BGP neighbor activate command
The neighbor activate command is used to enable the exchange of information with a BGP neighbor. It can be applied in both router configuration mode as well as address-family mode.
Note that by default, the exchange of addresses with BGP neighbors is enabled for the IPv4 address family. Address exchange for all other address families is disabled. So any prefixes configured within the IPv6 address-family mode must have this command within the address-family configuration in order for them to be exchanged.
Links:
https://forum.networklessons.com/t/multiprotocol-bgp-mp-bgp-configuration/1177/62?u=lagapides