Transformation migrate database

configname: CONFIG_XFRM_MIGRATE

Linux Kernel Configuration
└─>Networking support
└─>Networking options
└─>Transformation migrate database
In linux kernel since version 2.6.21 (release Date: 2007-04-25)  
A feature to update locator(s) of a given IPsec security
association dynamically. This feature is required, for
instance, in a Mobile IPv6 environment with IPsec configuration
where mobile nodes change their attachment point to the Internet.

If unsure, say N.