BGP

Border Gateway Protocol, the path-vector protocol that holds the internet together and increasingly runs inside enterprise data centers. Articles tagged BGP cover fundamentals, neighbor states, path attributes, best-path selection, traffic engineering, and Cisco IOS XE configuration.

39 posts

BGP

MP-BGP: Multiprotocol BGP Address Families Explained

MP-BGP (RFC 4760) is what lets a single BGP session carry IPv6, VPNv4, EVPN, and more. The AFI/SAFI model, route distinguishers, and how modern data center fabrics use MP-BGP for everything.

Apr 25, 2026 6 min read

BGP

BGP Neighbor States: The 6-State FSM and How to Diagnose It

BGP's finite state machine has six states: Idle, Connect, Active, OpenSent, OpenConfirm, Established. What each means, why Active is a problem state, and the diagnostic that maps each stuck state to a real cause.

Apr 25, 2026 7 min read

BGP

BGP vs OSPF: When to Use Each Routing Protocol

BGP and OSPF solve different problems and almost always run together in production. The technical differences, when each is the right answer, and the architecture pattern most enterprises end up with.

Apr 25, 2026 7 min read

BGP

BGP Path Attributes Explained: Well-Known vs Optional

BGP path attributes are the foundation of every traffic engineering technique: local preference, MED, AS-path prepending, communities. Understand the well-known vs optional attribute matrix before touching policy.

Mar 28, 2026 4 min read

BGP

BGP Message Types: OPEN, UPDATE, KEEPALIVE, and NOTIFICATION

BGP uses just four message types: OPEN, UPDATE, KEEPALIVE, and NOTIFICATION. Understanding the field-level format of each makes debug output and packet captures far more readable for anyone troubleshooting BGP.

Mar 28, 2026 4 min read

BGP

eBGP vs iBGP: What's the Difference and When to Use Each

eBGP and iBGP look similar at a glance but behave very differently around TTL, next-hop, AS-path, and route advertisement. Treating them as the same protocol gets you in trouble fast; here are the rules.

Mar 28, 2026 4 min read