|  | 8.5 | Planning Structured Cabling: Horizontal and Backbone Cabling
| 8.5.2 | MDF location in a multi-story building

The main hub of an extended star topology Ethernet LAN is usually centrally located. This central location is so important that in a high rise building, the MDF is usually located on one of the middle floors of the building, even though the POP might be located on the first floor, or in the basement.

The main graphic illustrates where the backbone cabling and horizontal cabling would be used in an Ethernet LAN, in a multi-story building. In the Figure to the left, the backbone cabling (red lines) connects the POP to the MDF. Backbone cabling is also used to connect the MDF to the IDFs located on each floor. Horizontal cabling runs (blue lines) radiate out, from the IDFs on each floor, to the various work areas. Wherever the MDF is the only wiring closet on the floor, horizontal cabling radiate from it to the PCs on that floor.

Upcoming Changes in Cabling Standards

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