How OSPF SPF Algorithm and LSDB Work
OSPF builds the LSDB, then runs Dijkstra (SPF) to calculate best paths. Here is what triggers partial vs full SPF and how to tune the throttle timers.
1 min read
Blog
OSPF LSA Types Explained (Type 1–7)
OSPF uses seven LSA types (1 through 7) to describe routers, networks, summaries, and externals. Here is what each one carries, who generates it, and where it floods.
5 min read
OSPF Subnet Mask Mismatch: How to Troubleshoot and Fix
On broadcast networks, mismatched subnet masks leave OSPF stuck in Init or 2-Way. Here is the fast diagnosis with show ip ospf neighbor and the one-line fix.
1 min read
OSPF Design Best Practices for Enterprise Networks
Real OSPF design rules: keep Area 0 stable and small, cap routers per area, use stub where you can, and make summarization a feature of your area boundaries.
4 min read
Understanding RADIUS in 802.1X Authentication
RADIUS is the glue between a Catalyst switch and Cisco ISE in 802.1X. Here is how the Access-Request carries EAP, why UDP 1812/1813 matters, and where failures surface.
9 min read
EAPOL Explained: How 802.1X Traffic Moves Over the Wire
EAPOL carries EAP between the supplicant and switch at Layer 2. It never leaves the segment, which is why captures and debug have to happen on or at the port.
8 min read