Patent ID: 7539209

Claim:
A method of preserving data link layer pacing information across a synchronous transport medium comprising: (a) receiving serial data at a deserializer from a client in a first protocol format at a first rate, wherein said first protocol format is SBCON; (b) recovering a clock signal from said received serial data; (c) converting said received serial data to parallel data and inputting said parallel data to a FIFO queue; (d) detecting the end of a preceding client frame at a receive controller and clearing an inter-frame time counter having an associated count, wherein said detecting comprises detecting an end of frame delimiter in said preceding client frame, and wherein said clearing is responsive to detecting said end of frame delimiter; (e) incrementing said inter-frame time counter until the start of a current client frame is received; (f) detecting the start of said current client frame; (g) inserting in the current client frame a start of frame delimiter followed by the associated count of said incremented inter-frame time counter, wherein said associated count of said incremented inter-frame time counter comprises a variable indication of time between when a start of said current client frame and an end of said preceding client frame were received; (h) adjusting said inter-frame counter responsive to synchronization between a reference clock at a client receiver and a reference clock at a client transmitter; (i) inserting said end of frame delimiter when the end of said current frame is detected, wherein said end of frame delimiter signals a frame boundary of said current frame across said synchronous transport medium, and wherein said end of frame delimiter is utilized to reset said inter-frame counter; (j) extracting said current client frame from said receive buffer to a mapper; and (k) synchronously mapping said current client frame into a synchronous protocol format associated with said synchronous transport medium, and serializing said mapped frame for transmission across said synchronous transport medium at a second data rate, wherein said synchronous transport medium is a SONET network, wherein said first client frame is encoded following extraction to maintain character synchronization, and wherein a rate of said first protocol format is one of greater and lesser than a rate of said synchronous transport medium.