The intrabuilding backbone connects the main cross-connect in the building to each of the other cross-connects. An optical fiber intrabuilding backbone has emerged as the medium of choice due to its ability to support multiple high-speed networks in a smaller cable without crosstalk concerns.
Also more users are using fiber to support voice and private branch exchange (PBX) applications by placing small remote PBX shelves within cross-connects supported by the intrabuilding backbone.
A fiber optic LAN network backbone includes the following major parts.
1. Cable pathways
Cable pathways are shafts, conduits, raceways, and floor penetrations that provide routing space for fiber optic cables
ERs are areas where telecommunications systems are housed and connected to the telecommunicationis wiring system
TRs are the areas or locations that contain telecommunications equipment for connecting the horizontal cabling to the backbone cabling systems
4. Telecommunications service entrance facility
This is an area or location where outside plant cables enter a building
5. Transmission Media
Transmission media are the actual cables. They can be optical fibers, twisted-pair copper cable, or even coaxial copper cable.
Connecting hardware for the transmission media include connecting blocks, patch panels, interconnections and cross-connections.
6. Other facilities
Other facilities include cable support hardware, firestopping, grounding hardware and other protection and security hardware.
Intrabuiding backbone design is usually straightforward; however, various options exist. A single hierarchical star design between the building cross-connect and the horizontal cross-connect is strongly recommended.
The only possible exception happens in very large buildings, such as high-rise, where a two-level hierarchical star may be needed.