Blog

The 802.1Q VLAN tag is 4 bytes inserted into Ethernet frames to carry VLAN identity across trunks. TPID, TCI, PCP, DEI, VID, and the native VLAN explained byte by byte.

RSTP (802.1w) replaced classic 802.1D's 30-50 second convergence with sub-second failover. The five key changes that make it possible, and how to deploy Rapid PVST+ on Cisco IOS XE.

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.

A complete, copy-pasteable walkthrough of deploying wired 802.1x with Cisco ISE as the RADIUS server and a Catalyst switch as the authenticator — from Policy Sets to IBNS 2.0 CLI to show commands and Live Logs.

Path steering is now table stakes. Real SD-WAN value in 2026 comes from Day-2 operations: template management, observability, policy drift, and upgrade discipline. Here is what actually matters once the rollout is done.

Catalyst Center CLI templates sit between full manual work and heavy automation frameworks. Here is how to use them for repeatable, non-fragile network changes across campus and enterprise sites without building a platform you regret in six months.