JPH09238143A - Node equipment and network resource reservation method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorter a transfer delay time when quality is revised by sending a packet according to required quality without awaiting a message for reserving a resource when a resource corresponding to the required quality is allowed to reserve. SOLUTION: A transmitter side user terminal equipment 111 sends transmission data of an IP packet to a communication network. Communication modes 121-123 convert a packet into fixed length cells and transfers the cells by ATM communication networks 133, 134 composed of virtual connections 151, 152 or the like set by ATM exchanged 131, 132 or the like. A receiver side user terminal equipment 112 sends a reservation message composed of an RSVP resource reservation protocol to request service quality to the transmitter side user terminal equipment 111. Upon receipt of a reservation message, the communication node, e.g. 122 sets a band width in response to the requested quality to the virtual connection 152. The communication node 122 transfers cells without awaiting an acknowledge of reserving the band width by setting the virtual connection 152 to an ABT/IT service.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an IP (Internet Protocol) using an ATM (Asynchronous Transfer Mode) communication network.
The present invention relates to a node device for transmitting and receiving a data packet such as a datagram and a network resource reservation method.

[0002]

2. Description of the Related Art When communication is performed using the Internet, the data transmitted by the sender is IP (Internet Protocol).
col) level, and is converted to a data packet called an IP datagram defined at the level and delivered to the recipient.

Conventionally, the data packet delivery service defined by IP is unreliable, and is best-effort.
(Best-effort) system. That is, there is no guarantee regarding the delivery of the data packet (it may be lost, but no measures are taken), but I
P is a delivery system that enthusiastically attempts to deliver data packets. That is, no quality guarantee was made for the conventional delivery of IP level data packets.

On the other hand, in recent years, IETF (Internet
The Engineering Task Force) has argued that it provides quality for delivery of IP level data packets as described above. As a result, Guaranteed service (Shenker et al .: “Specification of Guarantee
d Quality of Service ”, INTERNET-DRAF
T, draft-ietf-intserv-guaranteed-svc-03.txt), P
reditive service (Shenker et al .: "Specif
ication of Predictive Quality of Service ”, INT
ERNET-DRAFT, draft-ietf-intserv-predict
ive-svc-01.txt), Controlled Delay
Services (Shenker et al .: “Specification of Control
led Delay Quality of Service ”, INTERNET-
DRAFT, draft-ietf-intserv-control-del-svc-02.
New services such as txt) that specify the quality of data packet delivery have been proposed.

[0005] The various services described above will be outlined below. (1) Guaranteed service (Guaranteed Qua
lity of Service) A service that guarantees that data packets are delivered within a certain period of time. A transfer rate value is required as the quality of service. (2) Predictive service (Predictive Qua
lity of Service) A service that guarantees that data packets will be delivered within a certain period of time with a high probability (in other words, a service that guarantees that most data packets will be delivered to the other party within a certain period of time). Is. As service quality,
The service level (1, 2, 3) is required, and the lower the service level, the smaller the relative delay. Also,
In each communication node, the upper limit value of the transfer required time for each service level is set. (3) Controlled Delay service (Co
ntrolled Delay Quality of Service) A service level is required as a quality of service, but the upper limit of the required transfer time is not set. Although the data packet delivery delay changes dynamically, the best
-It can be delivered in less time than the Effort service. (4) Best Effort service This is a service that does not guarantee any quality, and no quality of service is requested.

On the other hand, a resource reservation protocol (Braden, et al .: "Resour" necessary for providing the above service)
ce ReSerVation Protocol (RSVP) -Version 1 Functional
Specification ", INTERNET-DRAFT, dr
aft-ietf-rsvp-spec-08.txt) has been proposed. The feature of this resource reservation protocol is that resource reservation is performed based on the request from the receiving user terminal. The receiving user terminal sends a reservation message called a Resv message to the sending user terminal, so that the R
It tries to reserve the reception quality of service described in the esv message. Then, in the data packet communication node (router device) that relays the data packet sent from the transmitting user terminal to the receiving user terminal, when the Resv message is received, it is necessary to provide the receiving quality of service in the Resv message. It is determined whether or not another resource reservation can be accepted, and if it is possible, the reservation request is accepted, and the Resv message is sent to the user terminal that transmits the data packet.

[0007]

An ATM (Asynchronous Transfer Mode) for exchanging / transferring cells, which are fixed-length data packets, as a unit and using an IP level by using a virtual connection set on a communication network. In the case of performing data packet transfer, IP is conventionally used.
Since it was not necessary to guarantee service quality for the transfer of level data packets and reserve network resources, only data packet accommodating methods for virtual connections that do not consider IP level quality when delivering data packets are being considered. The method of setting the virtual connection in consideration of providing the required quality of service at the packet level has not been studied.

