Currently, data networks mainly use routing protocols such as open shortest path first (OSPF) and border gateway protocol (BGP), and combined with multi-protocol label switching (MPLS) virtual private network (VPN) technology to build independent logical channels for different services, to achieve fast and safe data transmission.
The main equipment of the data network includes routers and switches. The router runs the OSPF and BGP routing protocols, so that the information of the local private network and the information of the remote private network can communicate with each other, and the MPLS VPN is configured to ensure the security of the data.
OSPF is a link-state-based interior gateway protocol developed by the IETF organization. It is a commonly used routing protocol and is used to discover the best path for data from the local to the remote. The OSPF protocol supports medium-sized networks, and the number of routers in a general network can reach several hundred. BGP is an exterior gateway protocol (EGP), which is a dynamic routing protocol applied between autonomous systems (AS). Different from OSPF, BGP is not mainly used to calculate the best route, but to transmit the best route. Its routing information can contain rich attributes and has excellent scalability.
VPN refers to a connection technology that builds a “virtual private network” on a public communication infrastructure. The difference between a VPN and a real network is that the VPN carries the information in the private network through the public network in a logically isolated manner, and nodes outside the VPN cannot communicate with it. A VPN realizes a secure private connection by establishing a private tunnel to connect remote users. VPN can provide firewall, authentication, encryption, tunneling, bandwidth control and other functions. The main function of VPN is to use encryption technology to enable secure transmission of information and data through public networks. MPLS is a technology that supports multiple Layer 3 protocols. It labels packets and replaces traditional IP forwarding with label forwarding. At present, virtual private network applications (BGP/MPLS VPN) are essentially VPNs that use labels automatically generated by the MPLS protocol as an encryption method for VPN tunnels.
The function of the switch is to insert the data that the user needs to transmit and transmit the data to the router. At present, common switches include Layer 2 switches and Layer 3 switches.
Layer 2 switching is hardware-based bridging. In a Layer 2 switch, the forwarding of data frames is processed by specialized hardware of ASIC (application specific integrated circuit, application specific integrated circuit), so the forwarding speed of the switch is very fast. However, Layer 2 switches cannot isolate broadcast domains. When a node sends a broadcast on the LAN, all nodes connected to the switch will receive the broadcast information. To solve the broadcast problem, switches provide a method of segmenting the broadcast domain called a virtual local area network (VLAN). In a switch, several ports can be divided into a VLAN, and stations in the same VLAN can receive broadcast messages from each other. After VLANs are divided, each VLAN in the switch is a broadcast domain. In a switch, the information of one VLAN cannot be directly propagated to another VLAN, and the communication between VLANs must be implemented through routers or Layer 3 switches.
Layer 3 switching technology is also called IP switching technology. Simply put, the Layer 3 switching technology is the Layer 2 switching technology + the Layer 3 forwarding technology. A Layer 3 switch is equivalent to a Layer 2 switch with Layer 3 routing functions, but it is an organic combination of the two, rather than simply superimposing the hardware and software of the router device on the Layer 2 switch.
