Troubleshooting S Series Switch Port and Interface Problems

Cause Description

When an interface changes from up to physically down, check whether improper operations are performed recently. For example, check whether cables are incorrectly removed and installed, accidental touch on the device causes loose cable connections, or misoperations are performed using commands on the device.

Troubleshooting Method

In any view of the interconnected two devices, run the display interface interface-type interface-number command to check the current running status and statistics of the specified interface.

<HUAWEI> display interface gigabitethernet 0/0/12
GigabitEthernet0/0/12 current state : DOWN  //Current physical status of the interface
Line protocol current state : DOWN
Description:
Switch Port, Link-type : access(negotiated),
PVID :1, TPID : 8100(Hex), The Maximum Frame Length is 9216
IP Sending Frames' Format is PKTFMT_ETHNT_2, Hardware address is 000b-0974-a475 
Last physical up time: 2013-08-10 21:09:51 
Last physical down time : 2013-08-10 21:10:51
Current system time: 2013-08-10 21:15:06
Port Mode: COMMON FIBER  //Working mode of the interface. COMMON COPPER indicates that the interface works as an electrical interface.
COMMON FIBER indicates that the interface works as an optical interface.
Speed : 1000,Loopback: NONE  //The rates, loopback status, and link status on two ends must be consistent.
Duplex: FULL,Negotiation: ENABLE//The duplex mode and auto-negotiation status of the interfaces
on both ends of the link must be consistent.

Recovery Measure

• In the command output, if the current state field displays Administratively down, the interface has been manually shut down. You need to run the undo shutdown command on the interface.
• If the current state field displays Down, check whether interfaces on both ends of the link have the same rate, duplex mode, and auto-negotiation mode. Use recovery methods based on the value of the Negotiation field.

  Negotiation Field Value	Recovery Method
  ENABLE	Indicates that the interface works in auto-negotiation mode. The interface rate and duplex mode are negotiated by both ends. If the negotiated interface rate and duplex mode are different on both ends, run the restart command on the interface to restart the interface for re-negotiation. If the negotiation fails, run the undo negotiation auto command on the interface to configure the interface to work in non-auto negotiation mode. For details about how to configure the interface rate and duplex mode, see the recovery method used when the Negotiation field displays DISABLE.
  DISABLE	Indicates that the interface works in non-auto negotiation mode. Run the speed { 10 | 100 | 1000 | 2500 | 5000 | 10000 } and duplex { full | half } commands in the interface view to adjust the rate and duplex mode of the interface to ensure that the two parameters on both ends are the same.

• If the current state field displays ERROR DOWN (down-cause), check whether the interface is shut down because of error events. You need to rectify the fault according to the down-cause field.

  Before taking recovery measures, you are advised to rectify service faults to prevent the interface from entering the ERROR DOWN state again.

  You can recover an interface from the ERROR DOWN state using either of the following measures:

  • Manual recovery

    Run the shutdown and undo shutdown commands or run the restart command in the interface view to restart the interface.

  • Automatic recovery

    Run the error-down auto-recovery cause down-cause interval interval-value command in the system view to enable an interface to automatically restore to Up state from the Error-Down state.

  The following table lists common values of the down-cause field.

