Abstract: An apparatus and method for protecting packet-switched network links, intermediate nodes, and/or end nodes from unauthorized traffic identifies authorized traffic via a signature contained in each packet that is associated with a stored cryptographic key. Packets are forwarded (or passed through) only if they contain a signature having a pre-defined correlation to the associated key. Optionally, means for controlling the protection can be provided, so that unauthorized traffic is rejected when the protection is operative but is passed when it is not. Also optionally, intermediate degrees of protection such as prioritization of authorized traffic over unauthorized traffic can be provided.

Abstract: A sill corner key for use in a sill assembly configured to be supported on a base surface, the sill assembly including a lineal base member and a vertical jamb. The sill corner key includes a vertical component having a top surface, a bottom surface, and an inner wall extending between the top surface and the bottom surface, the inner wall defining a sealant pathway formed therein. The inner wall is configured to slidably receive a portion of the lineal base member and the sealant pathway is configured to direct a fluid sealant to flow along the portion of the lineal base member within the inner wall.

Abstract: A sill corner for use in a sill assembly supported on a base surface, the sill assembly comprising a vertical jamb and a lineal base member. The sill corner comprises a vertical component with a top surface adapted to receive the vertical jamb and a bottom surface adapted to abut the base surface. A horizontal component extends transversely from the vertical component and the horizontal and the vertical components are a unitary element. The top and bottom surfaces of the vertical component are separated by a height, the height being between about 1.00 and about 3.00 inches.

Abstract: A multi-port LAN switch is provided that enables attached network devices to both communicate directly and to insert into a token-ring network through an attached concentrator. Each port of the multi-port LAN switch has a first transformer, a second transformer, and a switching system. The first transformer has a first winding connected to a first connection of the port. The second transformer has a first winding connected to a second connection of the port. The switching system switches to a port mode or an adapter mode as a function of a mode signal transmitted to the port In the adapter mode, the switching system connects a second winding of the first transformer to a transmitter circuit in the port, and its connects a second winding of the second transformer to a receiver circuit in the port.

Abstract: A route switching layer is provided to end stations on a local area network (LAN) segment between the network layer protocol stack and the LAN adapter device driver. The route switching layer reads the network layer protocol header in a data frame queued for transmission. If the data frame is destined for a station on a different LAN segment, the route switching layer compares the network layer address with entries stored in a local address table. If a match occurs, the route switching layer inserts the corresponding data link layer address from the table in the data link header that is appended to the data frame. The data frame is then transmitted directly from source to destination end station by a hardware switch. If an address table match does not occur, the source station route switching layer sends a query to a route server device for the data link layer address corresponding to the network layer address of the destination end station.

Abstract: Disclosed is a method of transmitting ATM cells from a sending unit to a receiving unit on an ATM link wherein each of the ATM cells includes a header portion and a data portion. In the sending unit, a header portion is identified which is common to a set of subsequent ATM cells. Then, the common header portion is transmitted from the sending unit to the receiving unit followed by all data portions of the set of subsequent ATM cells. In the receiving unit, the original set of subsequent ATM cells is generated by using the common header portion.

Abstract: A LAN switch includes port modules which receive frames from their respective LAN segments and forwards the frames simultaneously to all output ports and to a port look-up function which determines the output port to which the frames should be forwarded. If the port look-up function identifies the output port, frame transmission is halted at all ports except the identified port. By performing the forwarding function and port look-up function simultaneously, a zero latency switch is provided.

Abstract: A multi-port LAN switch is provided that enables attached network devices to both communicate directly and to insert into a token-ring network through an attached concentrator. Each port of the multi-port LAN switch has a first transformer, a second transformer, and a switching system. The first transformer has a first winding connected to a first connection of the port. The second transformer has a first winding connected to a second connection of the port. The switching system switches to a port mode or an adapter mode as a function of a mode signal transmitted to the port. In the adapter mode, the switching system connects a second winding of the first transformer to a transmitter circuit in the port, and its connects a second winding of the second transformer to a receiver circuit in the port.

Abstract: A method of automatically determining an attached device type for a multi-port LAN switch, and configuring the port based on the attached device type is provided. The method comprises setting a LAN switch port to a port mode, and determining, during a first period of time, whether an attached device is attempting to insert at the LAN switch port. If the attached device is attempting to insert during this first period of time, the method continues by configuring the LAN switch port in the port mode. If the attached device is not attempting to insert during the first period of time, the method continue by setting the LAN switch port in an adapter mode, transmitting a test frame to the attached device, and then determining, during a second period of time, whether a response frame is received from the attached device. If a response frame is received during the second period of time, the method further includes configuring the LAN switch port in the adapter mode.

Abstract: This invention relates to "clear pipe" communication networks meaning the nodes and links handle a variety of data frame types depending on their communication protocols such as Token Ring, Ethernet, FDDI or ATM. More particularly, this invention relates to node/link interface adapters at nodes which include switching nodes and end nodes. The adapters identify data frame type and adapt the node/link adapter operative elements to handle the various types of data frames as they travel through the network.The invention identifies the frame type at the source, flags the frame type to the nodes by use of unique SDEL (start delimiter) symbols or codes, uses the SDEL codes as received with the frame at each node to find the destination address in the frame and to adjust the transmission rate for the frame. The transmission rate is adjusted by inserting null non-data symbols in the frame to effectively slow the data rate to the data rate capacity of the protocol.

Abstract: A station in a communications network determines the mode (full-duplex or half-duplex) in which it communicates with a concentrator port by establishing a Registration routine between the station and the concentrator port. The station and concentrator port exchange frames which disclose the capabilities of the concentrator port. If the concentrator port has duplex capabilities, the station enters as a duplex station. Otherwise, the station enters in a half-duplex (token ring) mode.

Abstract: A data communications system including a network and a number of data communication stations attached to the network wherein each of the stations includes a processor, a memory, a bus, and a communications adaptor for operatively connecting the processor and memory to the network, the communications adaptor including a means for monitoring network activity on a real time basis and enabling or disabling data compression when network activity exceeds a predetermined threshold.

Abstract: In a local area network switch, a first mode of operation is selected wherein frames are examined for errors as the frames are passed from a source port to a destination port. The LAN switch calculates an error rate as a function of a percentage of the frames passing through the local area network switch which have errors. In response to the error rate exceeding a high error rate threshold, the operating mode is switched to a second mode wherein the entire frame is buffered and examined for errors before the frame is passed from the source port to the destination port. Thereafter, the operating mode may be returned to the first mode if the error rate falls below a low error rate threshold. The local area network switch may also change operating modes as a function of a trend, which indicates a rate of increase or decrease of the error rate.

Abstract: A system for utilizing a transmission media such as a token ring having multiple, independent channels operating in parallel. The invention provides optimal use of multi-channel bandwidth to a plurality of interconnected workstations, file servers, and other devices. The workstations and devices attach to the token ring via dedicated lobe rings connected to concentrators on the token ring. Each concentrator contains the processors, memory, and logic necessary to coordinate the transmission and receipt of data over the token ring among the interconnected workstations and devices. The multi-channel token ring provides increased bandwidth and reliability to an existing token ring without requiring modifications to existing physical devices, interfaces, or protocols.