Further, in the case of performing data packet transfer using the ATM communication network, when a message requesting a change in service quality (for example, a Resv message sent from a receiving user terminal in RSVP to a transmitting user terminal) is received, Attributes of the virtual connection accommodating the data packet corresponding to the message (service category,
It is necessary to change the reserved resource amount, etc.), and accordingly, the virtual connection may be reestablished so that the newly requested quality of service can be provided. As a result, it is impossible to transfer the data packet until a new virtual connection is set, which causes an adverse effect such as an increase in packet transfer delay.

The present invention has been made in consideration of the above circumstances, and is capable of providing the required service quality of the IP level when delivering the data packet of the IP level through the ATM communication network. An object of the present invention is to provide a node device and a network resource reservation method capable of immediately starting the transfer of data packets even when the required quality of service is changed.

[0010]

The present invention (Claim 1) includes:
Received data packet (Internet packet, I
P datagram) is converted to an ATM cell and a predetermined virtual connection (Virtual Channel / P)
In a node device that transmits data packets, a node device (terminal or router) that transmits or receives a data packet requests a service quality reservation (for example, RSVP (Resource).
ce ReSerVation Protocol) Resv message), the required resource amount (for example, bandwidth amount, cell transfer rate) obtained based on the required quality of service written in the message is received.
When it is determined that the reservation of the resource amount is possible, a message indicating that the resource amount has been reserved in the virtual connection in which the data packet is to be communicated (for example, RM (ATM (ATM Block Transfer) service) is received. CI (Congestion Indication) in a Resource Management cell
(n) bit is 0), and means for starting the transmission of the data packet according to the newly requested quality of service is provided.

According to the present invention (claim 2), in the invention of claim 1, the virtual connection is capable of changing a resource amount to be secured without re-establishing the connection (for example, ABT / IT ( Immediate Tr
ansmission) is a virtual connection according to).

According to the present invention (claim 3), in the invention of claim 2, the resource amount to be reserved is written in a resource management cell (for example, an RM cell in an ABT service) in order to secure the required resource amount in the virtual connection. Then, the data packet is transmitted according to the newly requested quality of service after being sent out on the virtual connection in.

Here, the virtual connection in which the node device writes and sends out the resource amount to be secured in the resource management cell is set from this node device to the next node device in the transfer path of the data packet, This node device is a virtual connection for transmitting ATM cells.

The required resource amount is, for example, necessary to provide a service quality satisfying the required service quality described in the message to the data packet transferred to the receiving user terminal. Resource amount, which is represented by, for example, a band amount, a cell transfer rate, and the like.

The setting of the virtual connection in which the resource amount to be secured can be changed without re-establishing the connection is performed prior to securing the resource amount. In the above determination, for example, the resource information and the residual resource information allocated at the data packet level are held in the node device, and when a service quality change request is made, based on the IP level resource information, It is determined whether or not it is possible to secure the amount of ATM level resources required to satisfy the service quality.

According to the present invention (claim 4), in the invention of claim 3, after starting transmission of a data packet according to a new required quality of service by using the virtual connection,
When the resource management cell in which the content indicating that the resource amount cannot be secured is entered is received, the transmission of the data packet according to the new required quality of service is stopped and the data packet according to the old required quality of service is transmitted. Is provided with a means for resuming.

According to the present invention (claim 5), in the invention of claim 3, after starting transmission of a data packet according to a new required quality of service by using the virtual connection,
When the resource management cell in which the content that the amount of resources cannot be secured is entered is received, the transmission of the data packet according to the newly requested quality of service is stopped and the transmission of the data packet is guaranteed with any quality. It is characterized in that it is provided with a means for restarting without doing.

According to the present invention (claim 6), the received data packet (Internet packet, IP datagram) is received.
To ATM cells and convert them into a predetermined virtual connection (Vi
rtual Channel / Path Conn
In the network resource reservation method for reserving the network resource used when transmitting the data packet, a message requesting the reservation of the quality of service from the user terminal that transmits or receives the data packet (for example, RSVP (Resource).
ce ReSerVation Protocol), determine the required resource amount based on the required quality of service written in the received message, and determine whether or not the required required resource amount can be secured. , When it is determined that the required resource amount (eg, bandwidth amount, cell transfer rate) can be secured, the securement of the resource amount is requested in the virtual connection in which the data packet communication is to be performed, It is characterized in that the transmission of the data packet according to the newly requested quality of service is started without waiting for the reception of the message indicating that the reservation has been made (for example, the RM cell in the ABT service whose CI bit is 0).

[0019]

Embodiments of the present invention will be described below with reference to the drawings. First, a basic configuration and an outline of the present embodiment will be described. FIG. 1 is an example of a basic configuration of a data packet communication network according to an embodiment of the present invention. In the data packet communication network, when data packets are transferred between data packet communication nodes 121 to 123 that transmit and receive data packets, the data packets are divided and converted into fixed-length data units called cells when the data packets are transferred.
Data packets are transferred by transferring the cells to the adjacent data packet communication node using the virtual connections 151 and 152 set on the communication networks 133 and 134. Here, the virtual connection is set by the ATM exchanges 131 and 132 between the nodes in the ATM communication networks 133 and 134, and is a virtual path connection.
ction), virtual channel connection (Virtual Channe
l Connection) is applicable.

