For some time now, I've been saying that networking is the key element to cloud architectures. While that's still true, it's probably more accurate to say that adequate bandwidth will make or break most enterprises' ventures on the cloud.

Indeed, while cloud backers routinely tout the technology's ability to deliver enterprises resources at a fraction of the cost of traditional data centers, the fact is those costs will vary significantly depending on how much bandwidth is needed to make it all happen.

Take Microsoft's Windows Azure Platform, for example. According to Allan Leinwand at GigaOm, the fee for the service is calculated in two ways, 15 cents per GB of downloaded data and 10 cents per GB uploaded. While that may not sound like much, it could add up depending on what sort of applications gets posted. The upload will be minimal, but if it's an app that is constantly downloading, you could find yourself shelling out hundreds or even thousands per month on top of the fee for the actual cloud service.

So what, some might ask? After all, no matter how you centralize data center resources, you'll need bandwidth to reach disparate users. True, but as Johna Till Johnson recently blogged on PC World, most cloud computing initiatives are being set up as expansions of existing resources, not mere reconfigurations. So you'll have to account for increases in bandwidth along with capacity upgrades.

There could be a silver lining in all of this, though. CNet's James Urquhart wonders if bandwidth considerations might prod software developers to start taking efficiency into account as they roll out new products. For too long, network resource utilization has taken a back seat to expanded features and other bells and whistles on most enterprise applications. Now that network inefficiency can be a major cost factor, perhaps the pendulum is about to swing back.

That, of course, would depend on whether new technologies arise to make cloud bandwidth a moot point. Oh, something like the new RapidNet service from Asankya, for instance. The company claims it can accelerate cloud applications about 40-fold using a system called the Cloud Acceleration Network that uses a series of network nodes placed throughout key Internet providers' backbone architectures. The system aggregates available bandwidth across multiple parallel pathways, allowing even encrypted applications to perform at or near LAN quality.

Even without acceleration services like RapidNet, cloud computing will remain the cheaper alternative to traditional data center infrastructures, simply by virtue of the elimination of standard hardware. But that doesn't mean the costs are non-existent.

If the cloud does become a standard IT component for the enterprise, keeping those costs low will be the order of the day. And that will mean paying particular attention to bandwidth usage.