MPLS L3VPN: Customer Routes Missing
MPLS L3VPN is where a provider core and customer routing meet, and route-targets are where it quietly breaks. This lab gives you a real LDP core with MP-BGP VPNv4 between PEs and per-customer VRFs, so you can watch a route-target mismatch present as missing customer routes rather than a down core.
Not a mockup, this is the real topology
The problem
Two customer sites in the same L3VPN can't reach each other. The MPLS core is up, LDP labels are exchanged, and each PE learns its own local CE routes, but the remote site's prefixes never appear in the customer VRF at the other PE.
What you'll practice
- Build an MPLS core with LDP label distribution
- Establish MP-BGP VPNv4 sessions between PE routers
- Configure per-customer VRFs with route-target import/export
- Diagnose why VPNv4 routes fail to install in a VRF
- Verify end-to-end CE-to-CE reachability across the L3VPN
The topology
A provider core of P and PE routers runs MPLS with LDP, and two PEs each attach to a customer CE inside one L3VPN. Labels switch across the core while MP-BGP carries the customer prefixes as VPNv4, so a route-target mismatch shows up as missing customer routes, not a broken core.
Topology diagram
Frequently asked
Is the core actually broken?
No, and that's the lesson. LDP and MP-BGP can be perfectly healthy while a route-target mismatch quietly filters the customer's VPNv4 routes at import.
Does this map to SPCOR?
Yes. MPLS, LDP, MP-BGP VPNv4 and L3VPN are core Cisco Service Provider (SPCOR) topics, exercised here on a real multi-router core.
Ready to run this lab yourself?
No setup, no image sourcing. Book a session or ask for a live demo.