R3303-HP 6600/HSR6600 Routers Layer 3 - IP Routing Configuration Guide

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Figure 72 AS number substitution configuration
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.
Use AS number substitution only in the specific scenario. Improper configuration can result in routing
loops.
To configure AS number substitution for a peer or peer group:
Step 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. Replace the AS number of a
peer or peer group in the
AS_PATH attribute as the local
AS number.
peer { group-name | ip-address }
substitute-as
Not configured by default.
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 64512 to 65535.
To remove private AS numbers from updates to a peer or peer group:
Step 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.