MPLS L3VPN: Customer Routes Missing
MP-BGP is carrying the prefixes and the VRF is empty. Find where they are being filtered, live, right below.
Symptom
The MPLS core is up and MP-BGP is peering, but two sites in the same L3VPN still can't see each other's routes.
Your mission
Inspect, recover, then verify
Format
Cisco IOS CLI
Investigate before you configure.
Use the CLI evidence to isolate the fault, make the smallest safe correction, then verify the network state changed.
Observe the symptom and link state.
Diagnose by comparing the protocol evidence.
Verify the expected device state and confirm the original symptom is resolved.
Console access: PE2 (receiving) · PE1 (originating)
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Need a hint?
Reveal the root cause when you're ready.
Try the investigation first, then use this as your escape hatch, not a dead end.
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Lab debrief
Turn the session into a repeatable troubleshooting pattern.
Use this reference after your attempt: first explain the symptom, then verify the evidence, then confirm the repair.
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
- Verify an MPLS core and its LDP neighbors
- Check the MP-BGP VPNv4 session between the PE routers
- Compare per-customer VRF route-target import and 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.
Commands to run yourself
The real diagnostic commands for this lab, copy-paste ready. Run these in the same order to reproduce the investigation on your own session.
show mpls ldp neighborshow bgp vpnv4 unicast all summaryshow vrf detail CUSTTopology diagram
Inside a real session
More genuine captures from this lab running on the platform, at full size so the console text stays readable.
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Fact-checked references
The commands and behaviour in this lab were checked against these primary references.
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.