Patent ID: 7539208

Claim:
A modular cable modem termination system (CMTS), comprising: at least one packet shelf operating a data over cable service interface specifications (DOCSIS) media access controller (MAC), wherein the MAC is configured to frame received data with DOCSIS frames and mark the DOCSIS framed data with destination addresses corresponding to downstream cable modems; one or more physical interface (PHY) shelves exchanging communications with the packet shelf over a packet switched network, wherein the one or more PHY shelves are configured to quadrature amplitude modulate the DOCSIS framed data for transmission over RF channels extending from the PHY shelves to the cable modems; wherein the functions of DOCSIS framing the data and conducting the quadrature amplitude modulation are distributed across the packet switched network, and wherein the packet switched network contains packet switching accruements configured to forward individually addressed packets such that different ones of the packets can traverse the packet switched network in different amounts of time; a timing system configured to measure a time delay associated with transporting the packets over the packet switched network between the packet shelf and at least one of the PHY shelves; the timing system configured to identify timestamp values included in the DOCSIS framed data; and the timing system configured to synchronize DOCSIS timing between the packet shelf and the one or more PHY shelves according to the measured time delay, wherein said synchronization includes dynamically adjusting the timestamp values on an individual basis according to the amount of delay experienced during the corresponding DOCSIS frame's traversal of the packet switched network.