What is Layer 2 and Layer 3 switches?

LAYER 2 SWITCH

A layer 2 switch, also known as a data link layer switch, is a network switch that operates at the second layer of the Open Systems Interconnection (OSI) model. The data link layer is responsible for creating and maintaining communication links between nodes on a network.

A layer 2 switch uses the Media Access Control (MAC) addresses of devices connected to it to make forwarding decisions. It builds a table of MAC addresses and associated port numbers, known as the MAC address table or forwarding table. When a packet is received, the switch looks up the destination MAC address in its table and forwards the packet out the appropriate port.

Layer 2 switches are commonly used in local area networks (LANs) to connect computers, printers, servers, and other network devices. They are faster than layer 3 switches since they do not perform any routing or packet filtering functions. However, they are limited to forwarding packets within a single broadcast domain and cannot be used to connect multiple networks or subnets.

What Does Layer 2 Switch Mean?

A layer 2 switch is a type of network switch that operates at the data link layer (layer 2) of the OSI (Open Systems Interconnection) model. The data link layer is responsible for providing reliable data transfer between network devices over a physical link, such as an Ethernet cable.


When a device is connected to a layer 2 switch, the switch automatically learns the MAC address of the device and associates it with the port on which it is connected. This process is known as MAC address learning. The switch builds a MAC address table or forwarding table, which maps MAC addresses to the corresponding switch ports. The switch uses this table to make forwarding decisions and to filter out frames that are not destined for a device connected to any of its ports.

LAYER 3 SWITCH

A layer 3 switch, also known as a multilayer switch, is a network switch that operates at the network layer (layer 3) of the OSI (Open Systems Interconnection) model. The network layer is responsible for providing logical addressing and routing services between different networks.

A layer 3 switch combines the features of a layer 2 switch and a router. It can perform the functions of both a switch and a router, which means that it can switch traffic at layer 2 and route traffic at layer 3.

A layer 3 switch uses IP addresses to make forwarding decisions. When a packet is received, the switch looks at the destination IP address of the packet and uses its routing table to determine the best path to forward the packet. The routing table contains information about network topology, such as IP addresses, subnet masks, and next-hop gateways.


Layer 3 switches are commonly used in enterprise networks to interconnect different subnets and VLANs (Virtual Local Area Networks) and to provide high-speed routing services between them. They can also provide advanced features such as Quality of Service (QoS) and Access Control Lists (ACLs) to enforce network policies.

Compared to layer 2 switches, layer 3 switches offer several advantages. They can interconnect different networks and subnets, which allows for better network segmentation and improved security. They can also reduce network congestion by routing traffic at layer 3, which reduces the amount of broadcast traffic on the network. Additionally, layer 3 switches can provide faster routing speeds than traditional routers, which can improve network performance.


In summary, a layer 3 switch is a network switch that operates at the network layer of the OSI model and combines the features of a layer 2 switch and a router. It uses IP addresses to make forwarding decisions and can provide advanced features such as QoS and ACLs. It is commonly used in enterprise networks to interconnect different subnets and VLANs and to provide high-speed routing services between them.

layer 2 switch vs layer 3 switch

LAYER 2 SWITCH

• A layer 2 switch operates at the data link layer (layer 2) of the OSI model, which is responsible for providing reliable data transfer over a physical link.
• Layer 2 switches use MAC addresses to make forwarding decisions. When a packet is received, the switch looks at the destination MAC address and forwards the packet to the appropriate port based on the MAC address.
• Layer 2 switches automatically learn the MAC addresses of devices connected to them and build a MAC address table, which maps MAC addresses to switch ports. They use this table to make forwarding decisions and to filter out frames that are not destined for devices connected to any of their ports.
• Layer 2 switches are commonly used in local area networks (LANs) to connect computers, printers, servers, and other network devices. They provide high-speed connectivity within a LAN and are faster than layer 3 switches because they do not perform any routing or packet filtering functions.
• One limitation of layer 2 switches is that they operate within a single broadcast domain, which means that they cannot be used to interconnect different networks or subnets.

LAYER 3 SWITCH

• A layer 3 switch operates at the network layer (layer 3) of the OSI model, which is responsible for providing logical addressing and routing services between different networks.
• Layer 3 switches use IP addresses to make forwarding decisions. When a packet is received, the switch looks at the destination IP address and uses its routing table to determine the best path to forward the packet.
• Layer 3 switches can perform the functions of both a switch and a router, which means that they can switch traffic at layer 2 and route traffic at layer 3. This makes them more versatile than layer 2 switches.
• Layer 3 switches are commonly used in enterprise networks to interconnect different subnets and VLANs and to provide high-speed routing services between them.
• Layer 3 switches can provide advanced features such as Quality of Service (QOS) and Access Control Lists (ACLs) to enforce network policies and improve network security.

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