A method and apparatus for coupling a plurality of channels of a communications network to a node. The node includes a plurality of ports, each adapted for connection to a corresponding channel and a system interface adapted for connection to a plurality of node clients in the form of host computers, peripheral devices, network interfaces, etc. The node includes a receiver and transmitter dedicated to each port and common circuitry for controlling and processing frames received and/or transmitted by the plurality of ports. A frame prioritization circuit forwards frames received by a selected port to a frame handler for processing and a frame routing circuit routes frames processed by the frame handler to at least one of the ports associated with at least one destination node. The node further includes a frame header buffer associated with each port for temporarily storing the header of each frame received by the respective port prior to forwarding of the header to the frame handler.

Method and apparatus for reordering frames

In a local area network (LAN) test instrument, a method for detecting duplicate internet protocol (IP) addresses without disrupting the LAN is provided. The LAN test instrument provides a method of choosing an IP address for itself without disrupting the ARP caches of devices connected to the LAN. Duplicate IP addresses between devices on the LAN may then be tested using a series of network broadcasts chosen to elicit responses from as many nodes on the network as possible because some nodes respond to some types of broadcasts and not others. A data base of the various nodes is collected and the newly arriving responses are dynamically compared with the responses already in the data base to detect duplicate IP addresses. Separate entries in the data base for devices having duplicate IP addresses are maintained and then displayed to the user of the LAN test instrument to selectably and reliably communicate with the devices having duplicate IP addresses for further diagnosis and correction.

Method of configuring a valid IP address and detecting duplicate IP addresses in a local area network

A system and method are disclosed for bypassing a participating application that receives data from a client connection between a proxy and a client and receives data from a server connection between a proxy and a server is disclosed. The method includes deriving a client originated packet sequence synchronization factor. The client originated packet sequence synchronization factor is derived from the difference between a last data sequence number sent by the participating application to the server and a last data acknowledgment number sent by the participating application to the client. A server originated packet sequence synchronization factor is derived from the difference between a last data sequence number sent by the participating application to the client and a last data acknowledgment number sent by the participating application to the server. A server originated data sequence number of a packet sent from the server to the client is adjusted using the server originated packet sequence synchronization factor. A client originated the data acknowledgment number of a packet sent from the client to the server is adjusted using the server originated packet sequence synchronization factor. A client originated data sequence number of a packet sent from the client to the server is adjusted using the client originated packet sequence synchronization factor. A server originated data acknowledgment number of a packet sent from the server to the client is adjusted using the client originated packet sequence synchronization factor. As a result, the data sequence and acknowledgment numbers are synchronized between the client and the server.

Method and apparatus for reducing overhead on a proxied connection

A distributed protocol for allocation of multicast addresses. A first node of a network sends an address request message identifying (1) a requested in multicast address, and (2) a multicast group identifier to which the requestor belongs. The request is in multicast on a network address reserved for address resolution. All other nodes of the network monitor the reserved network address for address request messages. If a second node receiving the address request message has already allocated the requested multicast address, then the second node sends an acknowledgment message identifying (1) the already allocated in multicast address, and (2) the multicast group for which the address has been allocated. This acknowledgment is transmitted on the same reserved network address on which the address request was sent. The first node, monitoring the reserved network address, receives the acknowledgment message. If the multicast group identified in the acknowledgment message matches the multicast group to which the first node belongs, then the first node also allocates the requested network address. If the multicast group identified in the acknowledgment message does not match the multicast group to which the first node belongs, then the first node abandons the requested network address. If the first node does not receive an acknowledgment message in response to any number of address request messages repeated for the same requested multicast address, then the first node either (1) allocates the requested network address, or (2) abandons the requested network address, if the node is not the first member of a multicast group to request allocation of the address. If address allocation succeeds, then the first node uses the allocated network address for multicasting. If address allocation fails, then the first node is free to select a different multicast address to request.

