Digital Equipment Corporation

Gary V Vacon

John A Visser

Stuart K Morgan

Michael Romm

Stephen D Metzger

Margaret L Hetfield

Willem A Engelse

Jeffrey A Lomicka

Peter Bellomo

Pat Gili

Lawrence Bibeau

An arrangement for selective filtering, e.g. one-way filtering, of messages received by a 2-port bridge from stations connected to two LANs of an extended LAN is provided. The bridge includes a message filtering database containing the addresses of all stations connected to one of the LANs. The database also contains a list of higher-level protocols employed by the stations. Associated with each protocol-type is information used by the bridge to dispose of the message. The message filtering database comprises a single table memory capable of supporting both ports of the bridge. The selective filtering process involves a two-step analysis by the bridge to determine whether to discard the message or forward it to another port. The analysis is based on a destination address and a protocol-type of the received message.

Disposition filtering of messages using a single address and protocol

A data communications network having a number of servers and a number of service providers employs an improved protocol for translating service names to network addresses. A server sends a multi-cast message to all service providers requesting a service needed by one of the user terminals connected to this server. In the request, the service is identified by function, rather than by address. Any node which provides this service, receiving the request and able to reply, sends a reply message immediately to the server. The reply message identifies the node (service provider) by network address, so a transaction with this provider can be initiated by the server immediately. If the service provider cannot reply, a third party node can send a reply to identify the provider by address. If the server does not receive a reply from either the provider or a third party, then a cache of network addresses of services most recently used by the server is searched for this particular service. The cache may include a separate local cache for each user terminal connected to this server, with each local cache containing the service and address for the last-used service for one of the user terminals. In addition, a secondary cache is maintained for all items replaced in the local caches when they are updated. When the cache is searched (both local and secondary), if the service address is found, a transaction is begun immediately by the server to utilize the service. If not found in the cache, the server waits for a service advertisement to appear on the network, and obtains the network address of the provider from the advertisement.

Service name to network address translation in communications network

An EMI/RFI shielded printed circuit board housing of compact design suitable for computer system products (such as, e.g., bridges and repeaters) permits such products to be used on office work surfaces or in a wall-mounted, high density storage system within an office environment. The housing has a five-sided printed-circuit-board container with a back wall defining at least on window for exposing an electrical connector that requires access from the exterior of the container, a removable front cover, a removable trough-shaped rear cover for covering the container back wall and protecting the exposed connector located thereat. The back wall is equipped with support features for permitting the housing to be supported in the high density storage system during use. The container and front cover have a plurality of interior surfaces coated with an EMI/RFI shielding material. In other aspects of the invention, the housing has printed-circuit-board-support features for precisely positioning and supporting the printed-circuit-board within the housing in such a way as to avoid contact between the printed circuit board circuitry and the EMI/RFI-shielding material. In addition, the housing has a connector-access button defining a recessed interior volume into which extends a male electrical connector mounted on the printed circuit board.

Shielded printed circuit board housing for high density storage

A terminal server architecture includes a central processing unit (CPU), a data movement module, local area network (LAN) interface and a plurality of connected terminals. The CPU manages pointers to data using command status registers to instruct the data movement module to actually perform data movement between the terminals and the LAN.

Terminal server architecture

A mounting system for the installation of communication termination blocks and communication boxes ('system blocks') on a backplane substantially reduces space requirements for a communications center. The system includes a system block that quickly and removably mounts to a slot in a track. A locking slide either automatically or manually engages the block to hold it securely in place, both mechanically and electrically. Lifting the locking slide releases the block. The block includes an elongated hook that provides lateral support for the block during installation and removal to ensure proper mating of electrical conductors.

Growing community of inventors

Melrose, MA, United States of America

Gary V Vacon