In the user terminals 111 and 112 using this data packet communication network, the data to be transmitted is transmitted by IP (In
The data packet is converted into a data packet called an IP datagram defined at a ternet protocol level, and transmitted on a communication network.

In the following, a data packet called an IP datagram will be called an IP packet. When the content of the IP packet explicitly indicates data,
Use the term data packet.

The communication between the user terminals 111 and 112 is a protocol higher than the IP level (for example, TCP (T
transmission Control Protocol
ol)), but in such a case, a method of converting the IP packet into an IP packet in the terminals 111 and 112 and then transmitting the IP packet to the communication network, or the terminal 11
Data packet communication node 12 closest to 1,112
1, 123, a method of converting a data packet arriving according to a protocol regulation higher than the IP level into an IP packet can be considered. In such a case, in the present embodiment, the former method is adopted.

The user terminal 111 and the data packet communication node 121, and the user terminal 112 and the data packet communication node 123 are (1) directly connected, (2) connected by an ATM network, and (3). It is possible to connect via other networks such as Ethernet. In the present embodiment, a description will be given assuming that they are directly connected.

In this embodiment, when transferring an IP packet between user terminals, the user terminal 111
The user terminal 112 will be described as a packet transmitting terminal, and the user terminal 112 will be described as an IP packet receiving terminal.

In this data packet communication network, as a service for IP packets, Guara as described above is used.
nteed service, Predictive service,
The Best Effort service shall be provided. Note that the Controlled Delay service is handled as a Predictive service in this communication network. The outline of each service is as described above. (1) Guaranteed service A service that guarantees delivery of IP data packets within a certain period of time. As service quality,
A transfer rate value is required. (2) Predictive service A service that guarantees that an IP data packet will be delivered within a certain period of time with high probability. As the service quality, the service level (1, 2, 3) is required, and the smaller the service level, the smaller the relative delay. In addition, in each data packet communication node, the upper limit value of the required transfer time for each service level is set. (3) Best Effort service A service that does not guarantee any quality. No quality of service requirements are made.

The Controlled Delay
A service is a service that requires a service level as a quality of service, but the upper limit of the required transfer time is not set. In the communication network of this embodiment, the service is treated as a Predictive service that requests the same service level.

In this data packet communication node, as shown in FIG. 2 or 3, the IP data packet is accommodated on the virtual connection. In each drawing, reference numeral 200 denotes a buffer unit that holds packets, and 202 denotes a transfer processing unit that extracts the packets in the buffer unit at a timing according to the allocated resource amount and transfers the packets to the next stage. Further, 204 is a buffer unit for holding ATM cells,
A transfer processing unit 206 extracts an ATM cell in the buffer unit and transfers the ATM cell to the virtual connection. The function of converting IP level packets into ATM cells is omitted.

For the Guaranteed service, as shown in FIG. 2, at the IP level, for each of the data packet flows g1 to gn, the resource amounts Rg1 to Rgn that satisfy the transfer rate value required by the packet are allocated. , A virtual connection (VC) accommodating an IP data packet belonging to the flow is set for each flow. Alternatively, as shown in FIG. 3, all flows are accommodated on the same virtual connection.

Predictive Service and Be
For the st Effort service, at the IP level, for each service level of the Predictive service, the relative magnitude of the delay between the levels and the upper limit value of the transfer required time set for each level are satisfied. Resource amounts R1 to R3 are respectively assigned, and Best
Guara out of the total amount of resources held in the data packet communication node for the Effort service
All services requesting the Predictive service and the Best Effort service by allocating an arbitrary value Rb within a range that does not exceed the resource amount obtained by subtracting the resource amount allocated to the Nteed service and the Predictive service (hereinafter, this is referred to as the residual resource amount). The flow is accommodated on the same virtual connection.

The bandwidth amount to be secured in the virtual connection is calculated based on the sum of the IP level resource amounts allocated to the respective data packet flows accommodated on the connection.

Also for the Predictive service, a method in which one virtual connection is associated with each level or a virtual connection is associated with each flow is considered.

In this data packet communication network, the IPTF resource amount shown above is secured by the IETF.
This is performed according to a resource reservation protocol called RSVP (Resource ReSerVation Protocol) proposed by (Internet Engineering Task Force). In RSVP, as shown in FIG.
A quality of service for an IP data packet (42 in the figure) issued from the communication terminal 11 is requested to the data packet communication network, and in this data packet communication network, resources are reserved so as to satisfy the request. Therefore, the receiving terminal 112 requesting the quality of service sends a reservation message called “Resv message” (41 in the figure) to the transmitting terminal 111, if necessary, in the opposite direction to the path for transferring the IP data packet. Send along.

