Chapter 10. Virtual Private Networks (VPN)
This chapter introduces the IPSec protocol and its role in providing VPN service. The focus is on implementing LAN-to-LAN VPNs using IPSec with preshared keys. The chapter also addresses interoperability issues between Cisco devices and other popular IPSec implementations.
The topics discussed in this chapter are as follows:
A virtual private network (VPN) enables private networks to communicate securely over the unsecured public network (that is, the Internet). These connections behave as a single virtual network, despite being geographically separated. VPNs provide inexpensive alternatives to expensive leased lines–WANs. VPNs also ...