or more. .

V for changing the band in conjunction with means 5
Regarding C, the change of the band is notified to the switching device and the terminal related to the VC. In response to this notification, the terminal changes the rate at which information is transmitted, and the terminal can transmit information at a rate that does not exceed the allocated bandwidth even after the bandwidth change. In other words, when the bandwidth is reduced, it is possible to prevent the terminal from transmitting information without knowing that the bandwidth has been reduced.

That is, the present invention is a communication network comprising a plurality of terminals, a plurality of switching devices, a plurality of physical transmission lines provided between the plurality of terminals and the plurality of switching devices, Means for setting a line and executing a process of changing the state of the line. A feature of the present invention resides in that a means for changing an allocated band of a line other than this line in cooperation with the line setting and / or state change processing is provided.

As a method of changing the allocated bandwidth of a line different from this line without triggering the line setting and / or state change processing, there is provided means for observing a transfer rate of information transferred on the line. It is desirable to have means for changing the assigned bandwidth of a line other than this line according to the change in the transfer rate observed by the observation unit.

The relationship between a plurality of lines whose bands are changed in conjunction with each other by the changing means, and the relationship between each of the plurality of lines and the other lines performed in conjunction with the generation of the line and the securing of the band. It is desirable to have means for storing the change width of the allocated band.

A control message for performing a line state change process allows the change of the bandwidth allocated to another line in conjunction with the change of the line state and the change in the information transfer rate observed on the line. It is desirable to have means for writing information indicating

Means for receiving the information indicating the allowance written in the control message and determining whether or not to change the allocated bandwidth of another line in conjunction with the state change processing of the requested line. It is desirable to provide.

Means for writing information indicating a line whose assigned band is to be changed in conjunction with a change in the state of the line and a change in the information transfer rate observed on the line in a control message requesting a state change of the line. It is desirable to provide.

It is preferable that a means for determining a line whose bandwidth is to be changed based on the information indicating the line to be changed written in the control message in accordance with the contents stored in the storing means is provided.

When changing the bandwidth to be allocated to another line in conjunction with the state change processing for the line, a bandwidth change permission / inhibition inquiry message for asking the terminal or the switching unit involved in the line for which the allocated bandwidth is to be changed whether or not the change is possible. And a means for determining whether or not to perform a state change process for the line according to the presence or absence of a response message to the bandwidth change inquiry message and the content of the response message.

A means for sending a response message in response to the band change permission / inhibition inquiry message and indicating whether or not the change of the band allocated to the line due to a change in the state of another line or a change in the transfer rate may be provided. desirable.

When changing another allocated band in conjunction with the line state change processing and the fluctuation of the information transfer rate observed on the line, the allocated band is allocated to a terminal or a switching unit involved in the line whose band is to be changed. It is desirable to have a means for sending a control message indicating a change in the band.

[0053]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. FIG. 1 is a diagram for describing an embodiment of the present invention with respect to a mode in which a cut-through VC is generated by activating a terminal, and illustrates an operation when a cut-through VC is generated. FIG. 2 is a block diagram of a main part of a terminal and a router according to the embodiment of the present invention. An embodiment of the present invention will be described with reference to a first embodiment of the present invention.

The embodiment shown here uses the present invention to implement I
FIG. 1 shows a P-ATM integrated communication network in which terminals A and B and ATM switches SW1 to SW
W7, the terminals A and B and the ATM switch SW
A communication including a physical transmission line provided between 1 and SW7 and a line control unit 50 as a means for setting a line on this physical transmission line and executing a state change process of this line as shown in FIG. It is a net. A feature of the present invention resides in that the line control unit 50 changes the assigned bandwidth of a line different from this line in conjunction with the line setting and / or state change processing.

Further, as shown in FIG. 2, there is provided a transfer rate observing section 51 which is a means for observing the transfer rate of information transferred on the line, and the line control section 50 monitors the transfer rate by the transfer rate observing section 51. The assigned band of a line different from this line is changed in accordance with the change in the transfer rate.

