Methods and apparatus for minimizing wander generation in constant bit rate asynchronously mapped digital transport systems

摘要

A client receive circuit receives client data from a network, decodes the client data and stores the client data within the memory. A frame transmit circuit is provided that includes a justification control logic and a framer and a justification control logic is provided that 1) determines each of a plurality of fill levels and 2) determines an average of the plurality of fill levels. The framer has circuitry to generate a wrapper including a justification opportunity having data based upon a difference between the average and a predetermined threshold.

主权项

1. A method, comprising:
passing client data through a memory of a network node of a network, the memory including a first-in-first-out memory; determining each of a plurality of fill levels, each of the plurality of fill levels being associated with an amount of the client data in the memory at each of a corresponding one of a plurality of instants in time; determining an average of the plurality of fill levels, wherein Average Fill Level(t) is the average of the plurality of fill levels at one of the plurality of instants in time (t), Average Fill Level(t) satisfies:
Average Fill Level(t)={FIFO(t)+FIFO(t−1)+ . . . FIFO(t−N)}/N, where N is a number of the plurality of fill levels, and each of FIFO(t), FIFO(t−1) . . . FIFO(t−N) is a respective one of the plurality of fill levels;
generating a wrapper including at least one portion of the client data, the wrapper including a justification opportunity, such that when the average of the plurality of fill levels is below a predetermined threshold, the justification opportunity is stuffed with null data, and when the average of the plurality of fill levels is above the predetermined threshold; a portion of the client data is placed in the justification opportunity; and transmitting the wrapper onto the network.