The BGP router must be configured to reject outbound route advertisements for any prefixes belonging to the IP core.

Overview

Finding ID	Version	Rule ID	IA Controls	Severity
V-207138	SRG-NET-000205-RTR-000006	SV-207138r604135_rule		Medium

Description
Outbound route advertisements belonging to the core can result in traffic either looping or being black holed, or at a minimum, using a non-optimized path.

STIG	Date
Router Security Requirements Guide	2021-03-16

Details

Check Text ( C-7399r382352_chk )
Review the router configuration to verify that there is a filter defined to block route advertisements for prefixes that belong to the IP core. The prefix filter must be referenced outbound on the appropriate BGP neighbor statements. If the router is not configured to reject outbound route advertisements that belong to the IP core, this is a finding.

Fix Text (F-7399r382353_fix)
Configure all eBGP routers to filter outbound route advertisements belonging to the IP core.