Cisco Cisco IOS Software Release 12.0(22)S

Virtual Private Network (VPN)—A group of sites that, as a result of a set of administrative policies, 
can communicate with each other over a shared backbone. 

VPNv4 addresses—When multiple VPNs use the same address space, the VPN addresses are made 
unique by adding a route distinguisher to the front of the address. 

VPN routing/forwarding table (VRF table)—A VRF table includes the routing information that 
defines a customer VPN site that is attached to a PE router. A VRF table consists of the following 
elements:

An IP routing table

A derived forwarding table

A set of interfaces that use the forwarding table

A set of rules and routing protocols that determine what goes into the forwarding table