Network design

How to design a LAN

Editor’s note: If your client wants you to design a LAN, there are many tasks to accomplish – working through a network hierarchy that extends from the access layer to the core, determining which subnet mask to use, and , in general, learn the customer’s network. conditions. This network design checklist provides guidance on how to create a LAN. So, draw those network diagrams and get to work.

You finally have the consulting project you’ve been waiting for: a client is building a new office and has asked you to design their entire local area network (LAN), because their current infrastructure is outdated and their ports are failing day by day .

It’s a consultant’s dream! However, it can become a nightmare for you and your business if you design the network incorrectly.

The following network design checklist examines some of the major network design issues to consider when designing a new LAN for your customers.

Plan network complexity to match customer’s IT expertise

Switches and routers come with hundreds of features and functions. However, integrating too many bells and whistles into the network can create support issues in the future if the customer’s IT staff does not have a basic understanding of the features and functions you implement. Recognize business needs without making the network too complex.

To PoE or not to PoE?

More and more customers are deploying wireless networking technology and IP telephony. Wireless LAN access points are easier to install when Power over Ethernet (PoE) is available. IP telephony uses telephones that connect to the local network and draw power from it. The days of the traditional private branch exchange (PBX) system are numbered; all vendors are moving towards IP PBX systems and handsets. Many customers will tell you “We don’t use wireless” or “We will never switch to IP telephony”. They may not be able to now – at least to their manager’s knowledge – but if you do a good job on this project, your client will keep their equipment for at least three to five years. You will be doing your customer a great service if you can convince them to buy PoE switches now. Then, when the CIO decides to switch to wireless LAN or IP telephony in 18 months, the non-PoE switches will not have to be replaced.

Determine network needs

Just because 10 Gigabit Ethernet is here today and higher speeds are coming doesn’t mean you need those ports on the entire LAN. Too often, customers buy the fastest equipment possible thinking they need it, even if their existing 100 Mbps network is only running at 5% capacity. While it’s certainly prudent to make sure the core switches can support these higher speeds, you can advise the customer that they’re wasting a lot of money if you tell them that 10Gb switches are needed everywhere.

Wireless LAN technology refreshes and upgrades are among the top networking initiatives of 2018.


Network availability becomes more critical every year. Spend time planning a design that offers network redundancy from a physical and logical point of view. For example, use dual-fiber uplinks between wiring closets and main switches. Make sure that chassis-based core switches have two CPU cards. Be sure to think about things like default gateway redundancy. You can design the most redundant physical network in the world, but if it is not properly configured to provide Layer 3 IP default gateway redundancy and a failure occurs, your customer’s network will go down abruptly and you can be sure that he will call you. ask why.

Standards and maintenance

When business network design, try to standardize on a few different types of devices, instead of using a different type of switch in each wiring closet, even if all your equipment is from the same manufacturer. Standardization on a few different types of hardware simplifies configuration and troubleshooting. It also allows the customer to keep cold spares of each device with next business day maintenance, enabling faster and more cost effective responses to device failures.

Network management tools

Although these always seem to be omitted from order forms, network management tools are invaluable in providing maximum network uptime. Software that periodically backs up all device configurations to a share on the network is simple but extremely useful. Also consider the following scenario: two switches provide default IP gateway redundancy on your customer’s network. One of them fails, but you don’t realize it because the network is redundant. When the other fails, the client experiences a total network outage. This can be easily avoided by using a simple tool to ping all network devices and report their status.

There are many other things to consider when designing a LAN for your customer. This network design checklist covers some of the most important ones that will hopefully point you in the right direction and, more importantly, provide you with a happy and loyal customer.

TechTarget network planning resources beyond this network design checklist include this feature on simplify overly complex networks and this glimpse of data center network design.

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