  Value of the down-cause Field	Scenario
  as-not-ready	When the device negotiates to the AS mode, its interface status becomes down and then becomes up after services in the service profiles have been delivered.
  auto-defend	After the auto-defend action command is used to configure actions against attack sources, the interface that receives attack packets is shut down to prevent the device from attacks.
  bpdu-protection	On an STP-enabled network, run the stp bpdu-protection command after BPDU protection is configured on edge interfaces of a switch, the switch sets the physical status of the edge interface that receives BPDUs to down to block services on this interface if the switch is attacked by forged BPDUs.
  efm-remote-failure	When the efm trigger error-down command associates a remote fault event with the current interface of a switch, the switch sets the protocol status of the interface to down to interrupt all services on the interface if EFM detects the critical-event, dying-gasp, link-fault, or timeout fault event.
  efm-threshold-event	When link monitoring is configured for an interface on a link, the link is considered unavailable if the number of errored frames, errored codes, or errored frame seconds detected by the interface reaches or exceeds the threshold within a specified period. You can run the efm threshold-event trigger error-down command to associate an EFM threshold crossing event with the current interface. The system then sets the administrative status of the interface to down. In this manner, all services on the interface are interrupted.
  error-statistics	When an Ethernet interface configured with a backup link receives error packets, faults such as service packet loss occur. Run the error-statistics threshold-event trigger error-down command. To ensure nonstop service transmission, when the number of received error packets reaches the alarm threshold, the interface is shut down and services are switched to the backup link.
  runts-error-statistics	An interface receives Runts error packets if the optical fiber, network cable, or optical module is removed and reinstalled, the shutdown or undo shutdown command is executed, or Runts packets are forwarded on the network. To avoid worse impact on the device or services, the device counts the number of Runts error packets received by an interface within 1 minute, and shuts down the interface if the number reaches the alarm threshold 5.
  link-flap	Cable faults or active/standby switchovers will cause an interface to frequently alternate between up and down. You can run the port link-flap protection enable command to enable link flapping protection on the interface. When the switch receives an interface up/down message, it checks the number of interface flappings and interval. If the number of interface flappings within the specified period reaches the configured limit, the switch shuts down the interface.
  storm-control	Run the storm-control action command. After the storm control action is configured as error-down on an interface, the interface is shut down when the average rate of received broadcast, multicast, and unknown unicast packets is larger than the specified limit within the interval for detecting storms.
  port-security	When interface security is configured on a switch, the MAC addresses learned by the switch become secure dynamic MAC addresses. If the port-security protect-action command sets the security protection action to shutdown on an interface, the interface is shut down when the number of secure MAC addresses learned by the interface exceeds the upper limit or static MAC address flapping is detected after static MAC address detection is enabled.
  mac-address-flapping	When MAC address flapping occurs on a user network because of loops, you can configure a loop prevention action for the switch to perform when MAC address flapping occurs. After the MAC address flapping action is configured on an interface, if the switch detects MAC address flapping on the interface, it sets the physical status of the interface to down.
  transceiver-power-low	When the optical power of an Ethernet optical interface configured with a backup link is reduced, faults such as packet loss occur. To ensure normal service operation, run the transceiver power low trigger error-down command. Then the interface is triggered to transit to the error-down state and services are switched immediately if the optical power is lower than the lower alarm threshold.
  data-integrity-error	After the switch runs for a long time, the chip memory identifier has a data integrity error.

Cause Description

When a card, an interface, or the peer device becomes faulty, the corresponding interface becomes physically down. Therefore, check whether hardware failures exist.

Troubleshooting Method

Run the display interface brief command in any view to check brief information about the status and configuration of all interfaces.

<HUAWEI> display interface brief
... 
Interface             PHY    Protocol InUti OutUti inErrors outErrors
GigabitEthernet0/0/1  down   down       0%     0%     0       0
GigabitEthernet0/0/2  down   down       0%     0%     0       0
GigabitEthernet0/0/3  down   down       0%     0%     0       0
GigabitEthernet0/0/4  down   down       0%     0%     0       0
GigabitEthernet0/0/5  down   down       0%     0%     0       0
GigabitEthernet0/0/6  down   down       0%     0%     0       0

• If multiple interfaces change from up to down, cards of the local device or peer device may become faulty and the peer device status may change. For example, an active/standby switchover is performed on the peer device, the peer device is in sleeping state or restarted.
• If a single interface changes from up to down, check whether any metal reeds in the two connected interfaces have sunk or shifted. If not, run the loopback internal command in the interface view to check whether hardware failures occur in the interface. If the interface status indicated by the current state field changes to up after the loopback internal command is executed, the internal connection of the interface is normal and no hardware failure occurs. If the interface status is still down, the internal connection of the interface is abnormal and a hardware failure occurs.

