The vrf's are logical separations. When you enable a vrf in bgp, the vrf still has route-targets that either import or export other route-targets to share information between vrfs. When you have multiple vrfs configured under bgp like this, they don't automatically share information because they're configured under the vrf. That depends on how you have your vrf configured.

Enabling vpnv4 address family doesn't automatically configure bgp with the vrf address-family configuration (unless I'm misunderstanding what you're stating). You will have to have the vrf configured under bgp in order to share your routing information to your other PEs. This is also the place where you configure redistribution of other protocols.

HTH,
John

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