Forum Discussion
NimbostratusBIG DNS failing health checks to application services
Nimbostratus
Iquery is in place. GTM wideIP is using its default big3d daemon to get the LTM VIP status. However, in this case we are trying to have TCP defined at LTM pool level and HTTPS at GTM pool. GTM send and receive strings were not being validated to listen the application services healtch check where we tried the HTTPS health check at LTM pool and we see it is working fine. But we need to have that level of health check at GTM level for easy failover across datacenters.
I tried the troubleshooting steps - ping, telnet and curl and all works good from GTM.
Can you elaborate the Iquery checks you are talking about...
NoctilucentAny reason why you are trying to have TCP at ltm pool level and https on GTM pool. Why not let the LTM have the https monitor at the pool level. And let the iquery do its job to tell the GTM if that LTM VIP is healthy or not. Are you seeing any issue there. Maybe that is what you have to troubleshoot 1st.
If the https monitor at the ltm pool is giving you right results, but the GTM in the event of VS being down still sending the traffic to that VIP is something to be looked at.
I see you are asking for easy failover across datacenters. The best method is the GA at the GTM pool level.
WIDEIP --> GTM Pool --> [VS1 (DC1-LTM-VS - GA Order 0 ) and VS2 (DC2-LTM-VS - GA Order 1)
When the DC1-LTM-VS goes down because of https monitor, the GTM Iquery will get the VS from the big3d daemon and markdown the GTM pool member.
Automatically the traffic will failover to VS2, which from DC2.
From troubleshooting standpoint, share us your curl output, masking the fields wherever needed. If curl is working fine like you say, returning 200 OK. But the GTM pool still marking it down,,, this could mean that GTM's big3d is stuck, the GTM probing to that server is stuck with some old session ID.
On the GTM, take a pcap for the destination.
Also share us the big3d version from both LTM & GTM,
/shared/bin/big3d -v - Narendra
When we have the HTTPS health check at LTM the GTM is working fine with no defined health monitor since it is using big3d agent itself. However, the scenario is different.. all applications are using only one LTM to route it to pool members with a pass through and we want to have one GTM per application with its own custom health check in that going further new applications LTM doesn't needs any modification since it just uses TCP.
This is little out of the skilled one.. the LTM's are tested with custom HTTPS monitor when we have no health check at GTM. GTM's are doing good in marking the LTM VS down in GTM pool whenever the application services were brought down. when we switch the LTM to TCP health check and put the ssam ecustrom HTTPS health check we used for LTM in the GTM, they are marked down when application services are up and running.
