Error detection/correction and fault detection/recovery – Data processing system error or fault handling – Reliability and availability
Reexamination Certificate
2000-10-03
2003-01-07
Wright, Norman M. (Department: 2184)
Error detection/correction and fault detection/recovery
Data processing system error or fault handling
Reliability and availability
C714S047300, C714S043000, C714S025000, C714S004110
Reexamination Certificate
active
06505311
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to a network system in which a plurality of internetwork apparatuses such as routers each connecting networks at the network layer level are used to connect a plurality of networks to one another, and more particularly to a network system having the redundant configuration in which a current internetwork apparatus is changed to a standby internetwork apparatus upon failure of the current internetwork apparatus.
In the system in which a plurality of networks are connected by a single router, when a failure occurs in the router, operation of the whole of the system is stopped, so that the whole of the system fails to be operated normally. On the other hand, there is a system having the redundant configuration using two routers one serving as a current router and the other serving as a standby router and in which in the normal state of the current router the system is operated by the current router and when a failure occurs in the current router the system is operated by the standby router instead of the current router to thereby attain a high reliability system.
Such a system having the redundant configuration is disclosed in, for example, JP-A-6-131208. In this system, when a failure occurs in a current network apparatus, operation of the whole of the current network apparatus is stopped and the current network apparatus is changed to a standby network apparatus to thereby realize the system having the redundant configuration.
Further, in a network system, various management information such as statistical information, set information and the like is exchanged among nodes in the network and is managed as a management information base (MIB).
SUMMARY OF THE INVENTION
In the system having the redundant configuration in the prior art, when a failure occurs in a port of the current network apparatus or in a connection portion between the port and the network, operation of the whole of the current apparatus is stopped. That is, operation of not only the port in which the failure occurs but also other all normal ports in the current network apparatus is stopped and operation is changed from the current network apparatus to the standby network apparatus. Accordingly, even in communication between the networks connected to the normal ports of the current network apparatus, it is necessary to disconnect the normal ports and to change the communication routes to the standby network apparatus.
Further, in this case, when data is transmitted from a terminal of the network, the relay port of the data is changed and accordingly an address thereof must be also changed.
In addition, even in transmission and reception of management information managed by using management information base (MIB), it is necessary to transmit and receive the management information in consideration of the physical configuration of the network apparatus in response to change of the route.
More particularly, in the system for managing networks on the basis of MIB information, that is, information based on the management information base (MIB) for each network, when a failure occurs in a certain port of a current apparatus, operation of the current apparatus is stopped completely and is changed from the current apparatus to the standby apparatus. Accordingly, MIB information of all ports (that is, all networks) of the current apparatus cannot be obtained. Thus, management of the networks cannot be performed on the basis of the MIB information available before occurrence of the failure.
It is an object of the present invention to provide a network system and a failure restoration method of the network system which is adapted to be solve the drawbacks in the prior art.
It is another object of the present invention to provide a network system and a failure restoration method of the network system in which when a failure occurs in a port of a current apparatus, data communication can be made without change of other normal ports of the current apparatus.
It is a further object of the present invention to provide a network system and a failure restoration method of the network system in which even a terminal having no dynamic routing function and address resolution protocol (ARP) function for conversion of address, that is, having only the routing function can make communication without considering change of a route due to occurrence of a failure.
It is another object of the present invention to provide a network system capable of collecting management information base (MIB) information without considering change of a route due to occurrence of a failure.
In order to achieve the above objects, according to an aspect of the present invention, there is provided a network system which includes a plurality of networks, a first internetwork apparatus including a plurality of first ports each connected to the plurality of networks, a second internetwork apparatus including a plurality of second ports each connected to the plurality of networks, and a data transmission unit connected to the first and second internetwork apparatuses to transmit data mutually between the first and second internetwork apparatuses, wherein the first internetwork apparatus includes a first transmitting and receiving unit connected to the plurality of first ports and the data transmission to transmit and receive data mutually among the plurality of first ports and the data transmission unit, a failure detection unit for detecting whether a failure occurs in any of one of the plurality of first ports and a route between one of the plurality of first ports and one of the plurality of networks connected thereto and, when occurrence of a failure is detected, issuing notification indicating a failure occurrence portion to transmit the notification through the first transmitting and receiving unit to the data transmission unit, and a first port control unit for causing each of the plurality of first ports to be able to transmit and receive data to and from the one of the plurality of networks in a normal state and causing the one of the plurality of first ports not to be able to transmit and receive data to and from the one of the plurality of networks in response to detection of occurrence of failure by the failure detection unit, and the second internetwork apparatus includes a second transmitting and receiving unit connected to the plurality of second ports and the data transmission unit for transmitting and receiving data mutually among the plurality of second ports and the data transmission unit and for receiving the notification transmitted through the data transmission unit to produce the notification, and a second port control unit for causing the plurality of second ports not to be able to receive data from the plurality of networks and to be able to transmit data to the plurality of networks in the normal state and responsive to the notification from the second transmitting and receiving unit to cause one of the plurality of second ports connected through the one of the plurality of networks to the one of the plurality of first ports to be able to transmit and receive data to and from the one of the plurality of networks.
According to one example of the present invention, the first port control unit sets an address of each of the plurality of first ports to a common address common to the port and a corresponding one of the plurality of second ports connected through a corresponding one of the plurality of networks in the normal state, the common address being different for each of the plurality of first ports, and the second port control unit sets an address of each of the plurality of second ports to an address inherent to the port in the normal state.
According to one example of the present invention, the first port control unit includes a unit for disconnecting the one of the plurality of first ports from the one of the plurality of networks in response to detection of occurrent of failure by the failure detection unit, and the second port control unit changes an address of the one of the p
Ichinohe Shinya
Nakamura Masao
Niwa Tokuhiro
Noyama Norihide
Hitachi , Ltd.
Mattingly Stanger & Malur, P.C.
Wright Norman M.
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