How can P routers forward VPN packets if they do not have VPN routes?
- They forward based on the MP-BGP next hop.
- They forward based on the VPN label.
- They forward based on a routing table lookup of the IP address.
- They forward based on the LSP label.
Explanation: In an MPLS L3 VPN, packets are sent across the provider core using a two-level label stack. The P routers (core routers) only examine the top label, which is the LDP-assigned label for the egress PE router. This label defines the LSP (Label Switched Path), allowing core routers to switch the packet toward the destination PE without needing any knowledge of the inner VPN routes.
Related exam: Checkpoint Exam: MPLS and VPN Technologies
