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|A sampling of service providers|
Where to find fiber-optic services
There are many sources for different types of fiber-based services that vary by geographical location. When talking with prospective fiber-optic bandwidth service providers, ask about estimated and measured latency, as well as service level agreements
between locations. If you're looking at wavelength services, check to see if there are any service provider restrictions on using TDM equipment for aggregation of slower and underutilized interfaces. Also verify with prospective service providers what they classify as a wavelength service, as some may consider a SONET OC-48 or OC-96 to meet that criteria, while others provide a true WDM-based lambda as a wavelength.
Some providers (see "A Sampling of service providers," this page) offer metropolitan services, others offer regional, while still others offer national and international services. Service providers will often have a map on their Web site showing coverage areas and types of services. Pricing for fiber-optic-based services can vary greatly depending on location, distance, type of service (protected or unprotected), amount of bandwidth, and managed or wavelength service. With bandwidth, you get what you pay for, so look at your application needs and match the appropriate level of capability to the specific requirement.
A common mistake is to look at bandwidth simply in terms of dollars per Gb/sec. The effective or actual usage amount is important, and with bandwidth that includes what level of utilization at a given response time (latency level) can be maintained without congestion and packet delay/loss. Some vendors estimate TCO savings of 25% to 30% (or more) when using a premium optical-based service, including SONET/SDH vs. an equivalent IP-based service, considering effective bandwidth, lower latency, less complexity and application improvements.
Don't make the mistake of prototyping a storage application at a reduced workload, and then assume that heavier workloads will scale linearly with regards to bandwidth and latency. Instead of linear scaling, effective bandwidth can drop off as workload is added along with additional latency, resulting in poor performance, particularly for synchronous-based storage applications. Test realistic workloads using different network bandwidth transport options to determine which ones meet your production needs and budget requirements. Pay close attention to details, including protected or unprotected services, diverse paths, problem resolution and network latency. Get various groups in your organization (storage, telecom and networking) to work with each other. First and foremost, understand your needs and the capabilities of these different technologies. Then align the appropriate technology to the specific task, application and cost of service.
This was first published in August 2005