There is a new KB Article out from VMware discussing a change in how the kernel managed ICMP replies.
If you’ll recall some ISCSI vendors needed workarounds for how replies worked in previous releases. The issue was the reply would return from the lowest numbered vmk rather than the receiving vmk.
It looks like this has been resolved for 5.1. If you ping a private-LAN vmk interface you’ll get a reply back from the same interface – provided you are on the same network as the VMK interface and don’t require routing from it. Provided you’re not routing your iSCSI/NFS traffic you’re in business.
The Equallogic paper referenced has not been updated to address this change yet.