Black Box Explains...Beyond T1—other standards for high-speed circuits.
While there are many applications for basic T1 rate service (1.536 Mbps), some applications require much more bandwidth. One of the most attractive features of T1 is the number of... more/see it nowoptions available to accommodate these kinds of demands. The important thing to remember is that all of these higher-speed services operate with the same consistent framing formats as the standard T1 service.
T1 is a high-speed service with a clock speed of 1.544 Mbps. It’s made up of 24 64-kbps DS0 (Digital-Signal [zero]) subchannels that together can support throughput rates of up to 1.536 Mbps. But there are higher levels of T1 service that are also available. For instance, T1C service doubles the T1 rate. It supports 3.152 Mbps with a total of 48 DS0s for top-speed applications. In a T1C environment, two T1 lines are combined into one using a special T1 mux.
The next-highest level of service is called T2. It offers 6.312 Mbps over 96 DS0s by multi-plexing 4 T1 lines into a single high-speed line.
The next two levels of service are exponentially larger than T2. A high-speed T3 trunk line is 28 times larger than a standard T1 line. T3 brings 44.736 Mbps to a customer site via 672 DS0s. This tremendous capacity is made possible by multiplexing 28 T1 lines or combina?tions of T2 and T1 lines.
Finally, T4 service offers a bandwidth potential of 274.176 Mbps, made up of 4032 64-kbps DS0 subchannels. At 168 times the size of a standard 1.544-Mbps line, T4 service dwarfs T1. The physical connections require multiplexing 6 T3 lines or 168 T1 lines into a single high-speed trunk.
With so many incredibly high-speed T-level service options available, system administrators have great flexibility to configure their operations for maximum efficiency and economy.
It’s important to remember that these various levels of T1 services can be implemented simultaneously within a particularly large enterprise to support complex network configurations.
Of course, this kind of application has the potential to become somewhat overwhelming from a management standpoint. However, as long as you keep track of the individual DS0s, you should always be able to accurately gauge how much available bandwidth you have at your disposal. collapse
Black Box Explains...DS-3 and DS-4
Digital signal (DS) speeds are used to classify the capacities of lines and trunks as designated by the Trunk (T) carrier systems. The most well-known T carrier system is the... more/see it nowNorth American T1 standard, which was originally designed to transmit digitized voice signals at 1.544 Mbps (DS-1). T carrier systems now carry digital data as well as voice transmissions.
DS-3 lines offer the functional equivalent of 28 T1 channels, operating at 44.736 Mbps (commonly rounded up to 45 Mbps). These lines handle up to 672 voice conversations and are used in high-speed interconnect and DS cross-connect (DSX) applications.
DS-4 offers 274.176 Mbps transmission—the same as 4032 standard voice channels—and has 168 times the capacity of T1. This performance level is generally used for carrier backbone networks.
Products offering DS-3 and DS-4 functionality comply with T3 and T4 standards, respectively, and with Bellcore GR-139-CORE specifications. collapse