3com MSR 20-20 참조 매뉴얼

BGP view/BGP-VPN instance view

med-value: Default MED value, in the range 0 to 4294967295.

Use the default med command to specify a default MED value.

Use the undo default med command to restore the default.

By default, the default med-value is 0.

Multi-exit discriminator (MED) is an external metric for routes. Different from local 
preference, MED is exchanged between ASs and will stay in the AS once it enters 
the AS. The route with a lower MED is preferred. When a router running BGP 
obtains several routes with an identical destination but different next-hops from 
various external peers, it will select the best route depending on the MED value. In 
the case that all other conditions are the same, the system first selects the route 
with the smallest MED as the best external route.

# In BGP view, configure the default MED as 25.

<Sysname> system-view

[Sysname] bgp 100

[Sysname-bgp] default med 25 

# In BGP-VPN instance view, configure the default MED as 25 (the VPN has been 
created).

<Sysname> system-view

[Sysname] bgp 100

[Sysname-bgp] ipv4-family vpn-instance vpn1

[Sysname-bgp-vpn1] default med 25 

BGP view/BGP-VPN instance view

None

Use the default-route imported command to allow default route redistribution 
into the BGP routing table.

Use the undo default-route imported command to disallow the redistribution.

By default, default route redistribution is not allowed.

Using the default-route imported command cannot redistribute default routes. 
To do so, use the import-route command.