A VCG that stores the relationship between a plurality of lines whose bandwidths are changed in conjunction with each other by the line control unit 50
It has a table T1 and a band-linked VC table T2 that stores, for each of the plurality of lines, a width of change in the allocated band of another line performed in conjunction with generation of the line and reservation of the band.

[0057]

DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) The first embodiment of the present invention relates to an application to a mode in which a terminal activates cut-through VC. A first embodiment of the present invention will be described with reference to FIGS. 1 and 3 show examples in which the present invention is implemented in a mode in which a terminal activates cut-through VC. FIG. 1 shows the operation when the cut-through VC is generated as described above. FIG. 3 shows an operation when the cut-through VC is released. Terminals A and B
Holds the adjacent routers a and c and the default VC. The VPI of the interface of the terminal A of the default VC held by the terminal A is 0, V
It is assumed that CI is 65.

A group of lines linked to each other is called a VCG (band-linked line group), and a VCGID (band-linked line group designator) is defined as an identifier of each VCG. VCGID is an integer from 1 to 255. For each VCG, a VC whose band is changed in conjunction with a state change process of a VC belonging to the VCG is defined as a first VC. The ATM switch SW1 to which the terminal A is connected has a port, VCGID, VP of the first VC for each VCG.
VCG table T1 storing I, VCI, and current band
Port, Call Ref for each VC belonging to and VCG
erence Value, VPI, VCI, VCG to which VCG belongs
Band-linked VC storing ID, change bandwidth to first VC
It has a G table T2, and implements a means for storing the relationship between lines that are controlled by linking the bands by using these two tables.

The VCG table T1 indicates that there is a VC group to which VCGID # 1 is allocated for the port #a accommodating the terminal A, and the first VC of this VC group
Indicates that (VPI, VCI) is (0, 65). That is, the default VC for the terminal A to perform the IP communication is set as the first VC. The default VC is a word indicating the role of the VC in performing the IP communication, and the first VC is a word indicating the role of the VC in performing the band interlocking control in the ATM communication in the present invention. The invention dare defines two different terms. However, hereinafter, the first VC and the default VC indicate the same VC as an entity.

The operation when terminal A generates a cut-through VC will be described with reference to FIG. The terminal A obtains the ATM address of the terminal B to which the cut-through VC is called by a conventional procedure (NHRP or the like). Next, perform the following steps.

Step 1-1 (cut-through VC generation request): A SETUP message is sent to the ATM switch SW1 to request the ATM network to generate a cut-through VC. Call Party Num in SETUP message
Fill in ATM address of terminal B in ber
Write the ATM address of itself (terminal A) in y Number. FIG. 4 is a diagram for explaining a form in which the VCGID is inserted into the caller ATM address. Figure 4 shows ATM Forum UN
This is the format of the ATM End System Address specified in I3.1. In one embodiment, as shown in FIG.
Write the value # 1 of the VCGID in the SEL field of the lling Party Number.

When the other VCs are not changed in conjunction with the generation of the cut-through VC, the value of the SEL field is set to "0". As a result, the terminal
On the occasion of transmitting the P message, indicates whether to change the band of another VC in conjunction with the generation of the cut-through VC,
VC to change band when changing band of other VC
Can be selected.

FIG. 5 is a diagram for explaining a form in which VCGID is entered as an information element as another form in which VCGID is entered in a signaling message. As another method of transmitting a band-linked circuit group, VCGI as shown in FIG.
A new information element that represents D is defined, and
A method of including it in the UP message is conceivable.

The ATM switch SW1 which has received the SETUP message from the terminal A first sends a call CALL P to the terminal A.
An ROC message (a message indicating that the SETUP has been received) is sent, and then the following step 2 is executed.

Step 1-2 (change of bandwidth of first VC): It is confirmed from the received SETUP message whether or not VCGID is entered. When the VCGID is entered, first, the band of the default VC after the generation of the cut-through VC is calculated, and then the VCG table is referred to using the VCGID as a key to determine the default VC of the band-linked line group. Then, the RM cell indicating that the band is to be changed and the band after the change are transmitted to the default VC.

