摘要:
Systems and methods are disclosed for utilizing slave (receive) time-stamp clock rates that are different from master (sender) time-stamp clock rates to randomize and thereby reduce systematic time-stamp granularity errors in the communication of network packets. The slave (receive) time-stamp clock rate for some embodiments is set to be a fixed value that has a relationship with the master (sender) time-stamp clock rate such that the ratio of the slave (receive) clock rate to the master (sender) clock rate is a rational number. Other embodiments use a time-varying frequency for the slave (receive) time-stamp clock rate to randomize the slave (receive) time-stamp clock with respect to the master (sender) time-stamp clock. Additional time-stamps can also be generated using a slave (receive) time-stamp clock having a rate set to equal the rate of the master (sender) time-stamp clock signal. Further spread spectrum and/or delta-sigma modulation techniques can be applied to effectively randomize the slave (receive) time-stamp clock.
摘要:
Systems and methods are disclosed that allow for improved management and control of packet forwarding in network systems. Network devices and tool optimizers and a related systems and methods are disclosed for improved packet forwarding between input ports and output ports. The input ports and output ports are configured to be connected to source devices and destination devices, for example, network sources and destination tools in a network monitoring environment. The network devices and tool optimizers disclosed can use a packet processing system whereby forwarding behavior is governed by matching packets in parallel against multiple user-specified packet filtering criteria, and by performing forwarding actions associated with all such matching filter criteria. The multi-action packet forwarding can be implemented using hardware configured to directly provide multi-action packet forwarding and/or hardware configured to provide single-packet-forwarding that has been subsequently configured using filter engines to provide multi-action packet forwarding.
摘要:
Systems and methods are disclosed for utilizing slave (receive) time-stamp clock rates that are different from master (sender) time-stamp clock rates to randomize and thereby reduce systematic time-stamp granularity errors in the communication of network packets. The slave (receive) time-stamp clock rate for some embodiments is set to be a fixed value that has a relationship with the master (sender) time-stamp clock rate such that the ratio of the slave (receive) clock rate to the master (sender) clock rate is a rational number. Other embodiments use a time-varying frequency for the slave (receive) time-stamp clock rate to randomize the slave (receive) time-stamp clock with respect to the master (sender) time-stamp clock. Additional time-stamps can also be generated using a slave (receive) time-stamp clock having a rate set to equal the rate of the master (sender) time-stamp clock signal. Further spread spectrum and/or delta-sigma modulation techniques can be applied to effectively randomize the slave (receive) time-stamp clock.
摘要:
Systems and methods are disclosed for utilizing large packet sizes to reduce unpredictable network delay variations in delivering timing packets across networks for use with respect to network timing protocols. By increasing the size of the timing packets, the disclosed embodiments reduce or eliminate the blocking effect caused by size differences between timing packets and relatively large packets carried through a packet network. By reducing or eliminating this blocking effect, the disclosed embodiments provide significant advantages in reducing the complexity of implementing robust timing protocols for handling unpredictable delays in the communication of timing packets. The size of timing packets can be increased, for example, by adding fill data to timing data to form large timing packets. A variety of large packet sizes can be used for the timing packets, and timing packets can preferably be made to be equal to the maximum transmission unit (MTU) for the network.
摘要:
Systems and methods are disclosed that allow for improved management and control of packet forwarding in network systems. Network devices and tool optimizers and a related systems and methods are disclosed for improved packet forwarding between input ports and output ports. The input ports and output ports are configured to be connected to source devices and destination devices, for example, network sources and destination tools in a network monitoring environment. The network devices and tool optimizers disclosed can use superset packet forwarding, such that ingress filter engines are configured with ingress filter rules so as to forward a superset of packets to output ports associated with overlapping filters. Egress filter engines are configured with egress filter rules to then determine which of the superset packets are actually sent out the output ports.
摘要:
Encoded blocks of video information are selected for transmission at a plurality of channel rates based on the corresponding location of the portions of the video image represented by the encoded blocks. Each encoded block is designated an image type which determines its transmitted channel rate. The image types are associated with spatial positions of a video image such that encoded blocks within a first area of the video image are designated a first image type and encoded blocks within a second area of the image are designated a second image type. In general, data blocks representing the central portion of the video image are transmitted at a channel rate having less susceptibility to noise or other degradation, thereby ensuring that such portion can be received in fringe areas.
摘要:
Systems and methods are disclosed that allow for improved management and control of packet forwarding in network systems. Network devices and tool optimizers and a related systems and methods are disclosed for improved packet forwarding between input ports and output ports. The input ports and output ports are configured to be connected to source devices and destination devices, for example, network sources and destination tools in a network monitoring environment. The network devices and tool optimizers disclosed can use superset packet forwarding, such that ingress filter engines are configured with ingress filter rules so as to forward a superset of packets to output ports associated with overlapping filters. Egress filter engines are configured with egress filter rules to then determine which of the superset packets are actually sent out the output ports.
摘要:
Systems and methods are disclosed for precise event time measurement using high-speed deserializer circuitry. The described embodiments utilize high speed deserializer circuitry to achieve a precision based upon a bit period associated with the operation of the high speed operation of the deserializer circuitry rather than upon slower speed clock periods associated with reference clock signals. In certain embodiments, the disclosed systems and methods receive an event occurrence signal and use deserializer circuitry to sample the event occurrence signal and to produce multi-bit parallel data representing the event occurrence signal. Precise timestamps can then be generated based upon the multi-bit parallel data. Advantageously, the precision of these time measurements is associated with the bit period of the high speed operation of the deserializer circuitry and are not limited to lower speeds at which other circuitry within the system may be operating, for example, based upon a slower reference clock signal.
摘要:
Systems and methods are disclosed for precise event time measurement using high-speed deserializer circuitry. The described embodiments utilize high speed deserializer circuitry to achieve a precision based upon a bit period associated with the operation of the high speed operation of the deserializer circuitry rather than upon slower speed clock periods associated with reference clock signals. In certain embodiments, the disclosed systems and methods receive an event occurrence signal and use deserializer circuitry to sample the event occurrence signal and to produce multi-bit parallel data representing the event occurrence signal. Precise timestamps can then be generated based upon the multi-bit parallel data. Advantageously, the precision of these time measurements is associated with the bit period of the high speed operation of the deserializer circuitry and are not limited to lower speeds at which other circuitry within the system may be operating, for example, based upon a slower reference clock signal.
摘要:
Systems and methods are disclosed for playback of detected timing events with detected phase variations. Disclosed signal generation embodiments can be used to generate digital signals having desired phase variation. Disclosed event detection circuitry can be used to generate event timing data representing one or more phase variations in detected events. The disclosed signal generation embodiments can utilize the event timing data to playback detect events along with the measured phase variations. Further, the signal generation circuitry and the event detection circuitry can be implemented in different devices or can be implemented in the same device.