In this chapter, we will primarily focus on layer 3 of the OSI reference model and learn how to analyze the layer 3 protocols (IPv4/IPv6) operations, as well as unicast and multicast traffic flow analysis. We will also look at the Address Resolution Protocol (ARP)/ND, dynamic and stateless IPv6 address configuration, and more. We will discuss the basic issues that you might face while troubleshooting these protocols.

We will learn how to analyze end-to-end IPv4 and IPv6 connectivity failures for unicast and multicast traffic using Wireshark.

While there are variously structured troubleshooting approaches available, the bottom-up troubleshooting approach is the most efficient and effective approach. It starts from the bottom layer (physical) of the OSI reference model. When there is an end-to-end connectivity failure between end points, this approach starts inspecting the elements at bottom layer and moves toward the top layer until the cause of the failure is identified. The approach is as follows: