Forum Discussion

Maria123's avatar
Maria123
Icon for Altostratus rankAltostratus
Dec 06, 2019

Diagnose the LB_FAILED Event

FB_FAILED is occurring even if all the server nodes are available. In the iRule logged the [event info] but noting is coming.   Is there any way to identify or diagnose the reason for this?   ...
application delivery
iRules
LTM
Lee_Sutcliffe's avatar
Lee_Sutcliffe
Icon for Nacreous rankNacreous
Dec 08, 2019

make sure your pool members have a route back via F5, sounds like a routing issue. LB_FAILED happens when the TCP handshake to the pool member is not completed successfully.

 

Try enabling auto-snat

 

I’m guessing you are using gateway_icmp as a health monitor (which is connectionless). This will mark your pool up, however a TCP connection might fail as it require a working return path via the F5