Today I was reading through some documentation about the fundamentals of networks (IP, Ethernet, MPLS, ...). And while looking at the Ethernet Types that can be used in the Ethernet Frame I saw there was an Ethertype for Simple Network Management Protocol (SNMP)(0x814C). But as I could remember, SNMP is an application protocol running over UDP. So why is there an EtherType for?
The SNMP EtherType (SNMP over Ethernet) is meant for devices that don't have support above Layer 2 of the OSI Model. For more information have a read of RFC 1089:
SNMP can run over TCP as well.
There is a nice comparison of using SNMP over both protocols here: https://stackoverflow.com/questions/3565975/why-is-snmp-usually-run-over-udp-and-not-tcp-ip