The Cisco CSR 1000V (Cloud Services Router) is a virtual platform that supports Cisco's SD-WAN technology. It is specifically designed to deliver routing, VPN, firewall, and other networking services in a virtualized form, making it suitable for deployment in cloud and virtual environments. Other options like the Cisco ASR 1000, Cisco Nexus 1000V, and Cisco ISR 4000 are either physical hardware or serve different purposes.