1. Nokia 7750 SR OS Services Guide, Release 22.10.R1, Chapter: Virtual Private Routed Network Services, Section: VPRN BGP. The documentation explicitly describes the configuration process where export policies are applied to the VPRN BGP instance. It states, "Export policies are used for routes advertised to other BGP peers." This includes the MP-BGP peers in the core, confirming that policies are used to control the redistribution from the VRF's BGP table into the core MP-BGP advertisements. The configuration context config>service>vprn>bgp>export is the mechanism for applying this control.
2. RFC 4364 - BGP/MPLS IP Virtual Private Networks (VPNs), Section 4.3.2, "Exporting VPN-IPv4 Routes from VRFs to BGP." This foundational RFC directly addresses the process. It states: "The PE's decision to export a particular route from a particular VRF is a matter of policy." This confirms that a policy-based decision is an integral part of the architecture for deciding which routes learned from a CE are advertised to other PEs.
3. Nokia Data Center Fabric with SR Linux Cookbook, Section 3.3.2.2, "EVPN-VXLAN L3 service for inter-subnet forwarding." While discussing a different encapsulation (EVPN-VXLAN), the principle remains identical for L3VPN services. The guide shows the application of an export policy (from-ip-vrf-1) to the BGP instance within the VRF to control which routes are advertised into the EVPN fabric. This demonstrates the consistent requirement for export policies in Nokia's L3VPN service architecture. The configuration snippet shows: bgp { export-policy from-ip-vrf-1; } within the VRF context, reinforcing the necessity of policy control.