Cisco Technology, Inc.

Yong Lu

Feisal Y Daruwalla

Joanna Qun Zang

John T Chapman

Daniel W Crocker

Guenter E Roeck

James R Forster

Jin Zhang

Sunil Khaunte

Xuan Wang

Jie Meng

De Fu Li

Kartik S Chandran

Jingfeng Zhang

Wenwen Dong

One embodiment of the invention includes a coax media converter (CMC) system communicatively coupled to at least one modem in a network system. The system includes a frequency reference configured to generate a clock signal in a local time domain. The system also includes a scheduling processor configured to extract a bandwidth allocation message from a data stream and to re-stamp each of at least one timestamp in the bandwidth allocation message in the local time domain based on the clock signal to generate a corresponding updated bandwidth allocation message comprising a respective at least one re-stamped timestamp. The system further includes a downstream physical interface configured to transmit the updated bandwidth allocation message to the at least one modem to schedule upstream burst transmissions from the respective at least modem based on the at least one re-stamped timestamp.

Network system time domain re-stamping

A protection CMTS is available to immediately service a cable modem should that modem's service from a working CMTS fail for any reason. To speed the service transfer (cutover) from the working CMTS to the protection CMTS, the cable modem may preregister with the protection CMTS well before the cutover becomes necessary. The cable modem's registration with both the working CMTS and the protection CMTS preferably employs a single IP address, so that the cable modem need not obtain a new IP address during cutover. While the cable modem may register with both the working CMTS and the protection CMTS, the devices are designed or configured so that only the working CMTS injects a host route for the cable modem into the appropriate routing protocol. Only after cutover to the protection CMTS does the protection CMTS inject its host route.

Method for a cable modem to rapidly switch to a backup CMTS

Disclosed are methods and apparatus for guaranteeing restoration of traffic between one or more cable modems and a backup cable modem termination system upon failure of an active cable modem termination system are disclosed. Subscriber information associated with one or more cable modems are received from an active cable modem termination system. The subscriber information includes one or more subscriber identifiers. For instance, the subscriber information may include a primary subscriber identifier that identifies a particular cable modem as well as a secondary subscriber identifier that is assigned to high priority traffic such as that being transmitted in real-time. In addition, the subscriber information may also include a scheduling type that is further used to categorize the real-time traffic, such as into voice or video traffic. The subscriber information is then prioritized in an order in which the transmission of messages between the one or more cable modems and the backup cable modem are to be restored. For instance, the subscriber information may be prioritized according to time of receipt of the subscriber information, presence of secondary subscriber identifier, and/or scheduling type. The cable modems are then polled according to this priority order.

Apparatus and method for restoring traffic during failover in a cable head end

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

Growing community of inventors

San Jose, CA, United States of America

Yong Lu