Broadcom Corporation

Broadcom Homenetworking, Inc.

3com Corporation

Brocade Communication Systems LLC

Tracy D Mallory

John T Holloway

Edward H Frank

Alan G Corry

Henry S Ptasinski

Kevin H Peterson

Larry C Yamano

Craig Stephen Forrest

Dane Snow

Timothy B Robinson

Jason A Trachewsky

Matthew James Fischer

Michael J Seaman

Mark S Isfeld

Nagaraj Arunkumar

Bruce W Mitchell

Eric Jon Ojard

Raymond Hayes

Subbu Subramaniam

Pyda Srisuresh

Jay Pattin

In a frame-switched network, a sender sends frames to a receiver over a possibly unreliable channel. Sent frames include frame identifiers that can be used for a limited automatic repeat request. Upon receipt of a frame, the receiver determines, from the frame identifier, if frames prior to the received frame were lost in transit. If the receiver determines that it missed a prior frame, the receiver sends the sender a negative acknowledgment (nack) for the missed prior frame or frames. Otherwise, if the receiver receives a frame correctly, it does not acknowledge the frame. The frame identifiers can be a set of sequential integers with frames transmitted in sequential frame order. In some embodiments, when a receiver receives a frame out of order, the receiver buffers the out of order frame in a receiver buffer for a receive buffer period until preceding frames are received or a receive buffer period expires. The sender can send a reminder frame to the receiver to allow the receiver to detect a missed prior frame missing from an end of a frame sequence. The channel between the sender and the receiver can be a bidirectional channel over a telephone wire, a cable, a radio frequency link or a power wire. Multiple logical channels might be set up between a given sender-receiver pair, to allow for traffic of varying priorities.

Limited automatic repeat request protocol for frame-based communication channels

Methods and apparatus for data communication are disclosed. An example method includes encoding a first plurality of transmitting frames, where a header segment of each frame is encoded in accordance with a fixed set of header encoding parameters and a payload segment of each frame is encoded in accordance with a first set of a variable set of payload encoding parameters. The example method also includes transmitting the first plurality of transmitting frames to a receiving station and receiving a request from the receiving station to change the first set of payload encoding parameters to a second set of the variable set of payload encoding parameters. The example method further includes selecting the second set of payload encoding parameters based on the request and encoding a second plurality of transmitting frames, where a header segment of each frame of the second plurality of transmitting frames is encoded in accordance with the fixed set of header encoding parameters and a payload segment of each frame of the second plurality of transmitting frames is encoded in accordance with the second set of payload encoding parameters. The example method still further includes transmitting the second plurality of transmitting frames to the receiving station.

Method for providing dynamic adjustment of frame encoding parameters in a frame-based communications network

A receiver circuit of the modem is coupled to receive a continuous analog signal from a communication channel. This analog signal includes both packet and idle information. A burst mode protocol is also provided, in which packets of digital information are modulated by a transmitter circuit of the modem, thereby converting the packets of digital information into analog signal bursts of discrete duration. These analog signal bursts are transmitted from the transmitter circuit to a telephone line. A receiver circuit monitors the telephone line to detect the analog signal bursts. Upon detecting the presence of the analog signal bursts on the telephone line, the receiver circuit demodulates the analog signal bursts using full processing capabilities of the receiver circuit. However, upon detecting the absence of the analog signal bursts on the telephone line, the demodulating function of the receiver circuit is disabled. The burst mode protocol enables multi-drop and multi-cast operation, as well as reducing required DSP resources.

Method and apparatus for reducing signal processing requirements for transmitting packet-based data

A method of sharing information among a plurality of stations on a communications network, each of the stations being capable of transmitting and receiving frames over the communications network. A group of agreed-upon flags is established, periodic timing is provided in each station that expires after an interval, and a common frame format is defined providing the capability of specifying a current transmit flag set, an old transmit flag set, and a current receive flag set. Each station maintains: a current transmit state set a recent and previous timer expiration set and a current and previous transmit received set. A control frame is generated and transmitted by a transmitting station to all other stations on the communications network each time a flag in a logical union of current transmit flag sets is set and upon the expiration of the timer in the transmitting station.

