Network Diagram Basics/network Key Icons and Shapes

Network Diagram Basics

Network diagrams can represent a number of different aspects about a network so it is important prior to starting to understand what the diagram will be used for. The best diagrams speak for themselves and require very little explanation. Some common uses include:

• Document physical equipment and connections

• Show routing path or switching path 

• Show logical connections or logical relationships between systems

• Document carrier or third party connections

Key Icons and Shapes

Using high quality icons is essential for developing professional looking network diagrams. If you need network icons here are some sites that provide good free resources:

Router Icon - Represented by a circle with four arrows engraved on top. This icon is used to represent Layer 3 routing devices only. 

Router Icon - Represented by a circle with four arrows engraved on top. This icon is used to represent Layer 3 routing devices only. 

Switch Icon - Represented by a rectange with four arrows engraved on top. This icon is used to represent Layer 2 switching devices.

Multilayer Switch Icon - Multilayer switches are a hybrid between routers and switches. In other words they are switches that have routing capabilities.

Dedicated Firewall - Used to represent devices that have the sole function of acting as a firewall.

Switch with Firewall Module - Some high end switches are able to run firewall modules allowing the device to double as a switch and a firewall. 

Key Connectors

Most connection points are represented using lines. You may vary the width of the line to represent greater or lesser bandwidth accross the link if required.

 

Link -  Network connections are represented by lines connecting to each device.

Etherchannel - A number of links grouped together into a single logical link. Negotiated ethercannels  use the LACP or PAGP protocols.

Cloud - Clouds represent any third party network not under your direct administrative control. The internet, for example, may be represented using a cloud.

 

Sample Physical Connections Diagram

This diagram shows the physical connection points in a small network. The diagram shows interface assignments, speed, router hostnames and management addresses.

 

Sample Routing Diagram

This diagram shows routing parameters in this small network. OSPF Area 0 is configured on the Fa0/2 interfaces of Router 1 and Router 2. OSPF Area 1, configured as a stub area is applied to Fa0/1 of Router 1 and Router 3. Router 3 redistributes its directly connected networks into OSPF. The OSPF router roles are also shown as well as non-OSPF routing functions such as directly connected routes and the trunk port to the switch.

If a network engineer was given the task of configuring routing on this network this diagram would give him/her the necessary information to apply a complete routing configuration on every device.

 

Third Party Connections 

Third party managed networks such as an Internet connection can be shown as a cloud. In this instance a layer 3 switch with a Firewall module connects this small office to the Internet.