US4827411A
Expired / Lapsed
US
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Method of maintaining a topology database
Assignee: International Business Machines Corp
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Filing: 1987-06-15
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Granted: 1989-05-02
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Expires: 2007-06-15
Abstract
Abstract Each network node in a communications network maintains its own copy of the network topology database defining network resources. Each resource record contains a "timer" field which is initially set to a maximum value but which may be decremented on a daily basis. If the timer field is decremented to zero without being reset, the node unilaterally removes the resource record from its copy of the database. The timer field will normally reach zero only for obsolete resource records since each network node responsible for a resource broadcasts a timer-resetting message for the resource (1) each time the resource status changes, (2) when the node first joins or rejoins the network, and (3) on a periodic (weekly) basis regardless of whether conditions (1) or (2) have occurred.
Inventors
- 👤 Andrew H. Arrowood
- 👤 Alan E. Baratz
- 👤 Philip F. Chimento, Jr.
- 👤 John E. Drake, Jr.
- 👤 John L. Eisenbies
- 👤 James P. Gray
- 👤 Karla J. Norsworthy
- 👤 Diane P. Pozefsky
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 16:19
CPC Classifications
H; H04; H04L; H04L69/00; Y; Y10; Y10S; Y10S707/00; Y10S707/99941; Y10S707/99944; Y10S707/99945; Y10S707/99951; Y10S707/99956; Y10S707/99957
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
72 words
A method of maintaining a topology database at a network node in a communications network, said database comprising individual records defining network resources, said method comprising the steps of: monitoring messages received from other network nodes in the network for network resources status updates; and removing a record from the topology database where that record defines a resource for which no update message has been received during a predetermined period of time.
Claim 2
Independent Claim
72 words
A method of maintaining a topology database at a network node in a communications network, said database comprising individual records defining network resources, said method comprising the steps of: monitoring messages received from other network nodes in the network for network resources status updates; and removing a record from the topology database where that record defines a resource for which no update message has been received during a predetermined period of time.
Claim 3
Dependent Claim
47 words
A method as defined in claim 1 wherein a database record defining a first type of network resource is removed automatically while a database record defining a second type of network resource is removed only if the resource has remained inoperative during the predetermined period of time.
Claim 4
Dependent Claim
158 words
In a communications network wherein each network node maintains a topology database defining network resources, said database comprising individual records defining individual resources, said resources being either nodes or communication links, a method by which each network node independently maintains a network topology database comprising the steps of: causing each network node to periodically broadcast a topology update measage defining a status of at least one resource in its database; causing each network node to monitor topology update messages received from other network nodes; causing each network node to remove any node-defining record from its database where that node has not been a subject of a topology update message received from another network node during a predetermined period of time; and causing each network node to remove any link-defining record where that link has been a subject of a topology update messages defining the link as being inoperative from another network node during the predetermined period of time.
Claim 5
Dependent Claim
158 words
In a communications network wherein each network node maintains a topology database defining network resources, said database comprising individual records defining individual resources, said resources being either nodes or communication links, a method by which each network node independently maintains a network topology database comprising the steps of: causing each network node to periodically broadcast a topology update measage defining a status of at least one resource in its database; causing each network node to monitor topology update messages received from other network nodes; causing each network node to remove any node-defining record from its database where that node has not been a subject of a topology update message received from another network node during a predetermined period of time; and causing each network node to remove any link-defining record where that link has been a subject of a topology update messages defining the link as being inoperative from another network node during the predetermined period of time.
Claim 6
Dependent Claim
252 words
In a communications network wherein each network node maintains a topology database defining network resources, a database comprising individual records, each having a resource identifying field, a resource characteristics fild and a time field, a method of maintaining the topology database, said method being implemented independently at each network node and comprising the steps of: assigning an initial value to the time field of a database record when the resource identified by that record is first added to the topology database; periodically altering the value of the time field of a database record by a predetermined amount when the record defines a resource of a first type; periodically altering the value of the time field of a database record by a predetermined amount only where that record defines a resource of a second type and the resource is characterized as being inoperative; reassigning the initial value to the time field for a database record defining a resource of the first type each time a status message for the resource is received from another network node; reassigning the initial value to the time field for a database record defining a resource of the second type each time a status message defining the resource as being operative is received from another network node; periodically comparing a current value of the time field of each database record to a second predetermined value; and removing a record from the database when a current value of the time field for the record equals the second predetermined value.
Claim 7
Dependent Claim
252 words
In a communications network wherein each network node maintains a topology database defining network resources, a database comprising individual records, each having a resource identifying field, a resource characteristics fild and a time field, a method of maintaining the topology database, said method being implemented independently at each network node and comprising the steps of: assigning an initial value to the time field of a database record when the resource identified by that record is first added to the topology database; periodically altering the value of the time field of a database record by a predetermined amount when the record defines a resource of a first type; periodically altering the value of the time field of a database record by a predetermined amount only where that record defines a resource of a second type and the resource is characterized as being inoperative; reassigning the initial value to the time field for a database record defining a resource of the first type each time a status message for the resource is received from another network node; reassigning the initial value to the time field for a database record defining a resource of the second type each time a status message defining the resource as being operative is received from another network node; periodically comparing a current value of the time field of each database record to a second predetermined value; and removing a record from the database when a current value of the time field for the record equals the second predetermined value.
References Cited (Backward Citations)
US4644532A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1992-05-01 | 1992-10-31 | 1993-05-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1996-05-01 | 1996-10-31 | 1997-05-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2000-05-01 | 2000-10-31 | 2001-05-02 | $7700.00 | Window Closed / Lapsed |