RADIUS — UDP AAA for Access & Accounting

Centralised AAA over UDP: authentication 1812, accounting 1813 (legacy 1645/1646). Only the password field is encrypted — headers and attributes travel in the clear, which is the core difference to TACACS+. Flow: Access-Request → Access-Accept/Reject/Challenge; authorization returns attributes (VLAN, ACL, session timeout); accounting sends start/stop/interim updates. The protocol of 802.1X and wireless (ISE downstream) — […]