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Cable Internet Users: Have You Switched to DOCSIS 3.0?

By Will Greenwald

Just how fast can cable internet really go?

Plenty of new terms have been flying around in the last few years describing advances in broadband technology. FiOS. 802.11n. WiMax. Add to that the continuing marketing war between Verizon, Comcast, and Time Warner Cable and you have a ton of jargon that ignores one of the more important broadband advances of the last half-decade. The Data Over Cable Service Interface Specification, or DOCSIS, is the international standard that governs cable-based broadband services. DOCSIS 1.0 was originally released in 1997, and 2.0 came out four years later in 2001. Currently, DOCSIS 2.0 is the most common standard among cable Internet service providers. DOCSIS 3.0 was released in 2006, and presents many advantages over the current standard. However, the standard is still very "new" in that few cable providers have widely adopted it. Time Warner and Comcast both offer DOCSIS 3.0 services in limited markets, but it is not a broadly available service. 
 

 
higher than 160 Mbps downstream and higher than 120 Mbps upstream bandwidth, a significant jump from  the 38/27 Mbps upstream/downstream bandwidth of DOCSIS 2.0. It accomplishes this through channel bonding, a method of using multiple digital channels together instead of the single channel design of DOCSIS 2.0. A DOCSIS 3.0 network must be able to support at least 4 channels at a time, effectively quadrupling the bandwidth available to a connection.  
 
The new standard also supports IPv6 and IPTV, two rapidly developing Internet services. IPv6 is the Internet Protocol scheduled to eventually replace IPv4 as the address space of the Internet. While IPv4 can support almost 4.3 million addresses, IPv6 can support up to 3.4 x 10^28 (34, followed by 27 zeros). As IPv4 address allocation gets exhausted, IPv6 will offer the necessary room the Internet needs to grow. IPv6 has yet to see broad adoption, but DOCSIS 3.0 means it will be compatible with future cable Internet networks. IPTV is a technology that allows television to be broadcast over the Internet. While it seems counter intuitive for television to go over the Internet, using coaxial cables that were originally laid to transmit television signals, IPTV offers greater interactivity with the television experience than conventional TV, and can be more economical than CATV transmissions. 
 
Time Warner Cable and Comcast have both embraced DOCSIS 3.0 as potential technology, but it's only available in some markets and the speeds offered to consumers fall short of the promised capacity of the standard. Time Warner calls its DOCSIS 3.0 service Wideband Internet, and offers 50 Mbps downstream and 5 Mbps upstream bandwidth to New York residents for a hefty $99 per month. Comcast calls its own DOCSIS 3.0 service Ultra and Extreme 50, with tiered pricing. Ultra service boasts 22 Mbps downstream and 5 Mbps upstream, while Extreme 50 offers 50 Mbps downstream and 10 Mbps upstream.  Neither services come close to the promised 160 Mbps downstream and 120 Mbps upstream bandwidth defined in DOCSIS 3.0.
 
The DOCSIS 3.0 services cost significantly more than the standard DOCSIS 2.0 Internet access most cable providers offer. They also require the lease or purchase of a new, DOCSIS 3.0-compatible cable modem; your current modem won't work with the service, even if it's available in your area (compatible modems sell for around $100 on Amazon). While DOCSIS 3.0 has been around as a technical specification for four years, it's still a very new technology that isn't quite ready for wide adoption yet.