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Forum Discussion

Keith_Richards_'s avatar
Keith_Richards_
Icon for Nimbostratus rankNimbostratus
Jul 05, 2007

LB_FAILED event

Please can someone tell me how long the LTM will wait, given that the selected server hasn't responded, before triggering the LB_FAILED event. I have noticed that when people are using LB_FAILED for...
application delivery
dev
devops
iRules
Deb_Allen_18's avatar
Deb_Allen_18
Historic F5 Account
Jul 05, 2007
Not sure what the timeout is before LB_FAILED is triggered, anybody else know?

 

 

The connection and persistence table relationships are not cleared if a selected node that looks UP fails to respond (thus triggering LB_FAILED). Only a monitor marking the node DOWN clears the related server-side table entries.

 

 

So with OneConnect, LB::detach is necessary before a re-select to clear the connection table relationship of the client to the backend server, otherwise the same node will be re-selected. (might not be specific to OneConnect, but I think I'm remembering that correctly, somebody will straighten me out I'm sure)

 

 

Same idea re: removing the persistence record in LB_FAILED when re-selecting. Not sure if it's as necessary, but it would ensure the old persistence table relationship is cleared, then a new one would be created when the connection is re load balanced.

 

 

(LB::down isn't well integrated with monitors yet, so I would recommend against using it in this situation, preferring instead good monitoring with appropriate intervals configured.)

 

 

HTH

 

/deb