In this chapter, we will focus on how to find and resolve layer 2-based problems with a focus on Ethernet-based issues, such as broadcast/multicast events, errors, and how to find the source. We will also focus on LAN protocols such as spanning tree and VLANs.
These issues need to be resolved before we go up to layer 3, layer 4, and application layers, since layer 2 problems will be reflected in the upper layer protocols. For example, packet losses in layer 2 will cause retransmissions in TCP (a layer 4 protocol), and result in application slowness.
