What is a Network Diagram

A network diagram is a visual representation of a computer or telecommunications network. It shows the components that make up a network and how they interact, including routers, devices, hubs, firewalls, etc. This network diagram shows a local area network (LAN):

Depending on its scope and purpose, a network diagram may contain lots of detail or just provide a broad overview. For instance, a diagram of a LAN might could show the IP addresses of individual computers, while the diagram of a MAN (metropolitan area network) could represent buildings or areas with a single node.

A network diagram can be either physical or logical.

Logical network diagrams

A logical network diagram describes the way information flows through a network. Therefore, logical network diagrams typically show subnets (including VLAN IDs, masks, and addresses), network devices like routers and firewalls, and routing protocols.

In the Open Systems Interconnection (OSI) model, logical network diagrams correlate with the information contained in layer 3 (L3). Also known as the “network layer,” L3 is an abstraction layer that deals with packet forwarding through intermediate routers. Level 2 shows the data links between adjacent nodes, while level 1 shows the purely physical layout.

Physical network diagrams

A physical network diagram shows the actual physical arrangement of the components that make up the network, including cables and hardware. Typically, the diagram gives a bird’s eye view of the network in its physical space, like a floorplan.

How are network diagrams used?

With their capacity for showing how network components interact, network diagrams can serve a variety of purposes, including:

• Planning the structure of a home or professional network
• Coordinating updates to an existing network
• Reporting and troubleshooting network problems
• To comply with PCI or other requirements
• As documentation for external communication, onboarding, etc.
• To keep track of components
• Sending relevant information to a vendor for an RFP (request for proposal) without disclosing confidential information
• Selling a network proposal to financial stakeholders
• Proposing high-level, syslog infrastructure changes

Network topology refers to the arrangement of elements within a network. Like network diagrams, network topologies can describe either the physical or logical aspects of a network. Logical topology is also known as signal topology.

Different topologies are best for certain situations, since they can affect performance, stability, and other outcomes.

Bus topology

Also known as the backbone, linear, or ethernet topology, this type of network is distinguished for having all of the nodes connected by a central medium (the “bus”) which has exactly two endpoints.

Bus topologies are easy to configure and require less cable length than some other topologies. However, if the central bus breaks down, so does the whole network, and it can be difficult to isolate the problem.

Ring topology

Nodes are connected in a circular pattern, and packets of information are sent through the ring until they reach their destination.

Ring networks can outperform those based on the bus topology, and they can be easily reconfigured to add or remove devices. However, they are still relatively vulnerable, since the whole network fails if a single node fails. Also, bandwidth must be shared across all the devices and connections.

Star topology

One of the most common topologies, the star topology consists of a central hub or switch, through which all of the data passes, along with all of the peripheral nodes connected to that central node.

Star topologies tend to be reliable because individual machines may crash without affecting the rest of the network. But if the central hub or switch fails, none of the connected nodes will be able to access it. Cable costs also tend to be higher for star networks.

Mesh topology

There are two types of mesh topology. In the first, which is called full mesh topology, each node is directly connected to every other node.

In a partial mesh topology, nodes are only connected to the nodes they interact with most.

Most networks employ some combination of topologies to yield what’s called a hybrid topology. For instance, the tree topology combines the bus and mesh topologies.

The logical and physical topology of a particular network may resemble one another, or they may be entirely different. For example, a twisted pair Ethernet network exists as a star topology physically but follows the bus topology logically.

Network diagrams can be used to represent virtually any network, which means that there’s a lot of variety. Network diagrams vary in two important ways: by the type of network they represent and by network topology, or the arrangement of components. Below are a few examples, and you can always visit our network diagram template to try it out yourself.

Virtual private network: allows users to access a private network over a public network as if they were directly connected to that private network

Server rack: shows the layout of a rack system

Enterprise private network: connects diverse elements within a business, such as multiple sites

DSL network connectivity: shows how information is relayed over telephone lines

Since a network diagram is a visual representation of an actual system, it relies on symbols to convey meaning. Some symbols represent actual physical entities, while others indicate the kinds of relationships that exist between entities.

Here are some of the most common symbols:

Cisco, AWS, GCP, and Azure symbols

Cisco Systems, Inc. is one of the largest providers of networking equipment in the world. As such, they have developed a comprehensive set of network topology icons that correspond with the equipment they offer. Cisco’s Advanced Services Team helps organizations optimize their networks for maximum uptime, and these icons offer a clear, convenient way to communicate about those networks.

Altogether, there are dozens of Cisco network diagram shapes. You can download the complete list here.

Amazon Web Services, Google Cloud Platform, and Microsoft Azure, three leading providers of cloud hosting services, also have their own sets of symbols for describing networks hosted on their services. Here's an AWS network diagram:

You can download the AWS, GCP, or Azure icons, or learn more about network diagram symbols in this guide. You can also view and experiment with all of the symbols in Lucidchart.

Before you start making a diagram, make sure you have a clear goal in mind. It’s better to create multiple diagrams, each capturing a different aspect of the network, than it is to try to cram all the information onto one diagram.

Once you’ve selected a network to map, follow these steps to produce a beautiful, useful network diagram.

1. Identify the equipment

   . At first, don’t worry about connections. Instead, just list all the workstations, servers, routers, firewalls, and other components that are part of the network. If you’re using network diagramming software, you can accomplish this by simply dragging shapes onto the canvas.

2. Group the shapes.

   To begin arranging your diagram, move related shapes closer to one another. Shapes may be related either logically or physically, depending on what kind of diagram you’re drawing.

3. Add connections.

   A line between two shapes shows that they are connected somehow, typically by the flow of information.

4. Label.

   Include any additional information about each shape that you consider useful to your audience. You may choose to place that information next to each component or to number the components, then add additional info in a legend.

5. Final formatting.

   Adjust the placement, size, color, and other attributes of your diagram elements until you’re satisfied.

For a more in-depth look at making network diagrams, including additional tips and tricks, check out this tutorial.