Tuning And Optimizing Bgp Networks; Configuration Prerequisites - HP MSR2000 series Configuration Manual

Specifying a fake AS number for a peer or 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 or 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 or peer group:
Step
1. Enter system view.
2. Enter BGP view.
3. Specify a fake AS number for a peer or
peer group.
Removing private AS numbers from updates to a peer or peer group
Step
1. Enter system view.
2. Enter BGP view.
3. Configure BGP to remove private AS
numbers from the AS_PATH attribute of
updates to a peer or peer group.
Ignoring the first AS number of EBGP route updates
Typically, BGP checks the AS_PATH attribute of a route update received from a peer. If the first AS number
is not that of the BGP peer, the BGP router discards the route update.
To ignore the first AS number of EBGP route updates:
Step
1. Enter system view.
2. Enter BGP view.
3. Configure BGP to ignore the first AS
number of EBGP route updates.

Tuning and optimizing BGP networks

Configuration prerequisites

BGP connections must be created.
Command
system-view
bgp as-number
peer { group-name | ip-address }
fake-as as-number
Command
system-view
bgp as-number
peer { group-name | ip-address }
public-as-only
Command
system-view
bgp as-number
ignore-first-as
213
Remarks
N/A
N/A
Optional.
Not specified by default.
This command is only
applicable to an EBGP peer
or peer group.
Remarks
N/A
N/A
By default, BGP updates
carry private AS numbers.
Remarks
N/A
N/A
By default, BGP checks the
first AS number of EBGP
route updates.