HPE 5800 Series Configuration Manual page 213

As shown in the above figure, CE 1 and CE 2 use the same AS number of 800. If AS number
substitution for CE 2 is configured on PE 2, and PE 2 receives a BGP update sent from CE 1, PE 2
replaces AS number 800 as its own AS number 100. Similar configuration must also be made on PE
1.
IMPORTANT:
Improper AS number substitution configuration may cause route loops; use this command with
caution.
To configure AS number substitution for a peer or peer group:
Step
Enter system view.
1.
Enter BGP view or
2.
BGP-VPN instance view.
Replace the AS number of a
3.
peer or peer group in the
AS_PATH attribute as the
local AS number.
Removing private AS numbers from updates to a peer or peer group
Private AS numbers are typically used in test networks, and need not be transmitted in public
networks. The range of private AS numbers is from 64,512 to 65,535.
To remove private AS numbers from updates to a peer or peer group:
Step
Enter system view.
1.
Enter BGP view or
2.
BGP-VPN instance view.
Configure BGP to remove
3.
private AS numbers from the
AS_PATH attribute of
updates to a peer or peer
group.
Ignoring the first AS number of EBGP route updates
Typically, BGP checks the AS_PATH attribute of a route update received from a peer. If the first AS
number is not that of the BGP peer, the BGP router discards the route update.
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 }
substitute-as
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 }
public-as-only
202
Remarks
N/A
Use either approach.
Not configured by default.
Remarks
N/A
Use either approach.
By default, BGP updates carry
private AS numbers.