BGP-4
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.
What It Defines
Border Gateway Protocol version 4 is the inter-domain routing protocol of the internet. BGP speakers exchange OPEN, UPDATE, NOTIFICATION, and KEEPALIVE messages over TCP 179. UPDATE messages carry NLRI (Network Layer Reachability Information) with path attributes: AS_PATH, NEXT_HOP, LOCAL_PREF, MED, COMMUNITY, and ORIGIN. BGP selects the best path via a deterministic decision process.
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
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.
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.
BFD is how networks achieve sub-second failover — without it, BGP takes 90+ seconds to detect a peer failure. Any high-availability design (active-active DC, SD-WAN, carrier) relies on BFD for fast convergence.
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.