Forum Discussion
about create wide ip,
i create generic host (Firewall) server and virtual server for wide ip,
i use health monitor is gateway_icmp but server and virtual server It keeps flapping between up and down, and the status is unstable.
i was cli device F5 ping test to device generic host ok, its ok, its dont have lost or packet loss
can you help me check issue
1 Reply
The flapping you’re seeing with GTM Wide IP using a gateway_icmp monitor is usually because GTM health checks behave differently from manual ping—factors like aggressive default intervals, multiple GTM devices probing inconsistently, firewall ICMP rate-limiting, or source IP differences can cause intermittent failures even when basic connectivity looks fine; since ICMP only checks reachability (not service health), it’s often unstable for this use case, so tuning the monitor or switching to a more reliable protocol-based check is the recommended approach.
few other Solutions to explore further:
1. Tune ICMP monitor: Increase interval/timeout to reduce sensitivity and avoid false downs.
2. Use TCP monitor: Check a port (e.g., 443) for more stable and meaningful health status.
3. Use HTTP/HTTPS monitor: Validate actual application response instead of just reachability.
4. Adjust quorum (multi-GTM): Prevent a single failing probe from flipping overall status.
5. Check firewall policy: Ensure ICMP from GTM is not rate-limited or blocked intermittently.
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Is there any possibility of using TCP monitor instead of ICMP, as TCP is minimum best for firewalls
If behind firewall:
Use HTTP/HTTPS monitor (if applicable)
Can you check and tell:
Is ICMP rate-limited?
Is GTM self-IP allowed?
Any IPS/DoS protection?
Avoid gateway_icmp for Wide IP health checks
its better to use
TCP monitor (minimum)
HTTP/HTTPS monitor (ideal)
If you want, share:
Your GTM topology (single / HA / multi-site)
Monitor config output (tmsh list ltm monitor)
tmsh show gtm server
I can dig further and will try to pinpoint the exact root cause in your setup.
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