Networking —

T-carrier Lines

T-carrier lines are high-speed dedicated digital lines that can be leased from telephone companies. This creates an always open, always available line between you and whomever you choose to connect to when you establish the service. T-carrier lines can support both voice and data transmissions and are often used to create point-to-point private networks. Because they are a dedicated link, they can be a costly WAN option. Four types of T-carrier lines are available:

  • T1 T1 lines offer transmission speeds of 1.544Mbps, and they can create point-to-point dedicated digital communication paths. T1 lines have commonly been used for connecting LANs.

  • T2 T2 leased lines offer transmission speeds of 6.312Mbps. They accomplish this by using 96 64Kbps B channels.

  • T3 T3 lines offer transmission speeds of up to 44.736Mbps, using 672 64Kbps B channels.

  • T4 T4 lines offer impressive transmission speeds of up to 274.176Mbps by using 4,032 64Kbps B channels

Of these T-carrier lines, the ones commonly associated with networks.

It is important to point out that T-carrier is the designation to the technology used in the United States and Canada. In Europe, they are referred to as E-carriers and in Japan, J-carriers. Table 2 shows the T/E/J carriers.

Table 2 Comparing T/E/J Carriers

Name

Transmission Speed

T-1

1.544Mbps

T-1C

3.152Mbps

T-2

6.312Mbps

T-3

44.736Mbps

T-4

274.176Mbps

J-0

64Kbps

J-1

1.544Mbps

J-1C

3.152Mbps

J-2

6.312Mbps

J-3

32.064Mbps

J-3C

97.728Mbps

J-4

397.200Mbps

E-0

64Kbps

E-1

2.048Mbps

E-2

8.448Mbps

E-3

34.368Mbps

E-4

139.264Mbps

E-5

565.148Mbps