Electrical computers and digital processing systems: multicomput – Computer network managing
Reexamination Certificate
1999-03-09
2003-06-03
El-Hady, Nabil (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer network managing
C709S224000, C709S226000, C707S793000
Reexamination Certificate
active
06574662
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates broadly to a computer network. More particularly, the invention relates to a network-device management apparatus and method including network management software, and to a recording medium.
2. Description of the Related Art
Recently, local area networks (LANs) in which computers are interconnected have come to be widely used. Such a local area network is constructed over a floor or the entirety of a building, a group of buildings (an enclosure), a local area, or a larger area. In some cases, such networks are interconnected, or connected to a worldwide network. In such interconnected LANs, various techniques for interconnecting hardware apparatuses and a plurality of network protocols are used.
In a simple isolated LAN, each user can manage apparatuses. That is, the user can exchange (add, remove or replace) apparatuses, install software, or check problems.
However, in a large-scale complicated LAN or a large group of interconnected LANS, “management” is required. The word “management” indicates both management by a human network manager and management according to software used by the manager. In the present application, “management” indicates management according to software for managing the entire system, and “user” indicates a person who uses network management software. The user is usually a person responsible for system management. By using network management software, the “user” can obtain management data on the network and change the data.
A large-scale network system is a dynamic system which always requires increase or removal of apparatuses, updating of software, detection of problems, and the like. In general, various systems possessed by various people and supplied by various suppliers are present.
Various methods for managing network devices on a network constituting such a large-scale network system have been provided by many standardization organizations. The International Organization for Standardization (ISO) has provided a general-purpose standard framework called an Open System Interconnection (OSI) model. The OSI model of a network control protocol is called a Common Management Information Protocol (CMIP). The CMIP is a common network management protocol used in Europe.
Recently, a modified protocol relating to the CMIP called a Simple Network Management Protocol (SNMP) is being used as a network management protocol which can be more commonly used (see “Introduction to TCP/IP Network Management for Pratical Management” written by M. T. Rose and translated by Takeshi Nishida, first edition Aug. 20, 1992 by Toppan Printed Company, Limited).
According to the SNMP network management technique, a network management system includes at least one network management station (NMS), some nodes to be managed, each having agents, and a network management protocol used by the management station or the agents in order to exchange management information. By communicating with agent software of a node to be managed using network management software of the NMS, the user can obtain management data on the network and change the data.
The word “agent” indicates software operating as a background process at each node to be managed. When the user requests management data from a node to be managed on the network, the network management software includes an object identifier (to be described later) in a management packet or frame, and transmits the resultant data to the agent of the node to be managed.
The agent interprets the object identifier and obtains data corresponding to the object identifier. The agent includes the data in the packet and transmits the resultant data to the network management software. At that time, the agent calls, in some cases, a corresponding process in order to obtain the data.
The agent also holds data relating to the node to be managed in the form of a database. This database is called an MIB (management information base).
FIG. 4
illustrates the concept of the structure of the MIB. As shown in
FIG. 4
, the MIB has a data structure in the form of a tree, where an identifier is uniquely provided for each node. In
FIG. 4
, the identifier for a node is defined based on the number written in the parentheses. For example, the identifier for a node
401
shown in
FIG. 4
is 1. Since a node
402
is a child of the node
401
, the identifier for the node
402
is 1·3. Similarly, the identifier for a node
403
is 1·3·6·1·2. Such an identifier for a node is an object identifier. In
FIG. 4
, a part of the MIB defined as a standard is extracted and shown.
The structure of the MIB is called a Structure of Management Information (SMI), and is defined by RFC1155 Structure and Identification of Management Information for TCP/IP-based Internets.
Next, the SNMP will be described. A PC (personal computer) where the network management software operates (hereinafter termed an “manager”) and a network device to be managed (where an SNMP agent operates) (hereinafter termed an “agent”) communicate with each other using the SNMP. The SNMP has five commands, which are called Get-request, Get-next-request, Get-response, Set-request and Trap.
FIG. 8
illustrates a manner in which these commands are exchanged between the manager and the agent.
The Get-request and Get-next-request commands are commands transmitted from the manager to the agent. The agent which has received these commands transmits the Get-response command to the manager in order to notify the manager of the value of the MIB object (
801
and
802
).
The Set-request command is a command transmitted from the manager to the agent in order to set the value of the MIB object of the agent. The agent which has received this command transmits the Get-request command to the manager in order to notify the manager of the result of the setting (
803
).
The Trap command is a command transmitted from the agent to the manager in order to notify the manager of a change in the agent's own state (
804
).
FIG. 7
is a diagram illustrating the formats of commands other than the Trap command, i.e., the Get-request, Get-next-request, Get-response and Set-request commands (generically termed “SNMP messages”). In
FIG. 7
, reference numeral
700
represents an SNMP message. The SNMP message includes a version
701
, a community name
702
, and a PDU
703
. Reference numeral
710
represents the detail of the PDU
703
.
The PDU
710
includes a PDU type
711
, a request ID
712
, an error status
713
, an error index
714
, and MIB information
715
. A value for identifying the command is stored in the PDU type
711
. The values 0, 1, 2 and 3 of the PDU type
711
indicates the Get-request, Get-next-request, Get-response and Set-request commands, respectively. A value indicating error information is stored in the error status
713
. A pair comprising an MIB object identifier and the value of the MIB object is stored in the MIB information
715
.
Next, a large-scale network which requires management will be described.
FIG. 1
is a diagram illustrating a network where a network board (NB)
101
for connecting a printer to the network is connected to a printer
102
having an open architecture. The NB
101
is connected to a local area network (LAN)
100
via a LAN interface, such as an Ethernet interface 10 Base-2 having a coaxial connector, 10 Base-T having RJ-45, or the like.
A plurality of PCs, such as a PC
103
, a PC
104
and the like, are also connected to the LAN
100
. These PCs can communicate with the NB
101
under the control of a network operating system. It is possible to assign one of the PCs, such as the PC
103
or the like, to be used as a network management unit. A printer, such as a printer
105
connected to the PC
104
, may be connected to each PC.
A file server
106
is also connected to the LAN
100
in order to manage access to a file stored in a large-capacity (for example, 10 billion bytes) network disk
107
. A print server
108
causes connected printers
109
a
and
109
b
, the printer
105
provided at a remote
Hamada Noboru
Sugiyama Akira
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