H3C Technologies H3C S7500E Series Switches - Manual (Page 235)

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Configuring the AS-PATH Attribute
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.
This task allows you to permit local AS number to appear in routes from a peer/peer group and specify
the appearance times.
To do… Use the command… Remarks
Enter system view system-view —
Enter BGP view bgp as-number —
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.
Disable BGP from considering AS_PATH during best route selection
Follow these steps to disable BGP from considering AS_PATH during best route selection:
To do… Use the command… Remarks
Enter system view system-view —
Enter BGP view bgp as-number —
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.
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 thus need not change their configurations. This feature ensures uninterrupted BGP
services.
Follow these steps to specify a fake AS number for a peer/peer group:
To do… Use the command… Remarks
Enter system view system-view —
Enter BGP view bgp as-number —
Specify a fake AS number for a peer/peer
group
peer { group-name |
ip-address } fake-as as-number
Optional
Not specified by default