So,

You have an xserve and trying to get ipmiutil for windows working.

You get errors like:

Invalid data field in request

LANPLUS error in RAKP3
Error: Unable to establish IPMI v2 / RMCP+ session

Try this:

ipmiutil health -N <ip.address.of.bmc> -U <username> -P <password> -F lan2 -V 3

This should work for you.