The Arista BGP router must be configured to reject outbound route advertisements for any prefixes belonging to the IP core.
An XCCDF Rule
Description
<VulnDiscussion>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.</VulnDiscussion><FalsePositives></FalsePositives><FalseNegatives></FalseNegatives><Documentable>false</Documentable><Mitigations></Mitigations><SeverityOverrideGuidance></SeverityOverrideGuidance><PotentialImpacts></PotentialImpacts><ThirdPartyTools></ThirdPartyTools><MitigationControl></MitigationControl><Responsibility></Responsibility><IAControls></IAControls>
- ID
- SV-256020r882402_rule
- Severity
- Medium
- References
- Updated
Remediation - Manual Procedure
Configure all eBGP Arista routers to filter outbound route advertisements belonging to the IP core.
Step 1: Configure an outbound route advertise filter and configure CE Arista MLS to advertise the filter to IP Core PE (100.1.0.128). Also configure an IP prefix list named FILTER_OUT to specify the 172.16.1.0/24 subnet for outbound route advertisements filtering.
LEAF-1A(config)#ip prefix-list FILTER_OUT seq 10 permit 172.16.1.0/24