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Network switch

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A network switch is a critical piece of hardware used to connect devices within a computer network.

ZyXEL desktop Ethernet switch
ZyXEL desktop Ethernet switch

It functions by using a process called packet switching to receive and forward data to a specific destination device. By managing how information flows, switches increase both the security and the efficiency of a network. They act as multiport network bridges that operate at the data link layer, also known as layer 2 of the OSI model. While most common in Ethernet networks, switches also exist for other systems like Fibre Channel or InfiniBand.

5 Port Gigabit Netzwerk-Switch TL-SG1005D 01
5 Port Gigabit Netzwerk-Switch TL-SG1005D 01

The mechanism of a switch relies on its ability to intelligently direct traffic. Unlike an Ethernet hub, which broadcasts data to every connected device, a switch learns the unique MAC addresses of all connected hardware. It stores these addresses in a specialized table, often called a CAM table, which uses high-speed content-addressable memory. When a data packet arrives, the switch examines the Ethernet header to find the destination address. It then forwards that packet only to the specific port connected to the intended recipient. This creates a separate collision domain for each port, meaning devices can send and receive data simultaneously without interference.

2550T-PWR-Front
2550T-PWR-Front

Switches can be categorized by how they handle data across different layers of the OSI model. A standard layer-2 switch focuses on bridging within a single technology. However, some advanced devices are known as multilayer switches or layer-3 switches. These devices incorporate routing functionality, allowing them to forward data at the network layer as well. This capability makes it much easier to interconnect different types of networks, such as Ethernet and Token Ring. By operating at higher layers, these switches can manage more complex communication tasks across diverse systems.

The history of switching technology began with the invention of the first MAC bridge in 1983. This was achieved by Mark Kempf, an engineer at Digital Equipment Corporation (DEC). Shortly after, DEC introduced the LANBridge 100, which was the first two-port bridge product. The company later developed multi-port switches like the GigaSwitch for Ethernet and FDDI. Because DEC chose to license its patents on a royalty-free, non-discriminatory basis, the technology became an industry standard. This decision allowed other companies, such as Kalpana, to develop their own multi-port switches. Kalpana later introduced the seven-port EtherSwitch in 1989 and 1990.

24-port 3Com switch
24-port 3Com switch

Modern switches are designed in various form factors to suit different environments. Small office or home office (SOHO) users often use small desktop units or residential gateways.

ZyXEL desktop Ethernet switch
ZyXEL desktop Ethernet switch

Larger businesses use rack-mounted switches that fit into equipment racks. Some of these are large chassis units that feature swappable line cards or modular interfaces. In industrial settings, switches might be mounted on a DIN rail. Advanced commercial switches can also implement Power over Ethernet, or PoE. This technology allows the switch to provide electricity through the data cable to devices like VoIP phones.

Smartswitch6000
Smartswitch6000

Connectivity is often enhanced through the use of pluggable modules. These modules, such as Small Form-factor Pluggable (SFP) modules, allow a switch to connect to different physical media like fiber optic cables. The technology has evolved through many stages, including XENPAK, XFP, and newer versions like QSFP and OSFP. A recent development is Co-packaged optics (CPO), which brings transceivers closer to the switching chip. This advancement helps reduce power consumption and makes it easier to use water cooling. Some switches even allow for the addition of specialized modules for security, such as firewalls or network intrusion detection systems.

Switches play a vital role in the hierarchical architecture of the internet and local area networks (LANs). They are used at the edge of a network to connect hosts, and deeper in the network to link other switches together. To prevent errors, the Spanning Tree Protocol (STP) is often used to regulate interconnects between switches. STP disables certain links to ensure the network remains a tree structure without dangerous switching loops. While STP is common, alternatives like Shortest Path Bridging and TRILL allow for multiple active paths. Through these complex systems, switches ensure that modern digital communication remains fast, organized, and reliable.

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🖼️ Images & Media (6)
File:2550T-PWR-Front.jpg
2550T-PWR-Front.jpg
File:Smartswitch6000.jpg
Smartswitch6000.jpg
File:5 Port Gigabit Netzwerk-Switch TL-SG1005D 01.jpg
5 Port Gigabit Netzwerk-Switch TL-SG1005D 01.jpg
File:24-port 3Com switch.JPG
24-port 3Com switch.JPG
File:ZyXEL desktop Ethernet switch.jpg
ZyXEL desktop Ethernet switch.jpg
File:19-inch rackmount Ethernet switches and patch panels.jpg
19-inch rackmount Ethernet switches and...
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