What is PAgP?

PAgP, or Port Aggregation Protocol, is a Cisco proprietary protocol designed to automate the process of bundling multiple physical ports into a single logical port channel, enhancing bandwidth and providing redundancy in network configurations. By using PAgP, devices can dynamically negotiate and manage port channels, simplifying the configuration and ensuring that connected devices agree on the parameters necessary to form a channel.

This is particularly useful in environments where link aggregation is utilized, as it helps to ensure that all participating interfaces are configured with the appropriate settings, thus reducing human error and configuration inconsistencies. In contrast to standard protocols such as LACP (Link Aggregation Control Protocol), which is an IEEE standard, PAgP specifically facilitates communication between Cisco devices, allowing them to form and maintain port channels automatically without manual intervention.