Abstract: A method and structure is disclosed for dispatching appropriate data to a network processing system comprising an improved technique for extracting protocol header fields for use by the network processor. This technique includes basic classification of a packet according to the types of protocol headers present in the packet. Based on the results of the classification, specific parameter fields are extracted from corresponding headers. All such parameter fields from one or more protocol headers in the packet are concatenated into a compressed dispatch message. Multiple of such dispatch messages are bundled into a single composite dispatch message. Thus selected header fields from N packets are passed to the network processor in a single composite dispatch message, increasing the network processor's packet forwarding capacity by a factor of N. Likewise, multiple enqueue messages are bundled into a single composite enqueue message to direct enqueue and frame alterations to be taken on the bundle of N packets.

Abstract: Modems, methods, and computer program products select a data rate based on error signals in a modem. In an illustrative embodiment, error signals representing the difference between an output of an equalizer and an output of a detector are accumulated and an average error value is computed therefrom. A signal to noise ratio is determined using the average error value. The signal to noise ratio is then used to select a data rate. In another illustrative embodiment, the mean squared error at the output of the equalizer is determined and then used, along with the probability of error in correctly detecting a symbol, to select a data rate. Incorrect decisions in detecting received data symbols can cause a catastrophic failure in a decision feedback equalizer used in a modem receiver as errors are repeatedly fed back causing the tap coefficients for the equalizer filters to be shifted from their normal operating values.

Abstract: Modems, methods, and computer program products select a data rate based on error signals in a modem. In an illustrative embodiment, error signals representing the difference between an output of an equalizer and an output of a detector are accumulated and an average error value is computed therefrom. A signal to noise ratio is determined using the average error value. The signal to noise ratio is then used to select a data rate. In another illustrative embodiment, the mean squared error at the output of the equalizer is determined and then used, along with the probability of error in correctly detecting a symbol, to select a data rate. Incorrect decisions in detecting received data symbols can cause a catastrophic failure in a decision feedback equalizer used in a modem receiver as errors are repeatedly fed back causing the tap coefficients for the equalizer filters to be shifted from their normal operating values.

Abstract: Methods, systems and computer program products are provided for constellation generation which determine initial ucode boundaries and an initial minimum signal level spacing. A work constellation set is generated based on the initial ucode boundaries and the initial minimum signal level spacing. The work constellation set is then iteratively adjusted so as to provide an adjusted work constellation set which achieves an error probability target. The adjusted work constellation set is then iteratively pruned so as to provide a pruned work constellation set which achieves a power limit. The pruned work constellation set is then iteratively fine-tuned so as to provide a final constellation set which is within a specified tolerance of the error probability target and/or the power limit.

Abstract: Error rate control systems, methods, and computer program products request a data rate slow-down based on the status of the error rate. A linear penalty is generated if a data rate slow-down is requested, which is then used to determine a minimum distance between constellation points in a signaling constellation or alphabet. Because the minimum distance between constellation points may be directly related to the error probability, the error rate may be controlled through the linear penalty.

Abstract: The decision within a packet processing device to transmit a newly arriving packet into a queue to await further processing or to discard the same packet is made by a flow control method and system. The flow control is updated with a constant period determined by storage and flow rate limits. The update includes comparing current queue occupancy to a threshold. The outcome of the update is adjustment up or down of the transmit probability value. The value is stored for the subsequent period of flow control and packets arriving during that period are subject to a transmit or discard decision that uses that value.

Abstract: A method and structure for counting and storing the number of occurrences of each of a plurality of events occurring in a processor complex, which processor complex has at least one processor which processes multiple groups of data in a multiplicity of ways, is provided. The structure includes multiple storage devices, each of which includes a plurality of arrays of memory storage for storing count information of each event, which arrays are divided into a plurality of separately addressable groups of memory addresses in each memory array. At least one counter element is associated with each array of memory. A table is provided which contains information, including a point of reference in each array to uniquely define the structure and location of each memory array. At least one processor generates a plurality of parameters for each of the events to uniquely identify the event.