As a result, it becomes possible for the ATM switch SW1 to change the band of the default VC and to transmit the changed band to the ATM switch and the terminal (including the router) related to the default VC. When the router a and the terminal A receive the RM cell, the following steps (step 1)
-3, execute steps 1-4).

Steps 1-3 and 1-4 (determination of whether or not the default VC band can be changed): It is determined whether or not the default VC band can be changed to the changed band indicated by the received RM cell. If so, the RM cell is returned without changing the band in the RM cell, and if not, the band in the RM cell is changed to the current band and the RM cell is returned.

Thus, the terminal A holding the default VC selects whether or not to change the band of the default VC, and if the band can be changed, the information transmission rate of the terminal A to the default VC is changed. It can be changed according to. Upon receiving the RM cell from the terminal A, the ATM switch SW1 executes the following steps 1-5.

Step 1-5 (confirmation of whether or not the default VC band can be changed): If the band entered in the RM cell is the same as when the RM cell was transmitted, it is determined that the change of the default VC band is permitted and the default VC is changed. The bandwidth is changed, and a signaling message for generating a cut-through VC is transmitted to the terminal B route. Further, an entry for the generated cut-through VC is created in the bandwidth-linked VC table, and the Call R entered in the SETUP message is created.
The eference value, the assigned VPI and VCI, and the band change width of the default VC performed in conjunction with the eference value are stored. If the bandwidth change is not permitted, the terminal A
RELEASECOMPLETE as response for P
Is sent.

After execution of step 1-5, similar to the conventional procedure for generating a cut-through VC, the cut-through VC is transmitted between terminal A and terminal B by transferring a signaling message.
C is generated, and communication on the cut-through VC is started. After the generation of the cut-through VC, the VCG table T1 and the band-linked VC table T2 of the ATM switch SW1 accommodating the terminal A are as shown in the frame of the broken line in FIG.
The VC generated in 123 belongs to the VC group of VCGID # 1, and the same VCGI is generated by generation of the VC.
The bandwidth of the first VC belonging to the VC group of D # 1 is 1 Mb
This indicates that ps has been reduced.

FIG. 3 shows a release procedure of the cut-through VC. Terminal A when communication on cut-through VC ends
Sends a RELEASE message to the ATM switch SW1 to request the network to release the cut-through VC. ATM which received RELEASE message
The switch SW1 performs the following steps.

Step 1-6 (Confirmation of default VC,
Default VC bandwidth change): Band-linked VC using Call Reference Value in RELEASE message
The table T2 is searched, and the VC group to which the VC to be released belongs, and the bandwidth of the first VC to be changed at the time of release (+1)
Mbps). Further, the VCG table T1 is searched to obtain the first VC of the VC group. And the first
An RM cell for changing a band is transferred on a VC (default VC for terminal A).

Steps 1-7, 1-8 (default VC
Change of band): The terminal A and the router a which have received the RM cell change the band of the default VC to the value indicated by the RM cell, and transfer the RM cell on the default VC.

As a result of steps 1-6, 1-7 and 1-8,
The default VC band returns to the value before the cut-through VC was generated. When the RM cell is received from the terminal A, the following steps are performed.

Step 1-9 (release of cut-through VC): The information relating to the cut-through VC in the band-linked VC table is deleted, and a response for confirming that the cut-through VC has been released is transmitted to the terminal A, and at the same time, the cut-through VC is released. A signaling message for releasing the through VC is transferred to the terminal B.

(Second Embodiment) The second embodiment of the present invention
-ATM integrated routers RA, RB, RC are cut-through V
It is an example of application to a form in which C generation is activated. FIG. 6 shows an implementation example of the present invention in the IP-ATM integrated routers RA, RB, and RC. IP-ATM integrated router RA, R
As in the first embodiment of the present invention, B and RC (only routers RA, RB and RC are shown) are default VCs which are linked with the generation of the cut-through VC as information on the VCG table T1 and the cut-through VC. It has a bandwidth-linked VC table T2 that stores the bandwidth change bandwidth. The IP-ATM integrated router RA that has detected the necessity of generating the cut-through VC performs the following steps.

