Comparing Layer 3 and Layer 2 Switches (2024)

FAQs

Comparing Layer 3 and Layer 2 Switches? ›

Layer 2 switches offer limited to no routing capabilities within network segments such as VLANs. Layer 3 switches offer routing between different network segments. Limited scalability. Higher scalability enabled by layer 3 switches' cross network segment routing capabilities.

Layer 2 switches offer limited to no routing capabilities within network segments such as VLANs. Layer 3 switches offer routing between different network segments. Limited scalability. Higher scalability enabled by layer 3 switches' cross network segment routing capabilities.

Layer 3 switches can connect different VLANs, and offer more security features than Layer 2 switches. Other functions, such as Quality of Service (QoS), allow for the prioritizing of network traffic for maximum efficiency.

The Layer 2 protocol you're likely most familiar with is Ethernet. Devices in an Ethernet network are identified by a MAC (media access control) address, which is generally hardcoded to a particular device and doesn't normally change. Layer 3 is the network layer and its protocol is the Internet Protocol or IP.

Cost is one of the main disadvantages of a Layer 3 switch. It costs much more than a traditional switch and configuring and managing these switches also requires more effort. Therefore, an organization must be ready to expend additional resources to configure Layer 3 switches.

Layer 2 switches are not able to route packets, meaning they are limited to forwarding packets based on MAC addresses. This means the switch will only forward traffic to other devices on its local network segment--and not across other segments or through routers.

A more positive way to identify a 3-way switch is to look at the body of the switch and count the number of screw terminals: a 3-way switch has three terminal screws plus a ground screw. Two of the terminals are a light color—bronze- or copper-colored—and are called travelers.

Check the switch model. Layer 3 capable switches are typically referred to as "multilayer switches" or "L3 switches." You can find the model number of your switch by looking at the sticker on the back of the device. You can then look up the model number on Cisco's website to see if it is a Layer 3 capable switch.

A virtual local area network (VLAN) is any broadcast domain that is partitioned and isolated in a computer network at the data link layer (OSI layer 2).

On the other hand, a Layer 3 managed switch is capable of forwarding traffic between different subnets, using a map of the IP network maintained in its routing table. In other words, if you need to send traffic between devices on different subnets, you will need a Layer 3 switch.

What does a layer 4 switch do? ›

Layer 4 of the OSI Model coordinates communications between systems. Layer 4 switches (L4 switches) are capable of identifying which application protocols (HTTP, SNTP, FTP, and so forth) are included with each packet, and they use this information to hand off the packet to the appropriate higher-layer software.

Layer 2 switches

They interconnect networks at layer 2, most commonly at the MAC sublayer, and operate as bridges, building tables for the transfer of frames among networks. Historically, layer 2 switches emerged to alleviate the contention problem of shared media LANs.