In the data packet communication node according to this embodiment, when the Resv message is received, the R
The amount of resources to be secured in order to provide the required quality of service described in the esv message is calculated, and it is determined whether or not the resources can be secured. If the amount of resources can be secured, After actually securing the resource amount, the Resv message is sent again toward the transmitting terminal 111.

In the present embodiment, the IP calculated above
A band corresponding to the level resource amount is secured at the virtual connection level. Further, in the present embodiment, the virtual connections 151 and 152 set between the data packet communication nodes are the I.S.
A service called ABT (ATM Block Transfer) recommended by H.371 is provided.

In the ABT, an AT surrounded by adjacent RM cells (Resource Management cells) as shown in FIG.
It is possible to dynamically change the transfer rate of the cells belonging to the M block without resetting the virtual connection. In an ABT connection, only the maximum cell transfer rate that can be provided by the connection is set in advance when the connection is set up, and when actually transferring a cell, the requested quality of service (cell transfer rate) is set in the upstream side data packet. The communication node notifies the ATM communication network using the RM cell (41 in the figure) at the beginning of the ATM block, and the ATM communication network receives the RM cell (42 in the figure) indicating the end of the block. ,
The amount of bandwidth required to provide the required quality of service is secured for the virtual connection. In the transfer route of the IP data packet from the transmitting terminal to the receiving terminal,
The side closer to the transmitting terminal is the upstream side, and the side closer to the receiving terminal is the downstream side. For example, the data packet communication node 122 of FIG.
Changes the bandwidth of the virtual connection 152.

The data packet communication node which has transmitted the RM cell (41 in the figure) in which the required quality of service is entered is the AT
By receiving the RM cell returned in the M network, it is possible to recognize whether or not the request has been accepted (whether or not the band required to provide the requested cell transfer rate has been secured). Become. This can be determined by looking at the CI (Congestion Indication) bit in the received RM cell.

In the ABT service, an ABT service (ABT / DT (Delayed Transmission)), which indicates whether or not the required bandwidth has been secured, starts transmission of the data cell after waiting for reception of the loopback RM cell, and R
An ABT service (ABT / IT (Immediate Transmissi) that can start data cell transfer without waiting for M cell response
on)) is easy. If you follow ABT / DT,
Since the transfer of the data cell is started after waiting for the recognition of securing the required band, reliable transfer is guaranteed, but the RM cell sent from the data packet communication node on the transmitting side is required for the recognition of securing the band. The time required for the packet to be returned in the ATM network and returned to the data packet communication node again increases the transfer delay value incurred by the packet transmitted via the ATM network. On the other hand, when the ABT / IT is followed, the transfer of the data cell is started without waiting for the recognition of the reservation of the required band, and therefore, when the band cannot be secured, the quality of the already transmitted data cell is Is not guaranteed.

Therefore, in the data packet communication node of this embodiment, it is judged whether or not the new request service can be accepted based on the resource management information at the IP level, and only when it is possible. , ABT / IT
The required bandwidth is secured and the data cell transfer is started according to the service at the ATM level according to the service.

FIG. 6 shows an example of the configuration of a resource management unit which is a part of the present data packet communication node. As shown in FIG. 6, when the data packet communication node receives the service quality change request, the IP level resource management unit 62 determines whether or not sufficient resources are available to provide the requested quality. Packet flow management table 63
If it is determined based on the internal information and it can be secured, a request for changing the secured resource amount of the corresponding ABT connection is sent to the ABT secured resource changing unit 65, and the changing unit 65.
In step 1, the corresponding ABT connection is instructed to transmit the RM cell in which the changed resource amount is entered.
And in the ABT connection that sent the RM cell,
Immediately start data cell transfer. The folded RM
After the reception of the cell, the information in the ABT connection management table 66 is rewritten.

FIG. 7 is a flow chart showing an operation algorithm of the resource management section. As shown in FIG. 7, when there is a service quality change request, first, the IP
Based on the level information, it is determined whether or not it is possible to secure the resource amount capable of providing the quality (step S
74). If it is determined that it is possible to secure at this point, the RM cell in which the changed resource amount is entered is transmitted to the corresponding ABT connection (step S75), and then the transfer of the data cell is started according to the newly requested quality of service. Yes (step S76). On the other hand, if it is determined that the guarantee is impossible, the service quality change request is rejected (step S77).

After step S76, in order to confirm whether or not the resource amount has been reliably secured, the R
If M cells have been received back (step S7)
8) It is determined whether or not resources have been secured (step S79). Then, if the resource is secured in the ABT connection, the data cell is continuously transferred in accordance with the quality of service after the change request (step S80). If the resource is not secured in the ABT connection, the quality of service is changed. The request is rejected (step S81).

If the required resource amount cannot be secured after the transmission of the IP data packet conforming to the new required service quality is started in step S76, the transmission of the IP data packet conforming to the new required service quality is stopped. Then, the transmission of the IP data packet according to the old required quality of service may be restarted, or the transmission of the IP data packet according to the new required quality of service may be stopped and the transmission of the IP data packet may be performed at any quality. May be restarted without guarantee.

