Which Layer Network Switch Do I Need? Layer 2 vs layer 3

Network Configurator

When looking at choosing the right switch for you and your business there are a number of factors that you need to consider, including the layer of your network that your switch will fit into. Switches can sit in layers 2, 3 or 4 of your network, with each layer switch offering different capabilities. Choosing the layer switch you need can be confusing and so we have put together this guide to help simplify the decision process and explain the ins and outs of each different device.

What You'll Learn 

  • The differences between layer 2, 3 and 4 networking switches as well as their benefits and shortfalls.
  • What to consider when looking at your next switch in relation to your individual network. 


Layer 2 Networking Switch

Layer 2 networking switches sit within layer 2 of the TCP/IP model for networking, also known as the data link layer. This layer is used to transfer data between connected devices and nodes in a LAN. At this level, frames (the smallest unit of bits on a layer 2 network) are sent and received between devices, allowing for the sharing of data between all connected technology.

Layer 2 networking switches sit in this data link layer; because of this they only deal with MAC addresses rather than IP addresses. Layer 2 switches use a MAC address table to determine where data frames are to be sent in the network. This means that layer 2 switches are more based on hardware; they use the unique MAC address of connected hardware devices to determine the path that data frames are to be sent.

These switches are perfect for anybody whose network solely functions on layer 2 of the OSI networking model. Whilst not the most capable of devices in the features they offer, generally layer 2 switches are cheaper and function perfectly within a layer 2 networking model.


Layer 3 Networking Switch

Layer 3 networking switches sit within the 3rd layer of the OSI reference model, also known as the network layer. This layer is where the handling of Internet Protocols begins and so IP addresses are dealt with here. Layer 3 networking switches, therefore, utilize both MAC and IP addresses; they essentially combine the functions of a switch and a router.

Layer 3 switches connect devices in the same manner as a layer 2 device, using MAC addresses to transfer frames and determine where data is to be sent. However, unlike layer 2 switches, these pieces of hardware support IP routing intelligence allowing the connected devices to access the Internet. Because of this dual functionality, layer 3 switches are often referred to as multilayer devices.

This hardware offers a new level of flexibility to your network and so they are great to consider for all businesses. Layer 3 switches, by acting as a router, don't require an extra step through another connected device to offer Internet access. This feature allows for a faster networking solution, as well as less IT equipment, improving the efficiency of space and resources for your business.

Thanks to separate routing tables, layer 3 switches are better at managing traffic, allowing for faster transfer times and reduced broadcast traffic volumes. They support both dynamic and static routing tables; dynamic tables intelligently choose the best and fastest route to transfer data. Static tables however have to be updated manually as they retain and use past data to route packets between devices.

Layer 3 switches offer efficiency, high-speed performance, and multi-functionality to your networking solution. They are worth considering for any business looking to establish or upgrade their networking system. 


Layer 4 Network Switches

Layer 4 switches are enhanced layer 3 switches that sit within the fourth layer of the OSI model, or the transport layer. Within this layer, the networking manages traffic between connected devices to promote complete data transfers. This layer controls how much data is transported and at what speed.

Layer 4 networking switches offer all of the capabilities of both layer 2 and layer 3 switches, however, they are also able to use TCP (Transmission Control Protocol) and UDP (User Datagram Protocol) to prioritize traffic by application. This means that your device can intelligently select the data that is sent and received between devices.

Layer 4 switches offer improved networking control and boosted performance from layer 2 and layer 3 switches. Therefore they are worth considering for larger business networks that host a lot of devices and users.


Which Layer Network Switch is best for me?

When considering which networking switch to add to your IT system it is worth looking into what you hope to achieve from your network and IT infrastructure. If your goal is to connect devices together to allow for data transfer, a layer 2 switch is more than sufficient. However, if your technology needs are greater and you require a more complex networking solution, layer 3 or 4 switches will provide a more comprehensive infrastructure for your IT system. 

It is also important to consider the forwarding rate, number of VLANs and memory of MAC when considering which layer switch is best for your business. 

The forwarding rate is the forwarding abilities of a backplane. When the total forwarding abilities are larger than the sum of speeds of all ports, this is called backplane non-blocking. Forwarding rate is necessary to consider for your switch; without a large enough forwarding rate for your business scale, you will find that the device cannot meet your demands.

The number of VLANs that the device is capable of supporting is also important to take into consideration to avoid bottlenecks and keep your network performing at its best. Layer 2 switches support up to 1024 VLANs, whereas layer 3 switches are capable of supporting up to 4096 VLANs. Therefore, a layer 3 switch is going to be the better choice for larger networks that require more capabilities.

In terms of memory, switches use CAM, or content addressable memory. This memory is used to store MAC addresses within the switch. The more entries/ values your CAM is able to support, the more powerful the switch; for larger companies requiring a powerful networking solution, the more entries/ values that can be added the better!

Our networking switch selector makes choosing your device easy by allowing you to choose the requirements that you need. Access our network switch selector here or get in touch with our experienced team for more information.

Network Configurator