Priority group activation and automatically closing connections when higher priorty group goes UP.

To meet your needs, you must use icall and user_ alert.conf

pool_server has 6 pool members,  (A,B,C) group priortity is 10; (D,E,F) group priority is 5:

ltm pool pool_server {
    members {
        192.168.100.1:telnet {
            address 192.168.100.1
            priority-group 10
            session monitor-enabled
            state up
        }
        192.168.100.11:telnet {
            address 192.168.100.11
            priority-group 5
            session monitor-enabled
            state up
        }
        192.168.100.12:telnet {
            address 192.168.100.12
            priority-group 5
            session monitor-enabled
            state up
        }
        192.168.100.13:telnet {
            address 192.168.100.13
            priority-group 5
            session monitor-enabled
            state up
        }
        192.168.100.2:telnet {
            address 192.168.100.2
            priority-group 10
            session monitor-enabled
            state up
        }
        192.168.100.3:telnet {
            address 192.168.100.3
            priority-group 10
            session monitor-enabled
            state up
        }
    }
    min-active-members 2
    monitor tcp
}

The master member has A, B and C(firstly create a icall_pool its pool member is A,B,C). You also have to create three pools (pool_icall-1, pool_ical-2, and pool_icall-3). The members are (A, B), (A, C), and (B, C) respectively

pool_back members is (D,E,F)

user_alert.conf

alert poolicall-1-DOWN "No members available for pool /Common/pool_icall-1" {
        exec command="tmsh generate sys icall event delete_backserver_session context { { name poolname value pool_ic
all } }"
}
alert poolicall-2-DOWN "No members available for pool /Common/pool_icall-2" {
        exec command="tmsh generate sys icall event delete_backserver_session context { { name poolname value pool_ic
all } }"
}
alert poolicall-3-DOWN "No members available for pool /Common/pool_icall-3" {
        exec command="tmsh generate sys icall event delete_backserver_session context { { name poolname value pool_ic
all } }"
}

When any of the pools has no available members, an icall event is triggered. Execute the exec linux shell in the icall script (icall script is based on tcl and wants to sleep for 120 seconds, and then execute the session action of deleting the standby node. Later, the test found that icall script deleted the after xxx ms {script} function of tcl, and cannot execute the after function. Instead, we call  use exec linux shell

#!/bin/bash
#sleep 120;
count=`tmsh list ltm pool pool_icall | grep "state up" | wc -l`
if [ $count -ge 2 ] 
then 
        for i in `tmsh show ltm pool pool_back members | grep -E "Ltm::Pool Member:" | awk '{print $NF}'`
        do 
                address=`echo $i | awk -F ":" '{print $1}'`;
                port=`echo $i | awk -F ":" '{print $2}'`
                tmsh delete sys connection ss-server-addr $address ss-server-port $port
        done
fi

 icall config:

list sys icall handler triggered delete_backserver_session 
sys icall handler triggered delete_backserver_session {
    script delete_backserver_session
    subscriptions {
        delete_backserver_session {
            event-name delete_backserver_session
        }
    }
}

list sys icall script delete_backserver_session           
sys icall script delete_backserver_session {
    app-service none
    definition {
        foreach var {poolname} {
            set $var $EVENT::context($var)
        }
        puts "poolname is $poolname"
        exec /bin/bash /var/tmp/delete_backserver_session.sh
    }
    description none
    events none
}