Method of sharing information among a plurality of stations in a frame-based communications network

A method for providing dynamic adjustment of frame encoding parameters to improve transmission performance for a transmitting frame being transmitted from a transmitting station to a receiving station over a transmission medium on a frame-based communications network, the transmitting frame having a header segment and a payload segment, the header segment being transmitted using a fixed set of encoding parameters, the payload segment being transmitted using a variable set of payload encoding parameters.

Limited automatic repeat request protocol for frame-based communications channels

For each node, elapsed periodic time intervals are provided and counted since the transmission of a link integrity indication frame, a frame which can be received by all other nodes on the network and which contains a source identifier. Frames are received from a sending node and a node state status and a current received frame source address are maintained during each periodic time interval. Upon expiration of the periodic time interval, if the node state status is not indicative of network traffic and a count of the elapsed periodic time intervals since transmission of a link integrity indication frame is greater than a predefined count limit, a link integrity indication frame is transmitted.

Method and apparatus for verifying connectivity among nodes in a communications network

A 'high availability' system comprises multiple switches under the control of one more control processors ('CPs'). Each CP performs a staged startup process when failing-over from another CP or otherwise booting up. The staged startup process involves multiple stages of processing of various executable components of the image. Some stages may depend on the prior execution of other stages. The preferred staged startup process includes the use of a staging table which permits the standby image's FSS facility to efficiently schedule the various stages of the fail-over process taking into account the inter-stage dependencies.

Staged startup after failover or reboot

A method and signal therfor embodied in a carrier wave for sending information from transmit stations to receive stations over a transmission medium of a frame-based communications network. The information is sent in transmit frames having a frame format comprising a fixed rate header, followed by a variable rate payload, followed by a fixed rate trailer. The fixed rate header includes a preamble. The preamble has a repetition of four symbol sequences for facilitating power estimation, gain control, baud frequency offset estimation, equalizer training, carrier sensing and collision detection. The preamble also includes a frame control field. The frame control field has scrambler control information for frame scrambling initialization, a priority field to determine the absolute priority a transmit frame will have when determining access to the transmission medium, a payload encoding field which determines constellation encoding of payload bits in the variable rate payload, and a header check sequence for providing a cyclic redundancy check. The variable rate payload is transmitted pursuant to dynamic adjustable frame encoding parameters for improving transmission performance for a transmit frame being transmitted from a transmitting station to a receiving station. The header also includes a destination address field, a source address field and an ethertype field.

Transceiver method and signal therefor embodied in a carrier wave for a frame-based communications network

A method of providing synchronous transport of packets between asynchronous network nodes. An asynchronous network node capable of transmitting and receiving packetson the asynchronous network is designated as a master node. Each non-master asynchronous network node which desires to synchronously transport packets across the asynchronous network is designated as a slave node. Best arrival times for packets transmitted from slave nodes to the master node are communicated from the master node to the slave nodes. Bestpacket assembly times for packets to be transmitted by the particular slave node to the master node in the future for the packets to be received by the master node at future master clock referenced best arrival times are determined. Packets for transmission at slave nodes are prepared and transmitted according to determined future bestpacket assembly time information.

Method of providing synchronous transport of packets between asynchronous network nodes in a frame-based communications network

A method of controlling data sampling clocking of asynchronous network nodes, each asynchronous network node having a local clock and transmitting and receiving packets to and from an asynchronous network according to an asynchronous network media access protocol. An asynchronous network node capable of transmitting and receiving packets on the asynchronous network is designated as a master node. Each non-master asynchronous network node which desires to synchronously transport packets across the asynchronous network is designated as a slave node. A master node clock of the master node is synchronized with a slave node clock of each slave node. Each slave node clock is continuously corrected compared with the master node clock to smooth slave clock error to an average of zero compared with the master clock as a reference using timestamp information from the master node. A derivative clock at the slave node is derived from the continuously correcting each slave node clock to control data sampling at the slave node.

