HP 6125XLG - Page 214

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the router to advertise a fake AS number 2 to its EBGP peers so that the EBGP peers still think that Router
A is in AS 2.
To advertise a fake AS number to a peer or peer group (IPv4):
Ste
p
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 | ip-address }
fake-as as-number
By default, no fake AS number is
advertised to a peer or peer group.
This command applies to only
EBGP peers or EBGP peer groups.
To advertise a fake AS number to a peer or peer group (IPv6):
Ste
p
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 } fake-as as-number
By default, no fake AS number is
advertised to a peer or peer group.
This command applies to only
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 to replace the AS number in route updates originated by the remote CE as its own AS number before
advertising them to the connected CE.