Abstract: A method is disclosed for controlling the flow of packets aggregated from multiple logical ports over a transport link. A directed flow control indicator is provided to the transmitting end station that causes a detected congestion condition. The directed flow control indicator causes the transmitting end station to suspend the transmission of further packets. The linear expansion header of the Generic Framing Procedure (GFP) linear mapping scheme is extended to include the flow control indicator, such as a bit indicating a potential overload condition. A directed flow control indication can be provided in one or more packets sent to the transmitting end station over the transport network without increasing the network overhead. If packets are not being sent to the appropriate transmitting end station, a packet generator can generate one or more packets with the flow control indicator to inform the appropriate transmitting end station of the congestion condition.

Abstract: A method and apparatus are disclosed for compensating for a frequency offset between an ingress local area network and an egress local area network that communicate over a transport network. The bandwidth of an egress port is adjusted by varying an inter-packet gap size between each packet so that the packets can be delivered without overflowing an egress buffer. The size of the inter-packet gap is reduced when the frequency of the ingress local area network is greater than the frequency of the egress local area network. The size of the inter-packet gap is increased when the frequency of the ingress local area network is less than the frequency of the egress local area network. The size of the egress inter-packet gap may be statically or dynamically adjusted to compensate for a frequency offset.

Abstract: Methods and apparatus are provided for improving the jitter tolerance in an SFP limit amplified signal. Jitter tolerance is improved in a communications receiver by applying a received signal to an SFP limiting amplifier; and applying an output of the SFP limiting amplifier to a low pass filter to improve the jitter tolerance. The low pass filter optionally applies a programmable amount of attenuation to high frequency components of the output. The low pass filter slew rate controls (i.e., rotates) a data eye representation of the received signal to increase the data eye representation along a time axis. The noise margin of the received signal can optionally be improved by applying an output of the low pass filter to an all pass filter. A slew rate controller can evaluate the data eye statistics to determine a setting for the low pass filter.

Abstract: One embodiment of the present invention processes a signal of interest through an optional reference channel, combines the resulting signal with white noise, and then processes the noisy signal through a reference receiver. Two metrics are calculated from the results of that processing: Non-Compensable Data-Dependent Jitter (NC-DDJ) and Enhanced Transmitter and Waveform Dispersion Penalty (Enhanced TWDP). Within the reference receiver, a variable delay module sweeps the eye opening defined by the noise-free samples of the signal of interest and determines the transition points (i.e., edges) of the eye opening. Those transition points are compared to the Unit Interval to yield NC-DDJ. Further, the signal-to-noise ratio (SNR) of the noisy samples of the signal of interest is compared to the SNR of an ideal receiver (i.e., matched filter) driven by an ideal transmitter via an ideal channel with additive white Gaussian noise n(t) to yield Enhanced TWDP.

Abstract: A method is disclosed for controlling the flow of packets aggregated from multiple logical ports over a transport link. A directed flow control indicator is provided to the transmitting end station that causes a detected congestion condition. The directed flow control indicator causes the transmitting end station to suspend the transmission of further packets. The linear expansion header of the Generic Framing Procedure (GFP) linear mapping scheme is extended to include the flow control indicator, such as a bit that is set to a predefined binary value to indicate a potential overload condition. A directed flow control indication can be provided in one or more packets that are sent to the transmitting end station over the transport network without increasing the network overhead.

Abstract: Operation of an adaptive filter includes determining a first filter coefficient and determining a second filter coefficient based on the first filter coefficient, in one embodiment, and in another embodiment includes comparing pseudo-error counts generated for each of several time intervals and setting filter coefficients based on the comparison. Adaptive filter coefficient generating apparatus includes a pseudo-error count generator adapted to receive the output of the adaptive filter and to generate counts of pseudo-errors occurring during successive time intervals, and a filter coefficient generator generating filter coefficients for the adaptive filter in response to the pseudo-error counts.

Abstract: A method is disclosed for controlling the flow of packets aggregated from multiple logical ports over a transport link. A directed flow control indicator is provided to the transmitting end station that causes a detected congestion condition. The directed flow control indicator causes the transmitting end station to suspend the transmission of further packets. The linear expansion header of the Generic Framing Procedure (GFP) linear mapping scheme is extended to include the flow control indicator, such as a bit that is set to a predefined binary value to indicate a potential overload condition. A directed flow control indication can be provided in one or more packets that are sent to the transmitting end station over the transport network without increasing the network overhead.

Abstract: Operation of an adaptive filter includes determining a first filter coefficient and determining a second filter coefficient based on the first filter coefficient, in one embodiment, and in another embodiment includes comparing pseudo-error counts generated for each of several time intervals and setting filter coefficients based on the comparison. Adaptive filter coefficient generating apparatus includes a pseudo-error count generator adapted to receive the output of the adaptive filter and to generate counts of pseudo-errors occurring during successive time intervals, and a filter coefficient generator generating filter coefficients for the adaptive filter in response to the pseudo-error counts.