Linksys WCM300 Cisco Cable Wideband Solution Design and Implementation Guide, - Page 56

Wideband Cable Modem Behavior Chapter 4 Implementing and Configuring the Solution The bonded channel enable option allows the provisioning system to require that a wideband cable modem operate in traditional DOCSIS 2.0 mode. When the bonded channel enable option has a value of 0 (disable), the CMTS ensures that a wideband-channel interface is not assigned to the wideband cable modem at registration time. Only a single occurrence of the bonded channel enable option may be specified in the DOCSIS configuration file. Secondary Bonding Group ID The secondary bonding group ID option is encoded as sub-type 16. • Type.Subtype: 43.16 • Length: 2 • Value: secondary bonding group ID The secondary bonding group ID option allows the provisioning system to specify secondary bonded downstream channels for the wideband cable modem to use. The modem can use one or two secondary bonded channels for multicast traffic. If the configured secondary bonding group ID is not valid, the CMTS causes the wideband cable modem to fail registration Up to two secondary bonding group IDs can be specified in the DOCSIS configuration file. The total of the RF channels in the primary and secondary bonded channels must comply with the 50 MHz capture-window limitation of the Linksys WCM300 modem. Note If a wideband channel is specified as a secondary bonded channel in the DOCSIS configuration file, the channel must be identically specified as a secondary bonded channel in the CMTS active, running configuration file. The cable bonding-group-id command specifies whether a bonding group is a primary or secondary bonding group. For information on this command, see the Cisco uBR10012 Universal Broadband Router SIP and SPA Software Configuration Guide. Scientific Atlanta DPC2505 and EPC2505 Modems The Scientific Atlanta DPC2505 and EPC2505 wideband cable modem makes use of Broadcom Corporation's BCM93381 cable modem chip. The BCM93381 chip provides three tuners, allowing the three downstream receivers to be independently tuned to any frequency. The M-CMTS and the DPC2505 wideband cable modem use these three channels as follows: • It uses one of these downstream RF channels as its primary downstream channel for MAC management and signalling messages. • It uses the other two downstream RF channels as non-primary downstream channels. These two RF channels can be bonded together to form one wideband channel. The DPC2505/EPC2505 wideband cable modem uses a selected subset of the DOCSIS 3.0 protocol for channel bonding. Channel bonding is the transmission of a stream of packets across multiple RF channels with the use of sequence numbers to ensure the modem receiver delivers packets in the proper order to the CPE. The DPC2505/EPC2505 wideband cable modem filters packets on a Destination Address and Security Association Identifier (SAID). The DPC2505/EPC2505 modem supports up to 16 independent re-sequencing contexts. The DPC2505/EPC2505 wideband cable modem does not support multicast traffic on the wideband channel. Multicast service flows that the modem sees on the bonded downstream channel are discarded. Cisco Cable Wideband Solution Design and Implementation Guide, Release 1.0 4-8 OL-10705-02