658 CHAPTER 38: MBGP M ULTICAST EXTENSION CONFIGURATION COMMANDS[3Com-bgp] ipv4-family multicast[3Com-bgp-af-mul] default local-preference 180default med Syntaxdefault med med-valueundo default medViewIPv4 multicast sub-address family viewParametermed-value: MED value, in the range of 0 to 4294967295. By default, it is 0.DescriptionUse the default med command to configure system MED value.Use the display bgp multicast group command to restore the default value.Multi-exit discriminator (MED) attribute is the external metric for a route. Unlikelocal precedence attribute, MED is exchanged, between ASs, and one it enters anAS, it does not leave the AS. MED attribute is used in best route selection. When arouter running BGP travels through different external peers and get the routeswith identical destination, but different next-hop addresses, it selects these routesaccording to their MED values. The route with smaller MED value will be selectedas the external AS route if other attributes are the same.Example# Configure system MED value as 25. system-viewSystem View: return to User View with Ctrl+Z.[SW8800] bgp 100[3Com-bgp] ipv4-family multicast[3Com-bgp-af-mul] default med 25display bgp multicastgroupSyntaxdisplay bgp multicast group [ group-name ]ViewAny viewParametergroup-name: Peer group. If no peer group is specified, the information about allpeer groups will be displayed.DescriptionUse the display bgp multicast group command to view the information aboutpeer groups.