Abstract: A method and system for converting a plurality of ranges of values for a plurality of packet classification rules in a computer system is disclosed. The plurality of ranges exists in at least one dimension. The method and system include mapping each of the plurality of ranges to a plurality of nonoverlapping prefixes. The method and system also include mapping the plurality of nonoverlapping prefixes to a plurality of overlapping prefixes corresponding to the plurality of ranges.

Abstract: Robbed Bit Signaling (RBS) and PAD digital impairments in sets of Digital Impairment Learning (DIL) signals that are repeatedly transmitted from a server modem to a client modem during DIL intervals are identified by identifying a PAD level for the sets of DIL signals in the DIL intervals and then identifying an RBS type for individual sets of DIL signals based upon the PAD levels so identified. The PAD level may be identified using model DIL signals that correspond to PAD levels that are not subject to RBS. The RBS type may be identified using model DIL signals that correspond to multiple RBS types that are subject to the identified PAD level. More specifically, one of the DIL intervals that contains DIL signals that are not subject to RBS is identified. A PAD level for the DIL signals in the one of the DIL intervals so identified then is determined.

Abstract: A structure and technique for preventing collisions using a hash table in conjunction with a CAM to identify and prevent a collisions of binary keys. A portion of the hash value of a binary key, which does not collide with a portion of the hash value of any other reference binary key, is used as an entry in the hash table. If two or more binary keys have identical values of the portions of the hash values, each of these binary keys are stored in their entirety, in the CAM. The key in the CAM provides a pointer to a data structure where the action associated with that binary key is stored. If the binary key is not found in the CAM, the binary key is hashed, and a specific entry in the hash table is selected using a portion of this hash value.

Abstract: Re-synchronization of sets of transmit and receive state variables in a communication system is achieved when an error is detected, without disrupting the connection. Each of first and second transceivers, connected by a communications channel, have a common set of transmit and receive state variables supporting a data encoding algorithm function. The transmitter of one of the first and second transceivers fist encodes data to be transmitted and updates the transmit state variables according to the data encoding algorithm and the receiver of the receiving transceiver validates whether or not each data block has been received correctly. During the process of decoding the data, the receive state variables are updated according to the same algorithm used to update the transmit state variables, thereby keeping the two sets of state variables in synchronism with each other.

Abstract: Modems, methods, and computer program products select a data rate based on error signals in a modem. In an illustrative embodiment, error signals representing the difference between an output of an equalizer and an output of a detector are accumulated and an average error value is computed therefrom. A signal to noise ratio is determined using the average error value. The signal to noise ratio is then used to select a data rate. In another illustrative embodiment, the mean squared error at the output of the equalizer is determined and then used, along with the probability of error in correctly detecting a symbol, to select a data rate. Incorrect decisions in detecting received data symbols can cause a catastrophic failure in a decision feedback equalizer used in a modem receiver as errors are repeatedly fed back causing the tap coefficients for the equalizer filters to be shifted from their normal operating values.

Abstract: Systems, methods and computer program products are provided for simultaneously transmitting data over a plurality of subscriber lines, such as twisted pair telephone wires, extending between a shared device and a respective plurality of remote devices using a symbol-based discrete multi-tone transmission scheme. A destination code within a first group of frequency bands and modulated data within a second group of frequency bands different from the first group of frequency bands, are transmitted from the shared device to the remote devices. The second group of frequency bands is selected for a subscriber line connected to a remote device having the destination code within the first group of frequency bands.

