摘要:
Disclosed is an Active Queue Management method and apparatus which uses traffic rate information for congestion control. Using a nonlinear fluid-flow model of Traffic Control Protocol, an integral controller in a closed loop configuration with gain settings characterized for stable operation allows a matching of the aggregate rate of the active TCP connections to the available capacity. Further disclosed is a method for calculation of the regime of gains for which stable operation of a given network obtains. This approach allows for capacity matching while maintaining minimal queue size and high link utilization.
摘要:
Network elements may be synchronized over an asynchronous network by implementing a master clock as an all digital PLL that includes a Digitally Controlled Frequency Selector (DCFS), the output frequency of which may be directly controlled through the input of a control word. The PLL causes the control word input to the master DCFS to be adjusted to cause the output of the master DCFS to lock onto a reference frequency. Information associated with the control word is transmitted from the master clock to the slave clocks which are also implemented as DCFSs. By using the transmitted information to recreate the master control word, the slaves may be made to assume the same state as the master DCFS without requiring the slaves to be implemented as PLLs. The DCFS may be formed as a digitally controlled oscillator (DCO) or as a Direct Digital Synthesizer (DDS).
摘要:
A system in which data signatures are used to identify copyrighted content passing through a network. The data signatures are derived from files containing copyrighted content to be identified. The signatures are used to search within peer-to-peer data streams flowing through one or more network nodes in a communications network. Any specific technique may be used for pattern recognition between the signatures and the monitored traffic. When a particular file of interest is identified, the system may operate to perform one or more of several possible actions, including stopping the transmission, allowing the transmission but recording the event, making an offer to the recipient allowing them to legally purchase the file, or sending alternative information or intentionally corrupting the information to render it useless to the recipient.
摘要:
Disclosed is an Active Queue Management method and apparatus which uses traffic rate information for congestion control. Using a nonlinear fluid-flow model of Traffic Control Protocol, a proportional-integral controller in a closed loop configuration with gain settings characterized for stable operation allows a matching of the aggregate rate of the active TCP connections to the available capacity. Further disclosed is a method for calculation of the regime of gain settings for which stable operation of a given network obtains. This approach allows for capacity matching while maintaining minimal queue size and high link utilization.
摘要:
A method for dynamically adjusting jitter buffer size according to buffer fill dynamics is disclosed. In one embodiment, an upper threshold and lower threshold for the jitter buffer are identified, wherein the lower buffer threshold identifies a minimum desirable number of packets in the jitter buffer, and the upper buffer threshold identifies a maximum desirable number of packets in the jitter buffer. Operating characteristics of the jitter buffer are monitored to identify instances when the jitter buffer size falls below or exceeds the desired thresholds. When a threshold is crossed, the adaptive algorithm alters the playback offset time, by introducing or deleting packets into the transmission path, to allow the jitter buffer size to return to a desirable target size within the threshold boundaries.
摘要:
Disclosed is a rate-based multi-level Active Queue Management with drop precedence differentiation method and apparatus which uses traffic rate information for congestion control. Using a nonlinear fluid-flow model of Traffic Control Protocol, an integral controller in a closed-loop configuration with gain settings characterized for stable operation allows a matching of the aggregate rate of the active TCP connections to the available capacity. Further disclosed is a method for calculation of the regime of gains over which stable operation of a given network obtains. An enhancement of the basic algorithm provides the ability to drop low-precedence packets in preference to higher precedence packets. This approach allows for a rate-based AQM approach for application in a differentiated service environment.
摘要:
The invention includes a technique for clock recovery in a network having master and slave clocks in respective Time Division Multiplexing (“TDM”) network segments which are interconnected by a non-TDM segment. Master clock timestamps are sent to the slave. The slave measures a master clock timestamp inter-arrival interval, and sends slave clock timestamps to the master. The master measures a slave clock timestamp inter-arrival interval, and sends that slave clock timestamp inter-arrival interval to the slave. The slave then calculates an error signal based at least in-part on the difference between the master clock timestamp inter-arrival interval and the slave clock timestamp inter-arrival interval, and employs the difference to recover the first service clock in the second TDM segment.
摘要:
Where a common network clock is available at both a TDM receiver and a TDM transmitter which communicate via a packet network, differential clock recovery can be accomplished by matching the number of service clock pulses in a network reference clock period at the transmitter and receiver. In one embodiment the transmitter need only send a counter value from a counter that is clocked and reset, respectively, by the service clock and network reference clock, thereby allowing use of different types of oscillators, both analog and digital, to be implemented at the transmitter and receiver. The technique is also general enough to be applied in a wide variety of packet networks including but not limited to IP, MPLS and Ethernet. In an alternative embodiment, a faster derived network clock fdnc drives both the transmitter and receiver counters, which in turn are reset, respectively by the slower transmitter service clock fsc and slower receiver service clock frc.
摘要:
A method and apparatus for designing a PLL enables initial component characteristics and design specifications of the PLL to be specified. Time constants for a loop filter that would be required to create a PLL having the desired design specifications and component characteristics are then computed. The performance or behavior characteristics of the PLL may then be computed for the PLL given the time constants and the initial set of components, to determine whether the performance of the PLL would be considered satisfactory. For example, PLL design software may determine whether a PLL would be sufficiently stable if it was to be created using the particular selected components given the required design specifications. Where the PLL does not meet particular behavior characteristics, the PLL design software may provide guidance as to what component characteristics would improve performance of the PLL. Designed PLLs may be used for timestamp based clock synchronization.
摘要:
A first level of control over operation of slave Digitally Controlled Frequency Selectors (DCFSs), such as DCOs or DDSs, may occur by periodic transmission of control words from the master clock to the slave clocks. To allow enhanced control over the output of the slave clocks, the frequency of the local oscillator used to generate the synthesized output of the master clock may also be conveyed to the slave clocks to allow a second level of control to take place. The second level of control allows the local oscillators at the slave clocks to lock onto the frequency of the master local oscillator to thereby allow the slave local oscillators to operate the slave DCFSs using the same local oscillator frequency. The first level of control synchronizes operation of the DCFSs while the second level control prevents instabilities in the local oscillators from causing long term drift between the slave and master clock outputs. Timestamps may be used to synchronize the master and slave local oscillators.