The Complete Cisco VPN Configuration Guide

IPsec Standards

There are many different ways of implementing VPNs, as discussed in Chapter 1. For example, you could use an SSL VPN solution to protect data between two devices; however, the main limitation of SSL VPNs is that they primarily provide application layer protection, which typically is limited to web browser-based connections, and specific applications the vendor has written code for, to tunnel through the SSL VPN. Their advantage, however, is that they can use an existing web browser on the user’s desktop.

IPsec, on the other hand, provides protection at the network layer; therefore, any IP traffic can be protected between peer devices. But IPsec is intrusive on the client (remote access) side; typically you need additional software ...