Get your test copy of Windows Server 2012 R2 Preview.
Windows Server 2012 R2 Preview Evaluation
https://technet.microsoft.com/en-US/evalcenter/dn205292
Note: Windows Server 2012 R2 = Windows Server 8.1 = Windows Server codename Blue
Test Lab Guide: Windows Server 2012 R2 Hyper-V Network Virtualization with System Center 2012 R2 VMM
https://www.microsoft.com/en-us/download/details.aspx?id=39284