Juniper BGP - CONFIGURATION GUIDE V 11.1.X Configuration Manual page 191

exit-address-family
neighbor activate
The default setting is to exchange IPv4 addresses in unicast mode from the
default router.
This command takes effect immediately.
Examples
host1:vr1(config-router)#address-family ipv4 multicast
host1:vr1(config-router)#address-family vpnv4
host1:vr1(config-router)#address-family ipv4 unicast vrf vr2
Use the no version to disable the exchange of a type of prefix.
See address-family.
Use to exit Address Family Configuration mode and access Router Configuration
mode.
Example
host1:vr1(config-router-af)#exit-address-family
There is no no version.
See exit-address-family.
Use to specify a peer with which routes of the current address family are
exchanged.
A peer can be activated in more than one address family. By default, a peer is
activated only for the IPv4 unicast address family.
The peer must be created in unicast IPv4 or VPN IPv4 before you can activate
it in another address family.
If you specify a BGP peer group by using the peerGroupName argument, all the
members of the peer group inherit the characteristic configured with this
command unless it is overridden for a specific peer.
The address families that are actively exchanged over a BGP session are
negotiated when the session is established.
This command takes effect immediately. If dynamic capability negotiation was
not negotiated with the peer, the session is automatically bounced so that the
exchanged address families can be renegotiated in the open messages when the
session comes back up.
If dynamic capability negotiation was negotiated with the peer, BGP sends a
capability message to the peer to advertise or withdraw the multiprotocol
capability for the address family in which this command is issued. If a neighbor
is activated, BGP also sends the full contents of the BGP routing table of the newly
activated address family.
Example
host1:vr1(config-router-af)#neighbor 192.168.1.158 activate
Chapter 1: Configuring BGP Routing
Configuring BGP Multicasting
155