We have VMWare 5.0 cluster across the 12 blades (6 per chassis) running a mixture of Red Hat and Windows 2008 R2 vms. The Red Hat boxes are two times two node Oracle RAC (primary and secondary), also apache web servers and jboss application servers. The Windows servers are for AV/DC/Management/Monitoring.
The problem is that intermittent network connectivity to random Windows and Red Hat boxes occur when the Oracle RAC builds up archive logs and then ships / applies them to the secondary nodes, between ESX nodes either on different blades in the same chassis or across the chassis and even when all RAC nodes are on the same ESX host.
We are using NFS, Oracle 11g and Red Hat 6.2.
Sorry if this info is a bit vague, im not an Oracle expert! :-)