In a previous post, I discussed the encapsulation of PDUs on trunk ports, focusing on three different Ethernet encapsulations: Ethernet II, 802.2 LLC, and 802 SNAP. Understanding the origins of Ethernet is crucial, dating back to the collaboration between Robert Metcalfe and David Boggs in the 70s, leading to the formation of the DIX consortium in 1979. The process of standardizing LANs, initiated by Maris Graube, resulted in the formation of Project 802, which eventually split into different groups due to disagreements. The development of Ethernet and the challenges faced by DIX in getting it approved as a standard highlight the interesting history and complexities of networking protocols.
https://lostintransit.se/2024/08/21/ethernet-history-deepdive-why-do-we-have-different-frame-types/