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Troubleshooting Guide

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Amy Buck edited this page May 30, 2017 · 6 revisions

​Investigating Packet Drops

Packet drops can be investigated by viewing counters using the show interfaces counters command.

  • RX_ERR/TX_ERR includes all physical layer (layer-2) related drops, such as FCS error, RUNT frames. If there is RX_ERR or TX_ERR, it usually indicates some physical layer link issues.

  • RX_DRP include all layer-2, layer-3, ACL related drops in the switch ingress pipeline, drops due to insufficient ingress buffer.

  • TX_DRP include mainly the egress buffer related drop due to congestion, including WRED drop.

  • RX_OVR/TX_OVR counts the oversized packets.

  • Example:

admin@sonic:~$ show interfaces counters
      Iface            RX_OK      RX_RATE    RX_UTIL    RX_ERR    RX_DRP    RX_OVR            TX_OK      TX_RATE    TX_UTIL    TX_ERR    TX_DRP    TX_OVR
-----------  ---------------  -----------  ---------  --------  --------  --------  ---------------  -----------  ---------  --------  --------  --------
  Ethernet0  471,729,839,997  653.87 MB/s     12.77%         0    18,682         0  409,682,385,925  556.84 MB/s     10.88%         0         0         0
  Ethernet4  453,838,006,636  632.97 MB/s     12.36%         0     1,636         0  388,299,875,056  529.34 MB/s     10.34%         0         0         0
  Ethernet8  549,034,764,539  761.15 MB/s     14.87%         0    18,274         0  457,603,227,659  615.20 MB/s     12.02%         0         0         0
 Ethernet12  458,052,204,029  636.84 MB/s     12.44%         0    17,614         0  388,341,776,615  527.37 MB/s     10.30%         0         0         0
 Ethernet16   16,679,692,972   13.83 MB/s      0.27%         0    17,605         0   18,206,586,265   17.51 MB/s      0.34%         0         0         0
 Ethernet20   47,983,339,172   35.89 MB/s      0.70%         0     2,174         0   58,986,354,359   51.83 MB/s      1.01%         0         0         0
 Ethernet24   33,543,533,441   36.59 MB/s      0.71%         0     1,613         0   43,066,076,370   49.92 MB/s      0.97%         0         0         0

Physical Link Signa​​l

Use the following command to get optical signal strength. Note: not all types of links have such channel monitor values. The AOC and DAC cables do not have such values.

Generally, optical power should be greater than -10dBm.

  • Example:
admin@sonic:~$ sudo sfputil --dom -p Ethernet12
Ethernet12: SFP detected

        Connector : Unknown
        EncodingCodes : Unspecified
        ExtIdentOfTypeOfTransceiver : GBIC def not specified
        LengthOM3(UnitsOf10m) : 144
        RateIdentifier : Unspecified
        ReceivedPowerMeasurementType : Avg power
        TransceiverCodes :
                10GEthernetComplianceCode : 10G Base-SR
                InfinibandComplianceCode : 1X Copper Passive
        TypeOfTransceiver : QSFP
        VendorDataCode(YYYY-MM-DD Lot) : 2013-11-29 
        VendorName : MOLEX
        VendorOUI : MOL
        VendorPN : 1064141400
        VendorRev : E th
        VendorSN : G13474P0120
        ChannelMonitorValues :
                RX1Power : -5.7398dBm
                RX2Power : -4.6055dBm
                RX3Power : -5.0252dBm
                RX4Power : -12.5414dBm
                TX1Bias : 19.1600mA
                TX2Bias : 19.1600mA
                TX3Bias : 19.1600mA
                TX4Bias : 19.1600mA
        ChannelStatus :
                Rx1LOS : Off
                Rx2LOS : Off
                Rx3LOS : Off
                Rx4LOS : Off
                Tx1Fault : Off
                Tx1LOS : Off
                Tx2Fault : Off
                Tx2LOS : Off
                Tx3Fault : Off
                Tx3LOS : Off
                Tx4Fault : Off
                Tx4LOS : Off
        ModuleMonitorValues :
                Temperature : 23.7500C
                Vcc : 3.2805Volts
        StatusIndicators :
                DataNotReady : Off

SONiC Tech-Support​​ Dump

Generate a dump of troubleshooting data. This is similar to a "show tac" command on other devices. An archive file containing the dump will be saved to the device which can be sent to the SONiC development team for troubleshooting.

  • Example:
admin@sonic:~$ show techsupport

Isolate SONiC Device from the Ne​twork

When there is suspicion that a SONiC device is dropping traffic and behaving abnormally, you may want to isolate the device from the network. Before isolating the device, please generate SONiC tech-support first.

You can shut down BGP sessions to neighbors using a form of the config bgp shutdown command. There are a few variations of this command, examples follow.

  • Shutdown BGP session with neighbor by neighbor's hostname:
  • Example:
admin@sonic:~$ config bgp shutdown neighbor SONIC02SPINE
  • Shutdown BGP session with neighbor by neighbor's IP address:
  • Example:
admin@sonic:~$ config bgp shutdown neighbor 192.168.1.124
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