Wireshark Tutorial: Mastering Network Analysis with Fragmentation and Priority Inspection

When it comes to understanding network communication, Wireshark is an invaluable tool that can help you analyze and troubleshoot complex issues. In this tutorial, we will explore the world of packet analysis using Wireshark, focusing on fragmentation, MTU inspection, and priority management.

To begin, let's start with a simple yet powerful technique: pinging with packet sizes that approach and then exceed the Maximum Transmission Unit (MTU). By doing so, you can observe how Wireshark decodes and handles fragmented packets. This exercise is essential for understanding how networks handle data transmission and what might happen when packets are too large to be transmitted in a single frame.

As you explore Wireshark's capabilities, take note of the MTU settings on your network devices and ensure that they are correctly configured. If you have OSPF (Open Shortest Path First) running on your network, this knowledge can help you identify potential issues related to packet fragmentation and reassembly.

Once you've mastered the basics of packet analysis, it's time to take your skills to the next level by filtering for specific devices or protocols. Boot up a device on your network, and use Wireshark's filter capabilities to track all traffic related to that device. This will help you understand how different layers of the OSI model interact with each other.

In addition to filtering by device, consider exploring spanning tree protocol (STP) and its impact on network traffic. STP can be overwhelming when dealing with large networks, but Wireshark's filtering capabilities can help you identify specific issues related to bridge protocols.

ARP (Address Resolution Protocol) is another essential aspect of packet analysis that warrants attention. Learn how to capture ARP requests and responses, as well as gratuitous ARPs, which are often used for network discovery and maintenance.

Furthermore, LLDP (Link Layer Discovery Protocol) is a valuable protocol for network administrators, allowing them to discover the identities and capabilities of adjacent devices on their network. Wireshark's support for LLDP enables you to analyze and troubleshoot issues related to device connectivity and configuration.

Priority management is also crucial in modern networks, where Quality of Service (QoS) plays a significant role in ensuring that critical applications receive adequate bandwidth allocation. Wireshark allows you to inspect layer 2 and layer 3 priority settings using the p-bit and DSCP (DiffServ Code Point), respectively.

To take your skills to the next level, consider attending SharkFest, an immersive Wireshark training experience featuring expert instructors like Gerald Combs, Hansang Bae, Kary Rogers, Sake Blok, Jasper Bongertz, Christian Landström, Phill Shade, and many more. You can also stay up-to-date with the latest news on Wireshark and SharkFest '19 by following their Twitter page.

For additional resources, download Hansang's trace files from 'BackToBasics-Part-1.zip' or watch the replay of the 2016 and 2017 Packet Trenches series. You can also explore custom LUA dissectors for root cause analysis, courtesy of Sake Blok.

Finally, if you're looking to dive deeper into Wireshark's CLI capabilities, check out Graham Bloice's tutorial on using PowerShell with TShark. For more information on packet analysis and troubleshooting, refer to the Packet Trenches series or Chris' hands-on course on in-depth Wireshark, TCP, and more.

By mastering these techniques and concepts, you'll be well-equipped to tackle even the most complex network analysis challenges with Wireshark by your side. So, let's get started and take our packet analysis skills to new heights!

Wireshark tutorial