The value of tmnxMobPdnApnPcrfDynPccFHSession specifies whether to
enable Failure-Handling Session when Policy and Charging Rules
Function (PCRF) is enabled.
When tmnxMobPdnApnPcrfDynPccFHSession is enabled, new sessions will be
allowed to set up even when both primary and secondary PCRF are down
or there is no secondary configuration and the primary PCRF goes down.
Such sessions will continue without any further PCRF control even when
PCRF recovers.