Forum Discussion
Hello,
Do you have your BIGIP systems configured in GTM as the Bigip redundant/standalone type? If so, a monitor is not required on the GTM side of things, as the LTM and GTM will transfer information about the state of a VIP. Your health monitors on the LTM will directly influence GTM's decision making. The iRule doesn't apply in this case. If all sites for a wideIP are down, then GTM's default behavior is to return all IP addresses, which would then hit your iRule. Users may see the maintenance page if the site they are connected to goes down, until the DNS TTL expires and they receive a different response.
If you have many LTM systems, you can control which system actually performs the checks by configuring a prober pool for the BIGIP server object. More information about prober pools could be obtained here: https://support.f5.com/kb/en-us/products/big-ip_gtm/manuals/product/gtm-implementations-11-6-0/15.htmlunique_990600193
The only case we use GTM's monitoring capability for is for services that are not traversing a LTM VIP, for example, network/VPN appliances.
Thanks.