Juniper JUNOSE 11.2.X BGP AND MPLS, Configuration Manual

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The neighbor remote-as command activated the IPv4 unicast address family for the
peer. The address-family command entered the context of the VPNv4 unicast family
and the neighbor activate command activated the address family for the peer.
Example 2 The following commands illustrate one way to disable the exchange of routes in the IPv4
unicast address family and enable the exchange of routes in the VPNv4 unicast address
family:
host1:vr1(config)# router bgp 777
host1:vr1(config-router)# neighbor 10.26.5.10 remote-as 100
host1:vr1(config-router)# address-family ipv4 unicast
host1:vr1(config-router-af)# no neighbor 10.26.5.10 activate
host1:vr1(config-router-af)# exit-address-family
host1:vr1(config-router)# address-family vpnv4 unicast
host1:vr1(config-router-af)# neighbor 10.26.5.10 activate
host1:vr1(config-router-af)# exit-address-family
In this case, the no neighbor activate command specifically disables the IPv4 unicast
address family for that peer alone; no other peers are affected. The VPNv4 unicast address
family is activated for the peer as in Example 1.
Example 3 The following commands illustrate another way to disable the exchange of routes in the
IPv4 unicast address family and enable the exchange of routes in the VPNv4 unicast
address family:
host1:vr1(config)# router bgp 777
host1:vr1(config-router)# no bgp default ipv4-unicast
host1:vr1(config-router)# neighbor 10.26.5.10 remote-as 100
host1:vr1(config-router)# address-family vpnv4 unicast
host1:vr1(config-router-af)# neighbor 10.26.5.10 activate
host1:vr1(config-router-af)# exit-address-family
In this case, the no bgp default ipv4-unicast command prevents the automatic enabling
of the IPv4 unicast address family for all peers subsequently configured with the neighbor
remote-as command. Previously configured peers are not affected. The VPNv4 unicast
address family is activated for the peer as in Examples 1 and 2.
Using a Single AS Number for All CE Sites
If you want to use the same AS number for all of your CE sites, you can substitute a PE
router’s autonomous system number for that of a neighbor by specifying the neighbor’s
IP address in the
neighbor as-override command. If you fail to do this, the CE router
recognizes its AS in the AS path of received routes and determines it has discovered a
routing loop; the routes are rejected.
Example In the following example, the router’s AS number of 777 overrides the neighboring router’s
AS number of 100.
host1:vr1(config)# router bgp 777
host1:vr1(config-router)# neighbor 172.16.20.10 remote-as 100
host1:vr1(config-router)# neighbor 172.16.20.10 update-source loopback0
host1:vr1(config-router)# address-family ipv4 vrf vpn1
host1:vr1(config-router-af)# neighbor 172.25.14.12 remote-as 100
447 Copyright © 2010, Juniper Networks, Inc.
Chapter 6: Configuring BGP-MPLS Applications