FastNetMon Advanced blackhole persistency during restart

By default, FastNetMon cleans up all blackhole announces during restart/commit operation. But you can disable this behavior and do not unblock blocked hosts during restart.

This guide requires FastNetMon 2.0.181 or more recent version.

After that, please enable following features:

sudo fcli set main keep_blocked_hosts_during_restart enable
sudo fcli set main do_not_withdraw_unicast_announces_on_restart enable
sudo fcli set main do_not_withdraw_flow_spec_announces_on_restart enable

NB! FastNetMon does not support flow spec announces persistence now but we’re working on this option.

After these changes, FastNetMon will store / load blackhole list during commit / restart operation. Also, new flag do_not_withdraw_unicast_announces_on_restart disables automatic BGP clean up after restart and BGP daemon will keep announces until FastNetMon removes it.