HP 5500 EI series Configuration Manual page 226

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* 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 should not be optimal.
You can configure the bestroute compare-med command to enable MED comparison for routes from the
same AS on Router D. After that, Router D puts the routes received from each AS into a group, selects the
route with the lowest MED from each group, and compares routes from different groups. This mechanism
avoids the above-mentioned problem. The following output shows the BGP routing table on Router D after
this feature is enabled. Network 10.0.0.0 learned from Router B is the optimal route.
Network
*>i
10.0.0.0
* i
* i
To enable MED comparison for routes on a per-AS basis (IPv4):
Step
1.
Enter system view.
2.
Enter BGP view or BGP-VPN
instance view.
3.
Enter BGP IPv4 unicast
address family view or
BGP-VPN IPv4 unicast
address family view.
4.
Enable MED comparison for
routes on a per-AS basis.
To enable MED comparison for routes on a per-AS basis (IPv6):
Step
1.
Enter system view.
2.
Enter BGP view.
3.
Enter BGP IPv6 unicast
address family view.
4.
Enable MED comparison for
routes on a per-AS basis.
Enabling MED comparison for routes from confederation peers
This task enables BGP to compare the MEDs of routes received from confederation peers. However, if a
route received from a confederation peer has an AS number that does not belong to the confederation,
BGP does not compare the route with other routes. For example, a confederation has three AS numbers
65006, 65007, and 65009. BGP receives three routes from different confederation peers. The AS_PATH
attributes of these routes are 65006 65009, 65007 65009, and 65008 65009, and the MED values of
them are 2, 3, and 1. Because the third route's AS_PATH attribute contains AS number 65008 that does
3.3.3.3
50
NextHop
MED
2.2.2.2
50
3.3.3.3
50
1.1.1.1
60
Command
system-view
Enter BGP view:
bgp as-number
Enter BGP-VPN instance view:
a.
bgp as-number
b.
ip vpn-instance
vpn-instance-name
address-family ipv4 [ unicast ]
bestroute compare-med
Command
system-view
bgp as-number
address-family ipv6 [ unicast ]
bestroute compare-med
215
0
LocPrf
PrefVal Path/Ogn
0
0
0
Remarks
N/A
N/A
N/A
By default, this feature is disabled.
Remarks
N/A
N/A
N/A
By default, this feature is disabled.
200e
300e
200e
200e

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