H3C Technologies H3C S5560 Series Switches - Manual (Page 254)

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Step Command Remarks
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. ip vpn-instance
vpn-instance-name
N/A
3. Advertise a fake AS number to
a peer or peer group. peer { group-name | ip-address
[ mask-length ] } fake-as as-number
By default, no fake AS number is
advertised to a peer or peer group.
This command applies only to
EBGP peers or EBGP peer groups.
To advertise a fake AS number to a peer or peer group (IPv6):
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. ip vpn-instance
vpn-instance-name
N/A
3. Advertise a fake AS number to
a peer or peer group.
peer { group-name | ipv6-address
[ prefix-length ] } fake-as
as-number
By default, no fake AS number is
advertised to a peer or peer group.
This command applies only to
EBGP peers or EBGP peer groups.
Configuring AS number substitution
IMPORTANT:
Do not configure AS number substitution in normal circumstances. Otherwise, routing loops might occur.
To use BGP between PE and CE in MPLS L3VPN, VPN sites in different geographical areas should have
different AS numbers. Otherwise, BGP discards route updates containing the local AS number. If two CEs
connected to different PEs use the same AS number, you must configure AS number substitution on each
PE. This substitution can replace the AS number in route updates originated by the remote CE as its own
AS number before advertising them to the connected CE.
Figure 60 AS number substitution configuration (in an IPv4 network)