Bandwidth Key Words: DS1, T-1, DS2, T-2, DS3, T-3, DS4, T-4, OC-1, OC-3, OC-12, OC-48, ATM, Bandwidth Resources, MPLS, Satellite, Internet and Bandwidth Speeds.

Explaining Bandwidth The Easy Way.

Hopefully, this will clear up and make some sense of some “Buzz words” that are commonly used.

  • T1 or DS-1 is the equivalent of 24 phone lines—a T1 handle 1.5 million bits per second [1.5Mbps]. The keyword is BITS, not bytes. Bits are much smaller than bytes and will vary compared to a byte. A bit is One – A byte can be 4,8,10,12,16, depending on what we are discussing – The telecommunications industry uses bits – so we do too. Please never confuse the two. From a PC standpoint, 8 bits equal one byte.
  • T2 or DS-2 – This is the equivalent of 4 T1s. The capacity is 6.3 million bits per second [6.3Mbps]
  • T3 or DS-3 – This is the equivalent of 28 T1s. The capacity is 45 million bits per second [45Mbps]
  • T4 or DS-4 – This is the equivalent of 6 T3s. The capacity is 274 million bits per second [274Mbps]. Sprint currently uses DS-4 for the backbone.
  • OC-1 – Sometimes called SONET. OC-1 uses ATM switches [as all OC-X does] and runs at 51 million bits per second [51Mbps]. Uses Fiber
  • OC-3 is the equivalent of 155 million bits per second [155Mbps]. MCI currently runs a few of these on its backbone.
  • OC-12 – 600 million bits per second [600 Mbps]
  • OC-48 – 2.4 gigabits per second [2.4 Gbps]

Frame Relay – Dead and gone as far as the Internet is concerned. Especially with the bandwidth requirements the way they are. Frame relay runs around 64kbps to 1.5Mbps [64,000 bits per second to 1.5 million bits per second]. Frame Relay is a shared line with other people, and your bandwidth depends on the current utilization of the line.

ATM – Asynchronous Transfer Mode. ATM is a costly switching solution that is used to carry OC-3 and OC-12 lines.

Connection TypeBits per SecondBytes per SecondThe download time of 5 Megs
14.4 Modem14,4001,60052 minutes
28.8 Modem28,8003,20026 minutes
33.6 Modem33,6003,80022 minutes
56k Line57,6007,16812 minutes
64k 1 ISDN B Channel65,5358,19210 minutes
128k 2 ISDN B Channels131,07216,3845 minutes
T1/DS11,536,000192,00043 seconds
T2/DS26,144,000768,0007 seconds
T3/DS346,080,0005,760,0001 second
T4/DS4276,480,00034,560,0000.2 seconds
Sonet/OC151,000,0006,380,0000.9 seconds
Sonet/OC3155,000,00019,370,0000.5 seconds
Sonet/OC12600,000,00075,000,0000.15 seconds

Originally by Dennis Cox From The Develop Company at Internet Global 

Bandwidth Coverage Area

Unlike DSL and other broadband technologies limited to densely populated areas, T1 Bandwidth service is available just about anywhere with a phone line. T1 Bandwidth, also known as DS1 Bandwidth, uses repeaters to boost the signal strength of the transmission – allowing it to travel up to 50 miles away from the nearest Central Office location. Our coverage area includes all of the United States.

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