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Configuration Guide - Interface Management

S1720, S2700, S5700, and S6720 V200R010C00

This document describes the principles and configurations of interfaces and provides configuration examples.

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Configuring the MDI Type

Configuring the MDI Type


Two types of twisted pair cables can be used to connect Ethernet devices:
  • Straight-through cable: connects different types of devices, such as a switch and a PC, or a switch and a router.
  • Crossover cable: connects the same type of devices, such as two switches, two routers, or two PCs.

Generally, if two interfaces are connected using a twisted pair cable, the transmit and receive pins of one interface are respectively connected to the receive and transmit pins of the other interface so that the link can be Up. Straight-through and crossover cables have different pin assignments. Ethernet interfaces must support negotiation and crossover of receive and transmit pins to adapt to the cables connected to them. The device supports three medium dependent interface (MDI) types: auto, normal, and across.

Generally, when two interfaces at both ends of a link use the auto type, they can communicate regardless of whether a straight-through or crossover cable is used. You need to manually set the MDI type to normal or across only when the device cannot identify the network cable type. When configuring the MDI type on an interface, pay attention to the following points:
  • When a straight-through cable is used, configure different MDI types for the local and remote interfaces. For example, configure the across type for one interface and normal type for the other interface.
  • When a crossover cable is used, configure the same MDI type for the local and remote interfaces. For example, configure the across or normal type for both interfaces or auto type for one interface.

Electrical interfaces support the MDI type configuration.

The XGE electrical interfaces on the ES5D21X02T01 card of the S5720EI can only use the auto MDI type.

The MDI type can be configured on an XGE optical interface that has a GE copper module installed.

The MDI type can be configured on a GE optical interface that has a GE copper module installed.


  1. Run:


    The system view is displayed.

  2. Run:

    interface interface-type interface-number

    The Ethernet interface view is displayed.

  3. Run:

    mdi { across | auto | normal }

    The MDI type is set for the Ethernet interface.

    By default, an Ethernet interface uses the auto type and automatically identifies the network cable type.

Checking the Configuration

Run the display interface [ interface-type [ interface-number ] ] command in any view or the display this interface command in the interface view to check the current interface status. Check the Mdi field in the command output.

Updated: 2019-12-28

Document ID: EDOC1000141936

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