268
instances on the same PE or PEs with the same AS number. Therefore, H3C recommends configuring
different tags for different OSPF VPN instances.
Configuring BGP AS number substitution and SoO
When CEs at different sites have the same AS number, configure the BGP AS number substitution function
to avoid route loss.
With the BGP AS number substitution function, when a PE advertises a route to the specified CE, if an AS
number identical to that of the CE exists in the AS_PATH of the route, it will be replaced with that of the
PE before the route is advertised.
If the PE connects to multiple CEs in the same site, use a routing policy to add the SoO attribute to the
routes received from the CEs.
Before you configure BGP AS number substitution and SoO, complete the following tasks:
•
Configure basic MPLS L3VPN.
•
Make sure CEs at different sites have the same AS number.
To configure BGP AS number substitution and SoO:
Step Command
Remarks
1.
Enter system view.
system-view
N/A
2.
Create a routing policy and
enter routing policy view.
route-policy
route-policy-name
permit node
node-number
Optional.
No routing policy is created by
default.
3.
Specify SoO attribute value.
apply extcommunity soo
site-of-origin
additive
Optional.
Not specified by default.
4.
Return to system view.
quit
N/A
5.
Enter BGP view.
bgp
as-number
N/A
6.
Enter BGP VPN instance view.
ipv4-family vpn-instance
vpn-instance-name
N/A
7.
Enable the BGP AS number
substitution function.
peer
{
ip-address
|
group-name
}
substitute-as
Disabled by default.
8.
Apply the routing policy to
routes received from the
specified peer.
peer
{
ip-address
|
group-name
}
route-policy
route-policy-name
import
Optional.
Not applied by default.
For more information about the
apply
extcommunity
,
peer
substitute-as, route-policy
and
peer
route-policy
commands, see
Layer 3—IP Routing Command Reference
.
Resetting BGP connections
When BGP configuration changes, you can use the soft reset function or reset BGP connections to make
new configurations take effect. Soft reset requires that BGP peers have route refreshment capability
(supporting Route-Refresh messages).
