Decades ago I understood the intricacies of AAA on Cisco IOS. These days I wing it and keep throwing spaghetti at the virtual wall until something sticks and I can log in (after all, it’s all in a lab, and I’m interested in routing protocols not interactions with TACACS+ server).

If you’re experiencing similar challenges you might appreciate AAA Deep Dive on Cisco Devices by the one and only Daniel Dib.