DS3 Explanation and Reasons For Using DS3 Bandwidth

Written by: Les Harper - Jan 8, 2009

DS3 (Digital Signal 3)

T3 is a dedicated connection supporting data rates of about 44.736 megabits per second. A T3 line actually consists of 672 individual channels, each of which supports 64 Kbps. The signals used in T3 carriers are called Digital Signal 3 or DS3. DS3 signals are used mainly by Internet Service Providers (ISPs) connecting to the Internet backbone and for the backbone itself. Today’s other primary DS3 users are high-traffic Web sites, medium to large Web-hosting companies, medical centers, call centers, universities and government offices. Using Time division multiplexing multiple T1 carriers can be multiplexed into higher-order carriers. 4 T1 channels can be multiplexed into 1 T2 channel. Each T1 carrier can carry 1.544 megabits per second. So, a T2 carrier can carry 4 times of 1.544 megabits plus some additional bits for framing and recovery i.e. approximately 6.312 megabits per second. At the next level, 7 T2 streams are combined to form a T3 stream. Thus T3 is 28 times higher than T1.

A DS3 has enough bandwidth to transmit full-motion real-time video and very large databases over a busy network. A DS3 signal would be used as a major networking channel for a large corporation or university with high volume network traffic. Businesses should consider a dedicated T1 connection as the minimum to support VoIP and other data traffic—but when that starts to feel cramped, upgrading to a DS3 line (or a fraction of one) should solve a company’s bandwidth problems for awhile.

DS3 lines, also called T3 lines, are not cheap. Also, DS3 lines are more complex than T1 - technically, they run 28 T1 lines alongside one another, and that takes extra equipment and software to work properly.

Usage of DS3 or T3 can be categorized as

Fractional DS3: In a fractional DS3 usage plan a fraction of DS3 bandwidth is available to the customer. For example, a customer can avail 6 Mbps of bandwidth which is just a fraction of 44.736 Mbps supported by DS3.

Full Rate DS3: Full Rate DS3 Internet access service provides unlimited DS3 connection at about 45 Mbps to meet the needs of businesses with high bandwidth requirements.

Burstable DS3: Burstable DS3 Internet access service provides flexible, high-bandwidth solution to businesses that have regular traffic patterns with periodic requirements for higher bandwidth. This Internet service offers the flexibility of paying for a lower, more predictable level of bandwidth, without removing the capability to burst above the committed bandwidth level.

Major telecom providers typically offer a range of services and speeds, including DS3. Some of the major DS3 service providers are AT&T Bellsouth, Verizon, Sprint, Qwest, New Edge Networks, Level 3, MegaPath, ACC Business, XO

DS3 service usually starts at $2,000/month and up, although prices are dropping as ever-more users need DS3 and competition in this market rises. The number of companies offering DS3 service has exploded. With more competition in the marketplace service providers have to reduce their DS3 prices to attract customers and keep them from going to competitors. A final reason for the reduction in DS3 pricing is the fact that equipment costs and the cost of supplying the bandwidth have decreased. This means that companies can supply the bandwidth at a lower cost. The only factor that seems likely to inhibit prices from falling much further is the "last mile" or the connection from the users premise to the service providers' POP (Point of Presence).