IOL vs IOSv in Containerlab: Which Image Passed Each Lab Test
Built in my home lab: twelve Containerlab tests decide IOL, IOL-L2 or IOSv-L2. IOSv-L2 won dynamic DHCP snooping and 802.1X; IOL-L2 won IPSG, RA Guard and SPAN.
Switching
Moving frames at layer 2 and everything that decides where they go. Articles tagged Switching cover MAC learning, forwarding and flooding, port behavior, and the switch-side half of a routing problem.
Latest posts
BPDU Guard Lab: Catch a Rogue Bridge on an Access Port
Built in my home lab: a Linux bridge sends BPDUs, BPDU Guard err-disables the Cisco access port, and shutdown/no shutdown restores it. Storm control stays untested.
STP Root Port Election Worked Example: Cost, Neighbor BID, and Port ID
Calculate root ports on six switches using cost, neighbor BID, and sender port ID. Check real outputs, then change one cost to move SW4’s root port.
Cisco Port Security vs MAC Flooding: Limit Learning, Fix Shutdowns
Test Cisco port security against MAC flooding: 17,991 learned entries, a three-MAC protected table, and a phone-plus-PC shutdown fixed with maximum 2.
Errdisable Recovery on Cisco: Every Cause and How to Bring the Port Back
An err-disabled port stays down forever by default, because nothing auto-recovers until you arm it. The full cause list from IOS XE 17.18.2, how to identify which one fired in ten seconds, and the captured proof that auto-recovery is a retry loop rather than a fix.