  <HUAWEI> system-view 
  [HUAWEI] interface gigabitethernet 0/0/1
  [HUAWEI-GigabitEthernet0/0/1] loopback internal
  [HUAWEI-GigabitEthernet0/0/1] display this interface 
  GigabitEthernet0/0/1 current state : UP 
  Line protocol current state : UP 
  ...

Recovery Measure

• Multiple interfaces become physically Down.
  1. If multiple interfaces become physically down and these interfaces belong to the same card and are connected to multiple normal peer devices, the card may be faulty. Run the reset slot slot-id command to reset the card. If the fault persists, replace this card.
  2. If multiple interfaces become physically down and these interfaces connect the local device to the same peer device, the peer device may be faulty. You need to log in to the peer device to check whether the corresponding card is faulty. If so, reset or replace it. If an active/standby switchover is performed on the peer device, or the peer device is in sleeping state or restarted, it is a normal situation that these interfaces become physically down. These interfaces will automatically return to the up state after the peer device becomes stable. In this scenario, the interfaces will frequently alternate between up and down, causing a large number of the following up/down logs:

     Apr 15 2013 03:46:14-05:13 dgg62aslhw3i %%01IFNET/4/IF_STATE(l)[46]:Interface
     GigabitEthernet1/0/1 has turned into UP state.
     Apr 15 2013 03:46:10-05:13 dgg62aslhw3i %%01IFNET/4/IF_STATE(l)[47]:Interface
     GigabitEthernet1/0/1 has turned into DOWN state.
     Apr 15 2013 03:45:35-05:13 dgg62aslhw3i %%01IFNET/4/IF_STATE(l)[48]:Interface
     GigabitEthernet1/0/1 has turned into UP state.
     Apr 15 2013 03:45:31-05:13 dgg62aslhw3i %%01IFNET/4/IF_STATE(l)[49]:Interface 
     GigabitEthernet1/0/1 has turned into DOWN state.
     Apr 15 2013 03:42:10-05:13 dgg62aslhw3i %%01IFNET/4/IF_STATE(l)[50]:Interface
     GigabitEthernet1/0/1 has turned into UP state.

     If the peer device is frequently restarted, for example, an AP connected to a switch is frequently restarted, the interface that connects the switch to the AP becomes physically down. You need to check the reason for the frequent AP restart and determine whether a network loop occurs, whether a large number of ARP broadcast packets exist, and whether a network attack occurs. If these problems exist, solve them to ensure that the interface becomes up.

Cause Description

Physical interfaces of switches include electrical and optical interfaces. Involved transmission media include RJ45 cables, optical modules, and fibers. When transmission media are aging or damaged or optical modules receive and send signals abnormally, interfaces become physically down.

Troubleshooting Method

Connection media failures of electrical interfaces

1. Check whether cables are connected correctly.

   Ensure that interfaces on both ends are connected using the same network cable. If the two interfaces are connected through the optical distribution frame, ensure that the network cables are connected correctly. Ensure that the interfaces are connected correctly, and that the cable is firmly installed and intact.

2. Check whether the cable specification and length comply with related standards.

   According to Ethernet cable standards, the network cable length cannot exceed 100 meters. A GE electrical interface working at 1000 Mbits cannot go Up when it uses a network cable of a category lower than Category 5. A network cable of a category higher than Category 5 is recommended for the connection between electrical interfaces.

3. Check whether the status of line pairs in cables is normal.

   If any of the four line pairs in a cable is damaged, connected electrical interfaces cannot go up. Use a cable tester or run the virtual-cable-test command in the interface view to check whether line pairs in cables are correctly connected.

   If the Pair state field displays Ok, line pairs are normal. If the Pair state field displays Unknown, you are advised to use a cable analyzer to perform a test. If the Pair state field displays another state (Open or Short for example), replace the cable with another cable.

