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[EX/QFX] Auto-MDI/MDIX feature does not support fiber switch port



Article ID: KB33190 KB Last Updated: 26 Oct 2018Version: 1.0

This article explains the Auto-MDI/MDIX feature and what it does and does not support.


MDI (Media Dependent Interface) is standard wiring for end devices. MDIX (Media Dependent Interface with crossover) is standard wiring for switches. It is specifically designed for Ethernet network (copper port). Twisted pair cable is used to connect the devices. A straight through or crossover cable is selected based on the neighboring  devices. For more details, refer the document on mdi-mode.


  • Auto MDI-X automatically detects the required cable connection type and configures the connection appropriately, removing the need for crossover cables to interconnect switches or connecting PCs peer-to-peer.

  • Auto-MDI/MDIX does not support fiber switch ports. It has a read-only value of 'not applicable'.

  • Auto-MDI/MDIX feature supports copper network ports.

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