Master Segment Routing with MPLS: From Basics to Advance

Explore why MPLS became popular through its 32 bit label and MPLS enabled services, debunking myth that label based forwarding is faster and noting segment routing's data plane with MPLS.

Understand the MPLS packet format, including a 20-bit label, three experimental bits, a bottom-of-stack bit, and 8-bit etl, and how label-based forwarding carries L2 or L3 payloads for unified transport.

Explore how MPLS blends the efficiency of layer two with the scalability of layer three, delivering flexible traffic engineering and the best of both approaches for service providers.

Explore how MPLS provides a unified network infrastructure that carries any layer 2 or layer 3 payload without a protocol field, benefiting service providers with a single traffic solution.

Learn how the MPLS data plane forwards packets by labels, enabling switch-like layer two and three traffic. LDP, BGP, RSVP, and segment routing distribute labels via OSPF and ISIS.

Explore how MPLS uses 32-bit label stack entries with a 20-bit label field, outer transport and inner service labels, and how LDP and OSPF distribute them while routers swap them.

Explore why label stacking uses a transport top label for hop-by-hop forwarding and a service label to identify VPN VRFs, enabling L3/L2 VPNs with multiple VPLS/VPI instances.

Explore MPLS label operations—push, swap, and pop—and how routers use the MPLS FIB to forward labels, while unknown labels are dropped without a fallback.

Explore how MPLS uses implicit null and explicit null labels, and how penultimate hop popping reduces lookups while preserving traffic class in the data plane.

Perform a hands-on MPLS lab to enable MPLS on interfaces, establish LDP neighbors, and verify forwarding with the MPLS forwarding table and debug outputs. Review label bindings and routing interactions.

Configure and verify mpls layer 3 vpn using ldp and bgp, including vrf setup, vpnv4 address family, redistribution, and tracing label forwarding across the mpls network.

Learn why segment routing simplifies MPLS by replacing multiple control-plane protocols with a streamlined approach, while MPLS data planes stay the same and BGP and IGP justify services.

Explore how segment routing unifies underlay and overlay networks across the data plane and control plane to support dynamic applications and streamlined end-to-end provisioning.

Explore how segment routing reduces complexity and enables automation by cutting reliance on RSVP, MPLS LDP, and related protocols, as shown through a real-world service provider story.

Discover practical reasons behind segment routing evolution in MPLS networks. See how segment routing simplifies the control plane, uses IGP labeling, and improves convergence and traffic engineering.

Explore how segment routing simplifies the MPLS control plane, replacing a heavy, protocol-laden SP transport network with a simpler SRX-driven stack, illustrated through a practical analogy.

Discover segment routing as a source-based architecture where the source encodes an ordered list of segments on the packet to specify the forwarding path.

Learn segment routing with prefix sid and adjacency sid, where igp carries the prefix and label; distinguish global prefix and adjacency segments using srgb and no dedicated label distribution protocol.

Explore how segment routing uses the IGP to carry MPLS labels, enabling prefix and adjacency segments, with OSPF as the carrier and label distribution.

Explore how segment routing simplifies the MPLS control plane by distributing labels via OSPF opaque aliases, with emphasis on SR IGP and OSPF integration for efficient forwarding.

Explains how to configure OSPF segment routing over MPLS, enabling SR, allocating SRGB, and interpreting opaque LSA and the MPLS forwarding table in IOS XR.

Explore how penultimate hop popping operates in segment routing with the MPLS data plane and how it differs from legacy MPL, including downstream-neighbor checks.

Demonstrates enabling segment routing on lab devices with OSPF and MPLS/LDP, configuring index values, and verifying SRX preferred forwarding via opaque LSAs.

Remove ldp and confirm sr-based forwarding remains active. Use traceroute to verify connectivity and note that all nodes must support sr, or use a mapping server during migration.