摘要:
A method and system for testing a plurality of filter rules in a computer system is disclosed. The plurality of filter rules are used with a key that is capable of matching at least one of the plurality of filter rules. The at least one filter rule corresponds to at least one action. The computer system has a cache including a plurality of bins and a decision tree. The method and system include searching a plurality of stored keys in the cache for the key. Preferably, this search of the cache for the key includes determining whether a stored key exactly matches the key. A plurality of stored filter rules corresponds to the plurality of stored keys. A plurality of stored actions corresponds to the plurality of stored filter rules. The cache stores each of the plurality of stored keys and at least one stored action in each bin of a portion of the bins. The method and system also include obtaining the at least one action from the cache if the key is found in plurality of stored keys and otherwise obtaining the at least one action using the decision tree. Preferably, searches of the decision tree and cache start simultaneously. The decision tree search is terminated if the key is found in the cache. The cache is written to if the at least one action is obtained using the decision tree, but preferably only if the at least one filter rule has a priority of one.
摘要:
A remote controller is coupled to a target system via a computer network A real time probe is installed in software executing on a target system, typically a Digital Signal Processor (DSP). The remote controller includes a “debugger user interface” which accepts and interprets scoping commands issued by a developer. A controller network driver constructs appropriate network packets to be sent over the network to the target system. The target system has a control processor which runs a target network driver for receiving the network packets containing the scoping commands. The scoping commands are sent to an “embedded debugger” which performs the requested probing/scoping. When the DSP code runs across an address where the probe is installed, the embedded debugger will collect the signal values. The collected scope data will be interleaved and sent to the target network driver which, will encapsulate the information into suitable packets to send back to the controller via the network.
摘要:
Packetized voice, video, and data traffic (data frames) are received in a communication traffic sorter. The data frames have a dispatch priority corresponding to their transmission characteristics (flow) and a quality of service parameters. The communication traffic sorter analyzes information in data packets within each data frame and determines an optimum flow for the data frames. A data frame is assigned to a selected queue based on an analysis of the information in its data packets. A data frame may also be assigned to a queue based on a prior analysis of a data frame with like transmission characteristics. Results of analysis are stored and indexed to facilitate processing of subsequent data frames. The network access sorter has circuits to un-pack and re-pack the data frame, when called for, to allow user transmitted data to be processed to create a modified data frame. The data frame may then be dispatched with a second dispatch priority on a bus for distribution to end users where previously assigned quality of service is maintained or exceeded.
摘要:
A packet network redistributes excess bandwidth for voice and data sessions applying a Quality of Service (QoS) algorithm. The network includes interacting client stations using H.323 protocol managing bit rate according to an algorithm as voice and data sessions are added or removed from the network. The client stations include codecs coupled to the network. The codecs provide voice sessions at a minimum bandwidth using a voice codec bit rate and preferred bandwidth using another voice codec bit rate. A first algorithm applies the QoS algorithm allocating bandwidth between interacting client stations after the addition of a new voice or data session when there is insufficient bandwidth for the new session to receive preferred bandwidth. A second algorithm is applied when a voice or data session is removed from the interacting client stations. If any session is allocated minimum bandwidth the QoS increases a voice session at minimum bandwidth to preferred bandwidth if excess bandwidth is available.
摘要:
A codec detects congestion in a packet network and responds via a session control protocol to re-negotiate codec-type and/or parameters with the receiving codec to reduce bit rate for supporting a session. Once the connection and session are established, encoded packets start flowing between the two codecs. A control entity sends and receives network congestion control packets periodically in the session. The congestion control packets provide a “heartbeat” signal to the receiving codec. When the network is not congested, all “heartbeat” packets will be passed through the network As network congestion increases, routers within the network discard excess packets to prevent network failure. The codecs respond to the missing packets by slowing down the bit rate or proceeding to renegotiate a lower bit rate via the session control protocol. If there are no missing packets, the codecs detect if the session is operating at the highest bit rate, and if not, re-negotiate a higher bit rate.
摘要:
A packet network congestion control system using a biased packet discard policy includes a plurality of end points having codecs operating in a framework, e.g. ITU-T H.323 protocol to establish a communication session. The protocol enables the codecs to negotiate codec type and associated parameters. Once a connection and session are established, compressed voice and data packets start flowing between the two end points. A control entity supplies congestion control packets periodically. The control packets provide a “heartbeat” signal to the codec at the other end of the session. Each codec receiver uses the “heartbeat” signal as an indication of network congestion. As network congestion increases, routers within the network discard excess packets to prevent network failure. The network discards all packets classified as congestion control packets whenever a flow control mechanism detects congestion or a trend toward congestion. As packets are discarded, the end points renegotiate codec type and/or parameters to realize lower bit rates.
摘要:
Digital impairments, including Robbed Bit Signaling (RBS) and impairments due to digital attenuation PAD (Packet Assembler/Disassembler) devices, may be identified in sets of Pulse Code Modulation (PCM) signal levels, such as sets of Digital Impairment Learning (DIL) signals transmitted from a server modem to a client modem during a plurality of DIL levels. Both signature analysis and signal level comparison analysis are preformed on the signals to identify digital impairments. Signature analysis compresses the set of signal levels into a signature. Digital impairments are determined based on the signature. In a preferred embodiment, the PCM signal levels are compressed into a signature by identifying clusters and/or skips. PCM signal level comparison analysis uses differences, between PCM signals and models of signals having various digital impairments. By using both techniques combination, the strengths of each technique are utilized while the weaknesses of each techniques are avoided.
摘要:
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. It is also preferred that, after determining the sum for the code point of interest, the running sum is set to zero and a new code point selected as the code point of interest.
摘要:
Methods, systems and computer program products are provided for monitoring performance of a modem which obtain diagnostic data directly from memory associated with the modem's digital signal processor (DSP). A secondary path to the DSP memory is utilized for the monitoring operations so that real time data can be obtained during connection startup procedures and during an active connection. First-in first-out (FIFO) buffers are incorporated in the DSP memory to track state transitions of one or more of the state machines within the modem and various performance data measurements may be obtained directly from the DSP memory responsive to different state transition events. The real time collected data may be stored in a file and provided to a remote location for use in diagnosing customer problems with specific customer line connections. Accordingly, real time monitoring of digital and analog line conditions and modem performance may be utilized to diagnose problems with modems and line connections.
摘要:
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. By adjusting the data rate in accordance with the error signals generated in a modem receiver, the decision feedback equalizer can operate with greater stability as the data rate can be reduced in response to increased noise conditions.