Abstract: Apparatus for monitoring and controlling data flow ina computer network device having a plurality of parts comprises control means for directly linking ports together on the basis of additional information stored in the control means whereby incoming packets are linked directly to an utput port to achieve high performance. The additional information is stored in one more look-up tables additional to the normal CAm with the or each table addressed by separate processing. This allows the implementation to be in hardware rather than in software.

Abstract: A data pattern enforcer provides secure network communications at an adaptor layer by comparing transmitted and received packets to a set of rules to verify that said packets are appropriately being transmitted or received. The data pattern enforcer prevents application or other software with access to an adaptor on a network from using the adaptor for packet sniffing or spoofing. In a specific embodiment, the data pattern enforcer verifies packets at the layer 2 adaptor level using a value bit vector (which may be alterable or may be preset to a value, including to zero), a count value, and a mask to compare to data found in packets.

Abstract: An Ethernet network or other CSMA/CD network includes a hub that is modified to generate a jamming signal on a communication line when a packet received over that line is directed to an unavailable destination. The destination may be unavailable due to full transmit buffers, full receive buffers, or congestion in other parts of the hub architecture. Jamming is detected by the source node as a collision and causes retransmission of the packet from the source node. The decision to jam may include a determination of the packet's priority which may be determined based on the packet's destination or source address.

Abstract: An Ethernet network or other CSMA/CD network includes hub adaptors that are modified to provide a known bounded low maximum access latency. The modified adaptors maintain a state variable whose values indicates whether the last operation by the adaptor was a transmit or a receive. In the case where the last operation was a receive, the adaptor transmits a packet with a minimum or zero backoff and as an option with a reduced interpacket gap. In the case where the last operation was a transmit, the adaptor waits before transmitting a packet a period of time that allows the other node on the channel to transmit a packet if the other node has a packet to transmit.

Abstract: The monitor system consists of a voltage controlled oscillator for produc an acoustic wave whose frequency is proportional to the voltage being measured. An acoustic waveguide is used for transmitting the wave to an electrically isolated acoustic to electrical transducer. The output of the transducer is amplified and then displayed on an appropriate readout calibrated in volts.