The switch is located in the data link layer device and is mainly used to realize data forwarding and connection within the local area network (LAN).
Functions: forwarding, learning, isolation, security
1. Forwarding data frames: Based on the lookup table of the target MAC address, the switch forwards the received data frames to the port where the target device is located, so as to realize fast and accurate data transmission. The switch is capable of handling multiple data streams simultaneously, enabling full-duplex communication.
2. Broadcast and multicast: In addition to forwarding the data frame to the target device, the switch can also broadcast the data frame to all other ports, so that all devices in the LAN can receive the broadcast information. In addition, the switch can also support multicast (Multicast) transmission, forwarding data frames to devices belonging to a specific group at the same time.
3. Automatic learning of MAC address: the switch can automatically learn the MAC address of each device by monitoring the source MAC address of the data frame, and store it in the MAC address table. In this way, in the subsequent data forwarding process, the switch can quickly search according to the table to find the port corresponding to the target device.
4. Network segmentation and isolation: By dividing the virtual local area network (VLAN) on the switch, different devices can be divided into different logical networks to realize network segmentation and isolation. This increases the security and management flexibility of the network.
5. Network monitoring and flow control: The switch can monitor the data flow in the network and control the flow as needed to avoid network congestion and performance degradation. Some advanced switches also support the Quality of Service (QoS) function, which can prioritize and process different types of data traffic according to them.
6. Redundancy and fault tolerance: In order to improve the reliability of the network, some switches support a redundant networking structure, and realize fault tolerance and backup of data by establishing redundant links between multiple switches. When a link or device fails, it can automatically switch to the backup link or device to ensure network connectivity.
7. Security and access control: Switches can support functions such as access control list (ACL) and port security, which are used to limit the access rights of specific devices and protect the security of the network. In addition, some advanced switches also support the AAA (Authentication, Authorization, Accounting) function, which is used to implement user authentication, authorization, and accounting.
Comparison with routers
A switch is a device used to forward data packets in a local area network. It realizes the forwarding of data packets by learning and filtering the source MAC address and destination MAC address of data packets. A switch is usually used to build a local area network, which can connect multiple devices inside the local area network, and forward data packets directly from the source device to the target device according to the MAC address to improve data transmission efficiency.
A router is a device used to connect different networks and forward data packets. The router realizes the forwarding of the data packet by learning and filtering the source IP address and the destination IP address of the data packet. It can connect multiple LANs or WANs, and determine the forwarding path of data packets according to the IP address. Routers are also able to perform functions such as network address translation (NAT), enabling communication between different networks.
Switches and routers usually work together in the network and cooperate with each other to complete data transmission and routing functions. In a network, switches are responsible for forwarding data packets within the LAN, while routers are responsible for forwarding data packets between different networks. When a data packet needs to be transmitted across different networks, the switch sends the data packet to the router, and the router determines the next-hop path according to the destination IP address, and then forwards it to the corresponding network.
So switches and routers play different roles in building a computer network. The switch is used for forwarding data packets within the internal LAN, while the router is used for connecting different networks and forwarding data packets between networks. Their cooperative work can realize a stable, efficient and secure network architecture.