Electrical computers and digital processing systems: multicomput – Computer network managing – Computer network monitoring
Reexamination Certificate
1999-03-23
2002-03-19
Maung, Zarni (Department: 2154)
Electrical computers and digital processing systems: multicomput
Computer network managing
Computer network monitoring
C709S223000
Reexamination Certificate
active
06360260
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention relates to network management in general, and in particular, to discovering the location of Management Stations and managed devices in the network.
2. Prior Art
The proliferation of computer networks has created a demand for improved apparatus and method for managing such networks. The management need is even greater because the networks are growing larger and more complex. Most conventional computer networks are comprised of stations (for example, word processors, personal computers, etc.) interconnected by communications infrastructure. Included in the communications infrastructure are routers, bridges, transmission media, gateways, switches, etc. The computer networks could be simple ones in which the stations are configured in a room, or a more elaborate ones in which the stations are distributed over a large geographical area, such as a large building, company site, a campus or several towns.
In more complex networks, one or more of the stations are designated Management Stations. One of the functions provided by Management Stations is keeping track of devices (called managed devices) as they (the managed devices) enter and/or leave the network. To provide tracking and other management functions, a Management Program, such as the Simple Network Management Protocol SNMP is executed in the Management Station and in the managed device. The portion of SNMP which is executed in the managed device is termed SNMP agent. Usually, the activities of managed devices are maintained in a data base (file) at the Management Station and can be used by the Management Station itself or a network operator to detect and/or correct fault in the network.
The conventional approach, to network management, addresses SNMP Management Stations and the SNMP managed devices operating at the LLC level of the protocol stack. The conventional technique uses an appropriate protocol, such as the well-known Internet Protocol (IP), to communicate and to “auto-discover” the SNMP managed devices or devices. Even though the approach works well for discovering LLC level devices, there are other network devices, termed MAC layer devices, which do not respond very well to LLC level protocols. The MAC (Medium Access Control) layer devices may include routers, concentrators, hubs, switches or like devices. As a consequence, these MAC layer devices are usually not discovered, by the Management Stations, using the conventional approach.
Several prior art patents describe devices and method for managing computer networks. The following patents are examples of the prior art devices and methods.
U.S. Pat. No. 5,233,510 describes a method of continuously self-configuring of a computer control system used in a manufacturing process. Each object in the process is assigned a unique ID or address. Each object in the manufacturing process uses its unique ID in all communications with other objects in the process. With this information, a control computer can locate and map all of the objects that are in the process.
Japanese patent number JP-3-123137 deals with the manual configuration of a MAC address into the forwarding table of a MAC layer bridge and storing these addresses into an NVRAM. Most MAC layer bridges “listen” to the MAC addresses on either side of the bridge and dynamically build forwarding tables. This patent provides a way to manually build this table eliminating the need for the bridge to “learn” the addresses.
U.S. Pat. No. 5,282,270 deals with the discovery of network devices that exists in a network running the AppleTalk protocol. The patent defines how routers within the AppleTalk protocol determine the location of the network element. The patent uses a multicast address which all routers running the AppleTalk recognize. The information passed between routers in these multicast frames is used to locate network elements.
U.S. Pat. No. 4,991,089 deals exclusively with workstations attached to a SNA network using the LU6.2 specification. The patent defines the method where the workstation notifies a host system of its terminal address via the SNA protocol.
U.S. Pat. No. 4,914,571 describes a method for locating resources in a computer network so that a session can be established between an origin and a destination station. The patent relates specifically with the SNA protocol. The LOCATE METHOD defined in the patent uses the SNA protocol to search for the destination target.
U.S. Pat. No. 5,408,618 discloses an Automatic Configuration Mechanism (ACM) which can be used by a node in a LAN to obtain configuration information from other nodes, to provide configuration information to other nodes and to respond to other nodes which seek configuration information. The frame format of this patent operates at the LLC layer of the ISO protocol stack.
U.S. Pat. No. 5,185,860 describes a method by which a Network Management Station (NMS) can “auto” discover devices containing SNMP agents in a network using TCP/IP protocol. Of all the above cited prior art, this patent appears most relevant to the field in which applicants' invention operates. However, it covers the discovery process as it relates to the Management Station only and does not address discovery as it applies to an agent. As networks become more complex and dynamic, addition and relocation of devices are likely to occur more frequently. As a consequence, new procedures and devices are required to “auto” discover changes in the network.
SUMMARY OF THE INVENTION
It is, therefore, an object of the invention to provide a more efficient and comprehensive “auto” discovery process than was heretofore been possible.
It is another object of the invention to provide the “auto” discovery process in devices to make their discovery more likely, by a Network Management System (NMS).
It is still another object of the invention to provide the “auto” discovery process in a network using TCP/IP Protocol to communicate and SNMP protocol to manage the network.
These and other objects are achieved by enabling a managed device to send special “auto” discovery frames to a Network Management Station or an intermediate station, such as a router, until the managed device is discovered. Thereafter, the device then monitors communications between itself and the Management Station and restarts the registration process if communication is lost or impaired. As a consequence, discovery of SNMP devices and continued knowledge of the whereabouts of the SNMP devices are ensured.
More particularly, a device on receiving a frame termed GET REQUEST FRAME (described below) from a Network Management Station, sets a “Watch Dog” timer. The Watch Dog timer is used to start a registration process if contact is lost with the Network Management Station. Lost contact is determined when an SNMP GET REQUEST FRAME has not been received from the Management Station during the “Watch Dog” timer interval.
In the case where the Watch Dog timer expires, and an SNMP GET REQUEST Frame has not been received during the Watch Dog interval, the Registration Process is restarted. Two Registration Processes, termed Auto-Discovery Trap and Router ARP Cache, are described.
In the Auto-Discovery Trap, the device sends Auto-Discovery Trap Frames at timed intervals selected by a user. The Auto-discovery Trap Frames contain Enterprise specific information (e.g., identifying the device as a hub, switch, etc.) about the managed device. The Trap Frames are sent to a Network Management Station until an SNMP GET REQUEST Frame is received. The reception of SNMP GET REQUEST Frame indicates that the device has been discovered by the Network Management Station.
In the case where the Watch Dog timer expires, and an SNMP frame has not been received during the “Watch Dog” timer interval, then the process is started again with the sending of the Auto-Discovery Trap.
In the Router ARP Cache process, the managed device sends frames termed “Ping Frames” to an address for a default router. When the default router receives the ping frames, it places the address of the devi
Compliment Dale Richard
Prorock Thomas Joseph
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