Skip to main content

Gigabit Ethernet: Dude, Where's My Bandwidth?


Why aren't our Gigabit networks delivering Gigabit speeds?

Surprise, they probably are!

While in real-world situations, the network will be severely bottlenecked by the hard drives. In a synthetic memory-to-memory scenario we demonstrated that our plain-Jane gigabit network delivered speeds very close to the theoretical 125 MB/s gigabit limitation. Typical drive-to-drive network speeds in a real-world situation will likely be limited from 20 to 85 MB/s, depending on the speed of the hard disks.

For fun, we also tested some short-run cable scapegoats such as power cable interference, cable lengths, and Cat 5e vs. Cat 6. In our small home network, we found that none of these really had a significant impact on performance, although we must point out that in a larger and more complex network with longer cable lengths, these factors might become viable concerns.

At the end of the day, we can heartily recommend that anyone who moves a lot of files should already have a Gigabit Ethernet network at home. If you're not there already, upgrading will yield a nice bump in speed when upgrading from 100 megabit, which will likely be in the range of a two-fold data transfer rate increase at the very least. 

Gigabit Ethernet in a home network can be leveraged to even higher multiples of performance if the network is based on a NAS running a hardware-controlled RAID array. In our real-world test network, this resulted in a 4.3 GB file transfer that took only one minute to copy. Over a 100 megabit connection, this same file would likely have taken about six minutes to copy.

Gigabit networks are coming into their own as an affordable standard. Now all we have to do is let hard drive speeds catch up. Or, take the more proactive approach and use your enthusiast smarts to build storage arrays able to work around the limitations of today's HDD technology. The result will undoubtedly be better throughput from your gigabit network.