Temple College Logo R. Craig Collins > Common> How To Bandwidth

Bandwidth © R. Craig Collins, 2005

How long does it take to fill a kiddie pool with a garden hose with the spigot mostly closed? (Analog phone line, say.)

How long would it take to fill the same pool with a garden hose with the spigot opened all the way? (ISDN digital phone line, say.)

How about with a fire hose? (Broadband.) The water isn't moving any faster than the garden hose, there is just more water being moved.
Bandwidth as hoses illustration
Bandwidth is the amount of information that can be moved across the Internet in a given amount of time; usually measure in bits per second. Just as with the garden hose vs. the fire hose, at some point you just can't move stuff any faster... but you can move more of it at a time.

So bandwidth is less about speed (the transfer rate of an individual bit per second) than it is about quantity (the total number of bits transferred per second); the more you move, the faster it appears!

An analog phone line's 'speed' is measured from about 28 kilobits to 56 kilobits per second. A digital phone line can be about 128 kilobits per second. But most broadband connections all can move at about 1.544 megabits per second. What separates DSL from T1 and T3 broadband connections is the additional capacity... a T1 has perhaps the capacity of about 24 ISDN 'hoses' while a T3 has the capacity of perhaps 28 T1 'hoses.'

Connection Capacity Time to download 3 MB Time to download 30 MB
Dial Up 14.4 to 56 Kb 7 minutes to 31 minutes 69 minutes to 5 hours
ISDN ~128 Kb 3 minutes 30 minutes
DSL/Cable 128 Kb~1.544 Mb 37 seconds at 640Kb 6 minutes at 640Kb
T1 1.544 Kb 15 seconds 2 minutes 30 seconds
Wireless LAN to 10 Mb 1 second 24 seconds
T3 44.736 Mb less than one second 5 seconds
Wired LAN 100 Mb less than one second 2 seconds
Fiber Optic to 2.488 Gb less than one second less than one second

Again, a lot of the bits travel about the same speed, but a T3 can move many more bits at a time, giving it a faster download time. FIber Optic does not have the 1.544 Mb limit, but rather is limited by how fast the sending device can put information into the network.

Note: LANs are fast at retrieving local data, but will limited to the Internet connection method speed for downloads.

Dial up Phone line (Cat 3 Twisted Pair) uses RJ11 connectors
Ethernet network line (Cat 5 or Cat 6 Twisted Pair) uses RJ45 connectors
Twisted Pair and connectors
Coax (coaxial) cable and connector
Coax and BNC connector

Fiber Optic cable (normally many cables bundled) and FDDI connector
Fiber Optic Cable and FDDI connector