It is possible to create a network diagram online using various tools available on the internet. Here are a few options:

1. Lucidchart: Lucidchart is a popular online diagramming tool that can be used to create network diagrams. It offers a wide variety of templates and shapes, making it easy to create a professional-looking diagram. You can sign up for a free account and start creating your diagram right away.
2. Gliffy: Gliffy is another online diagramming tool that offers a range of templates and shapes for creating network diagrams. It offers a free trial for new users and a paid subscription for more advanced features.
3. Draw.io: Draw.io is a free online diagramming tool that offers a variety of templates and shapes, including those for creating network diagrams. It integrates with Google Drive, Dropbox, and other cloud storage platforms.
4. Microsoft Visio Online: Microsoft Visio is a popular diagramming tool, and it also has an online version called Visio Online. It offers a range of templates and shapes for creating network diagrams, and it integrates with Microsoft Office 365.

These are just a few examples of the many online tools available for creating network diagrams. You can explore these options and choose the one that best fits your needs and budget.