Frequently Asked Questions (FAQs)
- Why should you use both TIA-942 and BICSI 002 when designing/maintaining your data center?
- What type of fiber do you recommend for data center applications?
- What is wide bandwidth multimode fiber and how is it used?
- What is WDM technology?
- How does WDM technology differ from parallel optics?
- Will WDM/SWDM ultimately replace parallel fiber optic solutions?
- What's the difference between Tier 1 and Tier 2 testing?
- Should I install singlemode or multimode fiber in my network?
- I have an existing copper infrastructure, what's the most cost-effective way to upgrade to fiber?
- What's the difference between 62.5 micron and 50 micron fibers?
- Why do I need to install optical fiber?
- I already have TRs in my building, is Centralized Cabling appropriate for an upgrade?
- Aren't fiber solutions more expensive than UTP copper solutions?
- Do media converters add a point of failure to the network? Why would I want to use them?
- What are SFF connectors, and why should I consider them?
- Since fiber is made of glass, will it survive harsh conditions?
- In TIA standards what is the difference between a TSB and an Addendum?
- Can the same fiber optic transceivers that are used with OM3 fiber, like X2-10GB-SRs, be used with OM4 fiber or are there new transceiver types that need to be used?
- Are Bend Insensitive Multimode Fiber approved by standards?
- Why should you use both TIA-942 and BICSI 002 when designing/maintaining your data center? ^top
- What type of fiber do you recommend for data center applications?^top
- What is wide band multimode fiber and how is it used?^top
- What is WDM technology?^top
- 4. How does WDM technology differ from parallel optics?^top
- Will WDM/SWDM ultimately replace parallel fiber optic solutions?^top
- What's the difference between Tier 1 and Tier 2 Testing?^top
- Should I install singlemode or multimode fiber in my network?^top
- I have an existing copper infrastructure, what's the most cost-effective way to upgrade to fiber?^top
- What's the difference between 62.5 micron and 50 micron fibers?^top
- Why do I need to install optical fiber?^top
ANSI/TIA-942 and BICSI 002 complement each other to ensure the optimum resiliency, efficiency, reliability, uptime, and availability of the data center. BICSI 002 is a best practices supplement to the TIA data center design and other relevant standards of ANSI/TIA-942, such as 568-C. Both TIA and BICSI standards incorporate other standards that affect the data center nationally and internationally, including ISO/IEC 11801, IEEE, ASHRAE, NEC, and NFPA to address applications beyond the cabling infrastructure: physical construction, space planning, electrical power, cooling, building automation, monitoring security, redundancy, maintainability, and commissioning. By adhering to ANSI/TIA-942 standards and considering BICSI 002 recommendations and best practices, data center managers are assured that their standards-based data center is operating at maximum reliability and cost efficiency.
To support the high bandwidths required in data centers, most companies are installing at least OM4, laser optimized multimode fiber. Some companies are installing single-mode fiber, but that requires more expensive optics. A new option that is emerging is OM5, a wide bandwidth multimode fiber which allows short wavelength division multiplexing. This means the fiber can carry multiple wavelengths of light over the same fiber, increasing bandwidth significantly and yet still allowing the use of lower cost multimode optics.
WBMMF is a relatively new fiber medium specified in ANSI/TIA-492AAAE and given the designation of OM5 multimode fiber by ISO/IEC and TIA. This 50/125 µm multimode laser optimized fiber was originally developed to support Short Wavelength Division Multiplexing (SWDM) and supports 4 wavelengths of 25Gb/s transmission for an aggregated 100 Gb/s transmission on a duplex LC link, a popular and familiar interface in the data center. WBMMF supports four wavelengths between 850 nm and 953 nm, using multimode optics. WBMMF was designed for use in data centers.
