Blog

OSPF has a lot of moving parts. The state machine. The LSA types. The area types and what each one

BGP has a lot of moving parts. The state machine. The 13-step path-selection algorithm. The dozen knobs that influence which

Configure GRE tunnels on Linux with ip tunnel add. Cisco-to-Linux interop, MTU, MSS clamping, IPsec, gretap (L2), and persistence with systemd-network

Step-by-step GRE tunnel troubleshooting on Cisco IOS XE. Five-minute triage, recursive routing, MTU drops, keepalive flap, debug commands, and EPC cap

Multipoint GRE, NHRP, and IPsec combined to form DMVPN. The three phases, hub and spoke config for Phase 3, verification commands, and design tradeoff

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.