Interface having some number for RX and TX after a while it went to - Inf dBm.

Customer can report Inf dBm in show interfaces diagnostic optics:

user@host> show interfaces diagnostics optics et-0/3/1:0

TX -RX level

Physical interface: et-0/3/1:0

   Module temperature                       : 0 degrees C / 32 degrees F

   Module voltage                           : 0.0000 V

   Module temperature high alarm            : Off

   Module temperature low alarm             : Off

   Module temperature high warning          : Off

   Module temperature low warning           : Off

   Module voltage high alarm                : Off

   Module voltage low alarm                 : Off

   Module voltage high warning              : Off

   Module voltage low warning               : Off

   Module temperature high alarm threshold  : 75 degrees C / 167 degrees F

   Module temperature low alarm threshold   : -5 degrees C / 23 degrees F

   Module temperature high warning threshold : 70 degrees C / 158 degrees F

   Module temperature low warning threshold : 0 degrees C / 32 degrees F

   Module voltage high alarm threshold      : 3.6300 V

   Module voltage low alarm threshold       : 2.9700 V

   Module voltage high warning threshold    : 3.4640 V

   Module voltage low warning threshold     : 3.1340 V

   Laser bias current high alarm threshold  : 130.000 mA

   Laser bias current low alarm threshold   : 25.000 mA

   Laser bias current high warning threshold : 120.000 mA

   Laser bias current low warning threshold : 40.000 mA

   Laser output power high alarm threshold  : 5.0119 mW / 7.00 dBm

   Laser output power low alarm threshold   : 0.2042 mW / -6.90 dBm

   Laser output power high warning threshold : 2.5119 mW / 4.00 dBm

   Laser output power low warning threshold : 0.5129 mW / -2.90 dBm

   Laser rx power high alarm threshold      : 5.0119 mW / 7.00 dBm

   Laser rx power low alarm threshold       : 0.1023 mW / -9.90 dBm

   Laser rx power high warning threshold    : 2.5119 mW / 4.00 dBm

   Laser rx power low warning threshold     : 0.2570 mW / -5.90 dBm

   Laser temperature high alarm threshold   : 75 degrees C / 167 degrees F

   Laser temperature low alarm threshold    : -5 degrees C / 23 degrees F

   Laser temperature high warning threshold : 70 degrees C / 158 degrees F

   Laser temperature low warning threshold  : 0 degrees C / 32 degrees F

 Lane 0

   Laser bias current                       : 0.000 mA

   Laser output power                       : 0.000 mW / - Inf dBm

   Laser receiver power                     : 0.000 mW / - Inf dBm

From logs we can see alarm set on optics RX-TX power level as well:

Aug 28 08:34:28.359 host-fpc0 picd: PICD_XCVR_LANE_ALARM: xcvr-0/3/1 chan 7  Tx LOS        alarm set 

Aug 28 08:34:28.359 host-fpc0 picd: PICD_XCVR_LANE_ALARM: xcvr-0/3/1 chan 3  RX LOS        alarm set 

Aug 28 08:34:28.359 host-fpc0 picd: PICD_XCVR_LANE_ALARM: xcvr-0/3/1 chan 5  Tx CDR LOL      alarm set 

Aug 28 08:34:28.359 host-fpc0 picd: PICD_XCVR_LANE_ALARM: xcvr-0/3/1 chan 7  Tx CDR LOL      alarm set 

At the same time interface could report others alarms:

Active alarms : LINK

Active defects : LINK, LOCAL-FAULT

This issue might be reported on both Juniper and non-Juniper XFP

• Collect the following outputs to analyze them:
• show chassis pic fpc-slot 0 pic-slot 3
• show chassis pic fpc-slot 0 pic-slot 5
• start shell pfe network fpc0 (corresponding fpc)
• show version
• show picd pic pic 3
• show picd pic pic 5
• show interfaces et-0/3/1
• show interfaces et-0/5/2
• show hwd chassis fpc state brief slot 0
• show picd channel summary ifd-status
• show picd xcvr summary
• show picd serdes pic 3 port 1 chan 0  
• show picd serdes pic 5 port 2 chan 0  
• show picd serdes summary  
• show picd optics fpc_slot <> pic_slot <> port <> cmd info
• show picd optics fpc_slot <> pic_slot <> port <> cmd alarm
• show picd optics fpc_slot <> pic_slot <> port <> cmd diagnostics
• show picd optics fpc_slot <> pic_slot <> port <> cmd error
• show syslog  
• show sandbox stats

• The issue looks to be on the optics, as getting RX Loss logs every time, so check Optic and cabling by replacing it.
• To check the other end device which kind of logs are receiving
• Even after replaced optic and cleaned or replaced fiber issue persist, performing a test loopback on interface
• Performing a re-seating for module and soft reboot could resolve the issue.

Related case 2024-0829-246714