For more than two decades, I've been involved in designing wide area networks to allow the various office locations within large companies to communicate with one another. I thought I'd seen everything. Then one day my company's CFO came to me with a troubling request. He asked me to reduce our voice and data networking costs by 40 percent.
My first reaction was not exactly unbridled cooperation. I knew right away that redundancy would have to be removed and that old habits such as private circuits and the latest networking equipment were now in the past. I could already hear the users complaining about robotic-sounding phone calls and choppy videoconferences. Worse, the people who ask you to cheapen things are usually the first to complain when there's a problem.
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In the end, we fell short of the 40 percent target, but we came close. By moving to 100Mbps Ethernet, we're conserving about $40,000 per year in WAN charges -- a 33 percent savings compared to the cost of our private T1 circuits. For details on the migration, see "Migrating from T1 to fiber WAN." In this article, I'll focus on the trade-offs from the business standpoint.
WANs yesterday and today
From a 30,000-foot view, a WAN needs to be 100 percent reliable and available 24/7. In a perfect world, this would be done with redundant, private data circuits in each office location. Redundancy is not just a matter of backup circuits and redundant routers and switches, but also leveraging multiple vendors; if one vendor has an issue, then the other vendor (hopefully) would still be chugging along.
Since we don't live in a perfect world, but one in which budgets are continually being restrained, the private data lines are becoming less and less viable in WAN design. Most of the alternatives require you to build your WAN with one vendor who will provide encrypted tunnels into its network backbone. You hope it has low latency and various levels of quality of service (QoS) that can guarantee higher priority to voice and videoconferencing than to the guy streaming the baseball game.
Other times, you may look at using a cheap Internet service provider with your own point-to-point VPN tunnels to get data between your different locations. Be warned: If you decide to use a cheap Internet line between your different sites, you will be plagued by issues such as high latency and inconsistent data speeds -- especially with unforgiving traffic such as phone conversations and videoconferencing.