According to this embodiment, when an IP data packet is delivered via an ATM communication network, when a service quality change request is made, the validity of the request is verified based on the resource information at the IP level. Only when it is determined that the change is possible, the resource management cell indicating the request to change the reserved resource amount is transmitted on the virtual connection that provides the ABT service set on the ATM network. Subsequently, since the transfer of the IP data packet can be immediately started, the delay incurred by waiting for the notification of the service change request approval / disapproval judgment notified from the ATM network is eliminated, and as a result, the quick data transfer is completed. It becomes possible to provide a packet transfer service.

In the above, the receiving terminal requests the service quality for the IP data packet issued from the transmitting terminal to the data packet communication network, and in this data packet communication network, resource reservation is made so as to satisfy the request. And so on. Instead, a message sent by the sending terminal to the receiving terminal (for example, RSVP P
resource reservation or the like in response to the "ath message".

The embodiments of the present invention will be described in more detail below. FIG. 1 is a configuration diagram of a data packet communication network according to an embodiment of the present invention. As shown in FIG. 1, this data packet communication network is a transmission terminal 11 that is a transmission side of an IP data packet including communication information issued by a user.
1. Receiving terminal 11 on the receiving side of the IP data packet
1, a data packet communication node 121 directly connected to the transmission terminal 111, a data packet communication node 123 directly connected to the reception terminal 112, a data packet communication node 12
A data packet communication network 122 located between 1 and 123,
ATM for connecting the data packet communication networks 121 and 122
The network 133 is composed of an ATM network 134 connecting the data packet communication networks 122 and 123. ATM network 13
ATM switches 131 and 132 for exchanging and transferring ATM cells are provided in 3,134, and a virtual connection (virtual path connection / virtual channel connection) 151 is provided between adjacent data packet communication nodes via the ATM switch. 152 is set. In addition, 14 in the figure
Reference numerals 1 and 142 denote IP level connections that are virtually set as seen from the IP data packet, and 16 denotes an I sent from the transmitting terminal 111 to the receiving terminal 112.
The flow of P data packet flow is shown.

In FIG. 1, the data packet communication node 12
Although only one user terminal is directly connected to each of 1,123, a plurality of user terminals may be directly connected. Further, in FIG. 1, the number of the data packet communication nodes 122 located between the data packet communication nodes 121 and 123 is one, but a plurality of data packet communication nodes 122 may exist. Further, in FIG. 1, one ATM exchange exists between adjacent data packet communication nodes, but there may be a plurality of ATM exchanges.

When an IP packet is transferred from one adjacent data packet communication node in the present data packet communication network to the other data packet communication node, each data packet communication node temporarily transmits the IP packet.
A virtual connection 151, which is set between data packet communication nodes by dividing and converting the ATM cell into M cells.
152. Then, the data packet communication node receiving the ATM cell converts the received ATM cell into an IP packet again.

In this data packet communication node,
It is assumed that information on the amount of resources at the IP level that can be used when transferring a data packet with an adjacent data packet communication node is held in advance.

When various services for the above-mentioned IP data packet are provided on the data packet communication network shown in FIG. 1, the IP as shown in FIG. 2 or FIG.
Packet-ATM cell correspondence is performed.

In the example of FIG. 2, one virtual connection is associated with one packet flow for the Guarded service, and the transfer rate value required by the Guaranteed service flow gm (1 ≦ m ≦ n) is set. An ABT accommodating the flow so that the IP packet level resource amount Rgm required to satisfy the flow can be secured.
The bandwidth amount PCRgm is secured in the connection VCgm. Predictive Service, Best E
For the forward service, all flows requesting these services are accommodated in one virtual connection, and the IP packet level resource amounts R1 to R3 and the Best Effort service allocated to each service level in the Predictive service. The bandwidth amount PCRr is secured in the ABT connection VCr accommodating the flow so that the total sum of the network resource amount Rb allocated to the flow can be secured.

In the example of FIG. 3, for the Guaranteed service, all the Guaranteed service flows are accommodated in one virtual connection, and each Guaranteed service flow is accommodated.
I assigned to the anteded service flow
The bandwidth amount PCRg is secured in the ABT connection VCg accommodating the flow so that the total sum of resource amounts at the P packet level (ΣRgm) can be secured. Pre
For the passive service and the Best Effort service, the same form as in FIG. 2 is used.

The IP packet level resource amounts R1 to R3 assigned to each service level of the Predictive service are such that the magnitude relationship of the delay values at each level is correct (that is, the smaller the level value, the lower the delay value). In addition, it is calculated and assigned so that the upper limit value of the required transfer time set for each level is satisfied. In addition, Best Eff
The resource amount Rb at the IP palette level allocated to the ort service is Guar based on the total resource amount allocated to the data packet communication node.
A resource amount that does not exceed the remaining resource amount obtained by subtracting the resource amounts Rg1 to Rgn assigned to the anteded service and the resource amounts R1 to R3 assigned to the Predictive service is arbitrarily assigned.

In the following, description will be made based on the correspondence between the IP packet and the ATM cell shown in FIG. 2 unless otherwise specified. When the above-mentioned RSVP is installed on the data packet communication network shown in FIG. 1, the receiving terminal 112 requesting the quality of service for the transfer of the IP data packet 42, as shown in FIG. , Resv message 41 is sent to the sending terminal 111. The data packet communication node having received this judges whether or not it is possible to provide the required quality of service described in the message, and if possible, the network necessary for providing the quality of service. Reserve resources. In the data packet communication network shown in FIG. 1, since the transfer of the IP data packet between the adjacent data packet communication nodes is performed via the ATM communication network, Re
The data packet communication node that has received the sv message secures the bandwidth of the virtual connection in which the IP data packet indicated by the Resv message is communicated so as to satisfy the required quality of service.

As a virtual connection set up between the data packet communication nodes, an ABT (ATM Block Tran
The ABT connection that provides a service called sfer) is adopted. In ABT, as shown in FIG. 5, A surrounded by adjacent RM cells (Resource Management cells) is used.
Since it is possible to dynamically change the bandwidth amount (transfer rate) reserved for the cells belonging to the TM block without resetting the virtual connection, the virtual connection is changed every time the required quality of service is changed. There is no need to reset.

At the time of initial setting of the ABT connection, if only the maximum cell transfer rate that can be provided by the connection is specified and it is desired to secure the resources in the network for the cell transfer, the data packet communication node on the upstream side has the head of the block. A desired cell transfer rate is entered in the RM cell 51 located at, and this is sent to the data packet communication node on the downstream side. ATM through which the RM cell passes
In the network, it is judged whether or not the band necessary for providing the requested cell transfer rate described in the RM cell can be secured, and if the band can be secured, CI (Congesti
on Indication) RM cell with 0 bit, if the bandwidth cannot be secured, RM cell with 1 CI bit
The cell is the UNI of the data packet communication node on the downstream side.
From the (User Network Interface) unit, the packet is sent to the upstream data packet communication node. When the upstream data packet communication node receives the RM cell with the CI bit set to 0, it recognizes that cell transfer can be performed at the requested cell transfer rate, and the CI bit is set to 1 When the RM cell is received, the requested cell transfer rate is recognized as rejected.

As described above, in the ABT service, the ABT / DT service that waits for the reception of the RM cell and then starts the cell transfer and the ABT / DT service that starts the cell transfer without waiting for the response of the RM cell / Although an IT service is prepared, in the present embodiment, it is assumed that the ABT / IT is used to start the transfer of the data cell without waiting for the recognition.

FIG. 6 shows an example of the configuration of the resource management unit which is one function of the data packet communication node in consideration of the characteristics of the ABT connection. As shown in FIG. 6, the present resource management unit includes an IP packet flow management unit 61, an IP
It comprises a level resource management unit 62, an IP packet flow information management unit 63, an ABT connection setting unit 64, an ABT secured resource amount changing unit 65, and an ABT connection information management unit 66.

The IP packet flow management unit 61 receives a new service provision request and a service quality change request related to an IP packet and gives an appropriate operation instruction. The IP level resource management unit 62 manages and controls resource information regarding the IP packet flow currently in service in this data packet communication node.

The IP packet flow information management unit 63 holds information on the amount of resources allocated to the IP packet flow currently in service. The ABT connection setting unit 64 sets an ABT connection on the ATM network when a new virtual connection needs to be set.

The ABT reserved resource amount changing unit 65 changes the amount of band to be reserved in the already set ABT connection. ABT connection information management unit 66
Holds information about the currently set ABT connection.

In the resource management unit, a request for providing a new service (a request to transfer a new IP packet flow or a request to change to a new service type) or service recognized by the data packet communication node accommodating the resource management unit With respect to the quality change request, it is determined whether or not the request can be accepted based on the IP packet flow information and the ABT connection information managed by the resource management unit. In the IP packet flow information management unit 63, the identifier of the flow that provides the Guaranteed service, the amount of resources allocated to the flow, P
The amount of resources allocated to each service level for a flow that provides the radical service,
It manages the amount of resources allocated to all the flows requesting the Best Effort service, and the information about the remaining bandwidth that can be allocated in this data packet communication node that is not allocated to any flows. Here, as the identifier of the IP packet flow, if the packet is based on the specification called Internet Protocol Version 6 (IPv6), a combination of both the flow label value and the source address value in the header part of the packet To use.

In the ABT connection information management unit 66,
The identifier of each connection and the amount of bandwidth secured by the connection are managed in association with each other. Here, the ABT connection identifier is a virtual path identifier (VPI).
Alternatively, a virtual channel identifier (VCI) is used.

The IP packet flow information management unit 63
The internal information and the information in the ABT connection information management unit 66 are configured such that the IP level resource amount and the information regarding the ABT connection that is the accommodation destination of the packet to which the resource amount is allocated are associated with each other. Is desirable.