Wavelength division multiplexing (WDM) allows multiple wavelengths, typically 2 or 4 wavelengths to be transmitted over a single fiber. The IEEE 802.3bs 200 Gb/s & 400 Gb/s Ethernet Task Force in 2016 added 200 Gb/s capability to support a cost and performance optimized migration path to 400 Gb/s that includes support for 200 Gb/s with at least 2 km of SMF (4 WDM duplex fiber) and at least 10 km of SMF (4 WDM duplex fiber)
Whereas WDM utilizes a single fiber, parallel optics uses multiple fibers and lanes at various transmission rates. At the 25G transmission rate and at 100 meters, for example, IEEE’s 400 Gb/s migration path requires 16 lanes (16 MMFs to transmit and 16 to receive) for a total of 32 multimode fibers. This parallel configuration launched new 16-fiber and dual-row 32-fiber MPO connectors for which TIA recently published a standard. At 500 meters for SMF, four lanes / 8 fibers total are required by the IEEE for 400 Gb/s. Currently, the IEEE P802.3cd is defining standards for 50 Gb/s, as well as next generation 100 Gb/s and 200 Gb/s Ethernet. Published release is expected in Q3 of 2018.
The consensus among FOTC members is that both solutions will coexist and depend upon specific data center network goals and applications. Employing parallel fiber solutions are currently necessary to transition between speeds, so that breakout capability is essential.
Tier 1 testing looks at loss, length and polarity. While Tier 1 fiber optic tests can identify problems in terms of pass or fail, they cannot determine the root cause or location of the problem. Tier 2 fiber optic testing is used to pinpoint root-cause locations and the amount of loss and optical return loss (ORL) from each problem contributor and is performed selectively in addition to Tier 1 testing under specific conditions and situations. Tier 2 fiber testing provides a deeper level of link visibility unlike any other fiber infrastructure tests. The optical time-domain reflectometer (OTDR) is used to perform Tier 2 fiber optic testing.
While some people choose to install singlemode fiber because of it's high bandwidth, multimode fiber continues to be a popular choice for enterprise applications. Newer grades of multimode fiber have the bandwidth to support most applications over the distances required, plus the cost for the optics remains lower than the cost of singlemode optics.
For companies that want to leverage their legacy electronics, need to upgrade only a portion of their network, or do not have the resources to upgrade their entire network at once, fiber can be installed incrementally. For these users, media conversion technology offers them a controlled migration strategy. Media converters do just what their name implies -- the devices convert the signal from one type of media to another, allowing seamless links between different media and supporting incremental upgrades to fiber. Media converters also allow users to continue to use their existing electronics, leveraging their existing investment.
Physically the two fiber types differ in the diameter of their cores, the light-carrying region of the fiber. This is signified by the numeric nomenclature. In 62.5/125 fiber, for example, the core has a diameter of 62.5 microns and the cladding diameter is 125 microns. In terms of performance, the difference lies in the fibers' bandwidth, or information-carrying capacity. Bandwidth is actually specified as a bandwidth-distance product with units of MHzkm. The bandwidth needed to support an application depends on the data rate. As the data rate goes up [MHz], the distance that rate can be transmitted [km], goes down. Thus, a higher fiber bandwidth enables you to transmit at higher data rates or for longer distances. 50 mm multimode fiber offers nearly three times more bandwidth (500 MHzkm) than FDDI-grade 62.5 mm fiber (160 MHzkm) at 850 nm. Network planners often choose 50 micron fiber when they know the network will need to carry high bandwidth applications over longer link distances, or when they anticipate running higher speed protocols in the future.
Network managers choose to install optical fiber for several reasons, depending on their application. A few of the major reasons are listed below
- Longer link lengths: Because of its high bandwidth and low attenuation, fiber cable can support much longer link lengths when compared to the industry standard of 100 meters for unshielded twisted-pair (UTP) copper cabling. For example, with 10GbE copper is limited to 100m, but OM4 multimode fiber can support at least 400m. The longer lengths that fiber can support allow designers much more flexibility for laying out their infrastructure and maximizing the use of their real estate.
- Network Infrastructure Longevity: Today’s multimode fibers offer users the ability to support their network needs well into the future. With laser-optimized multimode fibers (OM3 and OM4) companies can easily migrate to 40 or even 100 Gigabit Ethernet and higher in their backbones. These fibers offer enough “headroom” to support anticipated applications for at least 10 to 20 years!