Step 2-1 (confirmation of whether or not the band of the default VC can be changed): The band of the default VC after the generation of the cut-through VC is obtained. Then, a message is sent to the terminal A connected by the default VC, asking whether the default VC band can be changed. In step 2-1, an embodiment in which a message inquiring whether or not the bandwidth of the default VC can be changed is not transmitted is also conceivable.

The terminal A responds whether or not to permit the change of the bandwidth of the default VC. If the response message indicates that the bandwidth change is permitted, the IP-ATM integrated router RA
Transmits a control message for generating a cut-through VC to the IP-ATM integrated router RB according to the conventional procedure.
Transfer to The IP-ATM integrated router RA that has received the response message from the IP-ATM integrated router RB executes the following steps.

Step 2-2 (Execution of Change of Default VC Bandwidth, Notification of Bandwidth after Change): Change the default VC assigned bandwidth of terminal A set in the switch of IP-ATM integrated router RA. Then, the RM cell in which the changed band is written is transferred to the default VC. Further, the change width of the band of the default VC is stored in the band-linked VC table T2 as one element of the information regarding the cut-through VC. When receiving the RM cell from terminal A, IP-A
TM integrated router RA is VPI / VC of cut-through VC
An I notification message is sent to terminal A.

In step 2-2, as a means for notifying the terminal A of the change of the bandwidth of the default VC, the terminal A
An embodiment in which the bandwidth of the default VC is included in a control message related to IP communication between the IP-ATM integrated router RA and the terminal A, such as a VPI / VCI notification message of a cut-through VC sent to the terminal A, is also conceivable.

When the cut-through VC is released, I
The P-ATM integrated router RA uses the bandwidth-linked VC table T2.
, The change width of the band of the default VC is obtained, and the band of the default VC is restored. As a method of notifying the terminal A that the band of the default VC is to be returned to the original state, a form in which the terminal A is notified by an RM cell and a form in which the band is included in a control message regarding IP communication can be considered as in the case of generation.

(Third Embodiment) The third embodiment of the present invention
This is an example of application to a mode in which a band of a cut-through VC is secured by a cell. FIG. 7 shows an embodiment of the present invention in which the band is secured to the cut-through VC by using RM cells. In this embodiment, a cut-through VC is previously set as a PVC between the terminals A and B that frequently communicate frequently. However, a band is not always secured for the cut-through VC, but a band is secured as needed. The ATM switches SW1 to SW7 store the relationship between the lines whose bands are linked and controlled by the VCG table T1 and the band linked VC table T2, as in the first embodiment of the present invention. V of cut-through VC
PI and VCI are 0 and 70, and the default VC is set as the first VC of the VC group to which the cut-through VC belongs. In FIG. 7, RM (C) indicates an RM cell transferred on the cut-through VC, and RM (D) indicates an RM cell transferred on the default VC.

The terminal A sets an RM cell for securing a band for the cut-through VC as necessary.
Send on C. Then, the ATM switch SW1 executes the following steps.

Step 3-1 (Start change of band of default VC): Calculate the width of band change of the first VC to be performed in conjunction with securing of the band. And the VPI of the cut-through VC,
The VCG ID to which the cut-through VC belongs is obtained by referring to the band-linked VC table using the VCI as a key, and
The first VC of the VCG is acquired by referring to the VCG table using the ID as a key. Then, it transmits an RM cell for changing the band on the first VC (= default VC of terminal A).

Step 3-2, Step 3-3 (terminal,
Router A default VC band change): Terminal A and router a receiving the RM cell change the default VC band to RM.
Change to the value indicated by the cell and transfer the RM cell on the default VC.

Step 3-4 (Start of securing band of cut-through VC): RM for default VC from terminal A
Upon receiving the cell, the ATM switch SW1 confirms that the band in the RM cell has the changed value, and sends out the RM cell for securing the band in the cut-through VC onto the cut-through VC. Then, as information on the cut-through VC in the band-linked VC, the secured cut-through V
The value of the default VC band change performed in conjunction with the C band is stored.

