Concepts and Principles of data network switches

Switching) refers to the technology collectively used to send the information to be transmitted to the corresponding route that meets the requirements according to the needs of transmitting information at both ends of the communication. Generally, a switch is a device that implements information exchange in a communication system.

In computer network systems, the concept of exchange is an improvement of the shared working mode. The HUB we have previously introduced is A shared device. The HUB itself cannot identify the destination address. When A host in the same LAN transmits data to host B, data packets are transmitted in a HUB-based network in broadcast mode. Each terminal verifies the address information of the data packet header to determine whether to receive the data packets. That is to say, in this way, only a group of data frames can be transmitted over the network at the same time. If a collision occurs, retry. This method is shared network bandwidth.

The vswitch has a high-bandwidth back bus and an internal switching matrix. All the ports of the vswitch are attached to the back bus. After the control circuit receives the data packet, the processing port will look for the NIC in the memory address table to determine the hardware address of the target mac nic) on which port is mounted, data packets are quickly transmitted to the destination port through the internal switching matrix. If the destination MAC does not exist, the packets are broadcast to all ports, after receiving the port response, the switch "learns" the new address and adds it to the internal MAC address table.

You can also use a vswitch to segment the network. By comparing the MAC address table, the vswitch only allows necessary network traffic to pass through the vswitch. Through the filtering and forwarding of vswitches, the broadcast storm can be effectively isolated to reduce the occurrence of incorrect packets and wrong packets, so as to avoid sharing conflicts.

A vswitch can transmit data between multiple port pairs at the same time. Each port can be considered as an independent network segment, and the network devices connected to it enjoy all the bandwidth alone, so they do not need to compete with other devices. When node A sends data to node D, Node B can send data to node C at the same time, and both transmission enjoy all the bandwidth of the network and all have their own virtual connections. If a 10 Mbps Ethernet switch is used here, the total traffic of the switch is 2*10 Mbps = 20 Mbps. When a 10 Mbps shared HUB is used, the total traffic of a HUB does not exceed 10 Mbps.

In short, a vswitch is a network device that can encapsulate and forward data packets based on MAC address recognition. The switch can "Learn" the MAC address and store it in the internal address table. By creating a temporary exchange path between the initiator of the data frame and the Target receiver, the data frame can directly reach the destination address from the source address.

1. Basic Principles and forwarding process of Huawei L3 Ethernet Switches
2. Principle and Design of L3 Switches