   [HUAWEI] interface gigabitethernet 0/0/1
   [HUAWEI-GigabitEthernet0/0/1] virtual-cable-test 
   Warning: The command will stop service for a while, Continue?[Y/N] y 
   Info: This operation may take a few seconds. Please wait for a moment..........done. 
   Pair A length: 1meter(s) 
   Pair B length: 1meter(s) 
   Pair C length: 1meter(s) 
   Pair D length: 1meter(s) 
   Pair A state: Ok 
   Pair B state: Ok 
   Pair C state: Ok 
   Pair D state: Ok 

Recovery Measure

Connection media failures of electrical interfaces

If the cable of an electrical interface is faulty, you are advised to replace this cable.

Connection media failures of optical interfaces

1. If a non-Huawei certified optical module is installed, replace it with a Huawei-certified optical module. Non-Huawei certified optical modules cannot ensure transmission reliability and may affect service stability. Huawei is not responsible for any problem caused by the use of non-Huawei certified optical modules and will not fix such problems.

2. Run the display transceiver interface command to check the parameters of optical modules and whether these parameters are within the normal range according to the following table.
   • If the current of an optical module is too high or too low, replace the optical module.
   • If the transmit power of an optical module is too low or too high, replace the optical module.
   • If the receive power of an optical module is too low or too high, use an optical power meter to test the optical power attenuation of each part of the link and repair abnormal parts. If the fault persists, replace the optical module or fiber to ensure that the transmission distance and fiber type of the optical module meet networking requirements.

Cause Description

When connecting two devices, check whether optical modules match optical interfaces, whether optical modules match fiber models, and whether optical modules and fibers are connected correctly. When an interface becomes physically down, rectify the fault accordingly.

Troubleshooting Method

1. Run the display device command in any view to check the device model and component information. If the device is a modular switch, you can focus on the corresponding card names.

   <HUAWEI> display device 
   S9303 Device status://Device model. The following Type field indicates a card name.
   Slot Sub  Type      Online   Power   Register   Status   Role 
   ------------------------------------------------------------
   1     -   LE0MX4UXA Present  PowerOn Registered  Normal  NA
   
   2     -   LE0MF48TA Present  PowerOn Registered  Normal  NA
   3     -   LE0MG24SA Present  PowerOn Registered  Normal  NA
   4     -   LE0DMCUA  Present  PowerOn Registered  Normal  Master
   PWR1  -   -         Present  PowerOn Registered  Abnormal NA 
   FAN1  -   -         Present  PowerOn Registered  Normal   NA 

2. Use the hardware query tool to check whether the used optical module type matches the interface and whether the optical module matches the fiber model.
3. Run the display transceiver interface command in any view of the two devices to check whether optical module parameters on the two devices are consistent.

   <HUAWEI> display transceiver interface GigabitEthernet 0/0/1 verbose 
   GigabitEthernet0/0/1 transceiver information: 
   ------------------------------------------------------------- 
   Common information: Transceiver Type:1000_BASE_SX_SFP //Optical module model
   Connector Type:LC 
   WWavelength(nm):850      //Optical module wavelength
   Transfer Distance(m):500(50um),300(62.5um)//Optical module transmission distance
   Digital Diagnostic Monitoring:YES 
   Vendor Name:HUAWEI 
   Vendor Part Number:02315204 
   Ordering Name: 
   ------------------------------------------------------------- 
   Manufacture information: 
   Manu. Serial Number:NSK1NNV 
   Manufacturing Date:2014-11-09 
   Vendor Name:HUAWEI 
   -------------------------------------------------------------

4. Check whether fibers are connected correctly. An optical module provides a TX end and an RX end. When connecting two interfaces, you need to connect the TX and RX ends of one optical module to the RX and TX ends of the other optical module using two fibers.

5. Check whether the interface is a combo interface. If so, check whether the combo interface is used correctly. That is, check whether the current working mode of the interface is consistent with the current connection.

   Combo interface GE1/0/1 corresponds to two interfaces on the device panel: combo optical interface and combo electrical interface. The two interfaces cannot work at the same time. To configure the attributes of the combo optical or electrical interface, enter the same interface view of GE1/0/1.

