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[All About Switches] Q&A: What Can I Do If An Ethernet Interface Is Physically Down?

Latest reply: Jul 10, 2018 05:19:42 685 2 0 0 0
A: An Ethernet interface is physically down. The possible causes are as follows:<?xml:namespace prefix = "o" ns = "urn:schemas-microsoft-com:office:office" />


§  Devices on both ends are powered off or the cables between the devices are not properly connected.

§  The Ethernet interface is manually shut down.

§  The twisted pair or fiber connected to the interface is too long or the fiber attenuation is high.

§  The local and remote interfaces work at different duplex modes, rates, and negotiation modes.

§  The local and remote interfaces have different training configurations.

§  The local and remote interfaces, interface modules, or devices are faulty.


Step 1      Check whether the local and remote devices are powered on and whether the cable and interface modules are installed properly.

Check the cable connection.

·         Check whether the cable is loose or damaged.

·         Check whether any wires in the cable are damaged.

Ensure that the interface can work properly.

·         Check whether the metal reed of the interface is bent or deviates.

·         Run the loopback internal command in the interface view to configure loopback detection on the interface.

If the interfaces are still Down after the devices are powered on and connected properly, go to step 2.

Step 2      Check whether the interfaces have been manually shut down.

Run the interface interface-type interface-number command in the system view to enter the interface view, and then run the display this command to check the interface configuration. If the interface has been shut down using the shutdown command, run the undo shutdown command in the interface view.

If the fault persists, go to step 3.

Step 3      Check whether the two interfaces have the same duplex mode, rate, and negotiation mode.

Run the display interface

command on the two interfaces to check the rates, duplex modes, and negotiation modes of the interfaces.

If the fault persists, go to step 4.

Step 4     Check whether the interface modules and the linkbetween the interfaces work properly. If the two interfaces are connected by atwisted pair, check the following items.

If the two interfaces are connected by fibers,check the following items.

If the faultpersists, go to step 5.

Step 5      Checkwhether the two interfaces have the same training configuration. If theinterfaces are 40GE interfaces, perform the following operations.

Step 6     Check whether thelocal or remote device has a hardware fault. Connect the devices using otherinterfaces. If the fault persists, go to step 7.
Step 7     Collect thefollowing information and contact technical support personnel:

               ·   Results of the preceding troubleshooting procedure

               ·   Configuration file, logs, and alarms of the device


For details, see the S Series Switches InterfaceTroubleshooting Troubleshooting.     
Step 1: Log in to the enterprise technical support website at
Step 2: Click Switches.

Step 3: Click the name of the product to bequeried, for example, S7700.

Step 4: Choose Documentation> S7700&S9700Series Switches Troubleshooting – Preliminary to find theTroubleshootingfor your switch model. 

Step 5: Open the Troubleshooting.Choose Interface Faults > An Ethernet InterfaceIs Physically Down in the navigation tree on theleft, and follow the instructions.

S7700&S9700 SeriesSwitches Troubleshooting - Preliminary|21782164|21782186|22318632|6805481








This post was last edited by user_3074123 at 2018-06-25 09:40.

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MVE Created Jun 25, 2018 17:13:09

good job done, thanks
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Created Jul 10, 2018 05:19:42

Good stuffs, Keep it up.. thanks
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