CCIE SP inter-AS MPLS L3VPN
I have a few questions regarding inter-AS MPLS L3VPN
1] Why we have to use IBGP with MPLS ( mpls ip under the interface) inside an AS and EBGP with the command sen-label between AS .Why cannot we use IBGP with the command send-label inside an AS ?
2] Why we have to declare on inter-AS MPLS L3VPN architecture loopbacks networks on the PE which is directly connected to the other AS . for example on the inter AS option C exercice we declare on each side the loopbacks of R5, R2, XR2 and R6.
the question is why we have to declare them on the router R1 and XR1 and not on the routers that originate the networks?