Cisco UBR904 Troubleshooting Guide - Page 2

Feature Summary • The progression of normal data-over-cable communication events is clearly explained, simplifying the resolution of faulty system connections. • A cable technician can remotely telnet into a Cisco uBR904 cable modem, which could be installed in a customer's home, and perform simple diagnostic tasks. List of Terms CATV-Originally stood for Community Antenna Television. Now refers to any coaxial or fiber cable-based system that provides television services. Cable modem (CM)-Any device that modulates and demodulates digital data onto a CATV plant. Cable router-A modular chassis-based router optimized for data-over-CATV hybrid fiber-coaxial (HFC) applications. Channel-A specific frequency allocation and bandwidth. Downstream channels used for television in the United States are 6 MHz wide. CM-Cable modem. CMTS-Cable Modem Termination System. Any DOCSIS-compliant headend cable router, such as the Cisco uBR7246. DHCP-Dynamic Host Configuration Protocol. This protocol provides a mechanism for allocating IP addresses dynamically so that addresses can be reused when hosts no longer need them. DOCSIS-Data Over Cable Service Interface Specification. Defines technical specifications for equipment at both subscriber locations and cable operators' headends. Downstream-The set of frequencies used to send data from a headend to a subscriber. Headend-Central distribution point for a CATV system. Video signals are received here from satellite (either co-located or remote), frequency converted to the appropriate channels, combined with locally originated signals, and rebroadcast onto the HFC plant. For a CATV data system, the headend is the typical place to create a link between the HFC system and any external data networks. HFC-Hybrid fiber-coaxial (cable network). Older CATV systems were provisioned using only coaxial cable. Modern systems use fiber transport from the headend to an optical node located in the neighborhood to reduce system noise. Coaxial cable runs from the node to the subscriber. The fiber plant is generally a star configuration with all optical node fibers terminating at a headend. The coaxial cable part of the system is generally a trunk-and-branch configuration. Host-Any end-user computer system that connects to a network. In this document, the term host refers to the computer system connected to the LAN interface of the cable modem. MAC layer-Media Access Control sublayer. Controls access by the cable modem to the CMTS and to the upstream data slots. MCNS-Multimedia Cable Network System Partners Ltd. A consortium of cable companies providing service to the majority of homes in the United States and Canada. This consortium has decided to drive a standard with the goal of having interoperable cable modems. MSO-Multiple Service Operator. A cable service provider that also provides other services such as data and/or voice telephony. QAM-Quadrature Amplitude Modulation. A method of modulating digital signals onto a radio-frequency carrier signal involving both amplitude and phase coding. QAM is a modulation scheme mostly used in the downstream direction (QAM-64, QAM-256). QAM-16 is expected to be 2 Cisco IOS Release 12.0(3)T