How does one encapsulate and transmit ingress routes?

How to encapsulate and transmit ingress routes this article will introduce the encapsulation and transmission knowledge of routers in depth. Here we take the ingress route for VPN transmission as an example. To ensure security, data on the network cannot be transmitted in plain text. It is usually encrypted and encapsulated before transmission to prevent some sensitive data from being stolen, especially for the sake of security. Www.2cto.com 1. First, we need to know the route decision-making and packet encapsulation process of the VPN Client. Generally, the VPN Virtual Interface is a virtual point-to-point Link Interface, when the VPN Virtual Interface receives a packet, it encapsulates the packet obtained from the network layer into a PPP point-to-point data frame and performs encryption and sends it to the gateway. The gateway here is the VPN Client, therefore, the encapsulated PPP point-to-point data frame is returned to the local machine for further processing. This processing is actually a re-encapsulation process. 2. Because the frames encapsulated for the first time can only be transmitted through the Virtual VPN interface, if you want to transmit data through the actual interface, you must re-encapsulate the data on the actual link layer, before being finally encapsulated as a link layer data frame, You Need To perform other multi-level encapsulation on the PPP data frame encapsulated for the first time, because the specification cannot directly encapsulate the PPP frame in another link layer frame, some headers need to be added between them. The simplest PPTP encapsulation is to add a GRE header and IP header before the PPP frame. 3. A route decision is required when encapsulated into an IP header, for example, because the data packet must be explicitly sent to the VPN Server in the distance, it will find a route to the VPN Server in the distance, when a VPN connection is established, a route to the VPN Server is created at the same time, and the IP data packets encapsulated into PPTP format or L2TP format are sent to the specified interface of this route for processing. For an Ethernet interface, this packet is added with the Ethernet header. If it is a point-to-point packet, a point-to-point link header is added and sent to the network. Now, the router encapsulation technology has been introduced. If you are not familiar with this technology, you can refer to it. I believe it will be helpful for you to set up a router in the future, only after understanding the router can you set the router better.