At the time of release of the cut-through VC, the RM used by the terminal A to release the band on the cut-through VC
A cell is transmitted, whereby the ATM switch SW1 transmits an RM cell for restoring the band on the default VC on the default VC, and at the same time, transmits an RM cell for releasing the band of the cut-through VC on the cut-through VC. To send to.

Although three embodiments have been described for the ATM network, the same multi-band interlocking control can be applied to a packet switching network having a function of setting a logical line such as a frame relay network or a conventional circuit switching network. That is self-evident.

[0089]

As described above, according to the present invention,
In a mode in which the user activates the generation of the cut-through VC but does not charge the user for the generation of the cut-through VC and the reservation of the band, the occurrence probability of the shortage of the band of the ATM network can be extremely suppressed. It becomes. In addition, it is possible to improve the service fairness in the mode in which the IP-ATM integrated router activates the generation of the cut-through VC. As described above, according to the present invention, the bandwidth allocated to another line can be changed in conjunction with the state change processing (setting, release, band correction, etc.) of one line and the fluctuation of the information transfer rate.

[Brief description of the drawings]

FIG. 1 is a diagram for explaining an embodiment of the present invention in which a cut-through VC is generated by activating a terminal (generation of a cut-through VC).

FIG. 2 is a block diagram of a main part of a terminal and a router according to the embodiment of the present invention.

FIG. 3 is a diagram for explaining an embodiment of the present invention in which a cut-through VC is generated by activating a terminal (release of cut-through VC);

FIG. 4 is a view for explaining a form in which a band-linked line group designator is put in a caller ATM address;

FIG. 5 is a view for explaining a form in which a band-linked line group designator is defined as an information element of a signaling message.

FIG. 6 is a diagram showing an implementation example of the present invention in an IP-ATM integrated router.

FIG. 7 is a diagram showing an embodiment of the present invention in a form in which a band is secured to a cut-through VC by an RM cell.

FIG. 8 is a diagram for explaining an outline of IP communication.

FIG. 9 is a view for explaining an outline of ATM communication.

FIG. 10 is a diagram for explaining the concept of a VP.

FIG. 11 is a view for explaining a typical use form of ATM in IP communication.

FIG. 12 is an exemplary view for explaining a mode in which a cut-through VC is generated by activating a terminal.

FIG. 13 is a view for explaining an embodiment in which a cut-through VC is generated by activating an IP-ATM integrated router.

[Explanation of symbols]

50 Line control unit 51 Transfer Rate Observation Section A, B terminal ad router RA, RB, RC IP-ATM integrated router SW1 to SW7 ATM switch T1 VCG table T2 Band link VC table

Claims (16)

