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Disabling the Default Address Family

PE routers can exchange routes in the IPv4 address family, VPNv4 address family, or both. Issuing the neighbor remote-as command automatically activates the IPv4 unicast address family, meaning that the PE router exchanges routes in the IPv4 unicast address family with that peer.

Example 1

The following commands illustrate how to configure the exchange of routes in both the IPv4 unicast and the VPNv4 unicast address families for a BGP peer:



host1:vr1(config)#router bgp 777 

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

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.

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