Setting the MED Attribute

The MED attribute is equal to the metric used in IGP. After the MED attribute is set for routes, an EBGP peer can select a route with the smallest MED value for the traffic that enters an AS.

Context

The MED serves as the metric used by an IGP. It is used to determine the optimal route when traffic enters an AS. When a BGP4+ router obtains multiple routes to the same destination address but with different next hops through EBGP peers, the route with the smallest MED value is selected as the optimal route.

Procedure

Set the default MED value on the local device.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run ipv6-family unicast
  The IPv6 unicast address family view is displayed.
4. Run default med med
  The default MED value is set.
5. Run commit
  The configuration is committed.
Compare the MED values of the routes from different ASs.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run ipv6-family unicast
  The IPv6 unicast address family view is displayed.
4. Run compare-different-as-med
5. Run commit
  The configuration is committed.
Configure the method used by BGP4+ when there is no MED attribute in the route attributes.
1. Run system-view
  The system view is displayed.
2. Run bgp as-number
  The BGP view is displayed.
3. Run ipv6-family unicast
  The IPv6 unicast address family view is displayed.
4. Run bestroute med-none-as-maximum
  The maximum MED value is used for a route when there is no MED attribute in the route attributes.
  
  If this command is not run, BGP4+ uses 0 as the MED value for a route when there is no MED attribute in the route attributes.
5. Run commit
  The configuration is committed.