The Arista BGP router must be configured to limit the prefix size on any inbound route advertisement to /24 or the least significant prefixes issued to the customer.

An XCCDF Rule

Description

The effects of prefix de-aggregation can degrade router performance due to the size of routing tables and also result in black-holing legitimate traffic. Initiated by an attacker or a misconfigured router, prefix de-aggregation occurs when the announcement of a large prefix is fragmented into a collection of smaller prefix announcements.

ID: SV-256036r882450_rule
Version: ARST-RT-000570
Severity: Low
References: CCI-002385
Updated: 15 days ago

Remediation Templates

This requirement is not applicable for the DODIN backbone. 

Ensure all eBGP Arista routers are configured to limit the prefix size on any route advertisement to /24 or the least significant prefixes issued to the customer.

Step 1: Configure the prefix-list.
ip prefix-list ADVERTISE_ROUTES deny 0.0.0.0/0 ge 25
ip prefix-list ADVERTISE_ROUTES permit 0.0.0.0/0 le 32

Step 2: Apply the prefix-list in the BGP process inbound.

LEAF-1A(config)#router bgp 65000
LEAF-1A(config)# neighbor 10.1.12.2 prefix-list ADVERTISE_ROUTES in

The Arista BGP router must be configured to limit the prefix size on any inbound route advertisement to /24 or the least significant prefixes issued to the customer.

Description

Remediation Templates

A Manual Procedure