Electrical computers and digital processing systems: multicomput – Network-to-computer interfacing
Reexamination Certificate
2002-08-02
2004-06-15
Barot, Bharat (Department: 2155)
Electrical computers and digital processing systems: multicomput
Network-to-computer interfacing
C709S223000, C709S246000, C713S340000
Reexamination Certificate
active
06751676
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a network control system mainly comprising a managing device (typically a server) that provides various kinds of services, separate devices (typically, clients) that request various kinds of services and a repeater (typically, a hub) that interconnects the managing device and separate devices. The present invention also relates to a network apparatus, a repeater; and a connecting apparatus.
More particularly, the present invention pertains to a technique implemented in a client-server local area network (usually abbreviated to “LAN”) control system. The technique is intended to reduce electric power that is consumed by a client and a hub in the case in which, in the nighttime or when the power source of a client is turned off, a power source switch on the client is automatically turned on by means of a special packet, which in sent from a server and generally called “wake-up packet,” in order to perform various kinds of maintenance on the client under remote control from the server.
2. Description of the Related Art
Herein, in an effort to clarify problems underlying the related arts, a configuration of a convectional LAN control system and the operations performed by the LAN control system will be explained with reference to
FIG. 1
to
FIG. 3
that will be described later in “Brief Description of the Drawings.”
A block diagram schematically showing the configuration of a conventional client-server LAN control system is illustrated in FIG.
1
.
Herein, what is referred to as a “server” is hardware or software having the function of providing various services to other machines (that is, separate devices each including hardware or software and each being called, typically, a client) in a network configuration. Referring to
FIG. 1
, a server is a device S having hardware and software integrated thereinto. From a functional viewpoint, tho server often manages programs, databases, printers, and a network. On the other hand, a server may be defined as a device that receives requests. By the way, what is referred to as a “client” is a device that requests tho server to render services. In the client-server LAN control system, the client is often realized as a personal computer operated by a user. Heroin, a term “client-server LAN (or a client-server model)” defines a processing form in which the roles to be filled by computers interconnected over a LAN are clarified, that is, one of basic models of distributed processing. The client-server LAN accommodates a server that provides specified features and clients that utilize the features. Normally, the clients are realized as users' personal computers, and the server is realized as a computer having a high processing ability. Services provided by the server are often arithmetic operations that require a database or that must be performed at high speed. On the other hand, the server manages the whole of a client-server LAN control system.
As is obvious from the block diagram of
FIG. 1
, in the typical client-server LAN control system, the server S (managing device) that manages the whole of the system exists on a basic LAN (BL). A hub H in connected to the basic LAN in the form of a chip. The clients C (separate devices) are realized as personal computers (usually, simply called computers) and are connected on the basic LAN via the hub H. The hub H serves as a repeater for connecting a plurality of clients to a LAN. The protocol which the clients C and hub H use is Ethernet 10 Base-T (transmission rate: 10 megabits per sec (Mbps)) or Ethernet 100 Base-TX (transmission rate: 100 Mbps).
An alternating current (ac) power source cable AD led out from each client C is plugged into a mains ac outlet AS formed on a wall or the like. Electric power is distributed to each client through the ac outlet AS. Normally, the ac power source cable AP remains plugged in the ac outlet AS. The on-state or off-state of a power source of a personal computer realizing each client is determined with a power source switch PS on each client C (device). The power source of the client C is in off-state unless it is being used.
The server performs various kinds of maintenance on a specified client, through remote control, when the client is not being used and the power source thereof is in off-slate (in the nighttime). At this time, the power source switch on the client must be turned on in order to perform maintenance on the client. Therefore, the server transmits a wake-up packet WP (corresponding to an activating signal that will be described later) to the specified client. The wake-up picket is structured based on a specific packet format, and defined as a packet that, when the client receives the packet, turns on the power source of the client. The wake-up packet is transmitted to the specified client via the hub. When the power source switch on the client is in off-state, if the client receiver the wake-up packet, the client turns on the power source switch thereon automatically. Thereafter, software is upgraded or various kinds of information are transferred between the server and client.
A block diagram showing the internal configurations of a conventional client and a conventional hub, is illustrated in FIG.
2
. Further, a timing chart for explaining the conventional sequence of the delivery of power sources, is illustrated in FIG.
3
. Shown in
FIG. 2
are the practical configurations of a conventional client and a conventional hub included in a LAN control system.
As shown in
FIG. 2
, tho conventional client C mainly comprises a power source circuit
6
that generates electric power for the client, a circuit portion
4
including a CPU (central processing unit), a memory, and a chip set, and a LAN control circuit
1
including a LAN chip that controls a LAN. The power source circuit
6
receives ac power by way of an ac power source cable AP, internally converts the ac power to direct current (dc) power, supplies a first power source P-
1
to the circuit portion
4
including the CPU, and supplies second power source P-
2
to the LAN control circuit
1
.
Referring to the timing chart of
FIG. 3
, a description will be made regarding the sequence of the delivery of power sources in the client or hub. Normally, the ac power source cable is left plugged into the ac outlet, and an ac power source is always set to an on-state level ((1) in FIG.
3
). The delivery of the first power source P-
1
and a second power source P-
2
is controlled by the power source switch PS ((2) in FIG.
2
). When the power source switch PS is in on-state, that is, when the client is used, the first power source P-
1
is delivered. When the power source switch PS is in off-state, that is, the client is unused, the first power source P-
1
is not delivered ((3) in FIG.
3
). On the other hand, the power source circuit
6
must keep delivering the second power source P-
2
to the LAN control circuit
1
so that the LAN control circuit can receive the wake-up packet from the server
5
even when the client is unused. When ac power is having supplied, the second power source P-
2
is Ret to the on-state level irrespective of whether the power source switch PS is turned on or turned off ((4) in FIG.
3
). Furthermore, the third power source P-
3
delivered from a power source circuit
19
incorporated in the hub H is get to the on-state level, irrespective of whether the power source switch PS in turned on or turned off ((5) in FIG.
3
). This is intended to allow the hub h to receive the wake-up packet from the server S.
The power source circuit
6
delivers the first power source P-
1
to the circuit portion
4
including the CPU, memory, and chip set. When user uses the client personal computer (when the power source switch PS is turned on), the circuit portion
4
is activated and put into operation. In this case, the circuit portion
4
is connected to the LAN control circuit
1
over a personal computer interface (PCT) bus
5
. When a user uses the client personal computer, the user
Barot Bharat
Fujitsu Limited
Staas & Halsey , LLP
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