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RSchill_194035's avatar
RSchill_194035
Icon for Nimbostratus rankNimbostratus
Mar 26, 2015

Changed behaviour after after supposedly successful migration

We just replaced six older F5s (1500, 1600 and 3400 from 2005 and 2008) with 2 F5 Big IP 4000 using partions to separate the rulesets. Everthing works fine, just a minor inconvenience showed up, as t...
application delivery
LTM
management
security
StephanManthey's avatar
StephanManthey
Icon for Nacreous rankNacreous
Mar 26, 2015

Hi,

 

by default the virtual server will not change the source IP when forwarding the packets to the poolmember.

 

Exceptions for setups using OneConnect and PerformanceHTTP. In this case source IP may change as existing idle serverside connections are re-used (connection multiplexing).

 

If you noticed source NAT in the past I assume there is SNAT AutoMap configured for the virtual servers or there is a so called Default SNAT configured (lookup your SNAT List configurations, please).

 

The self IPs were used, if there was no floating self IP configured.

 

Since TMOS v11 it´s mandatory to have a floating self IP in the traffic-group used by your your virtual servers for proper SNATing.

 

I would recommend to grep your bigip.conf (separate files for admin partitions will be found in /config/partitions/ for SNAT entries (may also appear i.e. in iRules).

 

Thanks, Stephan