Hack the Route Start free Open app Dynamic routing
MED (multi-exit discriminator)
A BGP value a neighbour attaches to ask which of several links into it you should use.
Lower wins. An AS connected to you twice announces the same prefix on both links with different MEDs (set metric 50 on one, 100 on the other), and you send its traffic over the lower one. It is a request: it counts only
after your own local preference and AS path length, and by default only between routes from the same neighbouring AS.
Where local preference picks your way out, MED is the neighbour's say in its way in.