Network knowledge Review-about VPN

Network knowledge Review-VPN Virtual Private Network (VPN) refers to the technology for establishing a private Network on a public Network. It is called virtual network, mainly because the connection between any two nodes of the VPN network does not have the end-to-end physical link required by the traditional private network, but is built on the network platform provided by the public network service provider, for example, user data is transmitted in a logical network over the Internet, ATM (asynchronous transmission mode>, and FrameRelay (Frame Relay. It covers extensions of private networks that encapsulate, encrypt, and authenticate links across shared networks or public networks. Advantages of Virtual Private Network (1) VPN can reduce costs-using a public network to establish a VPN can save a lot of communication costs, without the need to invest a lot of manpower and material resources to install and maintain WAN (WAN) device and remote access device. (2) secure and reliable transmission data-VPC products use encryption, identity verification, and other security technologies to ensure the reliability of connected users and the security and confidentiality of data transmission. (3) convenient and flexible connection-if a user wants to connect to a partner without a virtual private network, the Information Technology Department of both parties must negotiate on how to establish a lease line or frame relay line between the two parties, with the virtual private network, you only need to configure the Security connection information for both parties. (4) full control-the virtual private network allows users to use ISP facilities and services while fully controlling their networks. You can only use the network resources provided by the ISP. You can manage other security settings and network management changes on your own. You can also create a virtual private network on your own within the enterprise. Features (1) security assurance VPN establishes a tunnel and uses encryption technology to encrypt transmitted data to ensure data privacy and security. (2) Service Quality Assurance VPN can provide different levels of service quality assurance for different users. (3) scalable and flexible VPN supports any types of data streams through the Internet and exists. (4) manageability VPN can be conveniently managed by users and operators. Application classification by VPN: 1) Access VPN (Remote Access VPN): data traffic from the client to the gateway that uses the public network as the backbone network to transmit the VPN between devices; 2) intranet VPN: connects the gateway to the gateway and connects resources from the same company through the company's network architecture; 3) Exclusive VPN: exclusive with the partner's enterprise network, connect a company to resources of another company. There are three main VPN tunnel protocols, PPTP, L2TP, and IPSec, which are classified by VPN protocol, the PPTP and L2TP protocols work on the second layer of the OSI model, also known as the second layer tunnel protocol. IPSec is the third layer tunnel protocol and the most common protocol. Combination of L2TP and IPSec is currently the best performance and the most widely used one. Classification by device type: network equipment providers develop different VPN network devices for different customer needs, mainly switches, routers, and firewalls. 1) vrovpn VPN: vrovpn VPN is easy to deploy. You only need to add the VPN service to the vro. 2) vswitch VPN: it is mainly used to connect VPN networks with fewer users. 3) Firewall VPN: firewall VPN is the most common VPN implementation method. Many vendors provide many methods to implement this configuration type of VPN, which are commonly used in the following four ways: 1) VPN Server. In a large Lan, you can build a VPN Server in the Network Center. 2) software VPN, which can be implemented through dedicated software. 3) Hardware VPN, which can be implemented through dedicated hardware. 4) Integrated VPN, many hardware devices, such as routers and firewalls, all contain VPN functions. However, hardware devices with VPN functions are generally more expensive than those without this function.