FastNetMon Advanced uses flexible counters which are dynamically allocated and can handle an extremely large number of monitored hosts in networks.
For debugging purposes, you can check number of counters allocated for hosts in your network this way:
sudo fcli show system_counters|grep hosts_hash_size
On modern hardware, FastNetMon Advanced can track up to 1m of active hosts, which reflects the size of multi-terabit network.
To maintain a high level of performance in environments with a very large number of monitored hosts, we have cleanup logic which removes tracking entries for hosts which do not generate or receive any traffic for a long period of time.
This logic is enabled by default for all new installations.
On an existing installation, you can enable it manually in the following way:
sudo fcli set main ipv4_automatic_data_cleanup enable sudo fcli set main ipv4_automatic_data_cleanup_threshold 300 sudo fcli set main ipv4_automatic_data_cleanup_delay 300 sudo fcli set main ipv6_automatic_data_cleanup enable sudo fcli set main ipv6_automatic_data_cleanup_threshold 300 sudo fcli set main ipv6_automatic_data_cleanup_delay 300 sudo fcli commit
Value ipvX_automatic_data_cleanup_threshold controls the period of time in seconds for which a host has had no traffic. ipvX_automatic_data_cleanup_delay controls how often we run cleanup logic. The cleanup operation is quite expensive and blocks the whole speed tracking structure. We do not recommend running it very often.