If you are utilizing Windows 2012 Servers with TCP Offloading enabled and seeing network issues ranging from low throughput to loss in connectivity, the following articles provide recomendation on disabling TOE on the Servers:
http://www.rackspace.com/knowledge_center/article/disabling-tcp-offloading-in-windows-server-2012
http://www.rackspace.com/knowledge_center/article/installing-xenserver-tools-on-next-generation-windows-cloud-servers