Linksys WCM300 Cisco Cable Wideband Solution Design and Implementation Guide, - Page 41

Chapter 3 Cisco Cable Wideband Architecture Wideband Channel Bonding The Cisco Wideband SPA on the uBR10012 router provides the logical RF channels for the DOCSIS 3.0 Downstream Channel Bonding feature. The service provider uses a customized set of Cisco IOS commands to configure the Wideband SPA for each wideband channel and its associated DOCSIS 2.0 downstream and upstream channels. Software Configuration for Fiber Nodes In a cable network, a fiber node is a point of interface between a fiber trunk and the coaxial distribution. A cable modem is physically connected to only one fiber node. Fiber node software configuration mirrors the physical topology of the cable network. When configuring fiber nodes with Cisco IOS CLI commands, a fiber node is a software mechanism to define the following: • The set of downstream RF channels that will flow into the fiber node • At least one primary downstream channel (traditional DOCSIS downstream channel) for the fiber node • The set of upstream channel ports on the cable interface line card that are connected to the fiber node and available as upstream channels The DOCSIS 3.0 Downstream Channel Bonding feature requires that a fiber node be associated with at least one primary downstream channel (traditional DOCSIS downstream channel). A fiber node can be associated with more than one primary downstream channel though only one primary downstream channel is used at any given point in time. On the uBR10-MC5X20 cable interface card, each primary downstream channel has an upstream port that is statically associated with the downstream port. For information on configuring fiber nodes, see the Cisco uBR10012 Universal Broadband Router SIP and SPA Software Configuration Guide. Virtual Interface Bundling for Primary Downstream Channels and Wideband Channels The Cisco IOS virtual interface bundling feature is used for the wideband channel and the primary downstream channels. Both the wideband channel and primary downstream channel must be members of the same virtual bundle. Virtual interface bundling prevents loss of connectivity on physical interfaces should there be a failure or problematic insertion and removal (OIR) of one line card in the bundle. The DOCSIS 3.0 Downstream Channel Bonding feature allows the following scenarios for wideband channel to primary downstream channel association on a fiber node: 1. WCMs on one wideband channel use the same primary downstream channel. 2. WCMs on one wideband channel use different primary downstream channels. 3. WCMs on different wideband channels use the same primary downstream channel. 4. Combinations of scenarios 2 and 3. Figure 3-2 provides an example of wideband channel to primary downstream channel association on a fiber node. • Wideband channel WB1 is associated with primary downstream channels PDC1 and PDC2. • Wideband channel WB2 is associated with only primary downstream channel PDC1. OL-10705-02 Cisco Cable Wideband Solution Design and Implementation Guide, Release 1.0 3-3