   Run the display interface command in any view to check whether the interface is a combo interface and whether its working mode is correct.

   <HUAWEI> display interface gigabitethernet 1/0/1 
   GigabitEthernet1/0/1 current state : DOWN 
   Line protocol current state : DOWN 
   Description:HUAWEI, Quidway Series, GigabitEthernet1/0/1 Interface
   ...
   Port Mode: COMBO AUTO //A combo interface supports three working modes. 
                            COMBO Auto: The combo interface automatically selects the working mode.
                            FORCE FIBER: The combo interface is configured to work as an optical interface.
                           FORCE COPPER: The combo interface is configured to work as an electrical interface.
   Current Work Mode:  COPPER //If the Port Mode field displays COMBO AUTO, 
                                 the Current Work Mode field displays the automatically selected working mode.
                                 COPPER indicates the electrical interface mode. FIBER indicates the optical interface mode.
   Speed : 100, Loopback: NONE 

Recovery Measure

1. Ensure that the currently used optical module matches the optical interface and fiber according to the hardware query tool. If they do not match, replace the corresponding component.
2. If the parameters of the optical modules on both ends of the link are inconsistent, replace the corresponding components.
3. Ensure that optical fibers are correctly connected.
4. If the current interface is a combo interface, ensure that its working mode meets the following requirements:
   • When the auto mode is specified, the system checks whether the combo optical interface has an optical module installed, and selects the interface working mode as follows. To specify the auto mode, run the combo-port auto command in the interface view. By default, a combo interface works in auto mode.

     Combo Interface Status	Working Mode of a Combo Interface
     The combo electrical interface is not connected, and the combo optical interface has an optical module installed.	The combo interface works as an optical interface.
     The combo electrical interface is connected using a network cable, the combo interface is up, and the combo optical interface has an optical module installed.	Before the switch restarts, the combo interface works as an electrical interface. After the switch restarts, the combo interface works as an optical interface.
     The combo electrical interface is connected using a network cable, the combo interface is down, and the combo optical interface has an optical module installed.	The combo interface works as an optical interface.

     In summary, when the auto mode is specified and the combo optical interface has an optical module installed, the combo interface works as an optical interface after the device restarts. Determine whether to install an optical module into the combo optical interface based on the connection medium (optical fiber or network cable).

   • When the working mode of the combo interface is the force mode, you can forcibly specify the working mode based on the type of the interface connecting the local and remote devices.

     Type of the Interface Connecting the Local Device to the Remote Device	Configuration Method
     The local combo electrical interface is connected to the remote electrical interface.	Run the combo-port copper command in the interface view to set the working mode of the combo interface to copper.
     The local combo optical interface is connected to the remote optical interface.	Run the combo-port fiber command in the interface view to set the working mode of the combo interface to fiber.

     In summary, after confirming that the transmission media (optical fibers or cables) are correct, check whether the working mode of the combo interface is correct. You can run the combo-port { copper | fiber } command to ensure that the working mode of the interface matches the connection media.

Cause Description

Switches can be used in various scenarios at any network layer. When a switch and its connection media become faulty because of environmental factors, interfaces of the switch may become physically Down.

Troubleshooting Method

• Check the temperature and humidity in the equipment room.

  For S series switches, the operating temperature is in the range 0ºC to 45ºC, the relative humidity is in the range 5% RH to 95% RH (non-condensing).

• Check cable layout.

  Power cables and service cables must be deployed separately. Low-current lines must be separated from high-current lines to prevent interference. Check whether network cables are damaged and aged out because of high temperature or rack wear.

Recovery Measure

• If the temperature in the equipment room cannot meet the requirement for a long time, you may need to repair or replace the air conditioning. If the relative humidity in the equipment room is high, you may need to install a dehumidifier. If the relative humidity in the equipment room is low, you may need to install a humidifier.
• If low-current lines and high-current lines are not separated, deploy these lines again to ensure that they are separated. If network cables are damaged and aged out because of environmental factors, replace the cables.