Basic-Switching-concepts-and-configuration - LAYER 3.pptx

Basic Switching concepts and configuration INTRODUCTION: In this lesson, we will explore switching concepts and the basic configuration of a switch. We will discuss the switch’s operation, layer 2 and layer 3 switching as well as other concepts. We will conclude with the basic configuration of a...

Basic Switching concepts and configuration INTRODUCTION: In this lesson, we will explore switching concepts and the basic configuration of a switch. We will discuss the switch’s operation, layer 2 and layer 3 switching as well as other concepts. We will conclude with the basic configuration of a switch and this will lead us into the discussion on VLANs. What is Switch? A switch is a networking device that connects multiple devices (such as computers, printers, and servers) within a local area network (LAN) and forwards data between them. It operates primarily at the Data Link Layer (Layer 2) of the OSI (Open Systems Interconnection) model, but some switches can also operate at the Network Layer (Layer 3) and provide routing capabilities. What is OSI? The OSI (Open Systems Interconnection) model is a conceptual framework used to understand and implement network protocols in seven distinct layers. Each layer serves a specific function and interacts with the layers directly above and below it. The OSI model helps standardize communication functions and ensures interoperability between different network devices and protocols. OSI MODEL LAYER 2 A Layer 2 switch is a network device that operates at the Data Link Layer (Layer 2) of the OSI (Open Systems Interconnection) model. Its primary function is to forward data frames between devices on the same local area network (LAN) based on the MAC (Media Access Control) addresses of the devices. Key Characteristics of a Layer 2 Switch: MAC Address-Based Forwarding: o A Layer 2 switch makes forwarding decisions based on the MAC address of devices. When a data frame arrives at a switch port, the switch reads the destination MAC address from the Ethernet frame's header. o The switch then checks its MAC address table (also known as the CAM table) to determine which port the destination MAC address is associated with and forwards the frame to the appropriate port.  MAC Address Table: The switch maintains a table that maps MAC addresses to specific switch ports. This table is dynamically populated as the switch learns the MAC addresses of devices connected to its ports. When a new frame arrives with a source MAC address that the switch has not seen before, the switch adds this MAC address to its table along with the port number it was received on.  Frame Filtering and Forwarding: If the destination MAC address is known and associated with a particular port, the switch forwards the frame only to that port (unicast). If the destination MAC address is unknown, the switch floods the frame to all ports except the one it was received on. Broadcast and multicast frames are forwarded to all ports except the source port.  No Routing Capabilities: Unlike Layer 3 switches or routers, Layer 2 switches do not perform IP routing. They do not have the capability to route packets between different IP networks or subnets. All devices connected to a Layer 2 switch must be within the same broadcast domain and subnet.  Collision Domains: Each port on a Layer 2 switch represents a separate collision domain, meaning that collisions are minimized because each connected device has its own dedicated bandwidth.  Broadcast Domain: All ports on a Layer 2 switch belong to the same broadcast domain by default. This means that broadcast frames (e.g., ARP requests) are sent to all ports on the switch.  VLAN Support: Many Layer 2 switches support VLANs (Virtual Local Area Networks), which allow the segmentation of a single physical network into multiple logical networks. VLANs help reduce the size of broadcast domains and improve security and performance by isolating traffic.  Spanning Tree Protocol (STP): Layer 2 switches often implement the Spanning Tree Protocol (STP) to prevent network loops in environments where redundant paths are used. STP ensures that only one active path exists between two network devices at any time, while redundant paths are placed in a blocking state to prevent loops. A Layer 2 switch is a fundamental networking device that efficiently handles data traffic within a single LAN by forwarding frames based on MAC addresses. It is an essential component in most local networks, providing connectivity, reducing collisions, and supporting VLAN segmentation, but it does not have routing capabilities like a Layer 3 switch or router.