LAYER 2 vs. LAYER 3 SWITCHES: Explained
What’s the difference between Layer 2 and Layer 3 network switches?
What is a network switch? A device with multiple LAN ports capable of accepting Ethernet connections from network devices is called a switch. Additionally, it serves to create networks by enabling data transmission and communication between devices.
The numerous layers in the OSI model are what are referred to as layers in this context. Open Systems Interconnection is what OSI stands for. This model explains how data travels across a network from software on one device to software on another. It was developed as a standard. Additionally, it achieves this by dividing the enormous work of data communication into seven distinct tiers.
Layer 2 Switches
As its name implies, a Layer 2 switch functions at the data link layer, or layer 2, of the OSI model. MAC addresses are dealt with in this layer. As such, a layer 2 switch determines where to send data based on a device’s MAC address.
A layer 2 switch will take note of the MAC addresses of connected devices and keep them in its database. A layer 2 switch will forward data packets to their intended ports when they are sent from a device connected to it.
For instance, if computer A wished to communicate with computer B, computer A would send the data packet to the switch along with computer B’s MAC address.
The switch will next seek for the port that corresponds to the given MAC address in its table after reading the destination’s MAC address. The data will then be forwarded to the port that computer B is connected to.
The most prevalent kind of switches are without a doubt Layer 2 switches. These are the conventional switches that are typically found in small to medium-sized businesses and homes.
Layer 3 Switches
Operating at layer 3 of the OSI model, a layer 3 switch is also known as a multi-layer switch. The network layer, or Layer 3, is concerned with routing, which uses IP addresses. Thus, IP addresses can be used by a layer 3 switch to route data. However, it can also function at layer 2, in addition to layer 3.
In other words, it may route data using IP addresses, which are layer 3, and forward data using MAC addresses, which are layer 2.
Let’s take an example where an organization wishes to separate network traffic from two distinct departments in order to prevent traffic from, say the marketing department from reaching the customer service department and vice versa. Making a few VLANs is the most effective and straightforward approach to accomplish this.
A network is divided into distinct broadcast domains by VLANs. An organization can build a VLAN for the customer service department, assign it to this IP address group, and name it VLAN 1. Next, it can set up a VLAN with a distinct IP address group for the marketing department, which it can refer to as VLAN 2.
Every department now has its own subnet thanks to VLANs. Therefore, no device in one VLAN can see or communicate with any other device in another VLAN.
However, what would happen if the network administrator wished to permit communication between the two VLANs? In this case, a Layer 3 device is needed for communication because the VLANs have different IP address groups.
A router could be employed by the network administrator as well, as they route based on IP addresses. However, deploying a Layer 3 switch is a more effective and straightforward method. Inter-VLAN routing, which enables communication between VLANs, can be achieved by using and configuring a Layer 3 switch. And it accomplishes this by setting up switch virtual interfaces, or SVIs, on the Layer 3 switch.
By establishing default gateways, these virtual interfaces enable data routing between VLANs. For instance, if computer A on VLAN 1 wishes to communicate with computer D on VLAN 2, computer A will send the data packet to the SVI assigned to VLAN 1, the default gateway. The Layer 3 switch will then, in the same manner as a router, check its routing table and forward the packet to the SVI of VLAN 2, and finally, computer D.
That is, in essence, how a Layer 3 switch functions.
Router vs. Switch
There are other devices that function at layer 3, which are routers. But routers only function at layer 3. However, layer 3 switches can function at both layers. As a result, they essentially combine switch and router operations.
A layer 3 switch can’t, however, perform all of a router’s functions. It lacks some of a router’s full routing functionality.
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To recap, Layer 2 switches routes data according to MAC addresses, while Layer 3 switches route data according to IP addresses. However, Layer 3 switches can also send data via MAC addresses.
While Layer 3 switches can route data between VLANs, Layer 2 switches are unable to do so.
Layer 3 switches require a more complicated configuration than Layer 2 switches, which require little to none at all.
In terms of cost, Layer 2 switches are reasonably priced, but Layer 3 switches are substantially more costly.
In terms of speed, layer 3 switches are slower than layer 2 switches, which are much faster.
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