The amount of data that can be transmitted over a network in a fixed amount of time. Bandwidth is the fundamental networking parameter, and is usually measured in kilobits, megabits or gigabits per second (Kbps, Mbps, or Gbps).
A second of |
Or live streaming |
9600bps = small email ~ 1,2 ko56kbps = web graphic ~ 7ko1Mbps = Document ~ 125 ko (cable, ADSL)10Mbps = 1 floppy disk ~ 1,25 Mo (ethernet)100Mbps = 2 MP3 songs ~ 12,25 Mo (ethernet)1Gbps = 10m CD audio ~ 125 Mo (ethernet)10Gbps = 2 CDs ~ 1,25 Go100Gbps = 2 DVDs ~ 12,5 Go |
56kbps = audio300kbps = very useful video (cable, ADSL)1500kbps, 2.2 Mbps= VHS video6Mbps = PAL video20Mbps = comp. HDTV270Mbps = raw PAL video1.5Gbps = raw HDTV1Tbps = 50,000 channels of compressed HDTV |
The standard for carriers and networks is that Mbps is
1000x1000 bits per second (and Gigabit/s is 1000x1000x1000). That's also the
transport rate, not the payload rate - so you need to allow for overheads of
whatever protocols you are using. (e.g. tcp/ip/atm/sdh - you lose a lot of payload
bandwidth that way.)
Conversely, if somebody quotes MB/s (Megabytes/s) they do usually mean 1024x1024
bytes per second.
Back in the bad old days, a 1 Megabyte floppy was 1024x1000 !