Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network monitoring
Reexamination Certificate
2000-10-11
2004-04-13
Caldwell, Andrew (Department: 2157)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network monitoring
Reexamination Certificate
active
06721791
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates generally to a trap control system including a manager and an agent which are connected via a network to each other, the agent issuing a trap to the manager, for monitoring, and more particularly, to a trap control system arranged to issue a trap to only the manager which has made an entry as an object of trap into the agent.
2. Description of the Related Art
With recent networks such as LAN expanded and complicated, the network management adds to its importance. For such a network management, use is made of various network management protocols, typically CMIP (Common Management Information Protocol) or SNMP (Simple Network Management Protocol). These management protocols basically use a polling system and an event system. In the polling system the manager asks equipment to be managed at a certain interval to check the status of the equipment to be managed at all times. This system is characterized by its correct monitoring capability but has a demerit tending to cause traffics and lacking in real-time performance. In the event system the equipment to be managed posts the manager on the variation of the status of its own. The event system serves to complement the polling system. Various restrictions are however imposed on the event system. Currently, in the field of the SNMP, typical network management protocol, the event system is called a trap. The trap is issued upon the occurrence of variation of the status from the equipment to be managed such as printers mounted with SNMP agents. The trap from the agent is accepted by a manager in order to grasp the status of the equipment to be managed. The SNMP trap issuance system can include a broadcast system and a unicast system.
FIG. 1
illustrates the broadcast system trap. Now assume that to a subnet
106
are connected an agent
100
, managers
102
-
1
and
102
-
2
and hosts
104
-
1
and
104
-
2
, with the agent
100
and the manager
102
-
1
making up a management group. Herein, the subnet
106
is e.g., a network having an address obtained by adding a 4-bit subnet to an 8-bit network ID, for the address of each node composed of the network ID and the host ID. In such a subnet
106
, by using the same address for the subnet of the network ID, the management group can be composed of the agent
100
and the manager
102
-
1
. In the ordinary state of operation the agent
100
issues a broadcast system trap. However, the broadcast trap issued from the agent
100
is accepted only by manager
102
-
1
lying in the network ID of the same subnet as the target of management. Nevertheless, in the broadcast system, the trap is issued to all the hosts
104
-
1
and
104
-
2
lying in the subnet
106
. For this reason, traffics tend to occur within the subnet
106
. In particular, recently, more and more networks employ switching techniques to control the traffics within the subnet, although there remains a problem of high ratio incapable of controlling the traffics by the broadcast trap. The broadcast issued trap acts not merely on the network traffics but also on the manager managing the trap. When the agent
100
issues a broadcast trap, the manager
102
-
2
not managing the agent
100
also accepts the trap. The manager
102
-
2
needs to seek a useful trap from the agent which is its own target of management among a multiplicity of traps accepted, resulting in an increased burden on the manager.
In order to solve such a problem of the conventional broadcast issued trap, it is conceivable to issue the trap in the unicast system. In the unicast system, a trap post manager is previously entered into each of the agents so that only the trap entered manager is posted on the trap. In case of the unicast system trap, however, the trap posted object must be entered into the agent previous to the start of use. Such entries are cumbersome and time-consuming, so that the broadcast system has eventually been employed. Furthermore, when the trap posted object is once entered, the agent continues to issue the traps till the cancellation of the entry irrespective of the manager down. Thus, in addition to the occurrence of traffics, the agent does the vain works, which may adversely affect the performances of the equipment to be managed.
Reference is then made to
FIG. 2
to consider the case where the trap is issued in the unicast system with the manager
102
-
1
of the subnet
106
being the object of trap which is entered into the agent
100
-
1
to
100
-n. At that time, in the event of the address modification of the manager
102
-
1
or the change to the manager
102
-
2
, the entries of the object of trap have to be changed in all the agents
100
-
1
to
100
-n. This change of entries may become enormous and fairly heavy in the circumstances including a lot of equipment to be managed. Furthermore, a limited amount of memory is provided on the equipment to be managed serving as the agent. Hence, if the entries of the object of trap unused are not deleted, more and more memories are used and the resources of the equipment to be managed are consumed.
The above problems are summarized. First, the broadcast system trap entails the problems which follow:
(I) When the trap is issued in the broadcast system, a lot of traffics occur in the network;
(II) The manager outside the subnet is unable to accept the broadcast system trap; and
(III) Due to indiscriminate sending of the broadcast trap to all the network apparatuses lying within the subnet, a heavy burden is imposed on each apparatus and managers.
Second, the unicast system trap entails the problems which follow:
(I) In case of the unicast trap, the objects of trap are previously entered, so that a burden is imposed on the manager, making it difficult to use the trap;
(II) Till the cancellation of the previously entered objects of trap, the traps are sent without managing the associated nodes by the manager;
(III) It is substantially impossible for all the entries of the objects of trap to correctly migrate when the management system configuration has been modified; and
(IV) The amount of use of the memory is increased in the equipment to be managed, owing to the entries of vain objects of trap.
Such problems may be attributable to a change in network environment being expanded and complicated. The conventional network management is directed mainly to the management of the network apparatuses such as routers and exchanges. On the network, however, there lies a less number of apparatuses such as the routers and exchanges, so that the frequency of occurrence of traffics is small irrespective of the issuance of traps in the broadcast system, thus imposing no burden on the network. In the event that there is a need to alter the setting of the objects of trap in the unicast system, it can be dealt merely by resetting a small number of hosts, and hence too a heavy burden will not occur even though it has manually been done.
The conventional information to be monitored mainly contains equipment status, especially failure information, so that less kind of information lies with limited number of traps issued. In the ordinary operation, the SNMP manager is installed on the dedicated server to manage the network equipment. On a single network the number of such SMNP managers is small and, once set and started to work, frequent change is not made. For this reason, it will suffice for the unicast system to have less information on the SMNP manager which is the object of traps to be entered into the equipment to be managed, with little or no change after the entries. Recently, however, the SNMP network management tends toward new trend together with the expanded and complicated networks. First, office apparatuses such as workstations, personal computers and printers are also managed by the SNMP, adding to the kind and number of the apparatuses to be managed. The information to be managed comes to contain not merely the conventional failure information but also information on tasks, jobs, expendable supplies in operati
Caldwell Andrew
Fuji 'Xerox Co., Ltd.
Westerman Hattori Daniels & Adrian LLP
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