HPE 5800 Series Configuration Manual page 212

Step
Enter BGP view or
2.
BGP-VPN instance view.
Disable BGP from
3.
considering AS_PATH
during best route selection.
Specifying a fake AS number for a peer or peer group
When Router A in AS 2 is moved to AS 3, you can configure Router A to specify a fake AS number of
2 for created connections to EBGP peers or peer groups. In this way, these EBGP peers still think
Router A is in AS 2 and need not change their configurations. This feature ensures uninterrupted
BGP services.
To specify a fake AS number for a peer or peer group:
Step
Enter system view.
1.
Enter BGP view or
2.
BGP-VPN instance view.
Specify a fake AS number
3.
for a peer or peer group.
Configuring AS number substitution
In MPLS L3VPN, if EBGP is used between PE and CE, sites in different geographical areas must
have different AS numbers assigned to ensure correct route advertisement. If CEs in different
geographical areas use the same AS number, you must configure the relevant PE to replace the AS
number of the CE as its own AS number. This feature is used for route advertisement only.
Figure 70 AS number substitution configuration
Command
•
Enter BGP view:
bgp as-number
•
Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
bestroute as-path-neglect
Command
system-view
•
Enter BGP view:
bgp as-number
•
Enter BGP-VPN instance view:
a. bgp as-number
b. ipv4-family vpn-instance
vpn-instance-name
peer { group-name | ip-address }
fake-as as-number
201
Remarks
Use either approach.
Optional.
By default, BGP considers
AS_PATH during best route
selection.
Remarks
N/A
Use either approach.
Optional.
Not specified by default.
This command applies to only
an EBGP peer or peer group.