That darned copper

The advent of software-defined networking promises new test challenges. But it may also portend more flexible test instruments.

It's the party guest who won't leave, even when you turn out the lights and go to bed. It's the horror movie monster that just won't die no matter how many times you shoot it, stab it, jolt it with electricity, set it on fire, or bury it under a ton of rubble. More precisely, it's the technology that continues to linger regardless of its performance inferiority compared with fiber optics. It's copper, and it promises to hang around in 2015.

True, fiber has pretty much wiped copper out of long distance, regional, and metro networks. But in the access arena and in enterprise/data-center networks, copper continues to dominate. There are two reasons for this: (1) it's still cheaper than fiber, particularly when (2) it's already in place. There's nothing like inertia (backed with a smaller price tag) to keep network infrastructure at rest.

Actually, there's also a third reason that reinforces this inertia: Every time you think copper can't keep up with the next step up in transmission rates, someone figures out a way to do it. In the access space, we've recently seen the popularity of VDSL2 with vectoring, which enables operators who lack the stomach for fiber to the home to support broadband access rates of around 100 Mbps. This year also will see major field trials of G.fast, which promises to support gigabit speeds over currently uncertain distances at some unknown point in the future. You can bet it will prove popular, particularly as some of the gray areas I was just poking fun at become less opaque.

Meanwhile, copper doesn't look like it will give up much ground in enterprise networks or in many data centers, either. Several activists in the optical communications industry thought copper's hold on these applications would slip as networks moved to 1 Gbps - and again at 10 Gbps, etc. And even though 10GBase-T has had its growing pains, the fact that engineers are prepping a copper-based version of 40 Gigabit Ethernet indicates that as the IEEE begins work on 25 Gigabit Ethernet, copper likely will find a place within those specifications - and eventually 50 Gigabit Ethernet - as well.

As John D'Ambrosia, chair of the IEEE P802.3bs 400 Gigabit Ethernet Task Force and head of the original 100 Gigabit Ethernet specifications effort, put it, "I have heard people write copper off for years. I was one of them, up until the point that I realized that, my God, I'm chairing the 100G task force, a group that was going to be developing 100G to go over copper cable. So I've got to broaden my perspective and give these guys who are extremely smart a chance to go off and prove that they can do it. Because you know what? They keep doing it."

Yes, they do, darn them. Copper technology engineers can't keep pulling rabbits out of their hats forever (at least I don't think so). But their continued cleverness means that the use of fiber will continue to face resistance in certain quarters for the foreseeable future.

stephenh@pennwell.com

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