Open Shortest Path First, the link-state IGP behind most enterprise networks. Articles tagged OSPF cover neighbor relationships, LSA types, areas, DR/BDR election, and Cisco IOS XE configuration.
SPF and LSA throttle timers control what OSPF does after a failure is detected. Learn the exponential backoff algorithm, the modern IOS XE defaults, and how to tune convergence without letting a flapping link spike every CPU in the area.
A complete dual-stack OSPFv3 configuration on Cisco IOS XE, from ipv6 unicast-routing to verified end-to-end reachability, with every capture taken from a live CML lab.
OSPFv3 is a protocol redesign, not OSPF with longer addresses, and with address families it carries IPv4 too. See what changed from OSPFv2, what stayed identical, and what it looks like on the wire in a live Cisco IOS XE lab.
Two border routers redistributing between the same domains give every prefix a feedback path. Build the forwarding loop live on Cisco IOS XE, capture it happening, then fix it with route tags the way production networks do.
Route redistribution end to end on Cisco IOS XE: how seed metrics work, what each protocol demands before accepting foreign routes, and what the routing table looks like at every stage. Every capture comes from a live CML lab.
Before LSA types make sense, you need what an LSA actually is: one record in the link-state database describing one piece of the network. This post covers the LSA as a building block and how it gets everywhere it needs to be.
OSPF passive-interface stops Hellos and adjacencies on an interface but still advertises its subnet. Config, the default pattern, and the route-filter gotcha.
When OSPF and BGP both know about the same prefix, who wins? A practical walkthrough of mutual redistribution, the admin-distance trap, and why BGP into OSPF needs a filter or it takes down your domain.
Nine printable pages of OSPF: the neighbor state machine, the six LSA types compared, area types and what each one filters, DR/BDR election rules, and the exact words to type when adjacency is stuck in EXSTART.
Run OSPF, EIGRP, and BGP across GRE tunnels on Cisco IOS XE. Recursive routing fix, OSPF network types, EIGRP metric tuning, and BGP update-source.
EIGRP vs OSPF in 2026. The technical differences, the convergence story, vendor reality (EIGRP is still Cisco-only in practice), and the design implications for new vs existing networks.
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.