HPE 5800 Series Configuration Manual page 208

Step
Enter BGP view or
2.
BGP-VPN instance view.
Enable the comparison of
3.
MED of routes from different
ASs.
Enabling the comparison of MEDs for routes on a per-AS basis
Route learning sequence may affect optimal route selection.
Figure 67 Route selection based on MED
As shown in
Router B has a smaller router ID, the route learned from it is optimal.
Network
*>i 10.0.0.0
* i
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, the route from Router C
becomes optimal.
Network
*>i 10.0.0.0
* i 10.0.0.0
* i
However, Router C and Router A reside in the same AS, and Router C has a greater MED, so
network 10.0.0.0 learned from Router C is not optimal.
Figure 67, Router D learns network 10.0.0.0 from both Router A and Router B. Because
NextHop
2.2.2.2
3.3.3.3
NextHop
1.1.1.1
2.2.2.2
3.3.3.3
Command
•
Enter BGP view:
bgp as-number
•
Enter BGP-VPN instance
view:
a. bgp as-number
b. ipv4-family
vpn-instance
vpn-instance-name
compare-different-as-med
MED
50
50
MED
60
50
50
197
Remarks
Use either approach.
Not enabled by default.
LocPrf PrefVal Path/Ogn
0
0
LocPrf PrefVal Path/Ogn
0
0
0
300e
200e
200e
300e
200e