Local area network for digital data processing system

• US 4,823,122 A
• Filed: 08/24/1987
• Issued: 04/18/1989
• Est. Priority Date: 06/01/1984
• Status: Expired due to Term

• Current Assignee: Enterasys Networks Incorporated (Extreme Networks, Inc.)
• Original Assignee: Digital Equipment Corporation (HP Inc.)
• Inventors: Duffy, Darrell, Mann, Bruce
• Primary Examiner(s): Weldon, Ulysses
• Application Number:
  US07/088,063
• Time in Patent Office: 603 Days
• Field of Search: 364/156, 364/200, 364/900, 340/825.26-825.29, 340/825.5, 370/85, 370/95, 370/96, 379/92-96, 379/102, 379/106
• US Class Current: 709/203
• CPC Class Codes: H04L 12/413 with random access, e.g. carrier-sense multiple-access with collision detection [CSMA-CD]
• CPC Class Codes: H04L 67/01 Protocols
• CPC Class Codes: H04L 67/51 Discovery or management thereof, e.g. service location protocol [SLP] or web services
• CPC Class Codes: H04L 67/54 Presence management, e.g. monitoring or registration for receipt of user log-on information, or the connection status of the users
• CPC Class Codes: H04L 69/00 Network arrangements, protocols or services independent of the application payload and not provided for in the other groups of this subclass networks security protocols H04L9/40; wireless communication networks H04W
• CPC Class Codes: H04L 69/18 Multiprotocol handlers, e.g. single devices capable of handling multiple protocols
• CPC Class Codes: H04L 69/24 Negotiation of communication capabilities
• CPC Class Codes: H04L 69/28 Timers or timing mechanisms used in protocols
• CPC Class Codes: H04L 69/326 in the transport layer [OSI layer 4] H04L69/16 takes precedence
• CPC Class Codes: H04L 69/329 in the application layer [OSI layer 7]

Abstract

A local area network for interconnecting terminals and other users and data processing systems and other service providers over a communications link. The users and providers connect to the communications link by means of interface units each of which may connect to several users or providers. The interface units communicate over the communications link by means of messages. When a user requires the use of a service, the interface unit establishes a virtual circuit between it and the interface unit connected to the service provider and a service session which allows the user and the service provider to communicate over the virtual circuit. If several users connected to the one interface unit as the first user require services provided by providers which connected to the same interface unit as the first provider, they communicate in sessions over the same virtual circuits. The session messages are accumulated into single virtual circuit messages that are acknowledged in unison by the receiving interface unit. Each virtual circuit in the users'"'"' interface units includes a timer which reset when a message is transmitted over the virtual circuit and a data waiting flag set whenever data is present to be transmitted over the virtual circuit. The interface units are inhibited from transmitting over a virtual circuit unless the timer has timed out and the data waiting flag is set.

Claims

1. A local area network including a plurality of device server units each of which connects to a service user and a node and a communications link to effect communications between the node and device server units,

A. said node including:

i. node message transfer means for transmitting service advertising messages and node data processing service messages over said communications link and for receiving device server data processing service messages from said communications link;

ii. service provider message transfer means for transmitting service provider information to and receiving processed service provider information from a service provider in connection with provision of a service by said service provider;

iii. service advertising message transmission enabling means for periodically enabling said node message transfer means to transmit service advertising messages to identify a data processing service provided by the service provider; and

iv. node data processing service message transfer means for generating, in response to the processed service provider information received by said service provider message transfer means, node data processing service messages for transfer by said node message transfer means for generating, in response to service provider data processing service messages received by said node message transfer means, service provider information for transfer by said service provider message transfer means to said service provider;

B. each device server unit including;

i. device server message transfer means for transmitting device server data processing service messages over and receiving node data processing service messages and service advertising messages from said communications link;

ii service user message transfer means for transmitting processed service user information to and receiving service user information from the service user connected thereto;

iii. service table means for establishing a service table including at least one entry including a node field and a service field identifying a node and a data processing service provided by the service provider connected to said node, the contents of the entry being provided by the service advertising messages received by said device server message transfer means;

iv. selection means responsive to a data processing service request from a service user for using said service table to select the node and service provider to provide a data processing service identified in said data processing service request; and

v. device server data processing service message transfer means for generating, in response to the service user information from the service user, service user data processing service messages for transmission by said device server message transfer means and for generating, in response to node data processing service messages received by said device server message transmission means, processed service user information for transfer by said service user message transfer means to said service user.

2. A local area network as defined in claim 1 in which said service advertising message whose transmission is enabled by said service advertising message transmission enabling means further includes a rating for each data processing service, said service table means further including means for establishing, in each entry, a rating field in response to the rating from the service advertising message, said selection means further including means for using the contents of said rating field in the selection of the node and service provider to provide the requested service.

3. A node for connection to service provider and a communications link in local area network including a plurality of device server units each of which connect to a service user, said communications link effecting communications between the node and device server units, said node including:

A. node message transfer means for transmitting server advertising messages and node data processing service messages over said communications link and for receiving device server data processing service messages from said communications link;

B. service provider message transfer means for transmitting service provider information to and receiving processed service provider information from said service provider in connection with provision of a service by said service provider;

C. service advertising message transmission enabling means for periodically enabling said node message transfer means to transmit service advertising messages to identify a data processing service provided by the service provider; and

D. node data processing service message transfer means for generating, in response to the processed service provider information received by said service provider message transfer means, node data processing service messages for transfer by said node message transfer means and for generating, in response to service provider data processing service messages received by said node messages transfer means, service provider information for transfer by said service provider message transfer means to said service provider.

4. A node as defined in claim 3 in which said service advertising message whose transmission is enabled by said service advertising message transmission enabling means further includes a rating for each data processing service.

5. A device server unit for connection to a service user and communications link, said communications link effecting communications between the device server unit and a node, said device server unit including:

A. device server message transfer means for transmitting device server data processing service messages over and receiving node data processing service messages and service advertising messages from said communications link;

B. service user message transfer means for transmitting processed user information to and receiving service user information from the service user connected thereto;

C. service table means for establishing a service table including at least one entry including a node field and a service field identifying a node and a data processing service provided by the service provider connected to said node, the contents of the entry being provided by service advertising messages received by said device server message transfer means;

D. selection means responsive to a data processing service request from a service user for using said service table to select the node and service provider to provide a data processing service identified in said data processing service request; and

E. device server data processing service message transfer means for generating, in response to the service user information from the service user, service user data processing service messages for transmission by said device server message transfer means and for generating, in response to node data processing service messages received by said device server message transmission means, processed service user information for transfer by said service user message transfer means to said service user.

6. A device server unit as defined in claim 5 in which said service advertising message further includes a rating for each data processing service, said service table means further including means for establishing, in each entry, a rating field in response to the rating from the service advertising message, said selection means further including means for using the contents of said rating field in the selection of the node and service provider to provide the requested service.