https://www.juniper.net/documentation/en_US/junos/topics/reference/configuration-statement/family-edit-protocols-bgp-route-target-vp.html

The family route-target statement is useful for filtering VPN routes before they are sent.

Provider edge (PE) routers inform the route reflector (RR) which routes to send, using family route-target to provide the route-target-interest information.

The RR then sends to the PE router only the advertisements containing the specified route target.

Route-Target Filtering for MBGP VPNs 

https://www.juniper.net/documentation/en_US/junose15.1/topics/concept/bgp-route-targets-overview.html

BGP route target filtering (RTF) 

https://www.juniper.net/documentation/en_US/contrail5.0/topics/task/configuration/route-target-filtering-vnc.html