Hello iam trying to connect 2 MSP432E mcu's to one ethernet port, iam thinking a 3 port ethernet switch would work or a optical isolator would work.I was curious if other ways exists such as just being able to connect both Mcu's ethernet traces to each other.any iput is appreciated thanks

 

You connect the 2 MCUs as separate nodes, and all the network stuff works as intended. You cannot effectively multiplex 2 MCUs on to one port. To even suggest such a thing betrays a fundamental misunderstanding of the MAC and Physical layers of the network, It would be highly impractical.