Cisco Technology, Inc.

Feisal Y Daruwalla

James R Forster

Joanna Qun Zang

John T Chapman

Hon Wah Chin

Guenter E Roeck

Yong Lu

David J Tsiang

George Suwala

Tony Bates

Daniel W Crocker

Michael R Thomas

Richard Woundy

Mark W Litwack

Mark E Millet

Richard Meller

Nicos Achilleoudis

Roland G Chan

John K Chen

Joseph O'Donnell

Ishita Sharan

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

A technique is provided for managing VPN packet flows over shared access data networks. Each node in the shared access network typically has an identifier or ID associated with it which is used at a Head End of the shared access network to uniquely identify that particular node from the other nodes in the network. According to the technique of the present invention, the node ID may be used at the Head End of the network to identify not only the corresponding node, but also to identify any virtual private networks (VPNs) of which the corresponding node is a member. Using the technique of the present invention, nodes which are members of the same VPN within a shared access network may exchange packets in a manner which does not require the packets to be routed outside the shared access network.

Technique and apparatus for using node ID as virtual private network (VPN) identifiers

Routing protocol based redundancy design for shared-access networks

An IP subnet sharing technique is described which allows multiple network devices of an access network to share an IP subnet without the need for each network device to run complex routing protocols, or bridging protocols. Further, the multiple network devices are able to share an IP subnet without the need to subdivide the IP subnet into smaller groups.

IP subnet sharing technique implemented without using bridging or routing protocols

The present disclosure relates an improved cable data switching unit that provides a fail-over system whereby one line card can protect a plurality of US (upstream) or DS (downstream) channel line cards, providing N+1 protection, with one linecard being able to protect N number of working linecards. When a failure is detected in a working linecard, the signals being routed by the failing linecards are re-routed seamlessly to a protect linecard. This disclosure provides for data to be passively routed, providing for data flow even if power is lost.

Method and apparatus for N+1 RF switch with passive working path and active protection path

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

Disclosed are methods and apparatus for selectively filtering data messages that are communicated between a head end complex and its associated cable modems. Filtering includes obtaining a copy of the message and sending the copied message to a memory device. The memory device is accessible, for example, via a user so that the filtered message may be analyzed. In a preferred embodiment, the memory device is a monitoring device in the form of a computer system (e.g., a router). Messages may be filtered to the memory or monitoring device based on any suitable filtering criteria that identifies specific message parameters. In a specific embodiment, filtering may be based on one or more message types. When filtering criteria specifies a particular message type, messages having such a specified type are filtered to the monitoring station. Additionally or alternatively, filtering may be based on one or more values of a particular field of the message. For instance, when filtering criteria is set to a particular field value, messages that contains that particular field value are copied and sent to the monitoring device. Filtering may also or alternatively be based on whether a message is associated with the downstream channel, the upstream channel, or a particular port number.

Apparatus and methods for sniffing data in a cable head end

A CMTS redundancy technique requires at least two CMTS interfaces (e.g., line cards) on one or more CMTS chassis at the head end of a cable network. One of the CMTSs serves as a backup or 'protecting' CMTS. When another CMTS (a 'working' CMTS) becomes unavailable to service its group of cable modems, the protecting CMTS takes over service to those cable modems. The SWITCHOVER takes place transparently (or nearly transparently) to the cable modems. The protecting CMTS provides service on the same downstream channel as used by the working CMTS. The cable modems need not modify any settings pursuant to their cable modem communication protocol (e.g., DOCSIS ranging). This transparency to the cable modems is realized by keeping the working and protecting CMTSs in synchronization regarding service parameters for the cable modems. In other words, the protecting CMTS maintains a list of current parameters for allowing service to the cable modems.

Cable network redundancy architecture

The present invention provides a protection protocol for fault recovery, such as a ring wrap, for a network, such as a two line bi-directional ring network. An embodiment of the present invention works in conjunction with a ring topology network in which a node in the network can identify a problem with a connection between the node and a first neighbor. The present invention provides 1 protection protocol which simplifies the coordination required by the nodes in a ring network. The nodes do not need to maintain a topology map of the ring, identifying and locating each node on the ring, for effective protection. Additionally, independently operating ring networks can be merged and the protection protocol will appropriately remove a protection, such as a ring wrap, to allow the formation of a single ring. It also provides for multiple levels of protection priority so that protection for a high priority failure, such as a physical break in a connection, would remove protection for a low priority failure, such as signal degrade, on another link.

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Fremont, CA, United States of America

Feisal Y Daruwalla