Internet Protocol Security (IPsec) Feature Overview and Configuration Guide
This guide describes Internet Protocol Security (IPsec) and its configuration. IPsec is a protocol suite for securing IP networks by authenticating and encrypting IP packets.
IPsec protects one or more paths between a pair of hosts, a pair of security gateways, or a security gateway and a host. A security gateway is an intermediate device, such as a router or firewall that implements IPsec. The connection between two devices using IPsec to protect data is called a VPN (Virtual Private Network).