Once it was necessary to monitor the level of the optical signal to the BDCOM OLT P3310C and P3608-2TE, after the trunk cables of different quality could stretch in the summer, and thus we lost contact with one of the OLT, although this situation could be predicted and prevented.

The SFP module must necessarily support DDM, and it is also necessary to activate DDM on the BDCOM OLT (old model P3310B does not support DDM):

ddm enable
write all

It so happened initially that we always connect all UPLINK SFPs to the GigabitEthernet 0/5 port, which, by the way, is an RJ45/SFP combo.

You can view DDM statistics using the command:

ixnfo_config#show interface gigaEthernet 0/5

GigaEthernet0/5 is up, line protocol is up
  Ifindex is 1, unique port number is 5
  Description: UPLINK
  Hardware is Giga-Combo-FX-SFP, address is 8479.73d9.2049 (bia 8479.73d9.2049)
  MTU 1500 bytes, BW 1000000 kbit, DLY 10 usec
  Encapsulation ARPA
  Auto-Duplex(Full),  Auto-Speed(1000Mb/s),  Flow-Control Off
  Transceiver Info:
    SFP,LC,1550nm,1000BASE-FX,SM 10KM
   DDM:YES,vend name:OEM
  DDM info:
    TX power:-5.49 dBM, RX power:-12.71 dBM
    SFP temperature:47.65 C,supply voltage :3.35V,Bias Current.:25.76mA

I note that the SFP module shows 10 KM, but in fact the module is 40 KM, this is due to the firmware of the module, but does not affect the operation, well, at least the wavelength shows 1550nm correctly and other information too.

For example, to find out the DDM optical signal level on the P3310C, I use SNMP OID: (TX) (RX)

And on the BDCOM P3608-2TE, the following OIDs:  (RX)  (TX)

For some reason, the result is rounded to integers.

From Linux, you can check the OID using snmpwalk:

snmpwalk -v2c -c public
SNMPv2-SMI::enterprises.3320. = INTEGER: -5
snmpwalk -v2c -c public
SNMPv2-SMI::enterprises.3320. = INTEGER: -11

I will also give an example of Zabbix triggers to receive notifications:

Name: SFP RX Signal> -7
Expression: {BDCOM P3310C:SFP_DDM_RX.last(0)}>-7.0000

Name: SFP RX signal less than -16
Expression: {BDCOM P3310C:SFP_DDM_RX.last(0)}<-16.0000

See my other articles on the topic of BDCOM.
Cisco Nexus SNMP OID for Transceiver

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