Legacy and modern protocols alike underpin communication within local networks, and this episode brings together three foundational ones: CSMA/CD, ARP, and Neighbor Discovery. We begin with CSMA/CD, once crucial in shared Ethernet environments, explaining how devices listened before transmitting and how collisions were handled. Although largely obsolete due to switched networks, CSMA/CD still appears on the exam and helps illustrate Ethernet history.

We then shift to ARP (Address Resolution Protocol), which maps IP addresses to MAC addresses in IPv4 networks, and ND (Neighbor Discovery), which performs a similar role in IPv6 environments. You'll learn how ARP tables are populated, how ARP spoofing works, and how ND leverages ICMPv6 to perform neighbor solicitation and router discovery. These are core networking concepts that you'll encounter often in both troubleshooting and exam content.

Spanning Tree Protocol (STP) is critical for preventing Layer 2 loops that can crash entire networks. In this episode, we explain how STP operates by detecting redundant paths and placing specific ports in a blocking state. You'll learn about key concepts like the root bridge, bridge ID, port roles (root, designated, and blocked), and the election process that determines which paths remain active.

We also cover Rapid STP (RSTP) and its faster convergence benefits, as well as configuration best practices and how to interpret STP behavior using switch logs and CLI commands. Misconfigured or disabled STP can lead to broadcast storms, MAC table instability, and massive outages—making this protocol essential knowledge for any network technician. Whether in an exam scenario or real-world network deployment, STP is a topic you can't afford to ignore.

Power over Ethernet (PoE) allows devices like access points, VoIP phones, and security cameras to receive power and data over a single Ethernet cable. In this episode, we explain how PoE and PoE+ work, including power classifications, standards like IEEE 802.3af and 802.3at, and how switches negotiate power with connected devices. You’ll learn how this technology simplifies installations by removing the need for separate power cables and outlets.

We also explore power budgets, device compatibility, and how to troubleshoot PoE-related issues such as insufficient wattage, improper cabling, or failed device detection. Whether you're deploying IP surveillance or building a wireless network, PoE is a time-saving and cost-effective solution. This episode prepares you to understand PoE architecture, select the right equipment, and solve common deployment challenges.

Switches rely on MAC address tables to decide where to forward frames, and this episode walks you through exactly how these tables are built and maintained. You'll learn how switches learn the source MAC address of each incoming frame and associate it with the port that received it. This learning process allows switches to make intelligent forwarding decisions, sending frames only to the appropriate destination port rather than flooding the network.

We also cover how MAC address tables age out entries over time, how this behavior impacts performance and security, and how static MAC entries can be manually configured for high-security environments. The episode explains how to view and interpret MAC tables using CLI commands and explores common troubleshooting scenarios, such as table overflow or MAC flapping. Mastering MAC address tables is key to understanding how Layer 2 switching works at a fundamental level.

Optimizing data transmission isn’t just about bandwidth—it also involves tuning frame size and port behavior. This episode explores jumbo frames, which are Ethernet frames larger than the standard 1500 bytes. You’ll learn how jumbo frames reduce overhead and improve efficiency for large data transfers such as backups or SAN replication. We also explain compatibility concerns, how to enable jumbo frames, and what happens if mismatched frame sizes occur between devices.

The second half of the episode focuses on Auto-MDI-X, a technology that eliminates the need for crossover cables by automatically detecting and adjusting pin configuration. You’ll understand why this matters when connecting similar devices and how it reduces setup complexity in dynamic environments. These features might seem minor, but they have a major impact on network performance and user experience.

Port security helps prevent unauthorized devices from connecting to your network by enforcing MAC address restrictions at the switch port level. In this episode, we cover how port security works, how to configure it on managed switches, and what actions can be taken when violations occur. You’ll learn about sticky MAC addresses, violation modes (protect, restrict, shutdown), and how to monitor security events.

We also discuss use cases such as securing office wall jacks, restricting guest access, and limiting the spread of rogue devices. Port security is especially important in environments with sensitive information or public-facing equipment. This episode provides both the conceptual understanding and practical tools needed to enforce Layer 2 security policies effectively.

Switch ports are the front line of network configuration and monitoring, and this episode walks through the most essential port settings. You'll learn how to assign ports to VLANs, configure speed and duplex, enable or disable ports, and label interfaces for better documentation. We also review the significance of auto-negotiation, port status LEDs, and default behaviors that can lead to communication failures when improperly configured.

The second half of the episode covers port mirroring using SPAN (Switched Port Analyzer), which allows administrators to capture and analyze traffic without disrupting the network. You’ll understand how to configure mirrored sessions, select ingress/egress directions, and monitor mirrored traffic with tools like Wireshark. Whether you’re troubleshooting, auditing, or securing the network, this episode teaches you how to get visibility where it matters.

When a single link isn’t enough to handle bandwidth demands or redundancy requirements, port aggregation offers a scalable solution. In this episode, we explain how LACP (Link Aggregation Control Protocol) is used to combine multiple physical interfaces into one logical link known as a port channel or EtherChannel. You’ll learn how LACP negotiates aggregation, prevents loops, and distributes traffic across links based on load-balancing algorithms.

We cover the difference between static and dynamic link aggregation, how to configure active and passive LACP modes, and how to monitor the health of your aggregated links. Port aggregation is commonly used between core switches, servers, and storage systems to boost throughput and ensure fault tolerance. This is a must-know feature for high-performance and redundant network design.

VLANs are powerful, but they require the right tagging protocol to work across multiple switches—and that’s where 802.1Q comes in. This episode explains how trunk ports carry traffic from multiple VLANs using VLAN tags inserted into Ethernet frames. You’ll learn how access ports differ from trunk ports, and why configuring native VLANs is important to avoid untagged traffic conflicts and security issues.

We also discuss Dynamic Trunking Protocol (DTP), the risks it poses, and why disabling unnecessary trunk negotiation is a best practice. Understanding tagging and trunking is essential when deploying multi-switch VLANs and connecting infrastructure like VoIP phones, which often require multiple VLANs on a single port. This topic regularly appears in both configuration labs and troubleshooting scenarios on the exam.

Virtual LANs (VLANs) are essential tools for logically segmenting a network, improving security, performance, and organization. In this episode, we explore how VLANs work by assigning different ports to different broadcast domains—even if those ports are on the same switch. You'll learn how VLANs separate voice and data traffic, simplify policy application, and reduce the spread of broadcast traffic. We also introduce best practices for numbering, naming, and documenting VLANs.

We discuss how VLANs are used in real environments to segment departments, devices, or traffic types. You'll see how VLAN design supports scalability and control, particularly when combined with trunking and routing. This foundational knowledge is critical for passing the exam and for understanding how to implement structured, secure networks.