Randy's Work Blog

RFC 9234
Title: Route Leak Prevention and Detection Using Roles in UPDATE and OPEN
Author: A. Azimov,
        E. Bogomazov,
        R. Bush,
        K. Patel,
        K. Sriram
Status: Standards Track
Stream: IETF
Date: May 2022
URL: https://www.rfc-editor.org/info/rfc9234
DOI: DOI: 10.17487/RFC9234

Route leaks are the propagation of BGP prefixes that violate assumptions of BGP topology relationships, e.g., announcing a route learned from one transit provider to another transit provider or a lateral (i.e., non-transit) peer or announcing a route learned from one lateral peer to another lateral peer or a transit provider. These are usually the result of misconfigured or absent BGP route filtering or lack of coordination between autonomous systems (ASes). Existing approaches to leak prevention rely on marking routes by operator configuration, with no check that the configuration corresponds to that of the External BGP (eBGP) neighbor, or enforcement of the two eBGP speakers agreeing on the peering relationship. This document enhances the BGP OPEN message to establish an agreement of the peering relationship on each eBGP session between autonomous systems in order to enforce appropriate configuration on both sides. Propagated routes are then marked according to the agreed relationship, allowing both prevention and detection of route leaks.