Core Issue
Distance vector protocols, including Routing Information Protocol (RIP), Interior Gateway Routing Protocol (IGRP), and Enhanced Interior Gateway Routing Protocol (EIGRP), advertise available routes in the routing table of the router. These protocols populate the routing table with routes received from neighbors. The updates that are sent and received by the router using these protocols can be controlled by configuring route filters.
Resolution
To prevent all the updates from being sent over a network, while receiving routes from neighbors, the interface belonging to the network is configured in passive mode for the specific routing protocol. This is done by issuing the passive-interface [default] {interface-type interface-number} command in router configuration mode.
To control what specific routes are advertised and received by a router, issue the distribute-list [access-list-number, name], in [interface-type interface-number] command and the distribute-list {access-list-number, access-list-name} out [interface-name, routing process, as-number] command in router configuration mode.
For more information about route filtering on distance vector IP Routing protocols, refer to Filtering Routing Updates on Distance Vector IP Routing Protocols
For more information about Passive Interfaces , refer to Configuring Passive Interfaces .