FIG. 7 is a flow chart showing an operation algorithm in the resource management unit of FIG. 6 which is one function of the data packet communication node of this embodiment. When the data packet communication node receives a request for providing a new service or a request for changing the service quality (step S71),
First, the resource management unit determines in the IP packet flow management unit 61 whether or not the change request is a new request for a Guaranteed service that is not described in the IP packet flow information management unit 63 (step S).
72). If the request is for a new Guaranteed service, the ABT connection setting unit 64
A new ABT connection for accommodating the flow is newly set (step S73). In addition, already Guaran
Even when a flow providing a service other than the teed service requests a change to the Guaranteed service, the ABT connection is newly set.

Next, the IP packet flow information management unit 63
Based on the information in the above, it is determined whether or not it is possible to allocate a sufficient resource amount for providing the service quality after the change request (step S74). At this time, the IP level resource management unit 62 determines that the flow is Guarante.
When requesting an ed service, an amount of resources sufficient to satisfy the transfer rate value requested by the flow (if the flow is already served as a Guaranteed service, the currently allocated resources are allocated). (The difference from the amount) is the remaining resource amount Rest or Best
It is determined whether or not the amount can be provided by adding the resource amount Rb allocated to the Effort service. When the flow requests a service that is slower than the requested transfer rate value, the service quality after the change request can be reliably provided. Further, when the flow requests the Predictive service, the upper limit value of the transfer required time of the service level requested by the flow and the transfer delay value between the service levels are large or small even when the flow is accepted. The resource amount Res is the increment of the resource amount necessary for the relationship to be correctly established.
It is determined by whether or not it can be provided by t or the resource amount Rb.

In the IP level resource management unit 62,
If it is determined that a sufficient amount of resources can be secured to satisfy the required quality of service, the ABT reserved resource changing unit 65 changes the reserved bandwidth amount of the ABT connection accommodating the flow. The RM cell in which the amount of reserved bandwidth after the change is written is transmitted to the ABT connection (step S75), and then the transfer of the data cell is started with the service quality concerned (step S7).
6). In other words, in ABT connection, ABT / IT
The service will be provided. At this time, the time from the transmission of the RM cell to the start of the transmission of the data cell is set by the ABT reserved resource unit 65 based on the attributes related to the ATM network to which the cell is transmitted.

On the other hand, if it is determined that the resource amount cannot be secured, the change request is rejected (step S7).
7). In order to secure the changed resource amount, Be
When reducing the amount of resources allocated to the stEffort service, first, Best Eff.
After transmitting the RM cell in which the reduced bandwidth amount is written on the ABT connection accommodating the ort service, the RM cell in which the reserved bandwidth amount after the change is entered is placed on the ABT connection accommodating the flow for which the change request is made. Send out.

When the RM cell transmitted before transmitting the data cell is looped back within the ATM network and received again by the data packet communication node (step S78), the band amount written in the RM cell is secured. It is determined by checking the CI bit whether or not the connection has been performed by the ABT connection (step S79). If the CI bit is 0, it means that the requested bandwidth amount has been secured, and therefore the data cell is continuously transferred (step S80).
If the CI bit is 1, it indicates that the requested bandwidth amount has not been secured, and therefore the requested change of service quality is stopped (step S81).

When the required resource amount cannot be secured after the transmission of the data packet conforming to the new required service quality is started in step S76, the transmission of the data packet conforming to the new required service quality is stopped, It is possible to restart the transmission of the data packet according to the old required quality of service. In this case, if a service is provided in which the resource amount in the ABT connection is set to 0 when the resource cannot be secured in the ABT connection and the quality of service change request is rejected, this data The packet communication node needs to retransmit the RM cell for returning the resource amount to the quality before the request, but if the service for returning the resource amount to the quality before the request is provided, transmits the RM cell again. do not have to.

If the required resource amount cannot be secured after starting the transmission of the data packet conforming to the new required service quality in step S76, the transmission of the data packet conforming to the new required service quality is stopped, The transmission of data packets may be resumed without guaranteeing any quality.

Next, in FIG. 8, without waiting for confirmation of network resource reservation and confirmation of the required resource amount performed via the Resv message when the virtual connection connecting the data packet communication nodes provides the ABT / IT service. The procedure of data packet transfer to be performed is shown.

This procedure is carried out, for example, by the data packet communication node 121 directly connected to the transmitting terminal 111 and the data packet communication node 122 located between the data packet communication nodes.

In FIG. 8, when the data packet communication node which has received the Resv message from the downstream side determines that the required resource amount can be secured as described above, the data on the downstream side which has sent the Resv message is transmitted. The RM cell representing the resource reservation request for the ABT connection set with the packet communication node is sent to the data packet communication node on the downstream side, and the received Resv message is sent to the user terminal on the data packet sending side. Then, the transmission of the data packet according to the newly requested quality of service is immediately started.

