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Medium Dependent Interface (MDI)

Last updated: August 18, 2011

What Does Medium Dependent Interface (MDI) Mean?

Medium dependent interface (MDI) refers to an Ethernet port connection that is used to connect network devices (hubs and switches) with other hubs and switches without the use of a crossover cable or null modem.

Also known as an MDI port or uplink port.


Techopedia Explains Medium Dependent Interface (MDI)

This small piece of hardware directly connects the electrical and physical elements of a network. Data communication uses different media to transmit data, each of which implements MDI in a different way.

For example:

  • Thick coaxial Ethernet: While using thick coaxial Ethernet, a clamp is installed - MDI is used as a clamp in this scenario.
  • Twisted Pair Ethernet: For twisted pair Ethernet, MDI is used as an eight-pins, or RJ-45, connector.

MDI is an uplink port designed for connecting different network devices. It is used in network interface card (NIC) ports. Because all inputs to NIC become outputs on hubs and switches, these devices have their input/output or transmitting/receiving reserved in a configuration that is known as MDI-X.

MDI ports are very common in satellite communication. For the purpose of TV and radio broadcasting, a local station must broadcast a signal supply from the land position to an orbiting satellite. This process is called satellite uplink. Many cellular companies and broadband service providers also pass on their systems’ upstream communication paths as uplink broadcasting. These types of uplinks can be cell phone SMS, voice messages or any other type of data sent through a source network.



MDI Port, Uplink Port

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