228
Step Command
Remarks
2.
Enter BGP IPv6 unicast
address family view or
BGP IPv6 multicast
address family view.
•
Enter BGP IPv6 unicast address family
view:
a.
bgp
as-number
b.
address-family ipv6
[
unicast
]
•
Enter BGP IPv6 multicast address family
view:
a.
bgp
as-number
b.
address-family ipv6 multicast
N/A
3.
Enable MED
comparison for routes
from different ASs.
compare-different-as-med
By default, this feature is
disabled.
Enabling MED comparison for routes on a per-AS basis
This task enables BGP to compare the MEDs of routes from an AS.
Figure 56
Route selection based on MED (in an IPv4 network)
As shown in
Figure 56
, Router D learns network 10.0.0.0 from both Router A and Router B. Because
Router B has a smaller router ID, the route learned from Router B is optimal.
Network NextHop MED LocPrf PrefVal Path/Ogn
*>i 10.0.0.0 2.2.2.2 50 0 300e
* i 3.3.3.3 50 0 200e
When Router D learns network 10.0.0.0 from Router C, it compares the route with the optimal route in its
routing table. Because Router C and Router B reside in different ASs, BGP does not compare the MEDs
of the two routes. Router C has a smaller router ID than Router B so the route from Router C becomes
optimal.
Network NextHop MED LocPrf PrefVal Path/Ogn
*>i 10.0.0.0 1.1.1.1 60 0 200e
* i 10.0.0.0 2.2.2.2 50 0 300e
* i 3.3.3.3 50 0 200e
