Other

Cisco Technology, Inc.

Achot Matevossian

Michael J Healy

Christopher J Kappler

Gregory S Goss

David Bryan Fox

Carl R Walker

Scott Smith

Methods and devices are provided for allowing upstream and downstream cable modem termination systems to be located in different physical locations. According to some embodiments of the invention, a downstream CMTS is located at a head end of a cable network and an upstream CMTS is located in each of a plurality of hubs in a cable network. Such a configuration provides more flexibility than prior art systems, especially when much of the traffic passing through the downstream CMTS is broadcast traffic, such as IP video, that will be passed to multiple hubs. Such configurations are more economical because they do not require every hub to have its own downstream CMTS. In preferred embodiments, the upstream and downstream functions are synchronized using a Global Positioning System ('GPS') reference source.

Synchronizing separated upstream and downstream channels of cable modem termination systems

One or more queues store data information such as packets or data flows for later transmission to downstream communication devices. A real-time clock tracks current time and an advancement of a moving time reference, which is displaced with respect to the current time of the clock by an offset value. Thus, as current time advances, the moving time reference also advances in time. Upon servicing a queue, a time stamp associated with the serviced queue is also advanced in time. To monitor a rate of outputting data from the one or more queues, a processor device at least occasionally adjusts the offset value so that the moving time reference and values of the time stamps advance in relation to each other. Consequently, by tracking a relative time difference between current time of the real-time clock and a relative advancement of time stamps, a rate of outputting data information from the queue is monitored over time.

Methods and apparatus for maintaining queues

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Chelmsford, MA, United States of America

Achot Matevossian