STP bug on IOL l2 image

Past 2 days was spent mainly to get familiar with secureCRT & Anki.

Today:

- converted my hand written note on some INE SD-WAN & L2 videos into Anki card

- Discovered a STP bug with i86bi-linux-l2-adventerprisek9-15.6.0.9S.bin, STP does not converge, 2 switches connected with 2 trunk link => both elect themselves as root and eventually crash 👀😕. downgraded to i86bi-linux-l2-adventerprisek9-15.2d.bin, all good. should have paid attention to the suggested image version on https://learningnetwork.cisco.com/s/article/ccie-enterprise-infrastructure-equipment-and-software-list. DONT BE ADVENTUROUS !!