Network switches and switch functions

Network switches are computer network devices. Network switches connect devices in a computer network by packet switching to receive process and send data to the destination device.

A network switch is a multi-port network bridge. That uses hardware addresses to process and forwards data at the data link layer (level 2) of the OSI model. Some switches can also process data at the network level (level 3) and also incorporate routing capabilities. These switches are commonly known as level 3 switches or multilayer switches.

Switches for Ethernet are the most common form of network switches. The first Ethernet switch was introduced by Kalpana in 1990 (Kalpana manufacturer of computer networking equipment). Switches also exist for other types of networks, such as Fiber Channel, Asynchronous Transfer Mode, and InfiniBand. 

Unlike the less advanced repeater concentrators, which transmit the same data from each of their ports and allow the devices to decide what data they want. A network only passes the data to the devices that need to receive it.

Network switches and switch functions

Overview

A switch is a device in a computer network that connects other devices to each other. Several data cables are inserted in a switch to allow communication between different devices connected to the network. The switches manage the flow of data through a network by transmitting a received network packet only to one or more devices for which the packet is intended. Each device connected to the network through a switch can be identified by its network address. This allows the switch to direct the flow of traffic and maximize the security and efficiency of the network.

A switch is smarter than an Ethernet hub. Hub simply retransmits the packets outside each port of the hub except the port where the packet was received. It is unable to distinguish the different recipients and achieves a lower overall efficiency of the network.

An Ethernet switch operates on the data link layer (level 2) of the OSI model to create a separate collision domain for each switch port. Any device connected to a switch port can transfer data to any of the other ports at any time and the transmissions will not interfere. As the transmissions continue to be sent to all devices connected through the switch, the newly formed network segment continues to be a transmission domain. The switches can also operate at higher levels than the OSI model, including the network layer and above. A device that also operates at these higher levels is known as a multilayer switch.

Also Read: Router its working and different types of routers

Role in (LAWNs)

The network switch plays a key role in most modern local area networks (LANs). Medium-to-large LANs contain several managed switches connected. Home Office/small office (SOHO) applications typically use a single switch or multifunction device as a residential gateway to access broadband services at home and at the office such as DSL cable or the Internet. In most cases, the end-user device contains a router and components that interact with a particular broadband physical technology. Internet user devices may also include a telephone interface for Voice over IP (VoIP).

Switch in networking

Switches are typically used as a network connection point for hosts on the edge of a network. In the hierarchical model of network interconnection and similar network architectures, the switches are also used deeper in the network to provide connections between switches on the edge.

The switches which are designed for commercial use, integrated or modular interfaces allow the connection of different types of networks, including Ethernet, Fiber Channel, RapidIO (high-performance packet-switched interconnect technology), ATM, ITU-T G.hn and 802.11. This connectivity can be in one of the mentioned layers. Although Layer 2 functionality allows bandwidth modification within a technology, interconnect technologies, such as Ethernet and Token Ring, are more easily accomplished in Layer 3 or through routing. The interconnected devices in layer 3 are usually called routers. Therefore, Layer 3 switches can also be considered relatively primitive and specialized routers.

When a thorough analysis of network performance and security is required, the switches can connect between the WAN routers as a location for the analysis modules. Some vendors offer firewall, network intrusion detection and performance analysis modules that can connect to switch ports. Some of these functions can be in combined modules.

With port duplication, a switch can create a mirror image of data. The data can be transmitted to an external device, such as intrusion detection systems and a packet sniffer.

A modern switch can implement Power over Ethernet (PoE). Which prevents connected devices, such as a VoIP phone or wireless access point, from having a separate power source. Because switches may have redundant power circuits connected to uninterruptible power supplies. The connected device may continue to operate even in the event of a typical office power failure.

Configuration options

Unmanaged switches do not have a configuration interface or options. These are plug_and_play. These are usually the least expensive switches and so they are often used in a small office/home office. Unmanaged switches can be mounted on a desktop or rack.

Managed switches have one or more methods to change the operation of the switch. The widely used management techniques include a command line interface. That can be obtained through a serial console, Telnet, or Secure Shell, an integrated SNMP agent that enables management from a remote console or management station or a Web-based interface for management from a web browser.  Some examples of configuration changes that can be made by a managed switch include enabling features such as spanning tree or port duplication, configuring port bandwidth, creating or changing VLANs (VLANs), and so on. Two subclasses of managed switches are intelligent and managed enterprise switches.

Smart (or intelligent) switches are managed switches with a limited number of management functions. Similarly, web-managed switches are switches that fall into a niche market between unmanaged and managed at a much lower price than a fully managed switch. They provide a Web interface (and typically no CLI access) and allow the configuration of basic settings such as VLAN, port bandwidth, and duplex.

The company-managed (or fully managed) switches have a comprehensive set of management features. These including a CLI, an SNMP agent, and a Web interface, as well as additional features to manipulate configurations, such as the ability to view, edit, execute backup and restore configurations. Compared to smart switches, business switches have more features. These switches can be customized or optimized and are typically more expensive than smart switches.

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