Conceptually, this is similar to other
bonding schemes (e.g., 802.3ad Ethernet Link Aggregation or RFC 1990 Multilink PPP);
however, because the DOCSIS link is a shared medium (one-to-many downstream and
many-to-one upstream) rather than a point-to-point link, the similarity ends there.
The DOCSIS 3.0 MAC layer has been enhanced to allow coordination of access to this
multichannel link in an efficient, flexible, and scalable manner.
Economic Assessment
The incremental capital costs to provide broadband data service over an existing twoway
HFC plant are fairly low. For a moderately sized cable system, the CMTS cost for
a typical MAC domain (one downstream channel and four upstream channels) capable
of serving four service groups (up to 500??“600 residential customers at a data rate of
5 Mbps downstream and 1 Mbps upstream) in the typical deployment discussed in
???Typical Deployment Scenarios??? would be in the range of $30,000. That averages out to
be $50??“$60 per subscriber. Add to that approximately $50 per subscriber for a current
DOCSIS 2.0 cable modem, and the result is a total capital cost on the order of $100 per
subscriber for the two ends of the data connection.
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