Dynamic assignment of multicast addresses

Provided is a method and apparatus for objectively and non-intrusively measuring voice quality on live calls without disrupting the call session or the network. A communication system includes plural communities each including a switch that controls access to a packet-based data network for call sessions. Each of the communities is coupled to the data network by respective packet-based trunks. Quality of service (QoS) monitoring devices are coupled to the respective packet-based trunks to monitor quality levels of routes between any two given communities. Each QoS monitoring device receives packets containing streaming data (which may be actual packets or test packets). From the received packets, the QoS monitoring device can derive QoS parameters, particularly for audio and speech signals on live calls without disrupting the call session.

Non-intrusive monitoring of quality levels for voice communications over a packet-based network

A method and apparatus for detecting invalid network topologies in a local area network (LAN). The stations comprising the LAN include single attachment stations (SAS), dual attachment stations (DAS), wire concentrators (WC), and DAS/WC combination stations. Adjacent stations exchange connection type information identifying a type of physical connection of the station sending the connection information. A station receiving the connection information determines whether the connection is valid for its physical connection type using a connection matrix. Invalid connections can result in a network topology where stations are physically connected, but are not logically connected, because the stations do not all form a primary ring. Invalid connections may be rejected and bypassed in each station. Alternately, a station detecting an invalid connection may reconfigure itself using an internal data switch. The actions of each station, taken together, achieve a globally designated primary ring.

Network topology control method and apparatus

An apparatus to detect stations having duplicated addresses, the stations of the type connected in a computer communications network, the stations of the type capable of having an assigned address and having a list of addresses for comparison with a destination address field of a frame detected on the network is disclosed. The apparatus does a transmit self test, and sets a self indicator to "pass" in the event that the self test frame is received, and sets the self indicator to "timeout" in the event that a timeout occurs. The apparatus does a neighbor response test, and sets a neighbor indicator to "timeout" in the event that a timeout occurs, and sets the neighbor indicator to "pass" in the event that a received response frame indicates no destination address match, and sets the neighbor indicator to "fail" in the event that a received response frame indicates that a destination address match did occur. The apparatus tests both the self indicator and the neighbor indicator, and in response to the testing of the self indicator and the testing of the neighbor indicator sets a duplicate address indicator in one of three states, a first state of the three states indicating that there is no duplicate address detected, a second state of the three states indicating that there is a duplicate address, and the third state of the three states indicating an unknown condition.

Testing a communications network for duplicate station addresses

RingOp/Claim oscillations due to duplicate addresses and transmit aborts are avoided by using token preserver frames to reset the TVX timer in a station. A communications network having a plurality of stations capable of transmitting frames onto the network, and the stations capable of detecting transmission on the network, and the stations capable of taking predetermined action in the absence of detecting the transmission for a predetermined first time interval, and a first timer for measuring the predetermined first time interval. Measuring a second predetermined time interval, the second predetermined time interval being chosen to be less than the first predetermined time interval; transmitting a reset frame onto the network by a selected station at time intervals substantially equal to the second predetermined time interval, and the reset frames being capable of causing a station to reset the first timer to a beginning value. The network may be a token controlled ring. The reset frame may be a token preserver frame.

Avoidance of false re-initialization of a computer network

***WITHDRAWN PATENT AS PER THE LATEST USPTO WITHDRAWN LIST***Network topology control method and apparatus

In a network Ring Op/Claim oscillations due to duplicate addresses and transmit aborts are avoided by using token preserver frames to reset the TVX timer in a station. The stations are capable of detecting transmissions on the network and of taking predetermined actions in the absence of detecting transmissions for a predetermined first time interval. There is further provided a timing means for measuring a second predetermined time interval and means for transmitting a reset frame onto the network by a selected station, the reset frames being transmitted at intervals substantially equal to the second predetermined time interval, causing a station to reset the first timer to a beginning value, the reset means capable of transmitting the reset frames between frames transmitted by the originating means.

Henry Yang

Papers

Network topology control method and apparatus

Testing a communications network for duplicate station addresses

Avoidance of false re-initialization of a computer network

WITHDRAWN PATENT AS PER THE LATEST USPTO WITHDRAWN LISTNetwork topology control method and apparatus

Avoidance of undesired re-initialization of a computer network