Virtual Network is a service that allows you to create a private, isolated network in Windows Azure and treat it as an extension of your datacenter. You can assign private IP addresses to virtual machines inside a virtual network, specify DNS, and connect it to your on- premises infrastructure using a Cisco or Juniper hardware VPN device in a 'site-to-site' manner.
References: https://azure.microsoft.com/en-us/blog/virtual-network-adds-new-capabilities- for-cross-premises-connectivity/