Tuning And Optimizing Bgp Networks - HP 4800G Series Configuration Manual

Figure 1-19 AS number substitution configuration
EBGP_Update:10.1.1.1/32
AS_PATH:800
AS 800
As shown in the above figure, CE 1 and CE 2 use the same AS number of 800. If AS number
substitution for CE 2 is configured on PE 2, when PE 2 receives a BGP update sent from CE 1, it
replaces AS number 800 as its own AS number 100. Similar configuration should also be made on PE
1.
Follow these steps to configure AS number substitution for a peer/peer group:
Enter system view
Enter BGP view
Replace the AS number of a peer/peer
group in the AS_PATH attribute as the
local AS number
Improper AS number substitution configuration may cause route loops; use this command with caution.
Remove private AS numbers from updates to a peer/peer group
Follow these steps to remove private AS numbers from updates to a peer/peer group:
Enter system view
Enter BGP view
Configure BGP to remove private AS
numbers from the AS_PATH attribute of
updates to a peer/peer group

Tuning and Optimizing BGP Networks

Prerequisites
BGP connections have been created.
AS 100
PE 1
MPLS backbone
VPNv4_Update:10.1.0.0/16
RD:10.1.1.1/32
AS_PATH:800
CE 1
To do...
To do...
PE 2
EBGP_Update:10.1.1.1/32
AS_PATH:100,100
CE 2
AS 800
Use the command...
system-view
bgp as-number
peer { group-name |
ip-address } substitute-as
Use the command...
system-view
bgp as-number
peer { group-name |
ip-address } public-as-only
1-31
Remarks
—
—
Optional
Not configured by default.
Remarks
—
—
Optional
By default, BGP updates
carry private AS
numbers.