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All Blog Articles / Enterprise Network / What Is a LAN Switch and How Does It Work?

What Is a LAN Switch and How Does It Work?

Posted on by FS.COM

With the dramatic increase in traffic and the faster CPU in computing operating systems, the LAN (Local Area Network) is becoming increasingly congested and overburdened. In order to reduce the congestion and improve the speed of LANs, many IT technicians seek to use LAN switching technology and LAN switches to improve the performance of traditional Ethernet technologies that don't require costly wiring upgrades or time-consuming host reconfiguration. What is a LAN switch and how does it work to route traffic by using LAN switching technology? This post will give you the answers.

LAN Switching Technology Basics

LAN switching is a form of packet switching in which the data packets are transferred from one computer to another over the LAN network. LAN switching technology is vital to network design, as it allows the traffic to be only sent to places that are required. LAN switching mainly includes 3 types of switching methods: the hardware-based Layer 2 switching based on MAC addresses, the Layer 3 switching based on IP addresses, and Layer 4 switching in which a QoS (Quality of Service) can be defined for each user. Among them, the Layer 2 switching is most widely used for network segmentation in LANs. As illustrated in the figure below, the LAN switch is connected between the bridge and the router to form four collision domains. It allows a flatter network design with more network segments than traditional networks joined by repeater, hubs and routers.

lan switching

A typical LAN includes one or more LAN switches that can be connected to a router, modem or bridge for Internet access. Other network devices such as firewalls, load balancers, and network intrusion detecters may also be included in a LAN network. Advanced LANs are characterized by their use of redundant links with LAN switches using the spanning tree protocol to prevent loops, to deliver QoS, and to segregate traffic with VLANs.

What Is a LAN Switch?

LAN switch is the essential component used in LAN networks. What is a LAN switch? A LAN switch is a network switch that interconnects two or more LANs and forwards the packets between these networks. The speed of a LAN switch is no more than Gigabit, normally at the maximum speed of 1000 megabits per second. LAN switching uses three types of LAN switches, namely the Layer 2 switch, Layer 3 switch and Layer 4 switch to route traffic in the LAN networks. As most LAN switches operate at the Data Link Layer (Layer 2), the Layer 2 switch is most commonly used and can be found in nearly any LAN. It offers some of the benefits of both bridges and routers. Like a bridge, a Layer 2 LAN switch can forward traffic based on the Layer 2 header. Like a router, it partitions the network into logical segments, providing better administration, security, and management of multicast traffic. Layer 3 or layer 4 switches require more advanced technology and are more expensive, thus they are more often utilized in larger LANs or in special network environments.

What Is a LAN Switch

Three Methods That a LAN Switch Uses for Routing Traffic

As aforementioned, LAN switches rely on packet-switching. In LAN networks, the LAN switch establishes a connection between two segments to send the current packets. Taking the Layer 2 switching as an example, the incoming packets are saved to a temporary memory area in the server. The MAC address information contained in the frame's header for the source and destination of the packet is read by the LAN switch and then compared to a list of addresses in the switch's lookup table. Here are the three methods that a LAN switch uses to route traffic in the Layer 2 switching process.

 Cut-through In the cut-through method, the LAN switch can read the MAC address as soon as a packet is detected by the LAN switch. After storing the 6 bytes that make up the MAC address information, they immediately send the packet to the destination node, even as the rest of the packet is coming into the switch.
 Store-and-forward The store-and-forward method will save the entire packet to the buffer and check it for errors before sending to the destination node. If the packet had an error, it would be discarded. If not, the switch will look up the MAC address and send the packet on to the destination node. Many LAN switches can combine these two methods, using cut-through until a certain error level is reached and then changing to store-and-forward mode.
 Fragment-free A less common method is fragment-free. It works similar as the cut-through method except that it stores the first 64 bytes of the packet before sending it on. The reason for this is that most errors, and all collisions, occur during the initial 64 bytes of a packet.

FS LAN Switches Solutions

LAN switching technology helps to improve the overall efficiency of local area networks and address the existing bandwidth issues with the good use of LAN switches. FS provides you with a complete array of LAN switches working at Gigabit speed, covering the Managed PoE+ switch, S3900/S5800 series Gigabit switches for Layer 2 or Layer 3 switching. Available with different port numbers and optional configurations, they can meet the demands for LAN switching efficiently.

Switch Type
Port Number
Switch Class
Switching Capacity
Max. Power Consumption
PoE+ Managed Switch
8 Port
18 Gbps
24 Port
52 Gbps
48 Port
180 Gbps
S3900 Series
24 Port
Layer 2+
24 Port
Layer 2+
48 Port
Layer 2+
S5800 Series
48 Port


LAN switching comes with high scalability and security with ease of management. Currently, the relatively low speed LAN switches are commonly used in Daisy-Chain and Ring topology due to the limited geographical extent of the LAN network. For wide area network (WAN) environment, network switches with higher speed and greater capacity such as 10gbe switch, 40gbe switch and 100gbe switch would be needed. If you have any requirement for high-performance network switches, feel free to contact us at sales@fs.com.

Related Article: FS.COM LAN Access 10G Switch Analysis How to Configure a VLAN via CLI and Web Interface? Voice VLAN Configuration Guidelines on Ethernet Switches