As a seasoned IT journalist you'd think I might know better than to base a buying decision on marketing blurb. But no, when Belkin launched its new Gigabit Powerline HD adapters claiming gigabit speeds over mains wiring, I jumped right in and ordered a pair. I was, to say the least, disappointed with the results.

I already use Powerline hardware, to extend my network out to a room where I've never got round to running UTP. But with a limit of just 200Mbps my existing Powerline AV adapters had become something of a bottleneck. The new Belkin devices seemed like the ideal replacement and, at first, all seemed well.

The starter kit I ordered contained two adapters which I simply plugged into the mains: one in my office, the other in the server room. I turned them on and the middle of three LEDs on the shiny black casings lit up to tell me they'd found each other and established a network link. I didn't bother with encryption, but that's pretty easy too, with a button on the top which, when pressed, causes the adapters to generate and share a random encryption key.

There's just the single Ethernet socket underneath and the big difference here is that it's a Gigabit Ethernet (10/100/1,000Mbps) interface rather than fast Ethernet (10/100Mbps) as on AV products. I therefore cabled each adapter to a local Gigabit Ethernet switch and began testing.

Now, I wasn't expecting the HD adapters to deliver anything like what I'd get from a cabled Gigabit connection. That's because the Belkin adapters are really Powerline AV products with local Gigabit Ethernet ports plus extra technology to boost throughput over the mains, courtesy of the Gigle Semiconductor chipset on which they're based.

I was, however, expecting a significant increase; 300-400Mbps perhaps. But, using iPerf to measure throughput, what I actually got was a miserly 27Mbps; slower even than the existing Powerline AV adapters which gave 33Mbps on the same setup.

Clearly something was wrong, the first clue being the central connection LED on the Belkin adapters which was glowing orange, not blue like the one for the connection to the Gigabit switch. On checking the manual I discovered that this meant they were unable to establish a high-speed link and had stepped down to 200Mbps or below. I then noticed that the adapters were attached to different ring circuits, connected via standard micro circuit breakers in my AC consumer unit.

“Aha”, I thought, "perhaps that's what's causing the problem."

It was. Moving the adapters onto the same mains wiring loop caused the LEDs to change to blue and deliver a much more respectable throughput of 295Mbps. Interestingly the AV adapters also improved when moved this way, but only to 50Mbps, well behind the new Belkin boxes.

I spoke to Belkin about this and they supplied new firmware which helped a little, but didn't really cure the problem.

If I could permanently locate the Belkin HD adapters on the same ring then all would be well. I wouldn't have proper Gigabit but I'd be more than happy with an actual speed of around 300Mbps. Unfortunately the layout of my wiring, and that of most modern buildings, means that I can't do that and to change it would involve more work than running conventional UTP cabling where it's needed. So, given that they‘re effectively slower than the existing AV adapters, on my network and a lot of others they're of little use.

Still, lesson learned. From now on I'll check out the claims before ordering and I'd advise anyone else to think long and hard before buying a Belkin Gigabit Powerline HD starter kit. Yes, it's faster than Powerline AV, but only where the adapters are on the same AC ring main and, even then, don't expect to get anything like real gigabit throughput.

As for me, I've decided to bite the bullet and run a cable out to my server room. Anyone want to buy a couple of Gigabit Powerline HD adapters?

Verdict
Although equipped with Gigabit Ethernet interfaces, these 'go-faster' Powerline AV adapters are unable to match the speed of a cabled Gigabit Ethernet network. More than that, if located on different ring mains they have trouble keeping up with standard Powerline AV products. In the right situation they're quicker, but further development is needed for them to be a good buy.

Company: Belkin

Contact: 0845 607 7787

Tags: ethernet gigabit ethernet iperf electrical wiring data communications wi-fi gigabit universal serial bus