Medium and larger size companies have long chosen DS3 services to obtain the bandwidth they need for broadband Internet access. Now there’s a new player in the marketplace that is looking to complement if not displace the venerable DS3 connection.
If you need business bandwidth higher than you can get by bonding T1 lines, you already know about DS3. But how much do you know about D3?
D3 is short for DOCSIS 3.0, a cable broadband standard that gives HFC (Hybrid Fiber Cable) systems a capability that rivals fiber to the premises. It is now possible to get 50 Mbps for business use from cable systems in many cities. Some have 100 Mbps available and more will have that service offering soon. DOCSIS 3.0 can provide 152 Mbps, with even higher speeds possible. Compare that with DS3 at 45 Mbps and you can see why there is a natural competition between the services.
The raw bandwidth specs don’t tell the whole story, however. D3 and DS3 are different technologies with different characteristics. You may find that one or both of these services make sense for your business.
DS3 stands for Digital Signal, level 3. It was developed as part of the T-Carrier specification by Bell Labs for use by the telephone companies to transport up to 672 simultaneous telephone calls between phone company switching centers. When provisioned over coaxial copper lines, it is called T3 line service. If you suspect that T3 is related to T1, you are right. A T3 line can transport the equivalent of 28 T1 lines on its higher bandwidth.
DOCSIS 3.0 has a Cable TV rather than a telephone company heritage. The DOCSIS standard was
developed by CableLabs (Cable Television Laboratories, Inc.) with contributions from other companies serving the cable industry. If you have Cable broadband, you are using a DOCSIS modem. It’s only a question of which version you are using. The original was DOCSIS 1.0, which has been supplanted by DOCSIS 1.1, DOCSIS 2.0 and now DOCSIS 3.0.
DS3 is based on multiplexing 672 channels of 64 Kbps each to create total bandwidth of 43 Mbps. Add the necessary synchronization and control bits and you have a bandwidth of 44.736 Mbps. Why so many channels? Each of those 64K channels is just the right size to carry one telephone call. That’s the telco heritage of DS3. Combine all the channels into one large pipe and you have nearly 45 Mbps of digital bandwidth.
D3 is also based on channels. In this case, each channel is 6 MHz wide. That’s the width of one television channel. Everything on a cable system is treated as a TV channel, so broadband services have to fit into those channels to get through the amplifiers and wiring on the system without interfering with any other channels. A 6 MHz channel can transport a 38 Mbps broadband signal in one direction. Cable operators bond channels together to get higher bandwidths. With 4 bonded channels, DOCSIS 3.0 can deliver a download speed of 152 Mbps.
So, are D3 and DS3 the same beyond their different technology heritages? Not really. The telco heritage of DS3 means that it is a dedicated symmetrical bandwidth service. You get 45 Mbps in both the upload and download directions. That bandwidth never varies. It is called dedicated because it is completely dedicated to your needs. Anytime you don’t use the full 45 Mbps, it just sits there and idles while waiting for more data.
D3 is an asymmetrical shared bandwidth service. You get different speeds in the upload and download directions. Download is faster to reflect the fact that most users download more content from the Internet than they upload. Typical business bandwidth services are 50 Mbps download and 10 Mbps upload or 100 Mbps download with 10 Mbps upload. This bandwidth is shared among many users on the system. Thus, you may experience your access speed varying all over the place depending on what other users are doing. If a lot of them are downloading movies or big software updates, everyone’s speed will be slowed.
DS3 service is generally sold with an SLA or Service Level Agreement that describes the expected performance and availability of the service, plus remedies if the provider doesn’t deliver as promised. D3 is a “best effort” service with no specific performance guarantees. Even so, it is in the provider’s best interest to provide adequate resources and service availability to keep the customers happy.
The difference in services are most dramatic when you look at the pricing. You might pay several thousand dollars a month for DS3 service with an SLA. D3 will probably cost you a tenth of that, with no guarantees. Which will work for your needs depends on if the cable system passes your business and if you can live with the variations in performance and lack of guarantees. Some companies have DS3 or even T1 lines installed for their mission critical or performance sensitive applications and D3 for general Internet access and low cost backup to their telecom services.
Are DS3, D3 or both bandwidth services right for your company? Why not talk to an expert consultant that can provide you with prices and availability of
DS3, D3, and other broadband options for your business needs? There is no charge for this helpful service and you may be able to realize a considerable cost savings while achieving the same or better network performance as you have now.
What is DOCSIS?
DOCSIS is the technology that enables traditional cable TV providers to also offer broadband Internet service on the same cable at the same time. The term is an acronym for Data Over Cable Service Interface Specification. It is the product of Cable Television Laboratories, Inc., CableLabs, a non-profit group supported by the cable system operators.
DOCSIS has evolved along with the Internet. The original spec was DOCSIS 1.0 released in 1997 and defined standards for 40 Mbps download and 10 Mbps upload. VoIP and QoS mechanisms were added by the early 2000’s, along with a boost in upstream data rates to 30 Mbps.
A significant improvement was introduced with DOCSIS 3.0 in 2006. Now cable companies could offer 1 Gbps downstream and 200 Mbps upstream with channel bonding. Support for IPv6 was also introduced at this time. With these improvements, it could be said that cable was a serious competitor to fiber optic services.
DOCSIS 3.1 in 2013 increased maximum downstream capacity to 10 Gbps with 1 to 2 Gbps upstream and is widely embraced by cable operators. DOCSIS 4.0, the latest version, increased the upstream rate to 6 Gbps in 2017. DOCSIS 4.0 is still in the early stages of production testing and deployment. The ultimate plan is to have full duplex symmetrical bandwidth on cable of 10 Gbps.
How Can Copper Cable Run So Fast?
Truth be told, it’s been a lot of years since cable TV networks were built with coaxial copper cable from the antennas at the head-end all the way to individual households and business locations. Virtually all systems of any size now use a technology called HFC or Hybrid Fiber Cable. The core network is fiber optic cable just like fiber network providers operate. The difference is that those companies run fiber right to the demarcation point within the building, while cable service terminates the fiber somewhere in the neighborhood and the makes the final run with the familiar coaxial cable. It was HFC that really enabled cable providers to offer serious broadband service.
Access Cable Fiber Networks Directly
Cable networks serve extensive metropolitan areas and their suburbs. Multi-system operators have fiber that interconnects their networks and connects to the Internet backbone. Major cable companies have gotten into the business of competing directly with competitive fiber optic networks by offering businesses the option to connect to their fiber networks without going through the copper interface.
There are advantages in going the fully fiber route. You may be able to get faster speeds and fully symmetric and dedicated connections by avoiding the cable modem. Remember that cable broadband is an inherently shared service. You are on the same last-mile Internet connection as dozens or hundreds of your neighbors. As such, you may find the the congestion level and speed of service vary throughout the day. It all depends on what everybody else is doing.
This is the reason that businesses, especially those with significant business processes running in the cloud, opt for dedicated Internet access and point to point private lines. You can get those at low speeds with traditional telco services such as T1 lines and higher speeds with DS3 bandwidth, SONET fiber optic services, Ethernet over Fiber and MPLS networks.
What service will meet your needs depends on how sensitive your operations are to line speed and latency, along with jitter and congestion. Cable broadband, especially at the DOCSIS 3.0 and above levels, provides many, many businesses with highly usable and reliable service at excellent pricing levels. Other companies with more sensitive needs may need to access fiber itself and set up more dedicated and private connections to achieve the performance they require for maximum productivity.
Find out now what cable, fiber and twisted pair copper broadband options are available for your business and what each has to offer.
