Segment Routing
SR is replacing RSVP-TE and MPLS LDP in modern SD-WAN, 5G transport, and hyper-scale DC networks. Cisco, Juniper, Nokia, and Arista have all standardized on it. Essential for modern network engineering.
What It Defines
Segment Routing encodes a network path as an ordered list of segments (node SIDs, adjacency SIDs, prefix SIDs) either in an MPLS label stack (SR-MPLS) or IPv6 extension header (SRv6). Eliminates need for RSVP-TE and LDP signaling while enabling traffic engineering, fast reroute, and service chaining. IGPs (IS-IS, OSPF) distribute SR segment IDs.
Canonical (Normative)
Convenient (Practical)
Related References
The canonical publication point for finalized RFCs. If a protocol is standardized as an RFC, the RFC Editor text is the normative final reference. Published by the IETF, IRTF, IAB, and independent stream.
Related Specs
MPLS is the forwarding substrate of carrier networks, MPLS VPNs, and traditional WAN services. Understanding FEC, LDP, and LSP concepts is essential for service provider or enterprise WAN networking.
BGP stitches the internet together — every AS, CDN, cloud provider, and multi-homed network runs it. Understanding AS path, communities, and prefix aggregation is essential for cloud networking, CDN design, and any serious network engineering role.
IS-IS is the IGP of choice in most Tier-1 and Tier-2 carrier networks and large-scale DC fabrics (Meta, Amazon). It runs under BGP in many hyperscale designs. Essential for service provider and large-scale DC networking roles.
OSPF is the interior routing protocol of choice for enterprise and carrier networks. Understanding area design, LSA types, and SPF convergence is essential for data center networking, WAN design, and network certification paths.