(57) [Claims] A packet is transmitted between terminals which are packet communication devices.
Packet exchange to generate a cut-through line
A communication network having a switching device, for generating or disconnecting a cut-through line between the terminals.
Is to add bandwidth to the cut-through line or
In conjunction with the reduction, the terminal communicates with the packet switching device.
Reduce the bandwidth of the default line
Is a communication network comprising means for adding and changing . And means for observing a transfer rate of information transferred on the cut-through line, wherein a default is set according to a change in the transfer rate observed by the observing means.
2. A system according to claim 1, further comprising means for changing a bandwidth allocated to the default line.
Communication network as described. 3. The method according to claim 1, wherein said changing means performs cut-through rotation.
Line creation or disconnection or cut-through line allocation band
Data whose bandwidth has been changed in conjunction with the addition or deletion of bandwidth
3. The communication network according to claim 1, further comprising means for storing identification information of the fault line and a change width of the allocated bandwidth. 4. Creation or disconnection of a cut-through line
Add or delete the bandwidth allocated to the cut-through line.
3. The communication network according to claim 1, further comprising means for writing, into the control message, information indicating that a change in the bandwidth allocated to the default line is permitted. 5. The allocation of production or cutting or cut-through lines cut through <br/> line receiving the received information indicating that the allowable written in said control message requesting
5. The communication network according to claim 4, further comprising means for determining whether or not to change the assigned bandwidth of the default line in conjunction with addition or deletion of the bandwidth. 6. Creation or disconnection of a cut-through line
There is generated in the control message for requesting the addition or deletion of allocated bandwidth of the cut-through line of the cut-through lines or
Or the addition of the allocated bandwidth for disconnected or cut-through circuits.
And means for writing identification information of a default line for changing an allocated band in conjunction with deletion or deletion.
Communication network as described. 7. The changing default written in the control message according to the storage contents of the storing means.
Network of claim 3 or 6, wherein comprising means for determining a default <br/> line to change the bandwidth by the identification information of the belt line. 8. A method for generating or disconnecting a cut-through line.
Addition or deletion of allocated bandwidth for disconnected or cut-through circuits
Means for sending a band change permission / inhibition inquiry message for asking the terminal or the packet switching apparatus involved in the default line for changing the allocated bandwidth when changing the allocated bandwidth for the default line in conjunction with the removal . Depending on whether or not a response message has been received in response to the bandwidth change availability inquiry message and the content of the response message, generation of the cut-through line can be performed.
Or the addition of the allocated bandwidth for disconnected or cut-through circuits.
3. The communication network according to claim 1, further comprising: means for determining whether or not to perform deletion . 9. A response message is transmitted in response to the bandwidth change permission / inhibition inquiry message to indicate whether or not it is allowed to change the bandwidth allocated to the default line by changing the state of another cut-through line or changing the transfer rate. 9. The communication network according to claim 8, comprising means. 10. Generation or disconnection of a cut-through line.
Or when changing the bandwidth allocated to the default line in conjunction with the addition or deletion of the bandwidth allocated to the cut-through line and the fluctuation of the information transfer rate observed on the cut-through line. 3. The communication network according to claim 1, further comprising means for sending a control message indicating a change in the allocated bandwidth to a terminal or a packet switching device involved in the default line. 11. A packet communication system provided in a packet communication network.
Cuts that transfer packets between terminals that are communication devices
A packet switching device that generates a loop line, and generates or disconnects a cut-through line between the terminals.
Is to add bandwidth to the cut-through line or
Default value maintained with the terminal in conjunction with reduction
Change the bandwidth by reducing or adding the bandwidth allocated to the line
Packet switching apparatus characterized by comprising a changing means. 12. Information transferred on a cut-through line
Means for observing the transfer rate of the
Default according to the observed fluctuation of the transfer rate.
Means for changing the bandwidth allocated to the communication line.
The packet switching device according to the above. 13. Generation or disconnection of a cut-through line.
Or add bandwidth to cut-through circuits or
Is the default whose bandwidth is changed in conjunction with the reduction
There is a cut-through line generation or disconnection for the line
Or add or reduce bandwidth to cut-through circuits
Default line identification information and assignment performed in conjunction
13. The apparatus according to claim 12, further comprising means for storing a change width of the band.
On-board packet switching equipment. 14. Generation or disconnection of a cut-through line.
Or assigning additional bandwidth to cut-through circuits.
Control message to reduce or save
Reduce or increase the bandwidth allocated to the default line
12. The method according to claim 11, further comprising means for writing information indicating that the information is permitted.
Packet switching equipment. 15. Generation or disconnection of a cut-through line.
Or addition of bandwidth to cut-through circuits or
Default value maintained with the terminal in conjunction with reduction
When changing the bandwidth by reducing or adding the bandwidth of the line
Change the assigned bandwidth,
Asks the terminal or packet switching device to make a change
Means for sending a bandwidth change availability inquiry message;
Receiving a response message to this inquiry message
According to the content of the response message
Processing or cut-through of generation or disconnection of through circuit
-Change the bandwidth by reducing or adding the bandwidth of the line
Means for determining whether or not to perform processing.
The packet switching device according to the above . 16. When changing the bandwidth of a default line.
The terminal or terminal involved in the default line whose bandwidth is changed
Indicates to other packet switching equipment that the allocated bandwidth has changed.
12. A device according to claim 11, further comprising means for transmitting a control message.
On-board packet switching equipment .