If networking was always easy, there wouldn’t be an entire profession dedicated to it. As such, when your networking goals and demands scale high enough, you're going to run into challenges with design and picking the right equipment.
Fortunately, other people have already thought about these problems, and you can learn a lot from industry standards.
In particular, Cisco has a networking layout philosophy that informs switch design. It's called the three-layer architecture, and utilizing these layers can help all aspects of your network.
To help you with that, we're going to spend a few minutes breaking down the distribution layer and the switches that typically work best in this layer.
What Is the Distribution Layer?
In order to understand distribution layer switches, we first have to tackle the distribution layer. Cisco has a three-layer hierarchy that makes up robust high-end, expansive networks. Many Cisco switches are designed around this three-tier idea, so it helps to understand those tiers.
They are the core, distribution, and access layers of a network. The core layer of the network consists of the switches that make up the backbone of the whole network. These switches are the gateways to the rest of the WAN (or the internet). They tend to be very high bandwidth switches, and they often don't need as many ports as switches for the other layers.
Next is the distribution layer. This layer of switches sits between the core and access layers. It's a nest of switches that form a bridge between access switches and core switches.
Put another way, the distribution layer primarily handles routing, quality of service, and security for the whole network.
The last layer is the access layer. These are the switches that directly connect endpoint devices to the rest of the network. Generally speaking, you will have more access switches than any other kind, although that will depend on the scale of the network.
What About Distribution Layer Switches?
Now that you understand the gist of the distribution layer, we can talk about what switches in this layer need to perform well.
For starters, they need robust management features. Most of your network management happens in the distribution layer, so you need switches that enable your management as you see fit.
Right alongside that, these switches need good security features and routing capabilities. Your network is optimized in this layer, so your switches have to be able to sort traffic and clean up data routes.
Aggregation is really the key here. Network efficiency hinges on the quality and use of distribution layer switches (which are typically Layer 3 switches). If they can aggregate and manage your data well, then your entire network will benefit.
Comparing to Other Switch Layers
Understanding the distribution layer and associated switches grows stronger when you compare the hardware in each of the primary networking layers. Core switches, distribution switches, and access switches all benefit from different features and design priorities. Let's explore those ideas to see what we can learn.
Core switches handle more total data than the other kinds of switches. Because of this, they need the highest bandwidth in the network. As a result, core switches are usually fiber optic switches, and they run on the most powerful components of your network.
At the same time, core functions are actually simpler than functions in the lower layers. The core doesn't have to be all that smart. Mostly, it's just passing data through the essential nodes of the network. In fact, many switches perform better when they have less to think about.
So, you can offload a lot of decision making to the lower layers and keep your core switches as fast and simple as possible.
On the other hand, the access layer doesn't need nearly as much bandwidth as the core layer. Ultimately, every device is supported by the core layer. The same is not true for access switches. These switches only interact with endpoint devices that connect directly to access switches and the distribution layer.
In some cases, the access layer might connect directly to the core layer, but in large networks, that's not common.
The point is that your access switches are usually the most affordable in the whole network. They have less work to do, and as they only support some of the endpoint devices on the whole network, they just aren't as important. Access switches are where you can save the most money when you understand which features you are fine without.
That's really all you need to get started. When you know the three layers of the Cisco switching hierarchy, you can purchase equipment accordingly. That can help you save money, maximize your network's potential, and plan for the future.
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