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Abdulrazzaq Aminu
Abdulrazzaq Aminu

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iBGP Route Reflector Design for MPLS Layer 3 VPN Backbone

I was responsible for designing and implementing the Route Reflector (RR) control-plane architecture across our core backbone. The infrastructure consisted of a centralized MPLS core, multiple PE routers deployed across regional Points of Presence (PoPs), and CE routers at customer branches throughout Nigeria.

The primary challenge was iBGP scalability: a full mesh between all PE routers would require a rapidly growing number of neighborships (n(n–1)/2). To solve this, I designed a redundant and geographically distributed Route Reflector topology.

These locations were chosen to ensure geographic redundancy, faster convergence during regional outages, and control-plane resilience. Loopback interfaces were advertised via OSPF Area 0, and RRs maintained control-plane-only functionality and no VRF or CE configurations to preserve CPU resources and isolate fault domains.

On each RR, I configured iBGP VPNv4 peering using peer groups, enabling:

  • send-community extended for Route Target propagation.
  • route-reflector-client for efficient route distribution.

Each PE formed iBGP sessions with both RRs using loopback interfaces. I explicitly avoided peering the two RRs with each other, relying on BGP originator-ID and cluster-ID to prevent routing loops. Each RR reflected only routes from its direct clients, maintaining deterministic control-plane behavior.

To validate the deployment, I:

  • Verified VPNv4 route visibility on each PE.
  • Confirmed correct RT and RD propagation.
  • Ensured successful VRF route import/export.
  • Tested CE-to-CE reachability across VRFs.

The result was a highly scalable, loop-free, and resilient iBGP control-plane:

  • Reduced iBGP complexity from multiple neighborships to 2 per PE.
  • Ensured full VPNv4 route reachability across all customer sites.
  • Enabled clean control/data plane separation, improving stability and simplifying troubleshooting.
  • This RR design allowed the MPLS backbone to scale seamlessly as new PEs and customers were added across regions.

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