Best Practices for Advertisement of Multiple Paths in BGP

Abstract

Add-Paths is a BGP enhancement that allows a BGP router to advertise multiple distinct paths for the same prefix/NLRI. This provides a number of potential benefits, including reduced routing churn, faster convergence and better loadsharing. This document provides recommendations to implementers of Add-Paths so that network operators have the tools needed to address their specific applications and to manage the scalability impact of Add-Paths. A router implementing Add-Paths may learn many paths for a prefix and must decide which of these to advertise to peers. This document analyses different algorithms for making this selection and provides recommendations based on the target application.