Many times, early on in my tinkering or trying to learn about computer systems, I would wonder about certain terms or ideas that would come up on a “higher level”. The capabilities of my brain sometimes couldn’t wrap up the thoughts that make up an idea or a concept into a single term, and so I didn’t understand some of these things, like when I saw MDF or IDF for the first time.

MDF is short for main distribution frame. This is the central point of a network, no matter the size. The MDF is responsible for interconnecting and managing the communications between itself and the many branches of the network, or IDFs.

IDF is short for intermediate distribution frame, which mainly connects internal wiring drops and endpoints to the MDF or main distribution frame.

You can think of this in practical applications quite simply:

  • You have an internet connection, router, and stack of switches in the basement of a facility.
    • This is considered an MDF
  • You have a managed 24-port switch on each floor of the facility, which is four stories high. All switches have high-throughput, low-latency or otherwise aggregated links running back to the MDF.
    • Each of these 24-port switches are considered an IDF

Those 24-port switches are responsible for creating an Ethernet connection in every room, at every station, and for every network device on that floor of the building. All together, this comprises a common network.



The IDFs and MDFs can be as simple or as complex as the network needs. MDFs can contain a single switch or a stack of switches. IDFs can even be remote branch offices communicating over a private network to the head office and MDF. Even though we may not use these terms every day, we all utilize MDFs and IDFs when connecting to the internet, constructing networks, and even when plugging a switch into your router back at home for extending the reach of your network.


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1 Comment

Tony · January 27, 2021 at 3:27 am

They used to call IDF the Access Layer, is this still the case and depends which terminoligy is used?

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