Network Interface (NIC) Data Transfer Speed

I have been continuously asked this question by my peers & juniors alike, but few seems to figure out the reality. Now, lets get into the business, first the basics:

I believe everyone knows this:

8 bits

= 1 byte
1024 bytes = 1 Kilobyte (KB)
1024 Kilobytes = 1 Megabyte (MB)
1024 Megabytes = 1 Gigabyte (GB)
1024 Gigabytes = 1 Terabyte (TB)

Now, if you believe this is correct, then your problem of understanding the transmission rate of a NIC just been made easier. Here is  how:

Line Speed

per second per minute per hour
1Mbit (old-school ADSL) 100 K/sec 6 MB/minute 360 MB/hour
2Mbit (slower ADSL) 200 K/sec 12 MB/minute 720 MB/hour
4Mbit (faster ADSL) 400 K/sec 24 MB/minute 1.1 GB/hour
10Mbit (ADSL / Cable) 1 MB/sec 60 MB/minute 2.8 GB/hour
100Mbit (Fast Ethernet LAN) 10 MB/sec 600 MB/minute 28 GB/hour
1000Mbit (Gigabit Ethernet LAN) 100 MB/sec 6 GB/minute 280 GB/hour

Yes, there is always a BUT. But please do remember, not every manufacturer builds and maintains the quality of the NIC processors, so, it differs. A $2USD NE2000 compatible will barely transmit at desired speed with consistency. But a server based Coupled NIC addresses many transmission requirements, but that’s another story for a later time. Also the sustained transmission cannot be continued for longer period of times. Having said that, many manufacturers in these days can now sustain 99% throughput of that was mentioned in that table. Some very good quality manufacturers are likely to be SolarFlare, Broadcom, Intel, QLogic etc.