Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

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Figure 18: Advertising a Route When Another Route is Present
The following commands represent a partial configuration of router R2:
host1(config)# router bgp 200
host1(config-router)# address-family ipv4 unicast
host1(config-router-af)# neighbor 10.2.0.1 remote-as 100
host1(config-router-af)# neighbor 10.2.0.1 advertise-map advertisetoR1 exist-map trigger1
sequence 10
host1(config-router-af)# neighbor 10.2.0.1 advertise-map alternatetoR1 exist-map trigger2
host1(config-router-af)# exit
host1(config-router)# exit
!
!Configure route map to send one route to R1
!
host1(config)#
access-list 77 permit 10.10.20.0 0.0.0.255
host1(config)# route-map advertisetoR1 permit 10
host1(config-route-map)# match ip address 77
host1(config-route-map)# exit
!
!Configure route map to match one trigger route from R3
!
host1(config)#
ip as-path access-list 1 permit ^300
host1(config)# access-list 70 permit 172.24.19.0 0.0.0.255
host1(config)# route-map trigger1 permit 10
host1(config-route-map)# match ip address 70
host1(config-route-map)# match as-path 1
host1(config-route-map)# exit
!
!Configure route map to send alternate route to R1
!
host1(config)#
access-list test permit 10.10.30.0 0.0.0.255
host1(config)# route-map alternatetoR1 permit 10
host1(config-route-map)# match ip address test
host1(config-route-map)# exit
!
!Configure route map to match alternate route from R3
!
host1(config)#
access-list check permit 172.24.20.0 0.0.0.255
host1(config)# route-map trigger2 permit 10
host1(config-route-map)# match ip address check
host1(config-route-map)# exit
Copyright © 2010, Juniper Networks, Inc. 66
JunosE 11.2.x BGP and MPLS Configuration Guide