Same Avocent garbage as everyone else I assume, it’s not like any of the OEMs make their own.
From what I’ve seen, Supermicro is no different - they use Avocent hardware like everyone else. Everything just depends on what generation of controller they ship.
EDIT: as an example, the iDRAC on my Dell R210 II’s, the IMM on my Lenovo TD340, and iLO 3 on my HP ML10 are all the same generation of Avocent hardware with few differences. My Dell RX20’s have newer OOB modules and suck less to work with, but so does comparably new hardware from other OEM’s because they’re all made by the same damned company.