One well-known BGP property, Local Preference (or LOCAL PREF), is utilized when more than one exit path exists from a single AS. Locally within an AS, the LOCAL PREF tells routers which exit path to take, in contrast to the MED’s usage outside of an AS to instruct routers which entrance path to take.

In addition,

• We choose the one with the highest local preference.
• Outside of an AS, the LOCAL PREF characteristic is never advertised; it is only used between iBGP peers to convey the local preference.

Example

To illustrate how LOCAL_PREF works, let’s have a look at an example.

We have built our topology and example on the following: