BGP Local Preference

BGP attribute local preference is the second BGP attribute, Local preference is a well known and discretionary BGP attribute.

BGP (Border Gateway Protocol) Local Preference is used to influence the route selection within an Autonomous System (AS), but it is not used to choose the exit path for an AS.

BGP Local Preference is an attribute used within a single Autonomous System (AS) to influence the selection of the best route among multiple routes to the same destination within that AS.

It helps determine which route will be preferred for outbound traffic within the AS. The route with the highest Local Preference is selected as the best route for outbound traffic within the AS and is advertised to other routers within the AS.

• Not exchanged between external BGP routers.
• The default value is 100.
• The path with the highest local preference is preferred

So, in summary, BGP Local Preference is used to influence route selection within an AS, but it doesn't determine the exit path for traffic leaving the AS.