CCNP Routing and Switching ROUTE 300-101 Official Cert Guide

Setting the Local Preference

Lesson 3: The Local Preference Attribute

The BGP Local Preference (Local_Pref) PA gives the routers inside a single AS a value that they can set per-route and advertise to all iBGP routers inside the AS, so that all routers in the AS agree about which router is the best exit point for packets destined for that prefix. By design, Local_Pref can be set by routers as they receive eBGP routes by using an inbound route map. The routers then advertise the Local_Pref in iBGP updates. As a result, all the routers in the same AS can then make the same choice of which route is best, agreeing as to which router to use to exit ...