Top 12 LAN Design Concepts

Learn these 12 LAN design concepts that will help you scale your network and prime it for future company growth.

Just like the OSI model, other concepts in networking are easier to talk about when using a reference model. Each one of the three tiers of the hierarchical LAN design model serve different functions and there are several features built for speed, power and availability of data.

Hierarchical LAN Design

In a hierarchical design, the access layer provides end users and devices with access to the network. When you connect to a network with a wired Ethernet cable or wireless card, you’re on the access layer. The failure domain of a device varies based on what is connected to it – for example, if only two computers are connected to a switch and there are multiple paths on the other side of that switch,

This layer puts together all of the access layers and distributes data across the network. It is the middle layer between the access and core layers, and is where redundancy is generally built for dealing with failures. Many switches may be used here in order to provide alternate paths for failover services, which basically means if one switch fails the data will still find a way to its destination.

The core layer forms the network backbone and provides connectivity between distribution layers. This layer often has the most expensive and powerful equipment and sends data out to the internet from a LAN once it passes through the access and core layers.

Failure Domain
The area of a network that is affected when a service or network device

Management Concepts

Port Density
The port density of a switch simply refers to the number of ports built in. These ports are available for devices to connect. The higher the port density the more devices can connect and the more the overall bandwidth increases.

Forwarding Rates
The forwarding rate of a switch is the amount of data that a switch can process every second.

Power over Ethernet (PoE)
When no power outlets are available, power can be delivered to a switch through Ethernet cabling. When a switch can be powered this way, it is considered capable of PoE passthrough.

Also called link aggregation, EtherChannel is a channel created by multiple links combining to form a single load-balancing link. This takes many physical ports and combines them into one logical port, which doubles the available bandwidth passing through that switch.

In-Band Device Management
When a device is monitored and configured over an active network connection, it is considered in-band. This requires a terminal emulator in order to connect.

Out-of-Band Device Management
A direct connection to the AUX or console port of a switch is made when there is no network connection available. It is considered an out of band connection because you are connecting directly instead of monitoring and configuring the device through the network.

Routing Design

Open Shortest Path First (OSPF)
A dynamic routing protocol that is based on the SPF algorithm.

Enhanced Interior Gateway Protocol (EIGRP)
A dynamic routing protocol based on the DUAL algorithm. A dynamic routing protocol automatically calculates the routes a packet takes through the network instead of the administrator having to enter routes manually. This may mean greater overhead — also called administrative distance, which you’ll learn about in a future lesson.

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