Brocade Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide (Supporting R05.6.00) - Manual (Page 755)

Multi-Service IronWare Multiprotocol Label Switch (MPLS) Configuration Guide 731
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BGP or MPLS VPN sample configurations
6
Brocade(config-vrf-vpn1)# route-target import 100:20
Brocade(config-vrf-vpn1)# route-target import 100:80
Brocade(config-vrf-vpn1)# route-target import 100:14
Brocade(config-vrf-vpn1)# exit-vrf
Autonomous system number override
In the example shown in Figure 80 the service providers network is in AS1 and the customer wants
both of his CE routers at different sites to use AS 2. When a route is sent from CE 1 to CE 2, it
contains an AS_PATH attribute containing AS 2. When CE 2 sees that the AS_PATH attribute
contains its own AS number, it rejects the route.
FIGURE 80 AS number override example
One solution to this problem is to configure PE 2 to override the AS_PATH attribute that contains AS
2. When this is enabled, the PE router determines when the AS_PATH attribute in a route intended
for a neighbor CE contains the same AS number as the CE. When this is determined, the PE router
substitutes its own AS number for the CE’s in the AS_PATH attribute. The CE is then able to receive
the route. The following addition conditions apply when this feature is in effect:
The following example describes the configuration of PE 2 required to enable Autonomous System
number override for the BGP neighbor CE 2.
Brocade(config)# router bgp
Brocade(config-bgp)# local-as 1
Brocade(config-bgp)# neighbor 10.2.2.1 remote-as 1
Brocade(config-bgp)# neighbor 10.2.2.1 update-source loopback0
Brocade(config-bgp)# address-family ipv4 unicast vrf VPN1
Brocade(config-bgp-ipv4u-vrf)# neighbor 10.33.36.2 remote-as 2
Brocade(config-bgp-ipv4u-vrf)# neighbor 10.33.36.2 as-override