The S/WAN (Secure Wide Area Network, pronounced "swan") initiative designates specifications for implementing IPSec, the security architecture for the Internet Protocol, to ensure interoperability among firewall and TCP/IP products. S/WAN's goal is to use IPSec to allow companies to mix-and-match the best firewall and TCP/IP stack products to build Internet-based Virtual Private Networks (VPNs). Currently, users and administrators are often locked in to single-vendor solutions network-wide, because vendors have been unable to agree upon the details of IPSec implementation. The S/WAN effort should therefore remove a major obstacle to the widespread deployment of secure VPNs.