R3721-F3210-F3171-HP High-End Firewalls Network Management Configuration Guide-6PW101

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Configuring the AS-PATH attribute
1. Permit local AS number to appear in routes from a peer/peer group
In general, BGP checks whether the AS_PATH attribute of a route from a peer contains the local AS
number. If so, it discards the route to avoid routing loops.
To permit local AS number to appear in routes from a peer/peer group and specify the
appearance times.
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Permit local AS number to
appear in routes from a
peer/peer group and specify
the appearance times.
peer { group-name | ip-address }
allow-as-loop [ number ]
Optional.
By default, the local AS
number is not allowed.
2. Disable BGP from considering AS_PATH during best route selection
To disable BGP from considering AS_PATH during best route selection:
Ste
p
Command Remarks
1. Enter system view. system-view N/A
2. Enter BGP view.
bgp as-number N/A
3. Disable BGP from considering
AS_PATH during best route
selection.
bestroute as-path-neglect
Optional.
By default, BGP considers
AS_PATH during best route
selection.
3. Specify a fake AS number for a peer/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/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/peer group:
Ste
p
Command Remarks
1. Enter system view.
system-view N/A
2. Enter BGP view. bgp as-number N/A
3. Specify a fake AS number for a
peer/peer group.
peer { group-name | ip-address }
fake-as as-number
Optional.
Not specified by default.
NOTE:
This command is only applicable to an EBGP peer or peer group.
4. Configure AS number substitution
To configure AS number substitution for a peer/peer group: