A typical network is composed of several key components:

• Nodes: These are the computers or devices that make up the network.
• Connection Medium: This can be either wired or wireless, facilitating communication between nodes.
• Network Equipment: Devices like routers, hubs, and switches are crucial for managing and directing data traffic within the network.

When it comes to the Internet, these components work together to allow your computer to communicate with another, even if that computer is on the other side of the world.

Switches are a fundamental part of most networks. They enable multiple users to send information across the network simultaneously without slowing each other down. While routers allow different networks to communicate, switches facilitate direct communication between nodes within the same network. A node, typically a computer, is a connection point in a network, and switches ensure smooth and efficient communication between these nodes.

There are various types of switches and networks. LAN switches are designed to provide a separate connection for each node within an internal company network. Essentially, a LAN switch creates temporary, individual networks between two communicating devices at any given moment. This article focuses on Ethernet networks utilizing LAN switches, explaining what a LAN switch is and covering topics like transparent bridging, VLANs, trunking, and spanning trees.

In the simplest modern networks, nodes are often connected using hubs. However, as the network grows, this setup can lead to several issues:

• Scalability: In a hub-based network, the bandwidth is shared among users, which can limit growth and performance. Modern applications require more bandwidth, often necessitating a network redesign to accommodate expansion.
• Latency: Latency is the delay in packet delivery. In a hub-based network, nodes must wait for a clear channel to transmit data, leading to increased latency as more nodes are added.
• Network Failure: One malfunctioning device in a hub network can cause problems for others, often due to incorrect settings or excessive broadcasts.
• Collisions: Ethernet networks use a protocol called CSMA/CD, where nodes wait for a clear channel before sending packets. If two nodes transmit simultaneously, a collision occurs, causing delays.

While hubs make it easy to scale up and reduce the distance packets travel, they don't segment the network effectively. This is where switches come in.

Switches differ from hubs in that each node connected to a switch port has full access to the network's bandwidth, rather than sharing it with other nodes. For example, on a 10 Mbps network, a hub-connected node would only get a portion of that bandwidth if others are communicating, whereas a switch-connected node could utilize the full 10 Mbps.

In fully switched networks, all hubs are replaced with switches, providing dedicated segments for each node. This setup allows for full-duplex Ethernet, where nodes can transmit and receive data simultaneously, effectively doubling the network's speed. These networks typically use twisted pair or fiber-optic cables, creating a collision-free environment.

While fully switched networks are ideal, they can be costly. Most networks use a mix of switches and hubs for a balance of efficiency and cost-effectiveness.

Switches primarily operate at Layer 2 (Data Link) of the OSI model, using MAC addresses, while routers work at Layer 3 (Network) using IP addresses. Unlike routers, switches handle broadcasts by passing them to all segments in a broadcast domain, allowing for seamless communication within the network.

LAN switches use packet-switching methods like cut-through, store-and-forward, and fragment-free to manage traffic. These switches also vary in design, with common configurations including shared-memory, matrix, and bus-architecture setups.

Most Ethernet LAN switches use transparent bridging technology to manage address lookup tables automatically, without requiring intervention from a network administrator. This technology comprises five key functions: learning, flooding, filtering, forwarding, and aging.

It includes the following topics -

• Switches and LED Switch Status
• Accessing the CLI and Password Security
• User and Enable Modes
• The debug and show Commands
• Configuration Sub modes and Contexts
• Storing Copying and Erasing Switch Configuration Files
• Initial Configuration