What is the difference between layer 3 switches and layer 2 switches?

The difference between Layer 3 switches and Layer 2 switches: 1. Layer 2 switches work at the data link layer, while Layer 3 switches work at the network layer; 2. Layer 2 switches are based on MAC address access and only forward data. , and the IP address cannot be configured, while the three-layer switch combines the two-layer switching technology and the three-layer forwarding function.

The operating environment of this article: Windows 7 system, Dell G3 computer.

The difference between Layer 3 switches and Layer 2 switches:

Layer 2 switches work on Layer 2 (data link layer) of the OSI model, so they are called Layer 2 switch.

A three-layer switch is a switch with some router functions. The most important purpose of a three-layer switch is to speed up data exchange within a large LAN. Its routing function also serves this purpose and can achieve one-time routing. , forwarded multiple times.

So what is the difference between layer 2 and layer 3 switches? The switch editor will introduce it to you.

1. Different working levels:

Layer 2 switches work at the data link layer, Layer 3 switches work at the network layer, Layer 3 switches not only implement data packet High-speed forwarding can also achieve optimal network performance according to different network conditions.

2. The principle is different:

The principle of the layer 2 switch is that when the switch receives a data packet from a certain port, it will first read the source of the packet. MAC address, then read the destination MAC address in the packet, and find the corresponding port in the address table. If there is a port corresponding to the destination MAC address in the table, copy the data packet directly to this port. The principle of the three-layer switch is relatively simple, that is, one route is exchanged multiple times. Generally speaking, it is the first time the source is routed to the destination. The three-layer switch will transfer this data to the second layer, so next time whether it is the destination to the source or the Fast exchange is possible from source to destination.

3. Different functions:

Layer 2 switches are based on MAC address access, only forward data, and cannot configure IP addresses, while Layer 3 switches use Layer 2 Switching technology and Layer 3 forwarding functions are combined, which means that Layer 3 switches add routing functions based on Layer 2 switches. IP addresses of different VLANs can be configured, and VLANs can be connected between different VLANs through Layer 3 routing. communication.

4. Different applications:

Layer 2 switches are mainly used for network access layer and aggregation layer, while layer 3 switches are mainly used for network core layer, but also There is a phenomenon that a small number of Layer 3 switches are used in the aggregation layer. The following figure is a practical application example of Layer 3 switches.

5. Supported protocols are different:

Layer 2 switches support physical layer and data link layer protocols, such as Ethernet switches, Layer 2 switches, and this hub HUB The functions are similar, and the three-layer switch supports physical layer, data link layer and network layer protocols.

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