Cisco Technology, Inc.

Daniel W Crocker

John T Chapman

Feisal Y Daruwalla

Yong Lu

Joanna Qun Zang

Alon Shlomo Bernstein

Michael J Healy

Daniel Yu Kwong Ng

Bruce Y Chen

Pawel Piotr Sowinski

David B Fox

Eric Youngman

An M-CMTS compatible UEQAM device implements circuitry to identify and analyze MAP message in the data stream sent from the M-CMTS Core with respect to timing information embedded in those messages. The improved UEQAM will then create a specific message as an extension to DEPI to communicate that information to the M-CMTS Core. The M-CMTS Core will employ that analysis to automatically adjust MAP message advance time to reduce delay and thus improve system performance. This invention will provide a closed-loop between the M-CMTS Core and the UEQAM where valuable transmission information will periodically be fed back from UEQAM-to-M-CMTS Core in real-time.

Map message expediency monitoring and automatic delay adjustments in M-CMTS

According to specific embodiments of the present invention, a standardized interface is provided for enabling controlled communication between MAC and PHY devices of an access network. In one embodiment, a vendor independent interface is described which may be implemented between a DOCSIS MAC layer and a DOCSIS PHY layer of a DOCSIS enabled data network, in order to enable any DOCSIS MAC and DOCSIS PHY devices (which may be from different vendors) to communicate with each other. Using the standardized interface, component manufacturers are able to combine different MAC and PHY devices from different vendors, thereby facilitating price and value competition between vendors. The standardized interface technique of the present invention may be extensible in ways which allow multiple PHY devices to share the same interface. Further, the interface technique of the present invention may be applied to a variety of different shared-access networks which use at least one shared access communication channel to communicate between a plurality of nodes in the network and a Head End of the network.

Technique for interfacing MAC and physical layers of access networks

A modular Cable Modem Termination System (CMTS) includes a packet shelf operating a Data Over Cable Service Interface Specifications (DOCSIS) Media Access Control (MAC) framer. One or more downstream Physical Interface (PHY) shelves receive DOCSIS data from the packet shelf over a packet switched network and modulate the DOCSIS data for sending on a downstream path of a cable plant. One or more upstream PHY shelves send DOCSIS data received from an upstream path of the cable plant over the packet switched network to the packet shelf. By separating the PHY components from the MAC and from the system software, the PHY components for a Hybrid Fiber Coax (HFC) plant may be replaced with different PHY components for other access technologies such as wireless, Digital Subscriber Lines (DSL), Ethernet-to-the-Home, Fiber-to-the-Home, or fiber Passive Optical Networks (PONs).

Downstream remote physical interface for modular cable modem termination system

A dynamic channel change technique is disclosed which may be implemented between nodes and a Head End of an access network. Initially a network device may communicate with the Head End via a first downstream channel and a first upstream channel. When the network device receives a dynamic channel change request which includes instructions for the network device to switch to a second downstream channel, the network device may respond by switching from the first downstream channel to the second downstream channel. Thereafter, the network device may communicate with the Head End via the second downstream channel and first upstream channel. Further, according to a specific embodiment, the dynamic channel change request may also include an upstream channel change request for causing the network device to switch from a first upstream channel to a second upstream channel.

Downstream channel change technique implemented in an access network

Upstream physical interface for modular cable modem termination system

A master clock reference signal may be provided to selected packet fiber nodes in order to synchronize the local clock reference signals generated at selected devices in a cable network. In this way, selected portions of the cable network may be synchronized to a common timing reference signal. Additionally, synchronized timestamp information may also be provided to selected network devices in order to achieve synchronization of timestamps across a selected portion of the cable network.

Technique for synchronizing network devices in an access data network

A technique is described which may be used to synchronize a plurality of different access controllers which control a plurality of distinct ports at the Head End of an access network. In the context of a cable network, the technique of the present invention may be used to synchronize desired upstream and/or downstream channels across different line cards within a Cable Modem Termination System (CMTS). The technique involves utilizing a master time reference device which maintains and updates a current time reference, and periodically distributes synchronization signals to desired line cards in the system in order to synchronize these line cards. In a specific embodiment, the synchronization signals include current timestamp data generated from the master time reference device and distributed to all (or selected) line cards in the system. A slave time reference device on each of the line cards receives the periodic synchronization updates and uses the synchronization data to remain synchronized with the master time reference device. There are also provisions in this protocol to allow for hot insertion and removal of line cards, software reset or loading of the master and/or slave time reference devices, and redundant master time reference devices, including master time reference device fault detection and automatic fail over.

Technique for synchronizing multiple access controllers at the head end of an access network

A data exchange system includes at least one transmitting agent, at least one receiving agent, and a plurality of data links each having a crossbar coupling respective transmitting agents and receiving agents. A stream of data packets including at least one Order Critical Flow of data packets having a critical order to be sent from the transmitting agent to the receiving agent is divided for transmission among the plurality of data links. Multiple Order Critical Flows between the transmitting agent and the receiving agent are possible and the packets within such Order Critical Flows can be intermixed for transmission (along with packets from other Non-Order Critical Flows).

Apparatus and method for manipulating packet ordering over parallel links of a crossbar based switch fabric

A synchronizer circuit manages signals in different clock domains by generating clock pulses synchronized with a system clock. The clock pulses are generated at a rate proportional to the frequency of a clock operating in a first clock domain. Digital circuitry is then driven at the frequency of the first clock and in the time domain of the system clock. A hand-shaking protocol prevents the synchronizer circuit from going into a metastable condition when passing clock or data signals into different time domains. A programmable digital filter includes multiple sampling stages that sample an input signal. A detection circuit has inputs coupled to the outputs of the multiple sampling stages and changes the logic state of an output signal when no glitches are detected in the samples of the input signal. A control circuit selectively varies a time period used by the filter for sampling the input signal.

System for managing signals in different clock domains and a programmable digital filter

A data exchange system includes at least one transmitting agent, at least one receiving agent, and a plurality of data links each having a crossbar coupling respective transmitting agents and receiving agents. A stream of data packets including at least one Order Critical Flow of data packets having a critical order to be sent from the transmitting agent to the receiving agent is divided for transmission among the plurality of data links. Multiple Order Critical Flows between the transmitting agent and the receiving agent are possible and the packets within such Order Critical Flows can be intermixed for transmission (along with packets from other Non-Order Critical Flows). The packets are transmitted over the data links so that packets from the same Order Critical Flow are transmitted over the same data link (while packets from that Order Critical Flow are in the Transmit Link Queue) and the packets are sequentially numbered, based upon the time when the packet was first received (and not the link over which the packet was received) upon the beginning of receipt by the receiving agent and reassembled by the receiving agent into a stream of data packets in accordance with the numbering sequence, thus maintaining the order of all Order Critical Flows.

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San Jose, CA, United States of America

Daniel W Crocker