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Phase 3 Concepts · MPLS & L3VPN Deep Dive

📖 Theory & Architecture Deep Dive. Understand the protocol mechanics, packet headers, and hardware forwarding tables under the hood before or after building the labs.

Concept Modules

  • 1 · MPLS Architecture & Header Mechanics

    32-bit MPLS Shim Header breakdown (Label, TC/Exp, Bottom-of-Stack S, TTL), Push/Swap/Pop hardware operations, LIB vs LFIB tables.

  • 2 · LDP & Label Distribution

    LDP UDP 646 hello discovery, TCP 646 session establishment, Downstream Unsolicited (DU) vs Downstream-on-Demand (DoD), Independent vs Ordered control modes.

  • 3 · L3VPN Control & Data Plane (RFC 4364)

    64-bit Route Distinguishers (RD), BGP Extended Community Route Targets (RT), MP-BGP VPNv4 (AFI 1 / SAFI 128), Two-Label Packet Walk, Penultimate Hop Popping (PHP RFC 3032).

  • 4 · Inter-AS Options A, B, & C

    Option A (back-to-back VRFs), Option B (ASBR VPNv4 label swap), Option C (BGP Labeled Unicast RFC 3107/8277 + Multi-hop MP-eBGP).

  • 5 · L2VPN & Pseudowire Architecture

    VPWS Point-to-Point Pseudowires (EoMPLS RFC 4664), Control Word (CW), VPLS Split-Horizon loop prevention rules, EVPN-VPWS / EVPN-ELAN.