Electrical computers and digital processing systems: multicomput – Computer network managing – Network resource allocating
Reexamination Certificate
1998-12-16
2002-09-17
Barot, Bharat (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer network managing
Network resource allocating
C709S204000, C709S205000, C709S223000, C709S224000, C709S238000, C370S356000, C370S340000, C370S400000
Reexamination Certificate
active
06453349
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a network system, and in particular to a network system comprising terminals and relaying nodes for transferring a packet.
In recent years, there have been introduced various applications for multi-media such as Internet FAX, Internet PHONE, and IP/TV. With the spread of the World Wide Web (WWW), Internet users have been easily able to share not only text information but also information such as voice and image. It is considered that the use of these applications brings on various merits such as an improvement in operation efficiency and a cost reduction. On the other hand, problems of increased multi-media traffic exhausting network resources and of failing to meet a satisfactory communication quality become serious.
Therefore, it is required to offer a service which selectively guarantees a communication quality by identifying and categorizing a network traffic. Namely, it is required to offer such a service as guarantees a certain communication quality regardless of the network usage rate or the network load by distinguishing the network traffic depending on the grade of users and the priority of applications, i.e. importance of business applications, and the communication quality such as delay or fluctuation of delay required by multi-media application.
In order to guarantee a certain communication quality, it is required that resources of more than a certain amount are allocated to a certain traffic (application) to guarantee the availability of such resources during the communication. For this purpose, it is necessary to provide a resource reservation mechanism which declares how much communication quality (delay, bandwidth, fluctuation, etc.) the traffic requires to the network or to devices on a route where the traffic is to be relayed, and which reserves the resources required for guaranteeing the communication quality.
2. Description of the Related Art
For the reservation of network resources used for communications, it has been known to use a resource reservation method called ST-II and to perform the reservation by procedures described as follows (see FIG.
24
):
(1) When it is desired to secure network resources (i.e. when a resource reservation is made) for a data packet (hereinafter simply referred to as a “packet”), a packet transmitting terminal
1
, which is going to transmit a package as a source, transmits a connection request (CONNECT) message to a packet receiving terminal
3
, which is going to receive the packet as a destination, in order to secure the resources for the packet at relaying nodes
2
a
and
2
b
. In the connection request message, an identification information for identifying the packet, a requested resource reservation value (FlowSpec) indicating the amount of the resources desired to be secured, and its own address of the terminal
1
for notifying that the terminal
1
itself has last transmitted this message are to be stored.
(2) The relaying nodes
2
a
and
2
b
existing between the packet transmitting terminal
1
and the packet receiving terminal
3
once receive the connection request message, and then perform the following operations:
Transmitting an acknowledgement (ACK) message notifying a relaying node which has last relayed, or a packet transmitting terminal which has last transmitted, the connection request message (hereinafter referred to as “previous HOP”) that the connection request message has been received.
Learning and storing the relaying node (previous HOP) which has last transmitted the connection request message.
Determining whether or not to accept the reservation request i.e. admission based on the resource reservation request value (FlowSpec) in the connection request message. If the reservation request should be accepted, then the connection request message is relayed. At the same time, in order to indicate that the node itself has last transmitted the message, the node puts its own node address into the connection request message.
(3) The packet receiving terminal
3
which has received the connection request message performs the following operations:
Transmitting an acknowledgement message notifying the relaying node which has last relayed, or the packet transmitting terminal which has last transmitted, the connection request message that the connection request message has been received.
Determining whether or not to accept the reservation request based on the resource reservation request value (FlowSpec) in the connection request message. If the reservation request should be accepted, in order to notify the packet transmitting terminal
1
that the connection request has been reserved at all the relaying nodes
2
a
and
2
b
, an acceptance (ACCEPT) message is transmitted to the relaying node which has last transmitted the connection request message.
(4) When receiving the acceptance message, the relaying nodes
2
a
and
2
b
perform the following operations:
Transmitting the acknowledgement message notifying the relaying node which has last relayed, or the packet receiving terminal which has last transmitted, the acceptance message that the acceptance message has been received.
Relaying the acceptance message to the previous HOP.
(5) When receiving the acceptance message, the packet transmitting terminal
1
transmits the acknowledgement message notifying the relaying node which has last relayed the acceptance message that the acceptance message has been received.
(6) The transmitting terminal
1
transmits the packet by way of a hop-by-hop route which passes through the relaying nodes with secured resources, i.e. a route on which the connection request message has been relayed.
The following applications will now be reviewed.
{circle around (1)} Files on a server are downloaded by using FTP (File Transfer Protocol).
{circle around (2)} A subscriber of a video-on-demand system requests to see a certain TV program.
In such applications, it is expected that a terminal equipment at a packet receiving end (a packet receiving terminal) can smoothly download files within a fixed period of time, or that packets can be transmitted with a delay shorter than a fixed period of time so that a constant reproduction quality may be maintained.
In these cases, it is required, not for a terminal equipment at the packet transmitting end (a packet transmitting terminal) to request the network for the resources to secure the communication quality, but for a packet receiving terminal to request the network for the resources to secure the communication quality. Namely, it is required for the packet receiving terminal to notify the amount of resources capable of securing the communication quality to the packet relaying nodes for the reservation of the resources.
However, such prior art, which makes the packet transmitting terminal perform the reservation of the network resources, is not applicable when the packet receiving terminal desires to reserve the network resources.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a network system in which a reservation of network resources may be requested from a packet receiving terminal side.
A network system according to the present invention for the achievement of the above-mentioned object is schematically illustrated in FIG.
1
.
This network system, as illustrated, comprises a packet transmitting terminal
1
, a packet relaying node
2
, and a packet receiving terminal
3
. Among these, the packet transmitting terminal
1
and the packet receiving terminal
3
both comprise reservation message processing units
4
,
9
, packet transferring units
5
,
10
; the relaying node
2
comprises a reservation acceptance determining unit
6
in addition to a reservation message processing unit
7
and a packet transferring unit
8
.
Each portion of this network system will now be described in the following:
Packet Transferring Units
5
,
8
, and
10
These units perform data processing with respect to a packet. In the packet transmitting terminal
1
a packet tra
Chugo Akira
Kano Shinya
Barot Bharat
Fujitsu Limited
Katten Muchin Zavis & Rosenman
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