Network transfer speeds in reality

Networking equipment advertises its maximum speed, usually in megabits per second (Mbit/s). But how close can it actually come to this speed?

While this was done on a very small sample, and only on consumer-level equipment, this should give a rough idea of what you're paying for. For example, is it really worth getting Gigabit wired networking? And can 802.11g wireless routers even come close to 54 Mbit/s?

I've taken the best of consumer-grade networking hardware for this test: a Linksys WRT54G router, an Intel Pro/1000MT Gigabit network card in one computer, and a Powerbook with Airport Extreme and built-in Gigabit. The wired tests were done using a crossover cable without a switch or hub. Wireless tests were done on an empty channel with the router 3 feet away from the Powerbook.

To measure real-world speed, I did a real-world task: copying a single 664 MB file from the Powerbook to the desktop using standard Windows file sharing. (I chose that direction so the Powerbook's slower hard drive wouldn't be a bottleneck.)

First, the wireless results:

EncryptionTransfer timeActual speed
256-bit WPA13 mins, 43 secs6.4 Mbit/s
64-bit WEP6 mins, 49 secs13.0 Mbit/s
None6 mins, 41 secs13.3 Mbit/s

While the router didn't mind the weaker WEP encryption, the strong WPA slaughtered transfer times. None of these are even close to the advertised 54 Mbit/s speed, and the computer is sitting right next to the router.

How about wired networks?

Advertised speedTransfer timeActual speed
100 Mbit/s1 min, 21 secs65.6 Mbit/s
Gigabit40 secs132.9 Mbit/s

Wow. That's a big difference. And since the Gigabit network transfered at about 16 MB/sec, it was probably limited by the target hard drive's write speed.

If you do a lot of file transfers, stick with a wired network. But it doesn't seem like Gigabit is worthwhile unless you can remove the hard drive bottleneck. The 100 Mbit network performed closest to its advertised speeds, at about two-thirds of its maximum rate.

Isn't it nice to know how inflated these marketing numbers really are?