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BGP and BGP4+ Introduction
Software Reference Supplement for SwitchBlade® x8112, x908, x900 and x610 Series Switches
C613-50032-01 REV D AlliedWare Plus
TM
Operating System - Software Version 5.4.3-2.6 1.41
How to apply BGP filtering for private AS numbers
Apply BGP filtering for private AS numbers using the neighbor <neighborid>
remove-private-AS command. See this example from Router Configuration mode:
If the non-default AS path attribute command is applied to the Router 2 BGP configuration
then the private AS is correctly filtered. See the sample console command entries below:
The show ip bgp command output on ISP Router 1 shows that the update for the network
10.0.0.0/24 received from Router 2 (192.68.0.1) has an AS path attribute 5. This is the AS
number of Router 2, without private AS path 65000.
In the ISP router BGP prefix table below, the only AS path attribute for the 10.0.0.0/24
network is '5', and the AS 65000 has been correctly filtered out from the update sent by
Router 2 received into ISP Router 1. This is displayed in the show ip bgp output below:
awplus#
configure terminal
awplus(config)#
router bgp 5
awplus(config-router)#
neighbor 192.168.0.2 remove-private-AS
Router 2#configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router 2(config)#router bgp 5
Router 2(config-router)#neighbor 192.168.0.2 remove-private-AS
Router 2(config-router)#exit
Router 2(config)#exit
Router 2#clear ip bgp *
Router 1#show running-config router bgp
!
router bgp 1
neighbor 192.168.0.1 remote-as 5
neighbor 192.168.0.2 remove-private-as
!
Router 1#show ip bgp
BGP table version is 1041, local router ID is 192.168.0.2
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal
l - labeled, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 10.0.0.0/24 192.168.0.1 0 0 5 i
*> 172.30.0.0 192.168.0.1 0 0 5 i
*> 192.168.0.0 192.168.0.1 0 0 5 i