HP VPN Firewall Appliances Network Management Configuration Guide

492
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view or BGP-VPN
instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
Use either method.
3. Enable the comparison of
MEDs for routes on a per-AS
basis.
bestroute compare-med
Optional.
Not enabled by default.
4. Enabling the comparison of MED of routes from confederation peers
The MED attributes of routes from confederation peers are not compared if their AS-path attributes
contain AS numbers that do not belong to the confederation, such as these three routes: AS-path
attributes of them are 65006 65009, 65007 65009, and 65008 65009, and MED values of
them are 2, 3, and 1. Because the third route contains an AS number that does not belong to the
confederation, the first route becomes the optimal route.
To enable the comparison of MED of routes from confederation peers:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view or
BGP-VPN instance view.
• Enter BGP view:
bgp as-number
• Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
Use either method.
3. Enable the comparison
of MED of routes from
confederation peers.
bestroute med-confederation
Optional.
Not enabled by default.
Configuring the NEXT_HOP attribute
By default, when advertising routes to an IBGP peer or peer group, a BGP router does not set itself as the
next hop. However, to make sure a BGP peer can find the correct next hop in some cases, you need to
configure the router as the next hop for routes sent to the peer.
For example, as shown in Figure 295,
Router A and Router B esta
blish an EBGP neighbor relationship,
and Router B and Router C establish an IBGP neighbor relationship. When Router B advertises a network
learned from Router A to Router C, if Router C has no route to IP address 1.1.1.1/24, you need to configure
Router B to set itself as the next hop (3.1.1.1/24) for the route to be sent to Router C.
Figure 295 NEXT_HOP attribute configuration