Hello @Aneek ,
the soft-reconfiguration feature is a BGP feature / optimization that can be activated per neighbor and that allows to perform the following:
by using additional memory an unfiltered version of the prefixes received by a neighbor is stored
The current inbound route filter is applied to received prefixes and the allowed prefixes are installed in the local RIB routing information base.
If at a later time the inbound per neighbor filter is changed with soft reconfiguration inbound there is no need to tear down the BGP session, because the unfiltered version of received prefixes is stored for this scope so the new filter is applied to the prefixes and the new matching prefixes are installed in the RIB.
To be noted this feature has an alternative in the route refresh capability that can be negotiated with the neighbor at BGP session setup. In this case the local router can ask the neighbor to re-send its prefixes on demand in order to process them with a new inbound filter.
Hope to help
Giuseppe
