How to configure pool to go down if multiple members are down

Question

Hello community,I have a requirement related to pool health and its impact on BGP announcements. By default, a pool in BIG-IP is considered up as long as at least one member is still healthy. However, in my case, I need the pool to be marked down if a certain number of members are unhealthy.For example:Suppose I have a pool with 10 nodes.I would like the pool to be considered down if 5 (or more) of those nodes are marked down.The purpose is to ensure that when the pool is in this degraded state, the associated virtual server is also marked down, so that the VIP is no longer advertised via BGP.In some specific cases, I have already applied monitors at the individual node level and configured the minimum number of monitors that must be available. While this works for isolated scenarios, I am looking for a more generic, scalable, and easy-to-maintain approach that could be applied across pools.Has anyone implemented this type of behavior?Is there a native configuration option in BIG-IP to achieve this?Or would it require an external monitor script / custom solution?Any guidance or best practices would be appreciated.Thanks in advance!

injeyan_kostas · Answer

Hello pablo_juarez​&nbsp;This is only achievable via external monitoryou can use a script like this#!/bin/bash
POOL="Your_Pool_name"
THRESHOLD=5

UP_COUNT=$(tmsh show ltm pool $POOL members | grep "Available Members" | awk '{print $4}')

echo "[$(date)] Pool $POOL has $UP_COUNT members up" &gt;&gt; /var/log/pool_monitor.log

if [ "$UP_COUNT" -lt "$THRESHOLD" ]; then
    echo "[$(date)] Pool DOWN: Only $UP_COUNT members up" &gt;&gt; /var/log/pool_monitor.log
    exit 1
else
    echo "[$(date)] Pool UP: $UP_COUNT members up" &gt;&gt; /var/log/pool_monitor.log
    echo "Pool is healthy" 
    exit 0
fi&nbsp;

pablo_juarez · Answer

I was working on this external monitor:#!/bin/bash## External monitor genérico para marcar DOWN un pool si tiene menos de N miembros UP## Variables de entorno pasadas desde el monitorPOOL=${POOL}MIN_UP=${MIN_UP:-1} &nbsp; # por defecto al menos 1# Obtenemos número de miembros activos del poolUP=$(tmsh show ltm pool $POOL | grep "Current Active Members" | awk '{print $5}')# Debug opcional en /var/log/ltmlogger -p local0.info "Monitor $POOL: $UP miembros UP, mínimo requerido $MIN_UP"if [ "$UP" -lt "$MIN_UP" ]; then&nbsp; # No mandamos nada a stdout -&gt; el monitor marcará DOWN&nbsp; exit 1else&nbsp; # Mandamos algo (ej: "UP") -&gt; el monitor marcará UP&nbsp; echo "UP"&nbsp; exit 0fi&nbsp;Is it necessary to use at least 2 monitors?How can the monitor check itself?I would think that another monitor is needed to verify is members are up or down.

injeyan_kostas · Answer

Indeed this would end in an infinite loop because pool would never recoveryou should have one pool with specific monitor to mark each memeber up or downthen create another pool with same members memebers and assign 2 monitors, one application specific and the external onenote that in extenral monitor you should add the first pool and in VS use the second pool