When EIGRP is up and operational, unicast and multicast EIGRP packets or constantly flooding the network to make sure EIGRP routes are up and are using the best path. These packets are important but not always necessary. There are situations when disabling an interfaces ability to spam the network with EIGRP packets is appropriate and will still allow for a fully operational EIGRP convergence. The way to achieve this is by configuring an interface to passive mode. EIGRP will still advertise the network/subnet configured on that interface, however, the interface will not participate in sending or processing of EIGPR packets.
Here is an example: