What are Layer 2 Switch and Layer 3 Switch?
Layers 2 switch and layer 3 switch are adopted in the Open System Interconnect (OSI) model, which is a reference model for describing and explaining network communications. The OSI model has seven layers: application layer, presentation layer, session layer, transport layer, network layer, data link layer and physical layer, among which layer 2 and layer 3 refer to the data link layer and network layer respectively, and the switches working in these layers are called layer 2 switch and layer 3 switch.
Layer 3 switch is a switch with some router functions, the most important purpose of Layer 3 switch is to speed up the data exchange within a large LAN, the routing function is also for this purpose, can achieve one route, multiple forwarding. What is the difference between a Layer 3 switch and a Layer 2 switch? In addition, Layer 3 switches and routers have routing functions, what is the difference between the two?
Layer 2 switches work at the data link layer, Layer 3 switches work at the network layer, Layer 3 switches not only realize high-speed forwarding of packets, but also achieve optimal network performance according to different network conditions..
Layer 2 switches are mainly used for network access layer and aggregation layer, while Layer 3 switches are mainly used for the core layer of the network, but there are also a small number of Layer 3 switches used for aggregation layer.
Layer 2 switches support physical layer and data link layer protocols, such as Ethernet switches, Layer 2 switches, which have similar functions to hub HUB, while Layer 3 switches support physical layer, data link layer, and network layer protocols.
Layer 2 switching technology is relatively mature, Layer 2 switch is a data link layer device, can identify the MAC address information in the packet, forward according to the MAC address, and record these MAC addresses and the corresponding ports in their own internal address table. Layer 3 switch is a switch with some router functions, the most important purpose of Layer 3 switch is to speed up the data exchange within a large LAN, the routing function is also for this purpose, can achieve one route, multiple forwarding. For regular processes such as packet forwarding, the hardware is implemented at high speed.
The traditional switching technology operates in the second layer of the OSI network standard model - the data link layer, while the three-layer switching technology realizes the high-speed forwarding of packets in the third layer of the network model, which can not only realize the network routing function, but also achieve the optimal network performance according to different network conditions. The most basic difference between Layer 2 and Layer 3 switches is that Layer 3 switches have routing functions and can be regarded as network layer devices (of course, they can also be used as Layer 2). Layer 2 switches are devices at the data link layer and do not have routing capabilities.
Layer 3 switching is proposed in relation to the traditional concept of exchange. As we all know, traditional switching technology operates at the second layer of the OSI network standard model, the data link layer, while the Layer 3 switching technology implements high-speed forwarding of packets at the third layer of the network model. Layer 3 switching technology is: Layer 2 switching technology + Layer 3 forwarding technology.
In conclusion, it is not always the case that more advanced device is better, but it is right to choose the most appropriate one for your specific application.
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