One day, after connecting several 40G transceivers to the Juniper QFX5100 and MX204 devices, messages from these devices began to arrive on the syslog server:
fpc0 qsfp-0/0/0: Temperature low warning cleared
fpc0 qsfp-0/0/0: Temperature low alarm cleared
fpc0 qsfp-0/0/0: Temperature low warning set
At the same time, judging by the graph in Zabbix, the temperature of the optical module was stable at 24 degrees, and the threshold for triggering a warning/alarm was 0/-5 degrees, which was not possible, since the devices were located in a data center with a stable temperature of 20-21 degrees Celsius.
show interfaces diagnostics optics et-0/0/0 | match "Module temperature"
Module temperature : 24 degrees C / 74 degrees F
Module temperature high alarm : Off
Module temperature low alarm : Off
Module temperature high warning : Off
Module temperature low warning : Off
Module temperature high alarm threshold : 78 degrees C / 172 degrees F
Module temperature low alarm threshold : -5 degrees C / 23 degrees F
Module temperature high warning threshold : 75 degrees C / 167 degrees F
Module temperature low warning threshold : 0 degrees C / 32 degrees F
More logs from another transceiver, this one has more of them:
fpc0 qsfp-0/0/0 Chan# 1: Rx power low warning cleared "
fpc0 qsfp-0/0/0 Chan# 1: Rx power low alarm cleared "
fpc0 qsfp-0/0/0 Chan# 0: Rx power low warning cleared "
fpc0 qsfp-0/0/0 Chan# 0: Rx power low alarm cleared "
fpc0 qsfp-0/0/0 Chan# 3: Rx loss cleared "
fpc0 qsfp-0/0/0 Chan# 3: Rx power low warning cleared "
fpc0 qsfp-0/0/0 Chan# 3: Rx power low alarm cleared "
fpc0 qsfp-0/0/0 Chan# 2: Rx loss cleared "
fpc0 qsfp-0/0/0 Chan# 2: Rx power low warning cleared "
fpc0 qsfp-0/0/0 Chan# 2: Rx power low alarm cleared "
fpc0 qsfp-0/0/0: Temperature low warning cleared "
fpc0 qsfp-0/0/0: Temperature low alarm cleared "
fpc0 qsfp-0/0/0 Chan# 3: Rx power low warning set "
fpc0 qsfp-0/0/0 Chan# 3: Rx power low alarm set "
fpc0 qsfp-0/0/0 Chan# 2: Rx power low warning set "
fpc0 qsfp-0/0/0 Chan# 2: Rx power low alarm set "
fpc0 qsfp-0/0/0 Chan# 1: Rx power low warning set "
fpc0 qsfp-0/0/0 Chan# 1: Rx power low alarm set "
fpc0 qsfp-0/0/0 Chan# 0: Rx power low warning set "
fpc0 qsfp-0/0/0 Chan# 0: Rx power low alarm set "
fpc0 qsfp-0/0/0: Temperature low warning set "
fpc0 qsfp-0/0/0: Temperature low alarm set "
mib2d[2071]: SNMP_TRAP_LINK_DOWN: ifIndex 517, ifAdminStatus up(1), ifOperStatus down(2), ifName et-0/0/0"
Such events were observed in the logs a couple of times a day, there was even a case when the link disappeared and came back up, after which the transceiver was replaced with a transceiver from another manufacturer (ordered from OmniLink), after which such messages no longer appeared in the logs.
I also saw information that the manufacturer FINISAR CORP. had a similar problem with false positives, which fixed it in new firmware versions, in my case, on the problematic transceivers, OEM is indicated in the manufacturer field:
show chassis hardware |find FPC
FPC 0
PIC 0
Xcvr 0 NON-JNPR QSFP+-40G-LR4
show chassis pic fpc-slot 0 pic-slot 0
PIC port information:
Fiber Xcvr vendor Wave- Xcvr JNPR
Port Cable type type Xcvr vendor part number length Firmware Rev
0 40GBASE LR4 SM OEM LQ-LR4-10 1310 nm 0.0 "
See also my article:
Juniper SNMP OIDs DDM for optical signal transceivers