Neighbors tab dissapears after a while

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1

I have two devices where the neighbors tab in the gui dissapeares after some time. When I discover the devices with

./discovery.php -h <device> -m discovery-protocols

the tab is back and the links (from LLDP) are back. I see with discovering that this is added again:

LLDP-MIB: ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++

On all the other devices this never happens.I cannot figure out why this is happening. Anyone a clue? Thanks.

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Component Version
LibreNMS 25.4.0 (2025-04-14T14:11:19+02:00)
DB Schema 2025_03_22_134124_fix_ipv6_addresses_id_type (331)
PHP 8.2.26
Python 3.9.2
Database MariaDB 10.5.19-MariaDB-0+deb11u2
RRDTool 1.7.2
SNMP 5.9
===========================================

[OK] Composer Version: 2.8.8
[OK] Dependencies up-to-date.
[WARN] Debug enabled. This is a security risk.
[OK] Database Connected
[OK] Database Schema is current
[OK] SQL Server meets minimum requirements
[OK] lower_case_table_names is enabled
[OK] MySQL engine is optimal
[OK] Database and column collations are correct
[OK] Database schema correct
[OK] MySQL and PHP time match
[OK] Distributed Polling setting is enabled globally
[OK] Connected to rrdcached
[OK] Active pollers found
[OK] Dispatcher Service is enabled
[OK] Locks are functional
[OK] Python wrapper cron entry is not present
[OK] Redis is functional
[WARN] IPv6 is disabled on your server, you will not be able to add IPv6 devices.
[OK] rrdtool version ok
[OK] Connected to rrdcached

2

What specifically are the two devices? Maybe the definitions for the devices have some bugs …

I recall once when doing development for a new device (I’m a beginner) at some point I was getting correct data during discovery, and then it was getting wiped or replaced during regular polling. In that case it was related to how the SNMP OIDs were being used in the code - I was missing a digit/index off the end or simialr. Not an expert in it - but it might help someone identify it if it’s unique to some devices.

3

Thanks for your reply.

The devices are Cisco NCS 5500, but we have over 500 of them in the field and somehow only two has this strange issue. I probably have to search for the difference indeed. Polling is done every 5 minutes but the dissapearance is I think a few hours later or so. I do not know where to look but I will try. Any tips are welcome.