Abstract: Methods, systems and computer program products are provided for refining constellation values in a Pulse Code Modulated (PCM) code point sequence of a PCM modem by averaging received levels associated with received symbols for a code point of interest received during data mode operation of the PCM modem so as to provide an average received level for the code point of interest and revising a constellation value corresponding to the code point of interest in the PCM code sequence based on the average received level for the code point of interest so as to provide a refined constellation value. Preferably, the averaging is performed by detecting that a symbol corresponding to the code point of interest has been received by the PCM modem and incorporating the received level of the symbol into a running sum of previously received levels for the symbol. If a predefined number of received levels have been incorporated into the running sum then the running sum is divided by the predefined number of receive levels.

Abstract: Broadband modems using data compression insure the physical connection between modems is solid prior to initiating error recovery procedures since its error detection runs on the compressed data. Escape sequences applicable to Transparent Mode of the Compression function enable both duplex and simplex compression functions and provide a more reliable mechanism for completion of error recovery procedures in the presence of subsequent line disturbances. Transparent Mode is used during the re-synchronization procedure. No special compression code words are required to accomplish the procedure, and there is no reduction in the number of code words available for actual compression encoding. The procedure works regardless of whether compression is being used in both directions, only one direction, or neither direction. A new Transparent Mode Command to request that the remote modem send a RESET Command is defined. The new command is termed RRESET.

Abstract: A method and system for performing network address translations for a session in a network is disclosed. The network includes at least one local network domain, and the at least one local network domain includes at least one computer system. Each computer system has a local address and is associated with a global address. The session exchanges packets that travel between the computer system within the local network domain and another computer system which may be outside of the local network domain. Each packet includes source and destination information. The method and system include determining a direction of travel for each packet, inbound or outbound, by searching a global address table for a match of a key for each packet. The key is provided using a portion of the destination information. The global address table includes at least one entry. Each entry corresponds to the global address for a first corresponding computer system.

Abstract: Severe error detectors, methods, and computer program products use constellation specific error event thresholds to detect severe error events in a signal comprising symbols from a plurality of symbol constellations. In particular, a plurality of constellation thresholds are defined that correspond to a plurality of symbol or signal constellations. An output signal sample, which is associated with one of the plurality of symbol constellations, is received from a decision feedback equalizer. The absolute value of the output signal sample is compared with the constellation threshold that corresponds to the particular symbol constellation associated with the output signal sample. If the absolute value of the output signal sample exceeds the constellation threshold, then a severe error is recognized. The ITU V.90 Recommendation allows up to six different symbol or signal constellations to be used in the same communication session.

Abstract: An adapter for providing data communications for a personal computer to other remote data communications systems of various communication platforms is disclosed. The remote data communications systems can be a data circuit terminating equipment (DCE) such as a modem, or a data terminating equipment (DTE) such as an ISDN terminal adapter. The adapter comprises a programmable digital signal processing device, a memory device and an assortment of transceiving devices. A software program is stored in the memory device for instructing the programmable digital signal processing device. The transceiving devices are controlled by the programmable DSP device such that the appropriate transceiving device can be activated for providing data communications, according to the type of communication platform utilized by the remote data communications equipment.

Abstract: A method and system for identifying a data structure associated with a packet of data. A processor internal to a packet processor may extract one or more fields in a packet header field of a received packet of data to generate a search key. The internal processor may then be configured to select which table, e.g., routing table, quality of service table, filter table, needs to be accessed using the search key in order to process the received packet of data. A determination may then be made by the internal processor as to whether a CAM or a hash table and a Patricia Tree are used to identify the data structure associated with the received packet of data. Based on table definitions in a register, the internal processor may make such a determination.

Abstract: A method and system for compressing and transmitting data using asynchronous transfer mode (ATM) is disclosed. The data include a plurality of segments. Each of the plurality of segments has a first end and a second end. In one aspect, the method and system include representing the first end of a segment with a partition compression code word and compressing a remaining portion of the segment. The method and system could also combine the marking of the boundary and subsequent data into a compound compression code word. In another aspect, the method and system include representing the first end of a segment with a transparent mode command, transmitting the transparent mode command, and transmitting a remaining portion of the segment.