Hi Marcus,
There are several memory OIDs in the private hpNetSwitch MIB.
Do a table walk starting with "iso(1).org(3).dod(6).internet(1).private(4).enterprises(1).hp(11).nm(2).icf(14).hpicfObjects(11).hpicfSwitch(5).hpSwitch(1).hpOpSystem(1).hpMem(2)"
Cheers