Why is multimode fiber cable used more than single mode fiber cable? Where should we use single mode?
Multimode fiber (MMF) optic cabling is more commonly used compared to single mode fiber (SMF) fiber optic cabling because it is less expensive than SMF, thus better on a cost basis for short-distance applications. While SMF is used in some relatively short-distance applications, it is primarily used for long and ultra long-range applications (for example, between buildings in campus environments and between cities). The fiber optic cabling that is utilized for long-range and ultra long-range applications (for example, spanning oceans and continents) is SMF-based.
Typically, the fiber optic cabling inside a storage subsystem or between servers, switches, storage and other devices will be MMF. SMF cable is capable of supporting longer distances by using a smaller diameter modal dispersion that is more expensive to produce. MMF fiber cabling has a shorter distance, thus easier to manufacture, more commonly used and less expensive. Note that as you migrate to faster interfaces including 10 Gb Fibre Channel and 10 Gb Ethernet where MMF might have worked for some extended campus and data center distances, you may be better off investing in SMF moving forward. Another cost factor to consider regarding fiber optics for Fibre Channel, Ethernet and other optics-based networks is the cost of the transceivers (GBICs, SFPs, XFPs, etc.). You can read more about fiber optic cabling in Chapter 5 "Fiber Optic Essentials" in my book Resilient Storage Networks.
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