OLT & ONU Troubleshooting

Connection failed

Test Connection shows Connection failed — no response from OLT:

1. Ping the OLT from the Zal Ultra server. If it does not answer, fix the route, VPN or firewall first.
2. Check SNMP on the OLT: SNMP v2c must be enabled.
3. Check the community string: it must match the OLT exactly (it is case-sensitive).
4. Allow the Zal Ultra server: many OLTs only answer SNMP from allowed IP addresses. Add your Zal Ultra server's IP.
5. Check the firewall: UDP port 161 must be open from the Zal Ultra server to the OLT.
6. Slow link: edit the OLT and raise SNMP Timeout to 10 seconds.

Discovery finds no ONUs, or fewer than expected

• Click Test Connection first. Make sure the Vendor and PON Type are right — Test Connection corrects the PON type and model automatically.
• Make sure your vendor is supported: Nokia, C-Data and Ecom are not supported yet. For a C-Data OLT that reports Vendor: V-Sol in Test Connection, choose V-Sol as the vendor.
• V-Sol EPON OLTs find ONUs through the MAC addresses the OLT has learned. An ONU with no traffic yet (nothing connected behind it) may not appear until it passes traffic. Run Discover ONUs again later.

Discovery or Refresh Metrics stays on "Starting..."

Discovery and bulk refresh run in the background on the Zal Ultra server. If the progress never moves, the server's background worker is not running. Contact Onezeroart Support.

Readings show N/A

• Offline ONUs have no readings — this is normal.
• Some models do not report every value. For example, the V-Sol V1600D4 (GPON) does not report temperature, voltage or current, and BDCOM GPON reports only RX/TX power. See What Zal Ultra reads for each ONU.
• Click Refresh Metrics on the ONU to read it again.

An ONU is listed but no longer exists

ONUs that are removed from the OLT stay in Zal Ultra. Delete them from the ONU list (Delete ONU). If you delete an ONU that is still on the OLT, the next discovery adds it again, unmapped.

The ONU list shows the wrong ONUs or old data

If an OLT was replaced or its ONU list is badly out of date, use Clear All ONUs on the OLT and run Discover ONUs again. Remember this removes all subscriber links on that OLT — see Clear all ONUs.

The MAC address column shows a serial number

On Huawei OLTs, the ONU is identified by its serial number (for example HWTC-0E16DDA5), which is shown in the MAC Address column. This is normal.

Need help?

Contact Onezeroart Support with the OLT's vendor and model and the result of Test Connection.