Because VPN is a secure private virtual network temporarily established on Internet, users can save the cost of renting special line. In the operation of funds, in addition to purchasing VPN equipment, the enterprise only pays a certain amount of Internet access fees to the ISP where the enterprise is located, and also saves the long-distance telephone costs. This is the reason why enterprise VPN is cheap.
According to different classification standards, enterprise VPN can be classified according to several standards.
1. Classification by protocal of enterprise VPN
There are three tunneling protocols in VPN, PPTP, L2TP and IPSec. PPTP and L2TP work in the second layer of OSI model, which is also called layer 2 Tunneling Protocol. IPSec is the third layer tunneling protocol.
2. Classification by enterprise VPN application
(1) Access VPN (remote access VPN): client to gateway, using the public network as the backbone network to transfer VPN data traffic between devices;
(2) Intranet VPN (intranet VPN): gateway to gateway, which connects resources from the same company through the network architecture of the company;
(3) Extranet VPN (extranet VPN): it forms an extranet with the partner enterprise network, connecting the resources of one company with that of another company.
3. Classification by the type of devices used by enterprise VPN
According to the needs of different customers, network equipment providers develop different VPN network equipment, mainly switches, routers and firewalls.
(1) Router VPN: corporate router VPN deployment is easy, as long as the VPN service is added to the router;
(2) Switch VPN: it is mainly used to connect VPN network with few users;
(3) Firewall VPN: firewall VPN is the most common way to realize VPN, and many manufacturers provide this configuration type.
4. Classification by the principle of corporate VPN
(1) Overlapping VPN: This VPN requires users to establish their own VPN links between end nodes, mainly including GRE, L2TP, IPSec and many other technologies.
(2) Peer to peer VPN: Like homenet router, network operators complete the establishment of corporate VPN channel in the backbone network, mainly including MPLS and VPN technology.
1. VPN server: in large LAN, VPN can be realized by building VPN server in the network center.
2. Software VPN: VPN can be realized by special software.
3. Hardware VPN: VPN can be realized by special hardware.
4. Integrated VPN: some hardware devices, such as corporate routers and firewalls, all have VPN functions. But generally, hardware devices with VPN function are more expensive than those without it.