An Access Control List (ACL) filters network traffic, either forwarding, dropping, or blocking traffic depending on your settings. Pioneered by Cisco, this technology is familiar to most on routers, but has recently expanded to switching technology – which is likely much less familiar.

This whitepaper details switch-based access lists, explores their common uses, and demonstrates how they are best used on IOS-based Catalyst devices, including RACLs, PACLs, and VACLs.