I Figure 7-4: Leased Line Speeds, Continued North American Digital hierarchy Line Speed Typical Transmission Medium 1.544 Mbps 2-Pair Data-Grade UTP Fractional t1 128 kbps, 256 kbps, 2-Pair Data-Grade UTP 384 kbps, 512 kbps 768 kbps Bonded T1s(multiple A few multiples of2-Pair Data-Grade UTP T1s acting as a single 544 Mbps line) T1 lines are very widely used Fractional t1 lines offer lower speeds for companies that need them Two or three T1 lines can be bonded for higher speeds T1, Fractional T1, and Bonded T 1s are the most widely used leased lines
7-16 Figure 7-4: Leased Line Speeds, Continued Line Speed Typical Transmission Medium Fractional T1 128 kbps, 256 kbps, 384 kbps, 512 kbps, 768 kbps 2-Pair Data-Grade UTP T1 1.544 Mbps 2-Pair Data-Grade UTP North American Digital Hierarchy Bonded T1s (multiple T1s acting as a single line) A few multiples of 1.544 Mbps 2-Pair Data-Grade UTP T1 lines are very widely used. Fractional T1 lines offer lower speeds for companies that need them. Two or three T1 lines can be bonded for higher speeds. T1, Fractional T1, and Bonded T1s are the most widely used leased lines
Figure 7-4: Leased Line Speeds, Continued North American Digital Hierarchy Line peed Typical Transmission Medium 1.544 Mbps 2-Pair Data-Grade UTP T3 44.736 Mbps Optical Fiber The jump from T 1 to T3 speeds is extremely large Few firms need T3 speeds, and they only need these speeds for some of their leased lines Some carriers offer fractional T3 lines to bridge the T1-T3 gap T3 lines and all faster leased lines use optical fiber 7-17
7-17 Figure 7-4: Leased Line Speeds, Continued Line Speed Typical Transmission Medium North American Digital Hierarchy T3 44.736 Mbps Optical Fiber The jump from T1 to T3 speeds is extremely large. Few firms need T3 speeds, and they only need these speeds for some of their leased lines. Some carriers offer fractional T3 lines to bridge the T1-T3 gap. T3 lines and all faster leased lines use optical fiber. T1 1.544 Mbps 2-Pair Data-Grade UTP
Figure 7-4: Leased Line Speeds, Continued CEPT Hierarchy Line Speed Typical Transmission Medium 64 kbps 64 kbps 2-Pair Data-Grade UTP E1 2.048 Mbps 2-Pair Data-Grade UTP E3 34.368 Mbps optical Fiber In Europe, most countries use the CEPT hierarchy E1 lines are slightly faster than T1 lines E3 lines are slightly slower than T3 lines 7-18
7-18 Figure 7-4: Leased Line Speeds, Continued Line Speed Typical Transmission Medium E3 34.368 Mbps Optical Fiber 64 kbps 64 kbps 2-Pair Data-Grade UTP E1 2.048 Mbps 2-Pair Data-Grade UTP CEPT Hierarchy In Europe, most countries use the CEPT hierarchy E1 lines are slightly faster than T1 lines E3 lines are slightly slower than T3 lines
I Figure 7-4: Leased Line Speeds, Continued SONET/SDH Speeds Line Speed(Mbps) Typical Transmission Medium OC3/STM1 155.52 Optical Fiber OC 12/STM4 622.08 Optical Fiber OC48/STM16 2,488. 32Optical Fiber OC 192/STM64 9, 953.28 Optical Fiber OC768/STM256 39, 813.12 Optical Fiber For speeds above 50 Mbps, the world uses one technology Called soneT in the United States, sdh in Europe SONET speeds measured in OC numbers, SDH in STM numbers Speeds are multiples of 51. 84 Mbps Used mostly by carriers
7-19 Figure 7-4: Leased Line Speeds, Continued Line Speed (Mbps) Typical Transmission Medium OC3/STM1 155.52 Optical Fiber OC12/STM4 622.08 Optical Fiber SONET/SDH Speeds OC48/STM16 2,488.32 Optical Fiber OC192/STM64 9,953.28 Optical Fiber OC768/STM256 39,813.12 Optical Fiber For speeds above 50 Mbps, the world uses one technology Called SONET in the United States, SDH in Europe SONET speeds measured in OC numbers, SDH in STM numbers Speeds are multiples of 51.84 Mbps Used mostly by carriers
Test Your understanding Page 319 4 7-20
7-20 • Test Your understanding • Page 319 • 4