Why Fiber Optic Networks are Preferred
•Virtually unlimited speed, limited only by the equipment you place on the ends of the fiber
•Can carry signals for long distances
–Undersea fiber cables go all the way across the oceans (1000s of miles)
–Will need to re-generate the signal every 60 miles or so
Some Fiber Optic Terminology
•Long haul networks
–These are networks operated by carriers/telecom providers that carry information over long distances
•Middle Mile networks
–This is the connection from a carrier facilities to a town or a last mile network
–For rural areas, this will connect a town or areas last mile network to a larger metropolitan area
•Last Mile networks
–Connection to the end user, either via wireless, copper, or fiber
Fiber Optic Technology
•There are two basic types of fiber optic cabling
–Multi mode: used to be popular for campus or building-wide networks due to lower cost for equipment to “light” it
–Single mode: always used in telecom/ISP networks due to much longer distances and faster speeds
•The real difference is the size of the glass that carries light
•You will always want single mode fiber due to the distance and speeds it supports
Close up of a Fiber Cable
•The core carries the light and varies in size
•The cladding acts as a mirror and keeps the light into the core and is almost always 125 microns
•The coating protects and identifies the fiber optic cable strand
Multi versus Single Mode
•Multimode fiber has much larger core to carry the light
-Can use LED or cheap laser to generate light
-Suitable for short distances less than 400 m, can use cheap laser or LED to generate light.
-Multiple paths- has a core large enough that light bounces and takes multiple paths through the glass
•Singlemode fiber has much smaller core
-Must use laser to generate light
– Better for long haul, has a thinner core 8-10 microns wide.
Multi versus Single Mode (continued)
•Equipment to “Light” Fiber
•A connection between equipment often requires two fibers
Equipment to “Light” Fiber
–One fiber is used to transmit in one direction, the other fiber in the opposite
•Common equipment for local area networks work like this
Optical Interfaces
•We refer to the module that is placed in a switch or router to attach to fiber optic cable as an optical interfaces
•Most common types used in local area networks are SFP, SFP+ and QSFP
A Closer Look at SFP/SFP+ and QSFP
Passive Optical Networks
•If you do Fiber to the Home (FTTH)
Passive Optical Network Equipment
•Fiber Optic Construction – Aerial
Fiber Optic Construction – Aerial
•Aerial construction is cheaper, even more so if there existing pole lines that have capacity to attach fiber
–Quicker to complete
–Less chance of unexpected barriers (bedrock, underground obstructions, inadvertent damage to existing underground utilities)
–Easier repairs
•Aerial construction is more susceptible to damage that could be costly
•Aerial Fiber Construction
Fiber Optic Construction – Underground
•Underground construction is more expensive than aerial
•Underground construction is more resilient to many hazards, including wildfire, weather (wind/ice), and vandalism
•Underground Fiber Construction
Slack Loops
-Needed to cut fiber open and build a drop to a building/customer
-Needed to be able to pull it into a splice truck to splice it
-Aerial fiber- for middle mile, you have splice cases. You need to build in slack into the splice case.
-Put 10% of fiber coiled up as slack loops in areas where you might have direction changes for example where there’s a railroad crossing/river etc, always have at least one on one side of that, sometimes both sides.
-Put in ground cases for underground
-1000-1500 ft between handholds or every 200m.
Fiber Optic Splicing
•Fiber optic cable is spliced one optical fiber at a time
•Recommended technique is to fusion splice fiber
–Fusion splicing melts two ends of bare optical fibers together using an electric arc
–This is the way to splice a fiber cable going to a home on to the cable in the street
–It is also how to terminate fiber optic cables into fiber optic patch panels
•Splicing is quite simple, but you need trained technicians and specialized tooling to keep your system in operating condition
Fusion Splicing Fiber
Fiber Optic Splice Enclosures
Fiber Optic Splice Trays
Mixed Fiber and Wireless Networks
•A common use of fiber is to serve wireless towers
•Tribal broadband role can be to install middle mile fiber from carrier facilities to wireless tower locations and
–Either provision your own 4G LTE services using the 2.5Ghz EBS spectrum you obtained in 2020 or
–Entice a mobile provider to use your fiber and tower to provision commercial services
Fiber Optic Systems Maintenance
•Fiber does not require routine maintenance
•Repair fiber damage
–Need bucket trucks, backhoes, fusion splicers, trained technicians, repair materials, and dispatch center to coordinate efforts
•Must respond to one-call locate service for locates
•Will have requests to move both aerial and underground fiber due to construction or other activities
•Electronic equipment operating a network on your fiber system will require routine updates, upgrades, and maintenance
Fiber Optic Systems Outages
Fiber Optic System Locates
–Document and map all assets!!!!
-Call 811 to get a locate done when you’re digging
-As a utility owner you have to respond to “locates”- you register your underground utilities. DOCUMENT: If you miss (due to imprecision), then you will have to pay to fix the problem.
-Use conduit with metal in it with a tone-based metal detector
-Use a warning “locate” tape with metallic element that says “warning” so the backhoe hits it first and they pull up the tape not your fiber.
Summary
•Fiber optic networks are the best alternative to providing high speed broadband services
•You will need experienced designers and contractors
•You will need trained technicians and sophisticated tooling
More Resources
–The Fiber Optic Association (https://thefoa.org)
•https://community.fs.com/blog/passive-optical-network-tutorial.html
•https://www.mdpi.com/2079-9292/9/7/1081/pdf
