ZyXEL Communications OLT2406 User Manual page 727

emitting a high level of optical power or a low splitting ratio. You may try to increase the attenuation
from the GPON port on the OLT or change the ONT's or ONU's optical module.
Make sure the distance between the OLT and the ONT/ONU does not exceed 20 km.
Make sure the ONT/ONU can get an IP address if the ONT/ONU is a routing gateway.
Check if the ONT's or ONU's settings are correct and match the settings on the OLT. For example, the
VLAN settings should be properly configured on the OLT's uplink ports, Gigabit Ethernet ports, GPON
port, and ONT/ONU port.
Check if the ONT/ONU is functioning normally. If not, you may replace it with another.
Check if the GPON port on the OLT is functioning ok.
The OLT cannot detect multiple ONTs/ONUs or ONTs/ONUs cannot connect to the OLT.
Check if the GPON port on the OLT is disabled by using the show interface olt pon-<slot>-<port>
status command. Activate it if it is disabled.
Make sure the distance between the OLT and each ONT/ONU does not exceed 20 km or 30 km
depending on whether you use a class B or a class C transceiver.
Check if the transmitting optical power of the GPON ports on the OLT is in the normal range (+7~+2
dbm). You may need to change the PON port optical modules if they are too low or too high.
Check or change the main fiber cables, GPON ports, optical splitters.
Check all ONU/ONT states in the same fiber network. If only one ONU/ONT can register but not the
others, this ONU/ONT may be malfunctioning.
Try to disconnect the ONT/ONU and test the OLT's receiving optical power. If there is some power, there
might be some other devices mistakenly connected in the ODN, for example, a PON-enabled switch.
You may need to check each connected ONT/ONU to find the problematic one.
Change to a new transceiver, change the GPON card, or just try connecting the ONT to a different
GPON port to see if it works.
Checking Service Related Settings on the OLT.
Check if the ONT's or ONU's settings are correct and match the settings on the OLT. For example, the
VLAN settings should be properly configured on the OLT's uplink ports, Gigabit Ethernet ports, GPON
port, and ONT/ONU port.
Check if the related QinQ (or VLAN stacking) settings are correct. For example, an access port has some
restrictions for VLAN translation.
Check if IPTV service is running properly and you can access the Internet successfully.
Chapter 109 Troubleshooting
OLT2406 User's Guide
727