Vmware compatability for server is there like system/servers, I/O devices, SAN storage.
for example i am usig qlogic adapter in server and i can check the compatabilt with VMware HCL link provided below.
http://www.vmware.com/resources/compatibility/search.php
For switches as long as the connectivity between server and switch is configured perfectly and work fine. that it. and it has got nothing to do with switch.
for switch compatabilty you need check with hardware vendor for particular I/O devices your going to use. compatabilty for server I/O device with VMware HCL matrix.
Thanks & Regards
Dharshan S
VCP 4.0,VTSP 5.0, VCP 5.0