When the data packet communication node which has transmitted the RM cell receives the RM cell with CI = 0, it is recognized that the requested resource amount has been reserved in the connection, and the new requested service quality is continuously set. The corresponding data packet is transmitted.

On the other hand, when an RM cell with CI = 1 is received, an error message is sent to the user terminal on the data packet receiving side that issued the Resv message.

If network resource reservation and data packet transfer are performed between the data packet communication nodes connecting the data transmitting terminal and the data receiving terminal by the above procedure and the resource reservation request is successful in all ABT connections, a new request is promptly made. The data packet transfer according to the quality of service is provided.

If the required resource cannot be secured by any of the ABT connections, an error message is passed to the receiving terminal, and the receiving terminal performs error processing as necessary.

As described above, in the present embodiment, the receiving terminal requests the service quality of the IP data packet issued from the transmitting terminal to the data packet communication network, and this data packet communication network satisfies the request. It was to reserve resources. Instead, a message sent by the sending terminal to the receiving terminal (eg ST-
II (Stream Protocol Version)
Resource reservation may be performed in response to the 2) COCONNECT message or CHANGE message). The present invention is not limited to the above-described embodiment, and can be implemented with various modifications within the technical scope.

[0079]

According to the present invention, when a data packet is delivered through an ATM communication network, a request written in a message sent from a user terminal that sends or receives a data packet to a user terminal that receives or sends the data packet. Determine whether it is possible to secure the required amount of resources required based on the quality of service, and if it is determined that it can immediately start transmitting data packets according to the newly requested quality of service. Thus, the delay incurred by waiting for the notification of the service change request approval / disapproval judgment notified from the ATM network can be eliminated, and a rapid data packet transfer service can be provided.

[Brief description of drawings]

FIG. 1 is a diagram showing a basic configuration of a data packet communication network according to an embodiment of the present invention.

FIG. 2 is a diagram showing an example of correspondence between IP packets and ATM cells.

FIG. 3 is a diagram showing an example of correspondence between IP packets and ATM cells.

4 is an RSVP in the data packet communication network of FIG.
Figure showing an application example of

FIG. 5 is a diagram for explaining an ABT service.

FIG. 6 is a diagram showing a configuration example of a resource management unit which is a function of a data packet communication node.

FIG. 7 is a flowchart showing an operation algorithm in the resource management unit of FIG.

FIG. 8 is a diagram showing an example of a network resource reservation and data packet transfer procedure between adjacent data packet communication nodes.

[Explanation of symbols]

 111 ... Sending terminal 112 ... Receiving terminal 133, 134 ... ATM network 121-123 ... Data packet communication node 131, 132 ... ATM switch 151, 152 ... Virtual connection 61 ... IP packet flow management unit 62 ... IP level resource management unit 63 ... IP packet flow information management unit 64 ... ABT connection setting unit 65 ... ABT reserved resource changing unit 66 ... ABT connection information management unit

Claims (6)

[Claims] 1. A node device for converting a received data packet into an ATM cell and transmitting the ATM cell to a predetermined virtual connection, receives a message requesting reservation of a quality of service from another node device transmitting or receiving the data packet. In this case, when it is determined that the required amount of resources required based on the required quality of service written in the message can be secured, the amount of resources in the virtual connection in which the data packet should be communicated The node device is provided with means for starting transmission of a data packet in accordance with the newly requested quality of service without waiting for the reception of the message indicating that the reservation has been made. 2. The virtual connection is a virtual connection in which the amount of resources to be secured can be changed without re-establishing the connection.
Node device. 3. In the virtual connection, in order to secure the required resource amount, after writing the resource amount to be secured in a resource management cell and transmitting it on the virtual connection, transmission of a data packet according to a new requested quality of service is performed. The node device according to claim 2, which is started. 4. When a resource management cell in which the content that the resource amount cannot be secured is entered is received after starting the transmission of a data packet according to the newly requested quality of service using the virtual connection. 4. The node device according to claim 3, further comprising means for stopping the transmission of the data packet according to the new required quality of service and restarting the transmission of the data packet according to the old required quality of service. 5. When a resource management cell in which the content indicating that the resource amount cannot be secured is received after starting the transmission of a data packet according to the newly requested quality of service using the virtual connection 4. The node device according to claim 3, further comprising means for stopping the transmission of the data packet according to the newly requested quality of service and restarting the transmission of the data packet without guaranteeing any quality. 6. A network resource reservation method for reserving a network resource used when converting a received data packet into an ATM cell and transmitting the ATM cell to a predetermined virtual connection, in which a quality of service is provided by a user terminal transmitting or receiving the data packet. Receiving the message requesting the reservation of the request, determining the required resource amount based on the required quality of service written in the received message, and confirming whether the required required resource amount can be secured. If it is determined that the required resource amount can be secured, a request is made to secure the resource amount in the virtual connection in which the data packet should be communicated, and a message to the effect that this securement has been performed. It is characterized by starting the transmission of data packets according to the newly requested quality of service without waiting for the reception of Network resource reservation method.