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Infinity05_1794's avatar
Icon for Nimbostratus rankNimbostratus
Aug 31, 2011

Will I lose/drop any connections on a failover?

I have a HA LTM pair with a internal floating IP and I need to reboot the active node. I've never done a fail over before (never needed to) so I wanted to ensure that when I switch my 2nd LTM to active that I won't lose any packets. Has anyone had any experience with this?



Also, to failover, do I just set redundancy state from "none" to "active"?






3 Replies

  • nathe's avatar
    Icon for Cirrocumulus rankCirrocumulus



    Firstly failover. To do this either from the cli run b failover standby or in the GUI go to High Availability and select Force to Standby. The Redundancy State Preference is there in case you'd rather one particular LTM always be the Active appliance, however, this can cause multiple failovers as once a failed Active that goes Standby is back online and set with a Preference of Active it will force a failover back so it's back to Active.



    As for the failover and connections, there are two options for you Connection and Persistence Mirroring. Both disabled by default, Connection Mirroring has a high overload so not always desirable, however, I'd recommend Persistence Mirroring - i.e. in the case of a failover a client will go to the same pool member (as the Standby is aware of the persistence record). No need if you're using http and cookie persistence though - the client is in control here.



    Hope this helps.





  • Yes you will loose packets. The TCP connections on the ingress/front/top side will all be broken. Clients will need to reconnect to the new box. As mentioned, you can use connection mirroring, but that does not scale to heavy loads.



    The Internet is unreliable by it's very nature, so clients should reconnect automatically. So it is seen as a momentary glitch that recovers very quickly.