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Mark_Cloutier's avatar
Mark_Cloutier
Icon for Nimbostratus rankNimbostratus
Apr 25, 2014

Monitoring a Generic Host from GTM, monitor is flapping

I am in the process of upgrading our OLD (version 9.4.6 on 1500 platform) infrastructure to a version 11.4.1 on 1600 infrastructure. In addition to "standard" load balancing of Web servers behind LTMs, we use a wip to provide automatic failover between our Juniper VPN servers. Our 9.4.6 GTMs have these setup as a server, with a virtual server of the same ip/port hosted on them. Monitoring for the server object, and the virtual server object is done with a gateway_icmp monitor. That works fine in my 9.4.6 environment. The version 11.4.1 environment, regardless of what type of monitor (icmp, tcp, or http, https) shows the monitors switching frequently from green to red and back. I've done some tcpdump analysis and so far don't see anything that would explain this.... Anyone encountered this already?

 

availability
BIG-IP DNS
deployment

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  • Mark_Cloutier's avatar
    Mark_Cloutier
    Icon for Nimbostratus rankNimbostratus
    Apr 25, 2014

    Little more info, when the monitor goes read, and I mouse over it, it tells me that the gateway_icmp has failed, but the address that issued the ping that failed is a self-ip on one of my ltms, that are also defined as servers, with several virtual servers on them. Is there some default prober config ( I can't find any probers defined for my datacenters, I haven't created any) that says a LTM automatically becomes a prober? Right now, the LTMs are on the dmz interface of my firewall, whereas the GTM is outside the firewall (mgmt int in a protected network) on the same vlan as the outside interface of my vpn server. The GTM can ping the vpn server no problem, but the firewall doesn't currently allow the LTM to ping the outside of the VPN server, as there is no need to, unless I can't figure out how to fix this....

     

  • bucklej3_128765's avatar
    bucklej3_128765
    Icon for Nimbostratus rankNimbostratus
    Mar 12, 2015

    One thing I have noticed is that it seems to happen with Servers in the Same "datacenter" on the GTM.

     

  • Gregory_Thiell's avatar
    Gregory_Thiell
    Icon for Employee rankEmployee
    Aug 06, 2015

    Hi,

     

    Please check my answer on that page, I strongly believe it applies to you too.

     

    The short answer is: GTM can delegate the monitoring of Generic Hosts to other BIG-IP devices. Maybe some other BIG-IP devices don't have the appropriate network access to monitor your server?