With iDRAC6, i will suggest you to take the inband approach of management i.e through OMSA because there is very limited support through iDRAC. With OMSA, you will be able to do most of the things. Yes, installing OMSA on Xen Server is not straight forward as Windows or Linux Server although this there is information on dell support site about this. You will need to to download the supplemental pack from support.dell.com. Check [View:] 
Hello We are running OpenManage Essentials (OME) v2.0.1.2222 in a Windows domain. I have seven PowerEdge R710 servers that are running Citrix Xenserve. I have created A records for their DRACs and have added them to Discovery and Inventory (D&I). DNS is correct with A records and reverse PTR records reporting correctly. The DNS DRAC name was set to the DNS A record for each of the DRACs (which caught me out). They are being discovered using SNMP and WSMAN. The Dell Troubleshooting Tool (v3.4.2) does not report any errors when querying the DRACs using SNMP & WSMAN by their A records. After a short time they all appear in the Device tree as the correct DNS A record. Five of them are normal - green tick and reporting correctly. However, two are showing up as unknown - reporting the serial number but not the model. As I have said, the troubleshooting tool reports everything correctly so I am at a lost as to why two should be unknown. They should all be identical.  Any advice as to more troubleshooting ? I have deleted them from the device tree and waited for another round of D&I but the result is the same - unknown devices. Many thank in advance John
Unknown devices in the Device Tree