Method of controlling data sampling clocking of asynchronous network nodes in a frame-based communications network

A method of enhancing network transmission between stations on a priority-enabled frame-based communications network, the communications network having multiple transmit priorities and transmitting frames such that a network access time to transmit a frame of a lower transmit priority is longer than a network access time to transmit a frame of a higher transmit priority, the number of transmit priorities being fixed and all stations being capable of transmitting frames at any transmit priority. The method applies to each station. An initial transmit priority is established for each frame to be transmitted. A set of initial transmit priorities assigned to frames transmitted on the communications network is maintained. A set of final transmit priorities is established containing highest possible priorities, one final transmit priority being associated with each member of the set of initial transmit priorities, such that a highest initial transmit priority is assigned to a highest possible priority, a next highest initial transmit priority is assigned to a next highest possible priority, and so forth. Ordered frames are transmitted onto the communications network, each frame using a final transmit priority associated with the initial transmit priority established for the each frame.

Method of enhancing network transmission on a priority-enabled frame-based communications network

A method for selecting an operating mode for a frame-based communications network consisting of a plurality of stations attached to a transmission medium. The plurality of stations include both a first type station and a second type station. The first type station is capable of transmitting and receiving first protocol frames in accordance with a first protocol. The second type station is capable of transmitting and receiving both first protocol frames and second protocol frames in accordance with a second protocol. The first protocol and the second protocol each use different signals on the transmission medium. The first type station is not capable of reliably detecting second protocol frames. The first protocol has a first protocol frame format containing at least two reserved bits in a first protocol frame header which are ignored in received frames by first type stations and always sent with a same fixed value by first type stations. The first protocol frame format is redefined to provide an updated first protocol frame header wherein two reserved bits in the first protocol frame header are allocated as a mode selection indicator field in the updated first protocol frame header. The mode selection indicator field has meaning for second type stations.

Method for selecting an operating mode for a frame-based communications network

A method for distributing sets of collision resolution parameters to be used for resolution of network access contention events among nodes of a non-centralized media access control shared medium network. A set of collision resolution parameters is provided which includes a sequence of fixed numbers for resolving a single network access contention event. A single collision signal slot master node is identified when one or more candidate collision signal slot master nodes exist. Collision signal slot request messages are sent from client nodes addressed to all network nodes. Collision signal slot assignment messages are sent from the master node to the client nodes. A collision resolution parameter set to be employed by that given client node is obtained at a given client node from within a received collision signal slot assignment message. Collision signal slot acknowledgment messages are sent from client nodes addressed to all network nodes. Collision signal slot drop messages are sent from client nodes addressed to all network nodes.

Method for distributing sets of collision resolution parameters in a frame-based communications network

A modem and method for operating same. A receiver circuit of the modem is coupled to receive a continuous analog signal from a communication channel. This analog signal includes both packet and idle information. The receiver circuit monitors the analog signal to detect the presence of idle information. Upon detecting idle information, the receiver circuit enters a standby mode in which the processing requirements of the receiver circuit are reduced. A burst mode protocol is also provided, in which packets of digital information are modulated by a transmitter circuit of the modem, thereby converting the packets of digital information into analog signal bursts of discrete duration. These analog signal bursts are transmitted from the transmitter circuit to a telephone line. However, the transmitter circuit does not generate any signals between the analog signal bursts. A receiver circuit monitors the telephone line to detect the analog signal bursts. Upon detecting the presence of the analog signal bursts on the telephone line, the receiver circuit demodulates the analog signal bursts using full processing capabilities of the receiver circuit. However, upon detecting the absence of the analog signal bursts on the telephone line, the demodulating function of the receiver circuit is disabled. The burst mode protocol enables multi-drop and multi-cast operation, as well as reducing required DSP resources.

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Palo Alto, CA, United States of America

Tracy D Mallory