- EMI/RFI Immunity: In some installations -- particularly industrial applications and some schools and hospitals -- electromagnetic interference (EMI) or radio frequency interference (RFI) from fluorescent lighting or industrial equipment can cause network problems. Because fiber is dielectric, it is immune to these problems. In addition, unlike copper facilities, all-dielectric fiber cabling systems do not conduct lightning strikes or electrical currents that can damage sensitive electronic transmission equipment.
Centralized cabling is more frequently used for new builds, because then network designers can plan spaces more efficiently. However, there are existing installations that have been able to successfully "reclaim" space that had been allocated to TRs. Some additional benefits of going to a centralized fiber architecture is that your port utilization improves and the number of points of administration decreases. By moving all of your equipment into one central location it is also easier to secure and troubleshoot the network. This configuration also enables greater energy efficiency because you eliminate the need for cooling in the TR and for the inclusion of a UPS, or the availability of an uninterruptible power supply distributed from a central source.
Not necessarily. We encourage you to download our interactive Network Architecture Model where you can compare the installed first costs of different architectures and media. In some applications, all-fiber systems are less expensive to install than networks using fiber in the backbone and UTP copper in the horizontal. If you look at lifecycle costs as well as installed first costs the rational for installing fiber-based systems often becomes even more compelling.
Media converters have extremely high reliability statistics. In fact, although some companies have viewed them as a temporary, migration solution, they have been so pleased with their performance that they made them permanent. Media converters are ideal for companies that have an existing copper infrastructure that want to upgrade the parts of their network that need increased bandwidth or higher speed transmission rates now, while at the same time leveraging existing electronics.
Small Form Factor (SFF) connectors were introduced several years ago by a number of different manufacturers. They are smaller than traditional fiber connectors, with a footprint similar in size to copper-based connectors. As a result, they hel increase port density, reduce the cost of hubs and switches, lower patch-panel and enclosure costs, and reduce jumper costs. They are easy to install, making fiber even faster to install.
Optical fiber is not your typical kind of glass. Made of ultra-pure silica, it is an extremely strong material that has the ability to handle exposure to temperature and pressure extremes. In fact, tensile strength (resistance to pulling) of optical fiber exceeds 600,000 pounds per square inch -- making it stronger than copper or steel strands of the same diameter and easily surpassing the strength requirements of today's communications applications. When cabled, glass fiber is protected and further strengthened by aramid or fiberglass yarns, a fiberglass rod, and/or an outer jacket constructed of non-conductive materials.
A TSB is a Telecommunications Services Bulletin. It is purely informational: we might look at a subject, collect information and share it with the industry. There is no normative information, - no "shall" statements. TSBs are often stepping stones in the standards process as we start to explore topics that might become part of a standard. In fact, a TSB can be referenced by a standard. An addendum is an official addition to a publish standard. Anything in the addendum has the same enforcement as a full, published standard. The contents can be normative or informative depending on the content and how the engineering committee positions the material as an addendum.
10Gbps pluggable modules, be used with OM4 fiber or are there new transceiver types that need to be used?^top
Yes, you can use the same fiber-optic transceivers for both OM3 and OM4 fibers because the two fiber types are basically the same except that OM4 fiber has higher bandwidth. The IEEE 10Gbps Ethernet standard states that 300m OM3 and 400m OM4 link lengths are supported with 10GBASE-S compliant transceivers.
The TIA/IEC standards bodies are currently in the process of evaluating how the existing multimode fiber standards can be updated to include the new Bend Insensitive Multimode Fibers. Currently, there are multiple designs for Bend Insensitive Multimode Fibers and those designs are being evaluated to determine how they affect the connector loss, bandwidth and system performance measurements and qualification processes. If you are interested learning more about the status of BIMMF or participating in the discussion you can access the schedule for TR-42.12 here and download recent meeting reports.