BGP-3107 is used as the label distribution protocol on the CSC interface. When BGP in a CSC VPRN needs to distribute a label corresponding to a received VPN-IPv4 route, it takes the label from the global label space. The allocated label will not be re-used for any other FEC regardless of the routing instance (base router or VPRN). If a label L is advertised to the BGP peers of CSC VPRN A then a received packet with label L as the top most label is only valid if received on an interface of VPRN A, otherwise the packet is discarded.
To use BGP-3107 as the label distribution protocol on the CSC interface, add the family label-ipv4 command to the family configuration at the instance, group, or neighbor level. This causes the capability to send and receive labeled-IPv4 routes {AFI=1, SAFI=4} to be negotiated with the CSC-CE peers.