We need to configure export and import RTs in a VRF so that while VPNv4 routes are exchanged between PEs so that PE will know which VRF a particular VPNv4 route has to be installed based on RTs. If RTs are not configured, then routes will not be installed in BGP routing table (exception if no bgp default route-target filter command is used).
However, if route reflector is used and PEs are estabalishing VPNv4 neighborship with RR, I noticed even without "no bgp default route-target filter" command, routes are getting exchanged and present in BGP routing table.
My question is with RR, is this an expected behavior that command is not required and still routes gets exchanged because routes are just getting reflected to other PEs.
by default all the routes install in the bgp table w.r.t vrf configured or not. This is simply wastage of memory. So after adding the command "no bgp default route-target filter" only those routes will be installed whose vrf need to be configured on that router.
By default when router is made RR, it si the default behavior with it.