H3C Technologies H3C S12500 Series Switches - Manual (Page 211)

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Figure 75 MED attribute
In general, BGP compares MEDs of routes received from the same AS only. You can also use the
compare-different-as-med command to force BGP to compare MED values of routes received from
different ASs.
• LOCAL_PREF
The LOCAL_PREF attribute is exchanged between IBGP peers only, and is not advertised to any
other AS. It indicates the priority of a BGP router.
LOCAL_PREF is used to determine the best route for traffic leaving the local AS. When a BGP router
obtains from several IBGP peers multiple routes to the same destination but with different next hops,
it considers the route with the highest LOCAL_PREF value as the best route. As shown in Figure 76 ,
traffic from AS 20 to AS 10 travels through Router C that is selected according to LOCAL_PREF.