FAQ. BDCOM OLT equipment polling
BDCOM GP3600 model range (of which firmware - unknown) has a problem of unordered OIDs in Q-BRIDGE-MIB::dot1qTpFdbTable table. For this reason it is impossible to read the whole table, because all OIDs should follow strictly with increasing values.
You can check if it is so on your device by executing the following command:
snmpwalk -v2c -c <public> -On <ip-address> .1.3.6.1.2.1.17.7.1.2.2.1.2
If you see Error: OID not increasing in the output, this problem is present on your hardware.