FastNetMon Advanced uses flexible counters which are dynamically allocated and can handle 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 size of multi terabit network.
To maintain high level of performance in environments with 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 quite long period of time.
This logic is enabled by default for all new installations.
On existing installation you can enable it manually this 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 period of time in second for which host had no traffic. ipvX_automatic_data_cleanup_delay controls how often we run cleanup logic. Cleanup operation is quite expensive and blocks whole speed tracking structure. We do not recommend running it very often.